Using multiple languages is the same project

August 21, 2019 Leave a comment

Most compilers can only handle a single syntax for any project, but the Elements compiler from RemObjects deals with 5 (five!) different languages -even within the same project. That’s pretty awesome and opens up for some considerable savings.

I mean, it’s not always easy to find developers for a single language, but when you can approach your codebase from C#, Java, Go, Swift and Oxygene (object pascal) at the same time (inside the same project even!), you suddenly have some options.  Especially since you can pick exotic targets like WebAssembly. Or what about compiling Java to .net bytecodes? Or using the VCL from C#? It’s pretty awesome stuff!

Check out Marc Hoffmans article on the Elements compiler toolchain and how you can mix and match between languages, picking the best from each — while still compiling to a single binary of llvm optimized code:

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Click on the picture to be redirected

 

RemObjects Elements + ODroid N2 = true

August 7, 2019 Leave a comment

Since the release of Raspberry PI back in 2012 the IOT and Embedded market has exploded. The price of the PI SBC (single board computer) enabled ordinary people without any engineering background to create their own software and hardware projects; and with that the IOT revolution was born.

Almost immediately after the PI became a success, other vendors wanted a piece of the pie (pun intended), and an avalanche of alternative mini computers started surfacing in vast quantities. Yet very few of these so-called “pi killers” actually stood a chance. The power of the Raspberry PI is not just price, it’s actually the ecosystem around the product. All those shops selling electronic parts that you can use in your IOT projects for example.

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The ODroid N2, one of the fastest SBCs in it’s class

The ODroid family of single-board computers stands out as unique in this respect. Where other boards have come and gone, the ODroid family of boards have remained stable, popular and excellent alternatives to the Raspberry PI. Hardkernel, the maker of Odroid boards and its many peripherals, are not looking for a “quick buck” like others have. Instead they have slowly and steadily perfected their hardware,  software, and seeded a great community.

ODroid is very popular at RemObjects, and when we added 64-bit ARM Linux support a couple of weeks back, it was the ODroid N2 board we used for testing. It has been a smooth ride all the way.

ODroid

As I am typing this, a collection of ODroid XU4s is humming away inside a small, desktop cluster I have built. This cluster is made up of 5 x ODroid XU4 boards, with an additional ODroid N2 acting as the head (the board that controls the rest via the network).

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My ODroid Cluster in all its glory

Prior to picking ODroid for my own projects, I took the time to test the most popular boards on the market. I think I went through eight or ten models, but none of the other were even close to the quality of ODroid. It’s very easy to confuse aggressive marketing with quality. You can have the coolest hardware in the world, but if it lacks proper drivers and a solid Linux distribution, it’s for all means and purposes a waste of time.

Since IOT is something that i find exciting on a personal level, being able to target 64-bit ARM Linux has topped my wish-list for quite some time. So when our compiler wizard Carlo Kok wanted to implement support for 64-bit ARM-Linux, I was thrilled!

We used the ODroid N2 throughout the testing phase, and the whole process was very smooth. It took Carlo roughly 3 days to add support for 64-bit ARM Linux and it hit our main channel within a week.

I must stress that while ODroid N2 is one of our verified SBCs, the code is not explicitly about ODroid. You can target any 64-bit ARM SBC providing you use a Debian based Linux (Ubuntu, Mint etc). I tested the same code on the NanoPI board and it ran on the first try.

Why is this important?

The whole point of the Elements compiler toolchain, is not just to provide alternative compilers; it’s also to ensure that the languages we support become first class citizens, side by side with other archetypical languages. For example, if all you know is C# or Java, writing kernel drivers has been our of limits. If you are operating with traditional Java or .Net, you have to use a native bridge (like the service host under Windows). Your only other option was to code that particular piece in traditional C.

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With Elements you can pick whatever language you know and target everything

With Elements that is no longer the case, because our compilers generates llvm optimized machine-code; code that in terms of speed, access and power stand side by side with C/C++. You can even import C/C++ header files and work directly with the existing infrastructure. There is no middleware, no service host, no bytecodes and no compromise.

Obviously you can compile to bytecodes too if you like (or WebAssembly), but there are caveats to watch out for when using bytecodes on SBCs. The garbage collector can make or break your product, because when it kicks in -it causes CPU spikes. This is where Elements step-up and delivers true native compilation. For all supported targets.

More boards to come

This is just my personal blog, so for the full overview of boards I am testing there will be a proper article on our official RemObjects blog-space. Naturally I can’t test every single board on the market, but I have around 10 different models which covers the common boards used by IOT and embedded projects.

But for now at least, you can check off the ODroid N2 (64-bit) and NanoPI-Fire 2 (32-bit)

Check out RemObjects Remoting SDK

July 22, 2019 2 comments

RemObjects Remoting SDK is one of those component packages that have become more than the sum of it’s part. Just like project Jedi has become standard equipment almost, Remoting SDK is a system that all Delphi and Freepascal developers should have in their toolbox.

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In this article I’m going to present the SDK in broad strokes; from a viewpoint of someone who haven’t used the SDK before. There are still a large number of Delphi developers that don’t know it even exists – hopefully this post will shed some light on why the system is worth every penny and what it can do for you.

I should also add, that this is a personal blog. This is not an official RemObjects presentation, but a piece written by me based on my subjective experience and notions. We have a lot of running dialog at Delphi Developer on Facebook, so if I read overly harsh on a subject, that is my personal view as a Delphi Developer.

Stop re-inventing the wheel

Delphi has always been a great tool for writing system services. It has accumulated a vast ecosystem of non-visual components over the years, both commercial and non-commercial, and this allows developers to quickly aggregate and expose complex behavior — everything from graphics processing to databases, file processing to networking.

The challenge for Delphi is that writing large composite systems, where you have more than a single service doing work in concert, is not factored into the RTL or project type. Delphi provides a bare-bone project type for system services, and that’s it. Depending on how you look at it, it’s either a blessing or a curse. You essentially start on C level.

So fundamental things like IPC (inter process communication) is something you have to deal with yourself. If you want multi-tenancy that is likewise not supported out of the box. And all of this is before we venture into protocol standards, message formats and async vs synchronous execution.

The idea behind Remoting SDK is to get away from this style of low-level hacking. Without sounding negative, it provides the missing pieces that Delphi lacks, including the stuff that C# developers enjoy under .net (and then some). So if you are a Delphi developer who look over at C# with smudge of envy, then you are going to love Remoting SDK.

Say goodbye to boilerplate mistakes

Writing distributed servers and services is boring work. For each function you expose, you have to define the parameters and data-types in a portable way, then you have to implement the code that represents the exposed function and finally the interface itself that can be consumed by clients. The latter must be defined in a way that works with other languages too, not just Delphi. So while server tech in it’s essential form is quite simple, it’s the infrastructure that sets the stage of how quickly you can apply improvements and adapt to change.

For example, let’s say you have implemented a wonderful new service. It exposes 60 awesome functions that your customers can consume in their own work. The amount of boilerplate code for 60 distributed functions, especially if you operate with composite data types, is horrendous. It is a nightmare to manage and opens up for sloppy, unnecessary mistakes.

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After you install Remoting SDK, the service designer becomes a part of the IDE

This is where Remoting SDK truly shines. When you install the software, it integrates it’s editors and wizards closely with the Delphi IDE. It adds a ton of new project types, components and whatnot – but the most important feature is without a doubt the service designer.

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Start the service-designer in any server or service project and you can edit the methods, data types and interfaces your system expose to the world

As the name implies, the service designer allows you to visually define your services. Adding a new function is a simple click, the same goes for datatypes and structures (record types). These datatypes are exposed too and can be consumed from any modern language. So a service you make in Delphi can be used from C#, C/C++, Java, Oxygene, Swift (and visa-versa).

Auto generated code

A service designer is all good and well I hear you say, but what about that boilerplate code? Well Remoting SDK takes care of that too (kinda the point). Whenever you edit your services, the designer will auto-generate a new interface unit for you. This contains the classes and definitions that describe your service. It will also generate an implementation unit, with empty functions; you just need to fill in the blanks.

The designer is also smart enough not to remove code. So if you go in and change something, it won’t just delete the older implementation procedure. Only the params and names will be changed if you have already written some code.

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Having changed a service, hitting F9 re-generates the interface code automatically. Your only job is to fill in the code for each method in the implementation units. The SDK takes care of everything else for you

The service information, including the type information, is stored in a special file format called “rodl”. This format is very close to Microsoft WSDL format, but it holds more information. It’s important to underline that you can import the service directly from your servers (optional naturally) as WSDL. So if you want to consume a Remoting SDK service using Delphi’s ordinary RIO components, that is not a problem. Visual Studio likewise imports and consumes services – so Remoting SDK behaves identical regardless of platform or language used.

Remoting SDK is not just for Delphi, just to be clear on that. If you are presently using both Delphi and C# (which is a common situation), you can buy a license for both C# and Delphi and use whatever language you feel is best for a particular task or service. You can even get Remoting SDK for Javascript and call your service-stack directly from your website if you like. So there are a lot of options for leveraging the technology.

Transport is not content

OK so Remoting SDK makes it easy to define distributed services and servers. But what about communication? Are we boxed into RemObjects way of doing things?

The remoting framework comes with a ton of components, divided into 3 primary groups:

  • Servers
  • Channels (clients)
  • Messages

The reason for this distinction is simple: the ability to transport data, is never the same as the ability to describe data. For example, a message is always connected to a standard. It’s job is ultimately to serialize (represent) and de-serialize data according to a format. The server’s job is to receive a request and send a response. So these concepts are neatly decoupled for maximum agility.

As of writing the SDK offers the following message formats:

  • Binary
  • Post
  • SOAP
  • JSON

If you are exposing a service that will be consumed from JavaScript, throwing in a TROJSONMessage component is the way to go. If you expect messages to be posted from your website using ordinary web forms, then TROPostMessage is a perfect match. If you want XML then TROSOAPMessage rocks, and if you want fast, binary messages – well then there is TROBinaryMessage.

What you must understand is that you don’t have to pick just one! You can drop all 4 of these message formats and hook them up to your server or channel. The SDK is smart enough to recognize the format and use the correct component for serialization. So creating a distributed service that can be consumed from all major platforms is a matter of dropping components and setting a property.

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If you double-click on a server or channel, you can link message components with a simple click. No messy code snippets in sight.

Multi-tenancy out of the box

With the release of Rad-Server as a part of Delphi, people have started to ask what exactly multi-tenancy is and why it matters. I have to be honest and say that yes, it does matter if you are creating a service stack where you want to isolate the logic for each customer in compartments – but the idea that this is somehow new or unique is not the case. Remoting SDK have given users multi-tenancy support for 15+ years, which is also why I haven’t been too enthusiastic with Rad-Server.

Now don’t get me wrong, I don’t have an axe to grind with Rad-Server. The only reason I mention it is because people have asked how i feel about it. The tech itself is absolutely welcome, but it’s the licensing and throwing Interbase in there that rubs me the wrong way. If it could run on SQLite3 and was free with Enterprise I would have felt different about it.

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There are various models for multi-tenancy, but they revolve around the same principles

To get back on topic: multi-tenancy means that you can dynamically load services and expose them on demand. You can look at it as a form of plugin functionality. The idea in Rad-Server is that you can isolate a customer’s service in a separate package – and then load the package into your server whenever you need it.

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Some of the components that ship with the system

The reason I dislike Rad-Server in this respect, is because they force you to compile with packages. So if you want to write a Rad-Server system, you have to compile your entire project as package-based, and ship a ton of .dpk files with your system. Packages is not wrong or bad per-se, but they open your system up on a fundamental level. There is nothing stopping a customer from rolling his own spoof package and potentially bypass your security.

There is also an issue with un-loading a package, where right now the package remains in memory. This means that hot-swapping packages without killing the server wont work.

Rad-Server is also hardcoded to use Interbase, which suddenly bring in licensing issues that rubs people the wrong way. Considering the price of Delphi in 2019, Rad-Server stands out as a bit of an oddity. And hardcoding a database into it, with the licensing issues that brings -just rendered the whole system mute for me. Why should I pay more to get less? Especially when I have been using multi-tenancy with RemObjects for some 15 years?

With Remoting SDK you have something called DLL servers, which does the exact same thing – but using ordinary DLL files (not packages!). You don’t have to compile your system with packages, and it takes just one line of code to make your main dispatcher aware of the loaded service.

This actually works so well that I use Remoting SDK as my primary “plugin” system. Even when I write ordinary desktop applications that has nothing to do with servers or services – I always try to compartmentalize features that could be replaced in the future.

For example, I’m a huge fan of ElevateDB, which is a native Delphi database engine that compiles directly into your executable. By isolating that inside a DLL as a service, my application is now engine agnostic – and I get a break from buying a truck load of components every time Delphi is updated.

Saving money

The thing about DLL services, is that you can save a lot of money. I’m actually using an ElevateDB license that was for Delphi 2007. I compiled the engine using D2007 into a DLL service — and then I consume that DLL from my more modern Delphi editions. I have no problem supporting or paying for components, that is right and fair, but having to buy new licenses for every single component each time Delphi is updated? This is unheard of in other languages, and I would rather ditch the platform all together than forking out $10k ever time I update.

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A DLL server can be used for many things if you are creative about it

While we are on the subject – Hydra is another great money saver. It allows you to use .net and Java libraries (both visual and non-visual) with Delphi. With Hydra you can design something in .net, compile it into a DLL file, and then use that from Delphi.

But — you can also compile things from Delphi, and use it in newer versions of Delphi. Im not forking out for a Developer Express update just to use what I have already paid for in the latest Delphi. I have one license, I compile the forms and components into a Hydra Module — and then use it from newer Delphi editions.

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Hydra, which is a separate product, allows you to stuff visual components and forms inside a vanilla DLL. It allows cross  language use, so you can finally use Java and .net components inside your Delphi application

Bonjour support

Another feature I love is the zero configuration support. This is one of those things that you often forget, but that suddenly becomes important once you deploy a service stack on cluster level.

apple_bonjour_medium-e1485166557218Remoting SDK comes with support for Apple Bonjour, so if you want to use that functionality you have to install the Bonjour library from Apple. Once installed on your host machines, your RemObjects services can find each other.

ZeroConfig is not that hard to code manually. You can roll your own using UDP or vanilla messages. But getting service discovery right can be fiddly. One thing is broadcasting an UDP message saying “here I am”, it’s something else entirely to allow service discovery on cluster level.

If Bonjour is not your cup of tea, the SDK provides a second option, which is RemObjects own zero-config hub. You can dig into the documentation to find out more about this.

What about that IPC stuff you mentioned?

I mentioned IPC (inter process communication) at the beginning here, which is a must have if you are making a service stack where each member is expected to talk to the others. In a large server-system the services might not exist on the same, physical hardware either, so you want to take height for that.

With the SDK this is just another service. It takes 10 minutes to create a DLL server with the functionality to send and receive messages – and then you just load and plug that into all your services. Done. Finished.

Interestingly, Remoting SDK supports named-pipes. So if you are running on a Windows network it’s even easier. Personally I prefer to use a vanilla TCP/IP based server and channel, that way I can make use of my Linux blades too.

Building on the system

There is nothing stopping you from expanding the system that RemObjects have established. You are not forced to only use their server types, message types and class framework. You can mix and match as you see fit – and also inherit out your own variation if you need something special.

firm_foundation-720x340For example, WebSocket is an emerging standard that has become wildly popular. Remoting SDK does not support that out of the box, the reason is that the standard is practically identical to the RemObjects super-server, and partly because there must be room for third party vendors.

Andre Mussche took the time to implement a WebSocket server for Remoting SDK a few years back. Demonstrating in the process just how easy it is to build on the existing infrastructure. If you are already using Remoting SDK or want WebSocket support, head over to his github repository and grab the code there: https://github.com/andremussche/DelphiWebsockets

I could probably write a whole book covering this framework. For the past 15 years, RemObjects Remoting SDK is the first product I install after Delphi. It has become standard for me and remains an integral part of my toolkit. Other packages have come and gone, but this one remains.

Hopefully this post has tickled your interest in the product. No matter if you are maintaining a legacy service stack, or thinking about re implementing your existing system in something future-proof, this framework will make your life much, much easier. And it wont break the bank either.

You can visit the product page here: https://www.remotingsdk.com/ro/default.aspx

And you can check out the documentation here: https://docs.remotingsdk.com/

Augmented reality, I don’t think so

July 20, 2019 Leave a comment

The world used to be a big place, but having worked around europe for a few years – and lately in the US, it appears to me much smaller. But the fact of the matter is, that different nationalities have different tastes and interests.

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The world is not as big as it used to be

In the US right now there is a strong interest in virtual-reality. The interest was so strong that Sony jumped on the VR bandwagon early, offering a full VR kit for the Playstation 4. This has been available for two years already (or is it three?). Here in Scandinavia though, VR is not that hot. People buy it, but not in the same volume we see in the US. It is expected to pick up this fall when the dark period begins; Norway, Sweden, Denmark and Finland are largely without sunlight most of the year – and during that time people use indoor hobbies more. But right now, VR is not really a thing up here.

In parallel with VR, Microsoft picked up the gauntlet that Google threw away earlier, namely that of augmented reality.  You probably remember the Google Glasses craze that hit California a decade ago right? Well Microsoft have continued to research and develop the technology which is now available for pre-order.

The problem? Microsoft Holo-lens II is a $3500 gadget that is presently aimed at business only. With emphasis on industrial design and medical applications. I don’t know about you, but forking up $3500 for what is ultimately just a curiosity is way out of my budget. There are much more important things to spend $3500 on to be frank.

Asia, the mother of implementation

While America and Europe are hotbeds of invention, it is ultimately Asia that implements, refine and eventually perfect technology. Some might disagree with that, there are always exceptions to the rule (3d printers and VR systems are very much American made), but what im talking about are “traits and inclinations” in the market. Patterns of commerce if you like.

What usually happens when something new is made, is that it costs a fortune. To push prices down companies move production to Asia, and there materials etc. are swapped out for cheaper alternatives. Some re-designing takes place — and before you know it, a product that cost $3500 when made in the US or the EU, can be picked up for $799 on Amazon. After some time, production volume has reached it’s zenith and the device that once cost an arm or a leg, can now be bought $299 or $199.

But, there are exceptions! When there is a technology that is wildly popular, like augmented reality and VR, Asia is quick to produce their own take on the technology early – trying to get a piece of the proverbial pie. This is often a good thing, especially for consumers. It can also be a good thing for the US and EU based companies – because mistakes and design-flaws they haven’t noticed yet are taken care of by proxy.

With that in mind, I ventured into the Asian markets to see what I could find.

Banggood and Alibaba

Having searched through an avalanche of cheap VR glasses for mobile phones, I finally found something that could be worth looking into. The advert was extremely thin, citing only augmented reality in english – with everything else in chinese (I presume, I must admit I would not spot the difference between chinese, japanese and korean if my life depended on it. Tibetan I can spot due to my Buddhist training, but that’s about it).

When I ran the string of characters through google, it returned this:

“VISION-800 3D Glasses Video Android 4.4
MTK6582 1G/2G 5MP AC WIFI BT4.0 2060P MIC”

Looking at the glasses they have pretty much everything you expected from an Augmented reality setup. There is a camera up front, lenses, audio jacks on both sides, a few buttons and switches – and the magic words “powered by Android  Wearable”. The price was $249 so it wouldn’t break the bank either.

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The Vision 800 in all their glory

I should also mention that websites like Banggood and Alibaba have pretty good return policies too. These websites are actually front-ends for hundreds (if not thousands) of smaller, local outlets. The outlets gets a place to sell their goods to the west, and Alibaba and Banggood takes a small cut of each sale.

To manage this and make it viable, they have a rating system in place. So if one of the outlets scams you – you can vote them down. 3 complaints is enough to get the outlet kicked from either site, which I presume is a dire financial loss (considering the volume these websites push on a daily basis). So there is some degree of consumer safety compared to direct order. I would never order anything directly from a tech cornershop in mainland china, because should they rip you off – there is nothing you can do about it.

Augmented? I don’t think so

When the glasses finally arrived i was surprised at how light they were. You might expect them to be top-heavy and tip forward on the ridge of your nose – but since the weight is actually the lenses, not the circuitry, they balance quite well.

But augmented reality? Im sorry, but these glasses are not even in the ballpark.

The device is running a fork of Android – but not the fork adapted for wearables! The glasses also comes with a stock mouse (cordless), and you are in fact greeted by a plain desktop. The cordless mouse does work really well though, but I thankfully had the sense to order a $5 air-mouse (read: remote control for android devices) or I would go insane trying to exit applications properly.

What you can do is download some augmented reality apps from Google Play. These will tap into the camera on the glasses, and you can play a few games. But that’s really it. I noticed that the outlet had changed the title and text for these glasses a few days before they arrived here, so the whole deal is a little bit fishy. Looking at the instruction leaflet, these glasses have been sold as “movie glasses”. I would even go so far as to say they have nothing to do with augmented reality.

Media glasses

Augmented reality aside, there are interesting uses for glasses like this. If the field of view is good enough, they could make for a novel screen “on the road”. I mean, if you plug in a hybrid USB dongle that gives you both keyboard and mouse, there is nothing in the way of using the glasses as a monitor / travel PC. You have the same apps that you enjoy on your phone; a modern browser that gives you access to cloud services etc.

The glasses also have an SD card slot which is super handy – and 2Gb onboard storage. So if you are taking a flight from Europe to Australia and want to tune out noise and watch movies – these glasses might just be the ticket.

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The audio works well

I must admit it was fun to install NetFlix on these and kick back. But this is  also when i started to have some issues.

The first issue is that there is no focal lense involved. You are literally looking at two tiny screens. And if you use regular glasses like I do, watching without my ordinary glasses is a complete blur. I had to use contact-lenses (which I hate) to get any use out of these. But if your eyesight is fine, you will no doubt have a better experience.

For me being 100% dependent on my regular glasses, it actually makes more sense to buy a cheap, second-hand Samsung Galaxy Edge, which were designed to be used as a proper VR display, and then permanently fixing it to a set of cheap Samsung VR casing. Even the most rudimentary VR casing offers focal lenses, so you can adjust the focus to compensate for poor eyesight.

The second issue has to do with display resolution. If you have 20/20 eyesight then high resolutions is wonderful. But in my case I would actually see better if the resolution was slightly lower. Sadly the devices seem fixed to what I can only presume is 1600×1024 (or something like that), and there are no options for changing resolution, offset display or skew the picture. Again, these are factors that only become important if you have poor eyesight.

Audio

The way they solved audio is actually quite good. On each arm of the glasses you have an audio-jack out. And the kit comes with two small earplugs. And again – if you are on a long flight and just want to snuggle up in your own world – this works really well.

If you have ear-pods like I do, you can use them via the standard BT interface. But I noticed that there was a slight lag when using these; no doubt the CPU had problems handling audio when playing a full HD movie. The lag was not there when i used the normal jack – so the culprit is probably the BT device cache.

Gaming?

I’m not a huge gamer myself, I mostly play games like Destiny in the Playstation. On the odd occasion that I jump into other games, it’s mostly retro stuff. And I have a house pretty much packed with Amiga, Silicon Graphics, and more arcade hardware than god ever intended a person to own.

Having said that, the device is capable of both native Android games – and emulation. I had no problem installing UAE (Unix Amiga Emulator), and it’s more than powerful enough to emulate an A1200 with AGA (advanced graphics architecture).

I didn’t test the casting option – because the device can display-cast to your living room TV. But somehow it seems backwards using these as a casting source – when you already have a supercomputer in your pocket. Any modern phone, be it a Samsung or Apple device, will outperform whatever is powering these glasses – so if gaming is your thing, look elsewhere.

Final words

glasses3These glasses have potential. Or perhaps better phrased – the technology holds a lot of promise. If they had opted for focal-lenses and a wider field of vision, they would have been a fantastic experience. I have no problem imagining this type of tech replacing monitors in the near future – at least for movie experiences.

I must admit it’s really tricky to hammer down a verdict. On one hand they are really fun, you can install NetFlix, browse the web and watch movies if you copy them over to an sd-card (the glasses come with a 16Gb sd-card). You have mouse control, BT and i have no problem seeing myself on a flight to hong-kong enjoying a movie marathon wearing these.

But are they worth $250 ? I would have to say no. A fair price would be something in the $70 region. If they corrected the lenses I would have no problem buying a pair at $99. And if they expanded the field of vision to cover the width of the glasses – I would absolutely pick them up at $150. But $250 for this? Sadly I can’t say they are worth the money.

I was also surprised to find pornhub as a pre-defined shortcut in the browser (I mean, who does that?). It made me laugh first, thinking it was a cheeky joke – but as a parent who could have bought these for a child, it is utterly unacceptable. It’s not the first time I have found smut on a device from Asia. But yeah, a bit creepy.

So, I would have to give them a 3 out of 6 verdict. If you have money to burn and a long flight ahead, then by all means – they will give you a comfy way of watching movies during the flight. But the technology is (for the lack of a better word) premature.

As for augmented reality – forget it. You are better off stuffing your phone inside a $100 Samsung VR casing. The official Samsung Galaxy Edge casing probably cost next to nothing by now. And for $250 you should have no problem sourcing a used Galaxy Edge phone too. Which will be 100 times better than this.

I started this post citing the inherent differences between nationalities in what they enjoy, but I must admit that through these, I can see why VR holds such potential. I can’t see myself strapping on a full suit, helmet and gloves just to play a game or do some work. But glasses like these (but not these) is absolutely in the vicinity of “practical”. Just a damn shame they didn’t do a full width LCD with focal lenses; then I would have promoted them.

Right now: a fun curiocity, good for watching the odd movie if you eyesight is perfect – but for the rest of us, it’s just not worth the dough

 

30% discount on all RemObjects products!

July 8, 2019 Leave a comment

This is brilliant. RemObjects is giving a whopping 30% discount on all products!

This means you can now pick up RemObjects Remoting Framework, Data Abstract, Hydra or the Elements compiler toolchain – with a massive 30% saving!

These are battle-hardened, enterprise level solutions that have been polished over years and they are in constant development. Each solution integrates seamlessly into Embarcadero Delphi and provides a smooth path to delivering quality products in days rather than weeks.

But you better hurry because it’s only valid for one week (!)

Use the coupon code: “DelphiDeveloper”

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Use the Delphi Developer coupon to get 30% discount – click here

 

A Delphi propertybag

July 7, 2019 10 comments

A long, long time ago, way back in the previous century, I often had to adjust a Visual Basic project my company maintained. Going from object-pascal to VB was more than a little debilitating; Visual Basic was not a compiled language like Delphi is, and it lacked more or less every feature you needed to produce good software.

source

I could probably make a VB clone using Delphi pretty easily. But I think the world has experienced enough suffering, no need to add more evil to the universe

Having said that, I have always been a huge fan of Basic (it was my first language after all, it’s what schools taught in the 70s and 80s). I think it was a terrible mistake for Microsoft to retire Basic as a language, because it’s a great way to teach kids the fundamentals of programming.

Visual Basic is still there though, available for the .Net framework, but to call it Basic is an insult of the likes of GFA Basic, Amos Basic and Blitz Basic; the mighty compilers of the past. If you enjoyed basic before Microsoft pushed out the monstrosity that is Visual Basic, then perhaps swing by GitHub and pick up a copy of BlitzBasic?  BlitzBasic is a completely different beast. It compiles to machine-code, allows inline assembly, and has been wildly popular for game developers over the years.

A property bag

The only feature that I found somewhat useful in Visual Basic, was an object called a propertybag. It’s just a fancy name for a dictionary, but it had a couple of redeeming factors beyond lookup ability. Like being able to load name-value-pairs from a string, recognizing datatypes and exposing type-aware read/write methods. Nothing fancy but handy when dealing with database connection-strings, shell parameters and the like.

So you could feed it strings like this:

first=12;second=hello there;third=3.14

And the class would parse out the names and values, stuff it in a dictionary, and you could easily extract the data you needed. Nothing fancy, but handy on rare occasions.

A Delphi version

Im mostly porting code from Delphi to Oxygene these days, but here is my Delphi implementation of the propertybag object. Please note that I haven’t bothered to implement the propertybag available in .Net. The Delphi version below is based on the Visual Basic 6 version, with some dependency injection thrown in for good measure.

unit fslib.params;

interface

{.$DEFINE SUPPORT_URI_ENCODING}

uses
  System.SysUtils,
  System.Classes,
  Generics.Collections;

type

  (* Exceptions *)
  EPropertybag           = class(exception);
  EPropertybagReadError  = class(EPropertybag);
  EPropertybagWriteError = class(EPropertybag);
  EPropertybagParseError = class(EPropertybag);

  (* Datatypes *)
  TPropertyBagDictionary = TDictionary ;

  IPropertyElement = interface
    ['{C6C937DF-50FA-4984-BA6F-EBB0B367D3F3}']
    function  GetAsInt: integer;
    procedure SetAsInt(const Value: integer);

    function  GetAsString: string;
    procedure SetAsString(const Value: string);

    function  GetAsBool: boolean;
    procedure SetAsBool(const Value: boolean);

    function  GetAsFloat: double;
    procedure SetAsFloat(const Value: double);

    function  GetEmpty: boolean;

    property Empty: boolean read GetEmpty;
    property AsFloat: double read GetAsFloat write SetAsFloat;
    property AsBoolean: boolean read GetAsBool write SetAsBool;
    property AsInteger: integer read GetAsInt write SetAsInt;
    property AsString: string read GetAsString write SetAsString;
  end;

  TPropertyBag = Class(TInterfacedObject)
  strict private
    FLUT:       TPropertyBagDictionary;
  strict protected
    procedure   Parse(NameValuePairs: string);
  public
    function    Read(Name: string): IPropertyElement;
    function    Write(Name: string; Value: string): IPropertyElement;

    procedure   SaveToStream(const Stream: TStream);
    procedure   LoadFromStream(const Stream: TStream);
    function    ToString: string; override;
    procedure   Clear; virtual;

    constructor Create(NameValuePairs: string); virtual;
    destructor  Destroy; override;
  end;

implementation

{$IFDEF SUPPORT_URI_ENCODING}
uses
  system.NetEncoding;
{$ENDIF}

const
  cnt_err_sourceparameters_parse =
  'Failed to parse input, invalid or damaged text error [%s]';

  cnt_err_sourceparameters_write_id =
  'Write failed, invalid or empty identifier error';

  cnt_err_sourceparameters_read_id =
  'Read failed, invalid or empty identifier error';

type

  TPropertyElement = class(TInterfacedObject, IPropertyElement)
  strict private
    FName:      string;
    FData:      string;
    FStorage:   TPropertyBagDictionary;
  strict protected
    function    GetEmpty: boolean; inline;

    function    GetAsInt: integer; inline;
    procedure   SetAsInt(const Value: integer); inline;

    function    GetAsString: string; inline;
    procedure   SetAsString(const Value: string); inline;

    function    GetAsBool: boolean; inline;
    procedure   SetAsBool(const Value: boolean); inline;

    function    GetAsFloat: double; inline;
    procedure   SetAsFloat(const Value: double); inline;

  public
    property    AsFloat: double read GetAsFloat write SetAsFloat;
    property    AsBoolean: boolean read GetAsBool write SetAsBool;
    property    AsInteger: integer read GetAsInt write SetAsInt;
    property    AsString: string read GetAsString write SetAsString;
    property    Empty: boolean read GetEmpty;

    constructor Create(const Storage: TPropertyBagDictionary; Name: string; Data: string); overload; virtual;
    constructor Create(Data: string); overload; virtual;
  end;

//#############################################################################
// TPropertyElement
//#############################################################################

constructor TPropertyElement.Create(Data: string);
begin
  inherited Create;
  FData := Data.Trim();
end;

constructor TPropertyElement.Create(const Storage: TPropertyBagDictionary;
  Name: string; Data: string);
begin
  inherited Create;
  FStorage := Storage;
  FName := Name.Trim().ToLower();
  FData := Data.Trim();
end;

function TPropertyElement.GetEmpty: boolean;
begin
  result := FData.Length < 1;
end;

function TPropertyElement.GetAsString: string;
begin
  result := FData;
end;

procedure TPropertyElement.SetAsString(const Value: string);
begin
  if Value  FData then
  begin
    FData := Value;
    if FName.Length > 0 then
    begin
      if FStorage  nil then
        FStorage.AddOrSetValue(FName, Value);
    end;
  end;
end;

function TPropertyElement.GetAsBool: boolean;
begin
  TryStrToBool(FData, result);
end;

procedure TPropertyElement.SetAsBool(const Value: boolean);
begin
  FData := BoolToStr(Value, true);

  if FName.Length > 0 then
  begin
    if FStorage  nil then
      FStorage.AddOrSetValue(FName, FData);
  end;
end;

function TPropertyElement.GetAsFloat: double;
begin
  TryStrToFloat(FData, result);
end;

procedure TPropertyElement.SetAsFloat(const Value: double);
begin
  FData := FloatToStr(Value);
  if FName.Length > 0 then
  begin
    if FStorage  nil then
      FStorage.AddOrSetValue(FName, FData);
  end;
end;

function TPropertyElement.GetAsInt: integer;
begin
  TryStrToInt(FData, Result);
end;

procedure TPropertyElement.SetAsInt(const Value: integer);
begin
  FData := IntToStr(Value);
  if FName.Length > 0 then
  begin
    if FStorage  nil then
      FStorage.AddOrSetValue(FName, FData);
  end;
end;

//#############################################################################
// TPropertyBag
//#############################################################################

constructor TPropertyBag.Create(NameValuePairs: string);

begin
  inherited Create;
  FLUT := TDictionary.Create();

  NameValuePairs := NameValuePairs.Trim();
  if NameValuePairs.Length > 0 then
    Parse(NameValuePairs);
end;

destructor TPropertyBag.Destroy;
begin
  FLut.Free;
  inherited;
end;

procedure TPropertyBag.Clear;
begin
  FLut.Clear;
end;

procedure TPropertyBag.Parse(NameValuePairs: string);
var
  LList:      TStringList;
  x:          integer;
  LId:        string;
  LValue:     string;
  LOriginal:  string;
  {$IFDEF SUPPORT_URI_ENCODING}
  LPos:       integer;
  {$ENDIF}
begin
  // Reset content
  FLUT.Clear();

  // Make a copy of the original text
  LOriginal := NameValuePairs;

  // Trim and prepare
  NameValuePairs := NameValuePairs.Trim();

  // Anything to work with?
  if NameValuePairs.Length > 0 then
  begin
    {$IFDEF SUPPORT_URI_ENCODING}
    // Check if the data is URL-encoded
    LPos := pos('%', NameValuePairs);
    if  (LPos >= low(NameValuePairs) )
    and (LPos  0 then
    Begin
      (* Populate our lookup table *)
      LList := TStringList.Create;
      try
        LList.Delimiter := ';';
        LList.StrictDelimiter := true;
        LList.DelimitedText := NameValuePairs;

        if LList.Count = 0 then
          raise EPropertybagParseError.CreateFmt(cnt_err_sourceparameters_parse, [LOriginal]);

        try
          for x := 0 to LList.Count-1 do
          begin
            LId := LList.Names[x].Trim().ToLower();
            if (LId.Length > 0) then
            begin
              LValue := LList.ValueFromIndex[x].Trim();
              Write(LId, LValue);
            end;
          end;
        except
          on e: exception do
          raise EPropertybagParseError.CreateFmt(cnt_err_sourceparameters_parse, [LOriginal]);
        end;
      finally
        LList.Free;
      end;
    end;
  end;
end;

function TPropertyBag.ToString: string;
var
  LItem: TPair;
begin
  setlength(result, 0);
  for LItem in FLut do
  begin
    if LItem.Key.Trim().Length > 0 then
    begin
      result := result + Format('%s=%s;', [LItem.Key, LItem.Value]);
    end;
  end;
end;

procedure TPropertyBag.SaveToStream(const Stream: TStream);
var
  LData: TStringStream;
begin
  LData := TStringStream.Create(ToString(), TEncoding.UTF8);
  try
    LData.SaveToStream(Stream);
  finally
    LData.Free;
  end;
end;

procedure TPropertyBag.LoadFromStream(const Stream: TStream);
var
  LData: TStringStream;
begin
  LData := TStringStream.Create('', TEncoding.UTF8);
  try
    LData.LoadFromStream(Stream);
    Parse(LData.DataString);
  finally
    LData.Free;
  end;
end;

function TPropertyBag.Write(Name: string; Value: string): IPropertyElement;
begin
  Name := Name.Trim().ToLower();
  if Name.Length > 0 then
  begin
    if not FLUT.ContainsKey(Name) then
      FLut.Add(Name, Value);

    result := TPropertyElement.Create(FLut, Name, Value) as IPropertyElement;
  end else
  raise EPropertybagWriteError.Create(cnt_err_sourceparameters_write_id);
end;

function TPropertyBag.Read(Name: string): IPropertyElement;
var
  LData:  String;
begin
  Name := Name.Trim().ToLower();
  if Name.Length > 0  then
  begin
    if FLut.TryGetValue(Name, LData) then
      result := TPropertyElement.Create(LData) as IPropertyElement
    else
      raise EPropertybagReadError.Create(cnt_err_sourceparameters_read_id);
  end else
  raise EPropertybagReadError.Create(cnt_err_sourceparameters_read_id);
end;


end.

BTree for Delphi

July 7, 2019 2 comments
lookup

Click here to read

A few weeks back I posted an article on RemObjects blog regarding universal code, and how you with a little bit of care can write code that easily compiled with both Oxygene, Delphi and Freepascal. With emphasis on Oxygene.

The example I used was a BTree class that I originally ported from Delphi to Smart Pascal, and then finally to Oxygene to run under WebAssembly.

Long story short I was asked if I could port the code back to Delphi in its more or less universal form. Naturally there are small differences here and there, but nothing special that distinctly separates the Delphi version from Oxygene or Smart Pascal.

Why this version?

If you google BTree and Delphi you will find loads of implementations. They all operate more or less identical, using records and pointers for optimal speed. I decided to base my version on classes for convenience, but it shouldn’t be difficult to revert that to use records if you absolutely need it.

What I like about this BTree implementation is that it’s very functional. Its easy to traverse the nodes using the ForEach() method, you can add items using a number as an identifier, but it also supports string identifiers.

I also changed the typical data reference. The data each node represent is usually a pointer. I changed this to variant to make it more functional.

Well, here is the Delphi version as promised. Happy to help.

unit btree;

interface

uses
  System.Generics.Collections,
  System.Sysutils,
  System.Classes;

type

  // BTree leaf object
  TQTXBTreeNode = class(TObject)
  public
    Identifier: integer;
    Data:       variant;
    Left:       TQTXBTreeNode;
    Right:      TQTXBTreeNode;
  end;

  [Weak]
  TQTXBTreeProcessCB = reference to procedure (const Node: TQTXBTreeNode; var Cancel: boolean);

  EBTreeError = class(Exception);

  TQTXBTree = class(TObject)
  private
    FRoot:    TQTXBTreeNode;
    FCurrent: TQTXBTreeNode;
  protected
    function  GetEmpty: boolean;  virtual;
    function  GetPackedNodes: TList;

  public
    property  Root: TQTXBTreeNode read FRoot;
    property  Empty: boolean read GetEmpty;

    function  Add(const Ident: integer; const Data: variant): TQTXBTreeNode; overload; virtual;
    function  Add(const Ident: string; const Data: variant): TQTXBTreeNode; overload; virtual;

    function  Contains(const Ident: integer): boolean; overload; virtual;
    function  Contains(const Ident: string): boolean; overload; virtual;

    function  Remove(const Ident: integer): boolean; overload; virtual;
    function  Remove(const Ident: string): boolean; overload; virtual;

    function  Read(const Ident: integer): variant; overload; virtual;
    function  Read(const Ident: string): variant; overload; virtual;

    procedure Write(const Ident: string; const NewData: variant); overload; virtual;
    procedure Write(const Ident: integer; const NewData: variant); overload; virtual;

    procedure Clear; overload; virtual;
    procedure Clear(const Process: TQTXBTreeProcessCB); overload; virtual;

    function  ToDataArray: TList;
    function  Count: integer;

    procedure ForEach(const Process: TQTXBTreeProcessCB);

    destructor Destroy; override;
  end;

implementation

//#############################################################################
// TQTXBTree
//#############################################################################

destructor TQTXBTree.Destroy;
begin
  if FRoot  nil then
    Clear();
  inherited;
end;

procedure TQTXBTree.Clear;
var
  lTemp:  TList;
  x:  integer;
begin
  if FRoot  nil then
  begin
    // pack all nodes to a linear list
    lTemp := GetPackedNodes();

    try
      // release each node
      for x := 0 to ltemp.Count-1 do
      begin
        lTemp[x].Free;
      end;
    finally
      // dispose of list
      lTemp.Free;

      // reset pointers
      FCurrent := nil;
      FRoot := nil;
    end;
  end;
end;

procedure TQTXBTree.Clear(const Process: TQTXBTreeProcessCB);
begin
  ForEach(Process);
  Clear();
end;

function TQTXBTree.GetPackedNodes: TList;
var
  LData:  Tlist;
begin
  LData := TList.Create();
  ForEach( procedure (const Node: TQTXBTreeNode; var Cancel: boolean)
  begin
    LData.Add(Node);
    Cancel  := false;
  end);
  result := LData;
end;

function TQTXBTree.GetEmpty: boolean;
begin
  result := FRoot = nil;
end;

function TQTXBTree.Count: integer;
var
  LCount: integer;
begin
  ForEach( procedure (const Node: TQTXBTreeNode; var Cancel: boolean)
    begin
      inc(LCount);
      Cancel  := false;
    end);
  result := LCount;
end;

function TQTXBTree.ToDataArray: TList;
var
  Data: TList;
begin
  Data := TList.Create();

  ForEach( procedure (const Node: TQTXBTreeNode; var Cancel: boolean)
    begin
      Data.add(Node.data);
      Cancel := false;
    end);
  result := data;
end;

function TQTXBTree.Add(const Ident: string; const Data: variant): TQTXBTreeNode;
begin
  result := Add( Ident.GetHashCode(), Data);
end;

function TQTXBTree.Add(const Ident: integer; const Data: variant): TQTXBTreeNode;
var
  lNode:  TQTXBtreeNode;
begin
  LNode := TQTXBTreeNode.Create();
  LNode.Identifier := Ident;
  LNode.Data := data;

  if FRoot = nil then
    FRoot := LNode;

  FCurrent := FRoot;

  while true do
  begin
    if (Ident  FCurrent.Identifier) then
    begin
      if (FCurrent.right = nil) then
      begin
        FCurrent.right := LNode;
        break;
      end else
      FCurrent := FCurrent.right;
    end else
    break;
  end;
  result := LNode;
end;

function TQTXBTree.Read(const Ident: string): variant;
begin
  result := Read( Ident.GetHashCode() );
end;

function TQTXBTree.Read(const Ident: integer): variant;
begin
  FCurrent := FRoot;
  while FCurrent  nil do
  begin
    if (Ident  Fcurrent.Identifier) then
      FCurrent := FCurrent.Right
    else
    begin
      result := FCUrrent.Data;
      break;
    end
  end;
end;

procedure TQTXBTree.Write(const Ident: string; const NewData: variant);
begin
  Write( Ident.GetHashCode(), NewData);
end;

procedure TQTXBTree.Write(const Ident: integer; const NewData: variant);
begin
  FCurrent := FRoot;
  while (FCurrent  nil) do
  begin
    if (Ident  Fcurrent.Identifier) then
      FCurrent := FCurrent.Right
    else
    begin
      FCurrent.Data := NewData;
      break;
    end
  end;
end;

function  TQTXBTree.Contains(const Ident: string): boolean;
begin
  result := Contains( Ident.GetHashCode() );
end;

function TQTXBTree.Contains(const Ident: integer): boolean;
begin
  result := false;
  if FRoot  nil then
  begin
    FCurrent := FRoot;

    while ( (not Result) and (FCurrent  nil) ) do
    begin
      if (Ident  Fcurrent.Identifier) then
        FCurrent := FCurrent.Right
      else
      begin
        Result := true;
        break;
      end
    end;
  end;
end;

function TQTXBTree.Remove(const Ident: string): boolean;
begin
  result := Remove( Ident.GetHashCode() );
end;

function TQTXBTree.Remove(const Ident: integer): boolean;
var
  LFound: boolean;
  LParent: TQTXBTreeNode;
  LReplacement,
  LReplacementParent: TQTXBTreeNode;
  LChildCount: integer;
begin
  FCurrent := FRoot;
  LFound := false;
  LParent := nil;
  LReplacement := nil;
  LReplacementParent := nil;

  while (not LFound) and (FCurrent  nil) do
  begin
    if (Ident  FCurrent.Identifier) then
    begin
      LParent := FCurrent;
      FCurrent := FCurrent.right;
    end else
    LFound := true;

    if LFound then
    begin
      LChildCount := 0;

      if (FCurrent.left  nil) then
        inc(LChildCount);

      if (FCurrent.right  nil) then
        inc(LChildCount);

      if FCurrent = FRoot then
      begin
        case (LChildCOunt) of
        0:  begin
              FRoot := nil;
            end;
        1:  begin
              if FCurrent.right = nil then
                FRoot := FCurrent.left
              else
                FRoot :=FCurrent.Right;
            end;
        2:  begin
              LReplacement := FRoot.left;
              while (LReplacement.right  nil) do
              begin
                LReplacementParent := LReplacement;
                LReplacement := LReplacement.right;
              end;

            if (LReplacementParent  nil) then
            begin
              LReplacementParent.right := LReplacement.Left;
              LReplacement.right := FRoot.Right;
              LReplacement.left := FRoot.left;
            end else
            LReplacement.right := FRoot.right;
          end;
        end;

        FRoot := LReplacement;
      end else
      begin
        case LChildCount of
        0:  if (FCurrent.Identifier < LParent.Identifier) then
            Lparent.left  := nil else
            LParent.right := nil;
        1:  if (FCurrent.Identifier < LParent.Identifier) then
            begin
              if (FCurrent.Left = NIL) then
              LParent.left := FCurrent.Right else
              LParent.Left := FCurrent.Left;
            end else
            begin
              if (FCurrent.Left = NIL) then
              LParent.right := FCurrent.Right else
              LParent.right := FCurrent.Left;
            end;
        2:  begin
              LReplacement := FCurrent.left;
              LReplacementParent := FCurrent;

              while LReplacement.right  nil do
              begin
                LReplacementParent := LReplacement;
                LReplacement := LReplacement.right;
              end;
              LReplacementParent.right := LReplacement.left;

              LReplacement.right := FCurrent.right;
              LReplacement.left := FCurrent.left;

              if (FCurrent.Identifier < LParent.Identifier) then
                LParent.left := LReplacement
              else
                LParent.right := LReplacement;
            end;
          end;
        end;
      end;
  end;

  result := LFound;
end;

procedure TQTXBTree.ForEach(const Process: TQTXBTreeProcessCB);

  function ProcessNode(const Node: TQTXBTreeNode): boolean;
  begin
    if Node  nil then
    begin
      if Node.left  nil then
      begin
        result := ProcessNode(Node.left);
        if result then
          exit;
      end;

      Process(Node, result);
      if result then
        exit;

      if (Node.right  nil) then
      begin
        result := ProcessNode(Node.right);
        if result then
          exit;
      end;
    end;
  end;

begin
  ProcessNode(FRoot);
end;

end.

Calling node.js from Delphi

July 6, 2019 Leave a comment

We got a good question about how to start a node.js program from Delphi on our Facebook group today (third one in a week?). When you have been coding for years you often forget that things like this might not be immediately obvious. Hopefully I can shed some light on the options in this post.

Node or chrome?

nodeJust to be clear: node.js has nothing to do with chrome or chromium embedded. Chrome is a web-browser, a completely visual environment and ecosystem.

Node.js is the complete opposite. It is purely a shell based environment, meaning that it’s designed to run services and servers, with emphasis on the latter.

The only thing node.js and chrome have in common, is that they both use the V8 JavaScript runtime engine to load, JIT compile and execute scripts at high speed. Beyond that, they are utterly alien to each other.

Can node.js be embedded into a Delphi program?

Technically there is nothing stopping a C/C++ developer from compiling the node.js core system as C++ builder compatible .obj files; files that can then be linked into a Delphi application through references. But this also requires a bit of scaffolding, like adding support for malloc_, free_ and a few other procedures – so that your .obj files uses the same memory manager as your Delphi code. But until someone does just that and publish it, im afraid you are stuck with two options:

  • Use a library called Toby, that keeps node.js in a single DLL file. This is the most practical way if you insist on hosting your own version of node.js
  • Add node.js as a prerequisite and give users the option to locate the node.exe in your application’s preferences. This is the way I would go, because you really don’t want to force users to stick with your potentially outdated or buggy build.

So yes, you can use toby and just add the toby dll file to your program folder, but I have to strongly advice against that. There is no point setting yourself up for maintaining a whole separate programming language, just because you want JavaScript support.

“How many in your company can write high quality WebAssembly modules?”

If all you want to do is support JavaScript in your application, then I would much rather install Besen into Delphi. Besen is a JavaScript runtime engine written in Freepascal. It is fully compatible with Delphi, and follows the ECMA standard to the letter. So it is extremely compatible, fast and easy to use.

Like all Delphi components Besen is compiled into your application, so you have no dependencies to worry about.

Starting a node.js script

The easiest way to start a node.js script, is to simply shell-execute out of your Delphi application. This can be done as easily as:

ShellExecute(Handle, 'open', PChar('node.exe'), pchar('script.js'), nil, SW_SHOW);

This is more than enough if you just want to start a service, server or do some work that doesn’t require that you capture the result.

If you need to capture the result, the data that your node.js program emits on stdout, there is a nice component in the Jedi Component Library. Also plenty of examples online on how to do that.

If you need even further communication, you need to look for a shell-execute that support pipes. All node.js programs have something called a message-channel in the Javascript world. In reality though, this is just a named pipe that is automatically created when your script starts (with the same moniker as the PID [process identifier]).

If you opt for the latter you have a direct, full duplex message channel directly into your node.js application. You just have to agree with yourself on a protocol so that your Delphi code understands what node.js is saying, and visa versa.

UDP or TCP

If you don’t want to get your hands dirty with named pipes and rolling your own protocol, you can just use UDP to let your Delphi application communicate with your node.js process. UDP is practically without cost since its fundamental to all networking stacks, and in your case you will be shipping messages purely between processes on localhost. Meaning: packets are never sent on the network, but rather delegated between processes on the same machine.

In that case, I suggest you ship in the port you want your UDP server to listen on, so that your node.js service acts as the server. A simple command-line statement like:

node.exe myservice.js 8090

Inside node.js you can setup an UDP server with very little fuzz:


function setupServer(port) {
  var os = require("os");
  var dgram = require("dgram");
  var socket = dgram.createSocket("udp4");

  var MULTICAST_HOST = "224.0.0.236";
  var BROADCAST_HOST = "255.255.255.255";
  var ALL_PORT = 60540;
  var MULTICAST_TTL = 1; // Local network

  socket.bind(port);
  socket.on('listening', function() {
    socket.setMulticastLoopback(true);
    socket.setMulticastTTL(MULTICAST_TTL);
    socket.addMembership(multicastHost);
    if(broadcast) { socket.setBroadcast(true); }
  });
  socket.on('message', parseMessage);
}

function parseMessage(message, rinfo) {
try {
  var messageObject = JSON.parse(message);
  var eventType = messageObject.eventType;
  } catch(e) {
  }
}

Note: the code above assumes a JSON text message.

You can then use any Delphi UDP client to communicate with your node.js server, Indy is good, Synapse is a good library with less overhead – there are many options here.

Do I have to learn Javascript to use node.js?

If you download DWScript you can hook-up the JS-codegen library (see library folder in the DWScript repository), and use that to compile DWScript (object pascal) to kick-ass Javascript. This is the same compiler that was used in Smart Mobile Studio.

“Adding WebAssembly to your resume is going to be a hell of a lot more valuable in the years to come than C# or Java”

Another alternative is to use Freepascal, they have a pas2js project where you can compile ordinary object-pascal to javascript. Naturally there are a few things to keep in mind, both for DWScript and Freepascal – like avoiding pointers. But clean object pascal compiles just fine.

If JavaScript is not your cup of tea, or you simply don’t have time to learn the delicate nuances between the DOM (document object model, used by browsers) and the 100% package oriented approach deployed by node.js — then you can just straight up to webassembly.

RemObjects Software has a kick-ass webassembly compiler, perfect if you dont have the energy or time to learn JavaScript. As of writing this is the fastest and most powerful toolchain available. And I have tested them all.

WebAssembly, no Javascript needed

RO-Single-Gear-512You might remember Oxygene? It used to be shipped with Delphi as a way to target Microsoft CLR (common language runtime) and the .net framework.

Since then Oxygene and the RemObjects toolchain has evolved dramatically and is now capable of a lot more than CLR support.

  • You can compile to raw, llvm optimized machine code for 8 platforms
  • You can compile to CLR/.Net
  • You can compile to Java bytecodes
  • You can compile to WebAssembly!

WebAssembly is not Javascript, it’s important to underline that. WebAssembly was created especially for developers using traditional languages, so that traditional compilers can emit web friendly, binary code. Unlike Javascript, WebAssembly is a purely binary format. Just like Delphi generates machine-code that is linked into a final executable, WebAssembly is likewise compiled, linked and emitted in binary form.

If that sounds like a sales pitch, it’s not. It’s a matter of practicality.

  • WebAssembly is completely barren out of the box. The runtime environment, be it V8 for the browser or V8 for node.js, gives you nothing out of the box. You don’t even have WriteLn() to emit text.
  • Google expects compiler makers to provide their own RTL functions, from the fundamental to the advanced. The only thing V8 gives you, is a barebone way of referencing objects and functions on the other side, meaning the JS and DOM world. And that’s it.

So the reason i’m talking a lot about Oxygene and RemObjects Elements (Elements is the name of the compiler toolchain RemObjects offers), is because it ships with an RTL. So you are not forced to start on actual, literal assembly level.

studio

If you don’t want to study JavaScript, Oxygene and Elements from RemObjects is the solution

RemObjects also delivers a DelphiVCL compatibility framework. This is a clone of the Delphi VCL / Freepascal LCL. Since WebAssembly is still brand new, work is being done on this framework on a daily basis, with updates being issued all the time.

Note: The Delphi VCL framework is not just for WebAssembly. It represents a unified framework that can work anywhere. So if you switch from WebAssembly to say Android, you get the same result.

The most important part of the above, is actually not the visual stuff. I mean, having HTML5 visual controls is cool – but chances are you want to use a library like Sencha, SwiftUI or jQueryUI to compose your forms right? Which means you just want to interface with the widgets in the DOM to set and get values.

jQuery UI Bootstrap

You probably want to use a fancy UI library, like jQuery UI. This works perfectly with Elements because you can reference the controls from your WebAssembly module. You dont have to create TButton, TListbox etc manually

The more interesting stuff is actually the non-visual code you get access to. Hundreds of familiar classes from the VCL, painstakingly re-created, and usable from any of the 5 languages Elements supports.

You can check it out here: https://github.com/remobjects/DelphiRTL

Skipping JavaScript all together

I dont believe in single languages. Not any more. There was a time when all you needed was Delphi and a diploma and you were set to conquer the world. But those days are long gone, and a programmer needs to be flexible and have a well stocked toolbox.

At least try the alternatives before you settle on a phone

Knowing where you want to be is half the journey

The world really don’t need yet-another-c# developer. There are millions of C# developers in India alone. C# is just “so what?”. Which is also why C# jobs pays less than Delphi or node.js system service jobs.

What you want, is to learn the things others avoid. If JavaScript looks alien and you feel uneasy about the whole thing – that means you are growing as a developer. All new things are learned by venturing outside your comfort zone.

How many in your company can write high quality WebAssembly modules?

How many within one hour driving distance from your office or home are experts at WebAssembly? How many are capable of writing industrial scale, production ready system services for node.js that can scale from a single instance to 1000 instances in a large, clustered cloud environment?

Any idiot can pick up node.js and knock out a service, but with your background from Delphi or C++ builder you have a massive advantage. All those places that can throw an exception that JS devs usually ignore? As a Delphi or Oxygene developer you know better. And when you re-apply that experience under a different language, suddenly you can do stuff others cant. Which makes your skills valuable.

qtx

The Quartex Media Desktop have made even experienced node / web developers gasp. They are not used to writing custom-controls and large-scale systems, which is my advantage

So would you learn JavaScript or just skip to WebAssembly? Honestly? Learn a bit of both. You don’t have to be an expert in JavaScript to compliment WebAssembly. Just get a cheap book, like “Node.js for beginners” and “JavaScript the good parts” ($20 a piece) and that should be more than enough to cover the JS side of things.

Adding WebAssembly to your resume and having the material to prove you know your stuff, is going to be a hell of a lot more valuable in the years to come than C#, Java or Python. THAT I can guarantee you.

And, we have a wicked cool group on Facebook you can join too: Click here to visit RemObjects Developer.

 

Enumerating network adapters in DWScript/Smart under Node.js

July 5, 2019 Leave a comment

This is something I never had the time to implement under Smart Pascal, but it should be easy enough to patch. If you are using DWScript with the QTX Framework this is already in place. But for Smart users, here is a quick recipe.

First, we need access to the node.js OS module:

unit qtx.node.os;

//#############################################################################
// Quartex RTL for DWScript
// Written by Jon L. Aasenden, all rights reserved
// This code is released under modified LGPL (see license.txt)
//#############################################################################

unit NodeJS.os;

interface

uses
  NodeJS.Core;

type

  TCpusResultObjectTimes = class external
    property user: Integer;
    property nice: Integer;
    property sys: Integer;
    property idle: Integer;
    property irq: Integer;
  end;

  TCpusResult = class external
    property model: String;
    property speed: Integer;
    property times: TcpusResultObjectTimes;
  end;

  JNetworkInterfaceInfo = class external
    property address:  string;
    property netmask:  string;
    property family:   string;
    property mac:      string;
    property scopeid:  integer;
    property internal: boolean;
    property cidr:     string;
  end;

  Jos_Exports = class external
  public
    function tmpDir: String;
    function hostname: String;
    function &type: String;
    function platform: String;
    function arch: String;
    function release: String;
    function uptime: Integer;
    function loadavg: array of Integer;
    function totalmem: Integer;
    function freemem: Integer;
    function cpus: array of TCpusResult;
    function networkInterfaces: variant;
    property EOL: String;
  end;

function NodeJSOsAPI: Jos_Exports;

implementation

function NodeJSOsAPI: Jos_Exports;
begin
  result := Jos_Exports(RequireModule("os") );
end;

end.

With that in place, we can start enumerating through the adapters. Remember that a PC can have several adapters attached, from a dedicated card to X number of USB wifi sticks.

Here is a little routine that goes through the adapters, and returns the first IPv4 LAN address it finds. This is very useful when writing servers, since you need the IP + port to setup a binding. And yes, you can just call HostName(), but the point here is to know how to run through the adapter array.

function GetMyV4LanIP: string;
begin
  var OSAPI := NodeJSOsAPI();
  var NetAdapters := OSAPI.networkInterfaces();

  for var Adapter in NetAdapters do
  begin
    // Skip loopback device
    if Adapter.Contains('Loopback') then
      continue;

    for var netIntf in NetAdapters[Adapter] do
    begin
      var address = JNetworkInterfaceInfo( NetAdapters[Adapter][netIntf] );
      if not address.internal then
      begin
        // force copy of string
        var lFam: string := string(address.family) + " ";

        // make sure its ipv4
        if lFam.ToLower().Trim() = 'ipv4' then
        begin
          result := address.address + " ";
          result := result.trim();
          break;
        end;
      end;
    end;
  end;

  if result.length < 1 then
    result := '127.0.0.1';
end;

Getting into Node.js from Delphi

July 1, 2019 Leave a comment

Delphi is one of the best development toolchains for Windows. I have been an avid fan of Delphi since it was first released, and before that – Turbo Pascal too. Delphi has a healthy following – and despite popular belief, Delphi scores quite well on the Tiobe Index.

As cool and efficient as Delphi might be, there are situations where native code wont work. Or at the very least, be less efficient than the alternatives. Delphi has a broad wingspan, from low-level assembler all the way to classes and generics. But JavaScript and emerging web technology is based on a completely different philosophy, one where native code is regarded as negative since it binds you to hardware.

Getting to grips with the whole JavaScript phenomenon, be it for mobile, embedded or back-end services, can be daunting if all you know is native code. But thankfully there are alternatives that can help you become productive quickly, something I will brush over in this post.

JavaScript without JavaScript

Before we dig into the tools of the trade, I want to cover alternative ways of enjoying the power of node.js and Javascript. Namely by using compilers that can convert code from a traditional language – and emit fully working JavaScript. There are a lot more options than you think:

qtx

Quartex Media Desktop is a complete environment written purely in JavaScript. Both Server, Cluster and front-end is pure JavaScript. A good example of what can be done.

  • Swift compiles for JavaScript, and Apple is doing some amazing things with the new and sexy SwiftUI tookit. If you know your way around Swift, you can compile for Javascript
  • Go can likewise be compiled to JS:
    • RemObjects Elements supports the Go language. Elements can target both native (llvm), .Net, Java and WebAssembly.
    • Go2Js
    • GopherJs
    • TARDISgo
  • C/C++ can be compiled to asm.js courtesy of EmScripten. It uses clang to first compile your code to llvm bitcode, and then it converts that into asm.js. You have probably seen games like Quake run in the browser? That was asm.js, a kind of precursor to WebAssembly.
  • NS Basic compiles for JavaScript, this is a Visual Basic 6 style environment with its own IDE even

For those coming straight from Delphi, there are a couple of options to pick from:

  • Freepascal (pas2js project)
  • DWScript compiles code to JavaScript, this is the same compiler that we used in Smart Pascal earlier
  • Oxygene, the next generation object-pascal from RemObjects compiles to WebAssembly. This is by far the best option of them all.
studio

I strongly urge you to have a look at Elements, here running in Visual Studio

JavaScript, Asm.js or WebAssembly?

Asm.js is by far the most misunderstood technology in the JavaScript ecosystem, so let me just cover that before we move on:

A few years back JavaScript gained support for memory buffers and typed arrays. This might not sound very exciting, but in terms of speed – the difference is tremendous. The default variable type in JavaScript is what Delphi developers know as Variant. It assumes the datatype of the values you assign to it. Needless to say, there is a lot of overhead when working with variants – so JavaScript suddenly getting proper typed arrays was a huge deal.

It was then discovered that JavaScript could manipulate these arrays and buffers at high speed, providing it only used a subset of the language. A subset that the JavaScript runtime could JIT compile more easily (turn into machine-code).

So what the EmScripten team did was to implement a bytecode based virtual-machine in Javascript, and then they compile C/C++ to bytecodes. I know, it’s a huge project, but the results speak for themselves — before WebAssembly, this was as fast as it got with JavaScript.

WebAssembly

WebAssembly is different from both vanilla JavaScript and Asm.js. First of all, it’s executed at high speed by the browser itself. Not like asm.js where these bytecodes were executed by JavaScript code.

water

Water is a fast, slick and platform independent IDE for Elements. The same IDE for OS X is called Fire. You can use RemObjects Elements from either Visual Studio or Water

Secondly, WebAssembly is completely JIT compiled by the browser or node.js when loading. It’s not like Asm.js where some parts are compiled, others are interpreted. WebAssembly runs at full speed and have nothing to do with traditional JavaScript. It’s actually a completely separate engine.

Out of all the options on the table, WebAssembly is the technology with the best performance.

Kits and strategies

The first thing you need to be clear about, is what you want to work with. The needs and requirements of a game developer will be very different from a system service developer.

Here are a couple of kits to think about:

  • Mobile developer
    • Implement your mobile applications using Oxygene, compiling for WebAssembly (Elements)
    • RemObjects Remoting SDK for client / server communication
    • Use Freepascal for vanilla JavaScript scaffolding when needed
  • Service developer
    • Implement libraries in Oxygene to benefit from the speed of WebAssembly
    • Use RemObjects Data Abstract to make data-access uniform and fast
    • Use Freepascal for boilerplate node.js logic
  • Desktop developer
    • For platform independent desktop applications, WebAssembly is the way to go. You will need some scaffolding (plain Javascript) to communicate with the application host  – but the 99.9% of your code will be better under WebAssembly.
    • Use Cordova / Phonegap to “bundle” your WebAssembly, HTML5 files and CSS styling into a single, final executable.

The most important part to think about when getting into JavaScript, is to look closely at the benefits and limitation of each technology.

WebAssembly is fast, wicked fast, and let’s you write code like you are used to from Delphi. Things like pointers etc are supported in Elements, which means ordinary code that use pointers will port over with ease. You are also not bound on hand-and-feet to a particular framework.

For example, EmScripten for C/C++ have almost nothing in terms of UI functionality. The visual part is a custom build of SDL (simple directmedia layer), which fakes the graphics onto an ordinary HTML5 canvas. This makes EmScripten a good candidate for porting games written in C/C++ to the web — but it’s less than optimal for writing serious applications.

Setting up the common tools

So far we have looked at a couple of alternatives for getting into the wonderful world of JavaScript in lieu of other languages. But what if you just want to get started with the typical tools JS developers use?

vscode

Visual Studio Code is a pretty amazing code-editor

The first “must have” is Visual Studio Code. This is actually a great example of what you can achieve with JavaScript, because the entire editor and program is written in JavaScript. But I want to stress that this editor is THE editor to get. The way you work with files in JS is very different from Delphi, C# and Java. JavaScript projects are often more fragmented, with less code in each file – organized by name.

typescript

TypeScript was invented by Anders Hejlsberg, who also made Delphi and C#

The next “must have” is without a doubt TypeScript. Personally im not too fond of TypeScript, but if ordinary JavaScript makes your head hurt and you want classes and ordinary inheritance, then TypeScript is a step up.

assemblyscriptNext on the list is AssemblyScript. This is a post-processor for TypeScript that converts your code into WebAssembly. It lacks much of the charm and elegance of Oxygene, but I suspect that has to do with old habits. When you have been reading object-pascal for 20 years, you feel more at home there.

nodeYou will also need to install node.js, which is the runtime engine for running JavaScript as services. Node.js is heavily optimized for writing server software, but it’s actually a brilliant way to write services that are multi-platform. Because Node.js delivers the same behavior regardless of underlying operating system.

phonegapAnd finally, since you definitely want to convert your JavaScript and/or WebAssembly into a stand-alone executable: you will need Adobe Phonegap.

Visual Studio

No matter if you want to enter JavaScript via Elements or something else, Visual Studio will save you a lot of time, especially if you plan on targeting Azure or Amazon services. Downloading and installing the community edition is a good idea, and you can use that while exploring your options.

dotnet-visual-studio

When it comes to writing system services, you also want to check out NPM, the node.js package manager. The JavaScript ecosystem is heavily package oriented – and npm gives you some 800.000 packages to play with free of charge.

Just to be clear, npm is a shell command you use to install or remove packages. NPM is also a online repository of said packages, where you can search and find what you need. Most packages are hosted on github, but when you install a package locally into your application folder – npm figures out dependencies etc. automatically for you.

Books, glorious books

41QSvp9fTcL._SX331_BO1,204,203,200_Last but not least, get some good books. Seriously, it will save you so much time and frustration. Amazon have tons of great books, be it vanilla JavaScript, TypeScript, Node.js — pick some good ones and take the time to consume the material.

And again, I strongly urge you to have a look at Elements when it comes to WebAssembly. WebAssembly is a harsh and barren canvas, and being able to use the Elements RTL is a huge boost.

But regardless of path you pick, you will always benefit from learning vanilla JavaScript.

 

Two new groups in the Developer family

July 1, 2019 2 comments

Delphi Developer is a group on Facebook that have been going strong for 12+ years. It was one of the first groups on Facebook, created the same week that Facebook allowed groups. With that group well established, it’s time to expand and clean up the feed.

RO-Single-Gear-512Last month I introduced a new group, RemObjects Developer, which is a group for developers that use RemObjects components, like the Remoting SDK, Data Abstract and/or Hydra – but more in particular, developers using Oxygene, C#, Swift, Java or Go via Elements (RemObjects compiler toolchain).

Two new groups

To further simplify syndication, and clean up the feeds (which so far has been a pot-purrey of many topics, dialects and products) an additional two groups is now in place:

Obviously there will be some overlapping. Since FPC and Delphi has much in common and are for the most part compatible, some news will be shared between those groups. But all in all this is to clean up the newsfeed which has so far been a mix and match of everything.

org

Simple overview of the groups

Node.js Developer is not meant to be purely about vanilla JavaScript. Node.js is ultimately a JavaScript runtime-engine. Which means you can use it to run or host WebAssembly libraries (as produced by Oxygene), or generate code via DWScript or Freepascal. You can think of it as a service-host if you like.

So if you are writing WebAssembly applications using Elements, then the node.js group will no doubt be interesting too. Same goes for DWScript users, Smart Pascal users and Freepascal users – providing web tech is what they like.

What is this Quartex Components?

It’s easier to manage multiple groups if you attach them to a parent-page. So if you wonder why all the groups says “by Quartex Components”, that is just a top-level page that helps me deal with with syndication. For some reason Facebook’s API only works for pages, not groups. So it’s impossible to auto-import news (for example) without a page.

The name, “Quartex Components” is ultimately the name of my personal company. I used to produce security components for Delphi, but decided to open-source those for the community.

So Quartex Components is just an organizational element.

Porting TextCraft to Oxygene

June 30, 2019 Leave a comment

TextCraft is a simple yet powerful text parser, designed for general purpose parsing jobs. I originally implemented it for Delphi, it’s the base-parser for the LDEF bytecode assembler amongst other things. It was ported to Smart Pascal, then Freepascal – and now finally Oxygene.

ldef

The LDEF Assembler is a part of the Quartex Media Desktop

The LDEF assembler and bytecode engine is currently implemented in Smart and compiles for Javascript. It’s a complete assembler and VM allowing coders to approach Asm.js from an established instruction-set. In short: you feed it source-code, it spits out bytecodes that you can execute super fast in either the browser or elsewhere. As long as there is a VM implementation available.

The Javascript version works really well, especially on node.js. In essence, i don’t need to re-compile the toolchain when moving between arm, x86, windows, linux or osx. Think of it as a type of Java bytecodes or CLR bytecodes.

Getting the code to run under Oxygene, means that I can move the whole engine into WebAssembly. The parser, assembler and linker (et-al) can thus run as WebAssembly, and I can use that from my JavaScript front-end code. Best of both worlds – the flamboyant creativity of JavaScript, and the raw speed of WebAssembly.

The port

Before I can move over the top-level parser + assembler etc, the generic parser code has to work. I was reluctant to start because I imagined the porting would take at least a day, but luckily it took me less than an hour. There are a few superficial differences between Smart, Delphi, Freepascal and Oxygene; for example the Copy() function for strings is not a lose function in Oxygene, instead you use String.SubString(). Functions like High() and Low() on strings likewise has to be refactored.

But all in all the conversion was straight-forward, and TextCraft is now a part of the QTX library for Oxygene. I’ll be uploading a commit to GIT with the whole shabam soon.

Well, hope the WordPress parser doesnt screw this up too bad.

namespace qtxlib;

//##################################################################
// TextCraft 1.2
//  Written by Jon L. Aasenden
//
//  This is a port of TC 1.2 from Freepascal. TextCraft is initially
//  a Delphi parser framework. The original repository can be found
//  on BitBucket at:
//
//  https://bitbucket.org/hexmonks/main
//
//##################################################################

{$DEFINE USE_INCLUSIVE}
{$define USE_BMARK}

interface

uses
  qtxlib, System, rtl,
  RemObjects.Elements.RTL.Delphi,
  RemObjects.Elements.RTL.Delphi.VCL;

type

  // forward declarations
  TTextBuffer         = class;
  TParserContext      = class;
  TCustomParser       = class;
  TParserModelObject  = class;

    // Exceptions
  ETextBuffer   = class(Exception);
  EModelObject  = class(Exception);

  // Callback functions
  TTextValidCB = function (Item: Char): Boolean;

  // Bookmark datatype
  TTextBufferBookmark = class
  public
    property bbOffset: Integer;
    property bbCol:    Integer;
    property bbRow:    Integer;
    function Equals(const ThisMark: TTextBufferBookmark): Boolean;
  end;

  {.$DEFINE USE_BMARK}

  TTextBuffer = class(TErrorObject)
  private
    FData:      String;
    FOffset:    Integer;
    FLength:    Integer;
    FCol:       Integer;
    FRow:       Integer;
    {$IFDEF USE_BMARK}
    FBookmarks: List;
    {$ENDIF}
    procedure   SetCacheData(NewText: String);
  public
    property    Column: Integer read FCol;
    property    Row: Integer read FRow;
    property    Count: Integer read FLength;
    property    Offset: Integer read FOffset;
    property    CacheData: String read FData write SetCacheData;

    // These functions map directly to the "Current"
    // character where the offset is placed, and is used to
    // write code that makes more sense to human eyes
    function    CrLf: Boolean;
    function    Space: Boolean;
    function    Tab: Boolean;
    function    SemiColon: Boolean;
    function    Colon: Boolean;
    function    ConditionEnter: Boolean;
    function    ConditionLeave: Boolean;
    function    BracketEnter: Boolean;
    function    BracketLeave: Boolean;
    function    Ptr: Boolean;
    function    Punctum: Boolean;
    function    Question: Boolean;
    function    Less: Boolean;
    function    More: Boolean;
    function    Equal: Boolean;
    function    Pipe: Boolean;
    function    Numeric: Boolean;

    function    Empty: Boolean;
    function    BOF: Boolean;
    function    EOF: Boolean;
    function    Current: Char;

    function    First: Boolean;
    function    Last: Boolean;

    // Same as "Next", but does not automatically
    // consume CR+LF, used when parsing textfragments
    function    NextNoCrLf: Boolean;

    // Normal Next function, will automatically consume
    // CRLF when it encounters it
    function    Next: Boolean;

    function    Back: Boolean;

    function    Bookmark: TTextBufferBookmark;
    procedure   Restore(const Mark: TTextBufferBookmark);
    {$IFDEF USE_BMARK}
    procedure   Drop;
    {$ENDIF}

    procedure   ConsumeJunk;
    procedure   ConsumeCRLF;

    function    Compare(const CompareText: String;
                const CaseSensitive: Boolean): Boolean;

    function    Read(var Fragment: Char): Boolean; overload;
    function    Read: Char; overload;
    function    ReadTo(const CB: TTextValidCB; var TextRead: String): Boolean; overload;
    function    ReadTo(const Resignators: TSysCharSet; var TextRead: String): Boolean; overload;
    function    ReadTo(MatchText: String): Boolean; overload;
    function    ReadTo(MatchText: String; var TextRead: String): Boolean; overload;

    function    ReadToEOL: Boolean;   overload;
    function    ReadToEOL(var TextRead: String): Boolean;   overload;

    function    Peek: Char; overload;
    function    Peek(CharCount: Integer; var TextRead: String): Boolean; overload;

    function    NextNonControlChar(const CompareWith: Char): Boolean;
    function    NextNonControlText(const CompareWith: String): Boolean;

    function    ReadWord(var TextRead: String): Boolean;

    function    ReadQuotedString: String;
    function    ReadCommaList(var cList: List): Boolean;

    function    NextLine: Boolean;

    procedure   Inject(const TextToInject: String);

    function    GetCurrentLocation: TTextBufferBookmark;

    function    Trail: String;

    procedure   Clear;
    procedure   LoadBufferText(const NewBuffer: String);

    constructor Create(const BufferText: String); overload; virtual;

    finalizer;
    begin
      {$IFDEF USE_BMARK}
      FBookmarks.Clear();
      disposeAndNil(FBookmarks);
      {$endif}
      Clear();
    end;
  end;

  TParserContext = class(TErrorObject)
  private
    FBuffer:    TTextBuffer;
    FStack:     Stack;
  public
    property    Buffer: TTextBuffer read FBuffer;
    property    Model: TParserModelObject;

    procedure   Push(const ModelObj: TParserModelObject);
    function    Pop: TParserModelObject;
    function    Peek: TParserModelObject;
    procedure   ClearStack;

    constructor Create(const SourceCode: String); reintroduce; virtual;

    finalizer;
    begin
      FStack.Clear();
      FBuffer.Clear();
      disposeAndNil(FStack);
      disposeAndNil(FBuffer);
    end;
  end;

  TCustomParser = class(TErrorObject)
  private
    FContext:   TParserContext;
  protected
    procedure   SetContext(const NewContext: TParserContext);
  public
    property    Context: TParserContext read FContext;
    function    Parse: Boolean; virtual;
    constructor Create(const ParseContext: TParserContext); reintroduce; virtual;
  end;

  TParserModelObject = class(TObject)
  private
    FParent:    TParserModelObject;
    FChildren:  List;
  protected
    function    GetParent: TParserModelObject; virtual;
    function    ChildGetCount: Integer; virtual;
    function    ChildGetItem(const Index: Integer): TParserModelObject; virtual;
    function    ChildAdd(const Instance: TParserModelObject): TParserModelObject; virtual;
  public
    property    Parent: TParserModelObject read GetParent;
    property    Context: TParserContext;
    procedure   Clear; virtual;
    constructor Create(const AParent: TParserModelObject); virtual;

    finalizer;
    begin
      Clear();
      FChildren := nil;
    end;

  end;

implementation

//#####################################################################
// Error messages
//#####################################################################

const
  CNT_ERR_BUFFER_EMPTY  = 'Buffer is empty error';
  CNT_ERR_OFFSET_BOF    = 'Offset at BOF error';
  CNT_ERR_OFFSET_EOF    = 'Offset at EOF error';
  CNT_ERR_COMMENT_NOTCLOSED = 'Comment not closed error';
  CNT_ERR_OFFSET_EXPECTED_EOF = 'Expected EOF error';
  CNT_ERR_LENGTH_INVALID = 'Invalid length error';

//#####################################################################
// TTextBufferBookmark
//#####################################################################

function TTextBufferBookmark.Equals(const ThisMark: TTextBufferBookmark): boolean;
begin
  result := ( (ThisMark  nil) and (ThisMark  self) )
        and (self.bbOffset = ThisMark.bbOffset)
        and (self.bbCol = ThisMark.bbCol)
        and (self.bbRow = ThisMark.bbRow);
end;

//#####################################################################
// TTextBuffer
//#####################################################################

constructor TTextBuffer.Create(const BufferText: string);
begin
  inherited Create();
  if length(BufferText) > 0 then
    LoadBufferText(BufferText)
  else
    Clear();
end;

procedure TTextBuffer.Clear;
begin
  FData := '';
  FOffset := -1;
  FLength := 0;
  FCol := -1;
  FRow := -1;
  {$IFDEF USE_BMARK}
  FBookmarks.Clear();
  {$ENDIF}
end;

procedure TTextBuffer.SetCacheData(NewText: string);
begin
  LoadBufferText(NewText);
end;

function TTextBuffer.Trail: string;
begin
  if not Empty then
  begin
    if not EOF then
      result := FData.Substring(FOffset, length(FData) );
      //result := Copy( FData, FOffset, length(FData) );
  end;
end;

procedure TTextBuffer.LoadBufferText(const NewBuffer: string);
begin
  // Flush existing buffer
  Clear();

  // Load in buffertext, init offset and values
  var TempLen := NewBuffer.Length;
  if TempLen > 0 then
  begin
    FData := NewBuffer;
    FOffset := 0; // start at BOF
    FCol := 0;
    FRow := 0;
    FLength := TempLen;
  end;
end;

function TTextBuffer.GetCurrentLocation: TTextBufferBookmark;
begin
  if Failed then
    ClearLastError();
  if not Empty then
  begin
    result := TTextBufferBookmark.Create;
    result.bbOffset := FOffset;
    result.bbCol := FCol;
    result.bbRow := FRow;
  end else
  raise ETextBuffer.Create
  ('Failed to return position, buffer is empty error');
end;

function TTextBuffer.Bookmark: TTextBufferBookmark;
begin
  if Failed then
    ClearLastError();
  if not Empty then
  begin
    result := TTextBufferBookmark.Create;
    result.bbOffset := FOffset;
    result.bbCol := FCol;
    result.bbRow := FRow;
    {$IFDEF USE_BMARK}
    FBookmarks.add(result);
    {$ENDIF}
  end else
  raise ETextBuffer.Create
  ('Failed to bookmark location, buffer is empty error');
end;

procedure TTextBuffer.Restore(const Mark: TTextBufferBookmark);
begin
  if Failed then
    ClearLastError();
  if not Empty then
  begin
    if Mark  nil then
    begin
      FOffset := Mark.bbOffset;
      FCol := Mark.bbCol;
      FRow := Mark.bbRow;
      Mark.Free;

      {$IFDEF USE_BMARK}
      var idx := FBookmarks.Count;
      if idx > 0 then
      begin
        dec(idx);
        FOffset := FBookmarks[idx].bbOffset;
        FCol := FBookmarks[idx].bbCol;
        FRow := FBookmarks[idx].bbRow;
        FBookmarks.Remove(idx);
        //FBookmarks.SetLength(idx)
        //FBookmarks.Delete(idx,1);
      end else
      raise ETextBuffer.Create('Failed to restore bookmark, none exist');
      {$ENDIF}
    end else
    raise ETextBuffer.Create('Failed to restore bookmark, object was nil error');
  end else
  raise ETextBuffer.Create
  ('Failed to restore bookmark, buffer is empty error');
end;

{$IFDEF USE_BMARK}
procedure TTextBuffer.Drop;
begin
  if Failed then
    ClearLastError();
  if not Empty then
  begin
    if FBookmarks.Count > 0 then
      FBookmarks.Remove(FBookmarks.Count-1)
    else
      raise ETextBuffer.Create('Failed to drop bookmark, none exist');
  end else
  raise ETextBuffer.Create
  ('Failed to drop bookmark, buffer is empty error');
end;
{$ENDIF}

function TTextBuffer.Read(var Fragment: char): boolean;
begin
  if Failed then
    ClearLastError();

  if not Empty then
  begin
    result := FOffset <= length(FData);
    if result then
    begin
      // return character
      Fragment := FData[FOffset];

      // update offset
      inc(FOffset)
    end else
    begin
      // return invalid char
      Fragment := #0;

      // Set error reason
      SetLastError('Offset at BOF error');
    end;
  end else
  begin
    result := false;
    Fragment := #0;
    SetLastError('Buffer is empty error');
  end;
end;

function TTextBuffer.Read: char;
begin
  if Failed then
    ClearLastError();

  if not Empty then
  begin
    result := Current;
    Next();
  end else
  result := #0;
end;

function TTextBuffer.ReadToEOL: boolean;
begin
  if Failed then
    ClearLastError();

  if not Empty() then
  begin
    if BOF() then
    begin
      if not First() then
        exit;
    end;

    if EOF() then
    begin
      SetLastError(CNT_ERR_OFFSET_EOF);
      exit;
    end;

    // Keep start
    var LStart := FOffset;

    // Enum until match of EOF
    {$IFDEF USE_INCLUSIVE}
    repeat
      if (FData[FOffset] = #13)
      and (FData[FOffset + 1] = #10) then
      begin
        result := true;
        break;
      end else
      begin
        inc(FOffset);
        inc(FCol);
      end;
    until EOF();
    {$ELSE}
    While FOffset < High(FData) do
    begin
      if (FData[FOffset] = #13)
      and (FData[FOffset + 1] = #10) then
      begin
        result := true;
        break;
      end else
      begin
        inc(FOffset);
        inc(FCol);
      end;
    end;
    {$ENDIF}

    // Last line in textfile might not have
    // a CR+LF, so we have to check for termination
    if not result then
    begin
      if EOF then
      begin
        if LStart = Low(FData)) and (FOffset = Low(FData)) and (FOffset = Low(FData)) and (FOffset = Low(FData)) and (FOffset = Low(FData)) and (FOffset = Low(FData)) and (FOffset = Low(FData)) and (FOffset = Low(FData)) and (FOffset = Low(FData)) and (FOffset = Low(FData)) and (FOffset = Low(FData)) and (FOffset = Low(FData)) and (FOffset = Low(FData)) and (FOffset <= high(FData) ) )
        and ( (FData[FOffset] = '= Low(FData)) and (FOffset ') );
end;

function  TTextBuffer.Equal: boolean;
begin
  result := (not Empty)
        and ( (FOffset >= Low(FData)) and (FOffset = Low(FData)) and (FOffset = Low(FData)) and (FOffset  LStart then
        begin
          // Any text to return? Or did we start
          // directly on a CR+LF and have no text to give?
          var LLen := FOffset - LStart;
          TextRead := FData.Substring(LStart, LLen);
          //TextRead := Copy(FData, LStart, LLen);
        end;

        // Either way, we exit because CR+LF has been found
        result := true;
        break;
      end;

      inc(FOffset);
      inc(FCol);
    until EOF();
    {$ELSE}
    While FOffset  LStart then
        begin
          // Any text to return? Or did we start
          // directly on a CR+LF and have no text to give?
          var LLen := FOffset - LStart;
          TextRead := copy(FData, LStart, LLen);
        end;

        // Either way, we exit because CR+LF has been found
        result := true;
        break;
      end;

      inc(FOffset);
      inc(FCol);
    end;
    {$ENDIF}

    // Last line in textfile might not have
    // a CR+LF, so we have to check for EOF and treat
    // that as a terminator.
    if not result then
    begin
      if FOffset >= high(FData) then
      begin
        if LStart  0 then
          begin
            TextRead := FData.Substring(LStart, LLen);
            //TextRead := Copy(FData, LStart, LLen);
            result := true;
          end;
          exit;
        end;
      end;
    end;

  end;
end;

function TTextBuffer.ReadTo(const CB: TTextValidCB; var TextRead: string): boolean;
begin
  if Failed then
    ClearLastError();

  TextRead := '';

  if not Empty then
  begin

    if BOF() then
    begin
      if not First() then
        exit;
    end;

    if EOF() then
    begin
      SetLastError(CNT_ERR_OFFSET_EOF);
      exit;
    end;

    if not assigned(CB) then
    begin
      SetLastError('Invalid callback handler');
      exit;
    end;

    {$IFDEF USE_INCLUSIVE}
    repeat
      if not CB(Current) then
        break
      else
        TextRead := TextRead + Current;

      if not Next() then
        break;
    until EOF();
    {$ELSE}
    while not EOF do
    begin
      if not CB(Current) then
        break
      else
        TextRead := TextRead + Current;

      if not Next() then
        break;
    end;
    {$ENDIF}
    result := TextRead.Length > 0;

  end else
  begin
    result := false;
    SetLastError(CNT_ERR_BUFFER_EMPTY);
  end;
end;

function TTextBuffer.ReadTo(const Resignators: TSysCharSet; var TextRead: string): boolean;
begin
  if Failed then
    ClearLastError();

  TextRead := '';
  if not Empty then
  begin

    if BOF() then
    begin
      if not First() then
        exit;
    end;

    if EOF() then
    begin
      SetLastError(CNT_ERR_OFFSET_EOF);
      exit;
    end;

    {$IFDEF USE_INCLUSIVE}
    repeat
      if not Resignators.Contains(Current) then
        TextRead := TextRead + Current
      else
        break;

      if not Next() then
        break;
    until EOF();
    {$ELSE}
    while not EOF do
    begin
      if not (Current in Resignators) then
        TextRead := TextRead + Current
      else
        break;

      if not Next() then
        break;
    end;
    {$ENDIF}

    result := TextRead.Length > 0;
  end else
  begin
    result := false;
    SetLastError(CNT_ERR_BUFFER_EMPTY);
  end;
end;

function TTextBuffer.ReadTo(MatchText: string): boolean;
begin
  if Failed then
    ClearLastError();

  if not Empty() then
  begin

    if BOF() then
    begin
      if not First() then
        exit;
    end;

    if EOF() then
    begin
      SetLastError(CNT_ERR_OFFSET_EOF);
      exit;
    end;

    var MatchLen := length(MatchText);
    if MatchLen > 0 then
    begin
      MatchText := MatchText.ToLower();

      repeat
        var TempCache := '';
        if Peek(MatchLen, TempCache) then
        begin
          TempCache := TempCache.ToLower();
          result := SameText(TempCache, MatchText);
          if result then
            break;
        end;

        if not Next then
          break;
      until EOF;
    end;

  end else
  begin
    result := false;
    SetLastError(CNT_ERR_BUFFER_EMPTY);
  end;
end;

function TTextBuffer.ReadTo(MatchText: string; var TextRead: string): boolean;
begin
  if Failed then
    ClearLastError();

  result := false;
  TextRead := '';

  if not Empty() then
  begin

    if BOF() then
    begin
      if not First() then
        exit;
    end;

    if EOF() then
    begin
      SetLastError(CNT_ERR_OFFSET_EOF);
      exit;
    end;

    if MatchText.Length > 0 then
    begin
      MatchText := MatchText.ToLower();

      repeat
        var TempCache := '';
        if Peek(MatchText.Length, TempCache) then
        begin
          TempCache := TempCache.ToLower();
          result := SameText(TempCache, MatchText);
          if result then
            break
          else
            TextRead := TextRead + Current;
        end else
          TextRead := TextRead + Current;

        if not Next() then
          break;
      until EOF;
    end;

  end else
  begin
    result := false;
    SetLastError(CNT_ERR_BUFFER_EMPTY);
  end;
end;

procedure TTextBuffer.Inject(const TextToInject: string);
begin
  if length(FData) > 0 then
  begin
    var lSeg1 := FData.Substring(1, FOffset);
    var lSeg2 := FData.Substring(FOffset + 1, length(FData));
    //var LSeg1 := Copy(FData, 1, FOffset);
    //var LSeg2 := Copy(FData, FOffset+1,  FData.Length);
    FData := lSeg1 + TextToInject + lSeg2;
  end else
    FData := TextToInject;
end;

function TTextBuffer.Compare(const CompareText: string;
    const CaseSensitive: boolean): boolean;
begin
  if Failed then
    ClearLastError();

  if not Empty() then
  begin
    if BOF() then
    begin
      if not First() then
        exit;
    end;

    if EOF() then
    begin
      SetLastError(CNT_ERR_OFFSET_EOF);
      exit;
    end;

    var LenToRead := CompareText.Length;
    if LenToRead > 0 then
    begin
      // Peek will set an error message if it
      // fails, so we dont need to set anything here
      var ReadData := '';
      if Peek(LenToRead, ReadData) then
      begin
        case CaseSensitive of
        false: result := ReadData.ToLower() = CompareText.ToLower();
        true:  result := ReadData = CompareText;
        end;
      end;
    end else
    SetLastError(CNT_ERR_LENGTH_INVALID);

  end else
  SetLastError(CNT_ERR_BUFFER_EMPTY);
end;

procedure TTextBuffer.ConsumeJunk;
begin
  if Failed then
    ClearLastError();

  if not Empty then
  begin

    if BOF() then
    begin
      if not First() then
        exit;
    end;

    if EOF() then
    begin
      SetLastError(CNT_ERR_OFFSET_EOF);
      exit;
    end;

    repeat
      case Current of
      ' ':
        begin
        end;
      '"':
        begin
          break;
        end;
      #8, #09:
        begin
        end;
      '/':
        begin
          (* Skip C style remark *)
          if Compare('/*', false) then
          begin
            if ReadTo('*/') then
            begin
              inc(FOffset, 2);
              Continue;
            end else
            SetLastError(CNT_ERR_COMMENT_NOTCLOSED);
          end else
          begin
            (* Skip Pascal style remark *)
            if Compare('//', false) then
            begin
              if ReadToEOL() then
              begin
                continue;
              end else
              SetLastError(CNT_ERR_OFFSET_EXPECTED_EOF);
            end;
          end;
        end;
      '(':
        begin
          (* Skip pascal style remark *)
          if Compare('(*', false)
            and not Compare('(*)', false) then
          begin
            if ReadTo('*)') then
            begin
              inc(FOffset, 2);
              continue;
            end else
            SetLastError(CNT_ERR_COMMENT_NOTCLOSED);
          end else
          break;
        end;
      #13:
        begin
          if FData[FOffset + 1] = #10 then
            inc(FOffset, 2)
          else
            inc(FOffset, 1);
          //if Peek = #10 then
          //  ConsumeCRLF;
          continue;
        end;
      #10:
        begin
          inc(FOffset);
          continue;
        end;
      else
        break;
      end;

      if not Next() then
        break;
    until EOF;

  end else
  SetLastError(CNT_ERR_BUFFER_EMPTY);
end;

procedure TTextBuffer.ConsumeCRLF;
begin
  if not Empty then
  begin

    if BOF() then
    begin
      if not First() then
        exit;
    end;

    if EOF() then
    begin
      SetLastError(CNT_ERR_OFFSET_EOF);
      exit;
    end;

    if  (FData[FOffset] = #13) then
    begin
      if FData[FOffset + 1] = #10 then
        inc(FOffset, 2)
      else
        inc(FOffset);

      inc(FRow);
      FCol := 0;
    end;

  end;
end;

function TTextBuffer.Empty: boolean;
begin
  result := FLength < 1;
end;

// This method will look ahead, skipping space, tab and crlf (also known
// as control characters), and when a non control character is found it will
// perform a string compare. This method uses a bookmark and will restore
// the offset to the same position as when it was entered.
//
// Notes: The method "NextNonControlChar" is a similar method that
// performs a char-only compare.
function TTextBuffer.NextNonControlText(const CompareWith: string): boolean;
begin
  if Failed then
    ClearLastError();

  if not Empty then
  begin

    if BOF() then
    begin
      if not First() then
        exit;
    end;

    if EOF() then
    begin
      SetLastError(CNT_ERR_OFFSET_EOF);
      exit;
    end;

    var Mark := Bookmark();
    try
      // Iterate ahead
      repeat
        if not (Current in [' ', #13, #10, #09]) then
          break;

        Next();
      until EOF();

      // Compare unless we hit the end of the line
      if not EOF then
        result := Compare(CompareWith, false);
    finally
      Restore(Mark);
    end;

  end else
  SetLastError(CNT_ERR_BUFFER_EMPTY);
end;

// This method will look ahead, skipping space, tab and crlf (also known
// as control characters), and when a non control character is found it will
// perform a string compare. This method uses a bookmark and will restore
// the offset to the same position as when it was entered.

function TTextBuffer.NextNonControlChar(const CompareWith: char): boolean;
begin
  if Failed then
    ClearLastError();

  if not Empty then
  begin
    if BOF() then
    begin
      if not First() then
        exit;
    end;

    if EOF() then
    begin
      SetLastError(CNT_ERR_OFFSET_EOF);
      exit;
    end;

    var Mark := Bookmark();
    try
      repeat
        if not (Current in [' ', #13, #10, #09]) then
          break;
        Next();
      until EOF();

      //if not EOF then
      result := Current.ToLower() = CompareWith.ToLower();
      //result := LowerCase(Current) = LowerCase(CompareWith);

    finally
      Restore(Mark);
    end;

  end else
  SetLastError(CNT_ERR_BUFFER_EMPTY);
end;

function TTextBuffer.Peek: char;
begin
  if Failed then
    ClearLastError();
  if not Empty then
  begin
    if (FOffset  0 do
        begin
          TextRead := TextRead + Current;
          if not Next() then
            break;
          dec(CharCount);
        end;
      finally
        Restore(Mark);
      end;

      result := TextRead.Length > 0;

    end else
    SetLastError(CNT_ERR_OFFSET_EOF);
  end else
  SetLastError(CNT_ERR_BUFFER_EMPTY);
end;

function TTextBuffer.First: boolean;
begin
  if Failed then
    ClearLastError();

  if not Empty then
  begin
    FOffset := Low(FData);
    result := true;
  end else
  SetLastError(CNT_ERR_BUFFER_EMPTY);
end;

function TTextBuffer.Last: boolean;
begin
  if Failed then
    ClearLastError();

  if not Empty then
  begin
    FOffset := high(FData);
    result := true;
  end else
  SetLastError(CNT_ERR_BUFFER_EMPTY);
end;

function TTextBuffer.NextNoCrLf: boolean;
begin
  if Failed then
    ClearLastError();

  if not Empty then
  begin
    // Check that we are not EOF
    result := FOffset <= high(FData);
    if result then
    begin
      // Update offset into buffer
      inc(FOffset);

      // update column, but not if its in a lineshift
      if not (FData[FOffset] in [#13, #10]) then
        inc(FCol);

    end else
    SetLastError(CNT_ERR_OFFSET_EOF);
  end else
  SetLastError(CNT_ERR_BUFFER_EMPTY);
end;

function TTextBuffer.Next: boolean;
begin
  if Failed then
    ClearLastError();

  if not Empty() then
  begin

    if BOF() then
    begin
      if not First() then
        exit;
    end;

    if EOF() then
    begin
      SetLastError(CNT_ERR_OFFSET_EOF);
      exit;
    end;

    // Update offset into buffer
    inc(FOffset);

    // update column
    inc(FCol);

    // This is the same as ConsumeCRLF
    // But this does not generate any errors since we PEEK
    // ahead into the buffer to make sure the combination
    // is correct before we adjust the ROW + offset
    if FOffset  Low(FData));
    if result then
      dec(FOffset)
    else
      SetLastError(CNT_ERR_OFFSET_BOF);
  end else
  SetLastError(CNT_ERR_BUFFER_EMPTY);
end;

function TTextBuffer.Current: char;
begin
  if Failed then
    ClearLastError();

  // Check that buffer is not empty
  if not Empty then
  begin
    // Check that we are on char 1 or more
    if FOffset >= Low(FData) then
    begin
      // Check that we are before or on the last char
      if (FOffset <= high(FData)) then
        result := FData[FOffset]
      else
      begin
        SetLastError(CNT_ERR_OFFSET_EOF);
        result := #0;
      end;
    end else
    begin
      SetLastError(CNT_ERR_OFFSET_BOF);
      result := #0;
    end;
  end else
  begin
    SetLastError(CNT_ERR_BUFFER_EMPTY);
    result := #0;
  end;
end;

function TTextBuffer.BOF: boolean;
begin
  if not Empty then
    result := FOffset  high(FData);
end;

function TTextBuffer.NextLine: boolean;
begin
  if Failed then
    ClearLastError();

  if not Empty then
  begin
    // Make sure we offset to a valid character
    // in the buffer.
    ConsumeJunk();

    if not EOF then
    begin
      var ThisRow := self.FRow;
      while Row = ThisRow do
      begin
        Next();
        if EOF then
        break;
      end;

      result := (Row  ThisRow) and (not EOF);
    end;
  end;
end;

function TTextBuffer.ReadWord(var TextRead: string): boolean;
begin
  if Failed then
    ClearLastError();

  TextRead := '';

  if not Empty then
  begin
    // Make sure we offset to a valid character
    // in the buffer.
    ConsumeJunk();

    // Not at the end of the file?
    if not EOF then
    begin
      repeat
        var el := Current;

        if (el in
        [ 'A'..'Z',
          'a'..'z',
          '0'..'9',
          '_', '-' ]) then
          TextRead := TextRead + el
        else
          break;

        if not NextNoCrLf() then
          break;

      until EOF;

      result := TextRead.Length > 0;

    end else
    SetLastError('Failed to read word, unexpected EOF');
  end else
  SetLastError('Failed to read word, buffer is empty error');
end;

function TTextBuffer.ReadCommaList(var cList: List): boolean;
var
  LTemp: String;
  LValue: String;
begin
  if cList = nil then
    cList := new List
  else
    cList.Clear();

  if not Empty then
  begin
    ConsumeJunk();

    While not EOF do
    begin
      case Current of
      #09:
        begin
          // tab, just skip
        end;
      #13, #10:
        begin
          // CR+LF, consume and continue;
          ConsumeCRLF();
        end;
      #0:
        begin
          // Unexpected EOL
          break;
        end;

      ';':
        begin
          //Perfectly sound ending
          result := true;
          break;
        end;
      '"':
        begin
          LValue := ReadQuotedString;
          if LValue.Length > 0 then
          begin
            cList.add(LValue);
            LValue := '';
          end;
        end;
      ',':
        begin
          LTemp := LTemp.Trim();
          if LTemp.Length>0 then
          begin
            cList.add(LTemp);
            LTemp := '';
          end;
        end;
      else
        begin
          LTemp := LTemp + Current;
        end;
      end;

      if not Next() then
        break;
    end;

    if LTemp.Length > 0 then
      cList.add(LTemp);

    result := cList.Count > 0;

  end;
end;

function TTextBuffer.ReadQuotedString: string;
begin
  if not Empty then
  begin
    if not EOF then
    begin

      // Make sure we are on the " entry quote
      if Current  '"' then
      begin
        SetLastError('Failed to read quoted string, expected index on " character error');
        exit;
      end;

      // Skip the entry char
      if not NextNoCrLf() then
      begin
        SetLastError('Failed to skip initial " character error');
        exit;
      end;

      while not EOF do
      begin
        // Read char from buffer
        var TempChar := Current;

        // Closing of string? Exit
        if TempChar = '"' then
        begin
          if not NextNoCrLf then
            SetLastError('failed to skip final " character in string error');
          break;
        end;

        result := result + TempChar;

        if not NextNoCrLf() then
          break;
      end;

    end;
  end;
end;

//##########################################################################
// TParserModelObject
//##########################################################################

constructor TParserModelObject.Create(const AParent:TParserModelObject);
begin
  inherited Create;
  FParent := AParent;
  FChildren := new List;
end;

function TParserModelObject.GetParent:TParserModelObject;
begin
  result := FParent;
end;

procedure TParserModelObject.Clear;
begin
  FChildren.Clear();
end;

function TParserModelObject.ChildGetCount: integer;
begin
  result := FChildren.Count;
end;

function TParserModelObject.ChildGetItem(const Index: integer): TParserModelObject;
begin
  result := TParserModelObject(FChildren[Index]);
end;

function TParserModelObject.ChildAdd(const Instance: TParserModelObject): TParserModelObject;
begin
  if FChildren.IndexOf(Instance) < 0 then
    FChildren.add(Instance);
  result := Instance;
end;

//###########################################################################
// TParserContext
//###########################################################################

constructor TParserContext.Create(const SourceCode: string);
begin
  inherited Create;
  FBuffer := TTextBuffer.Create(SourceCode);
  FStack := new Stack;
end;

procedure TParserContext.Push(const ModelObj: TParserModelObject);
begin
  if Failed then
    ClearLastError();

  try
    FStack.Push(ModelObj);
  except
    on e: Exception do
    SetLastError('Internal error:' + e.Message);
  end;
end;

function TParserContext.Pop: TParserModelObject;
begin
  if Failed then
    ClearLastError();
  try
    result := FStack.Pop();
  except
    on e: Exception do
    SetLastError('Internal error:' + e.Message);
  end;
end;

function TParserContext.Peek: TParserModelObject;
begin
  if Failed then
    ClearLastError();
  try
    result := FStack.Peek();
  except
    on e: Exception do
    SetLastError('Internal error:' + e.Message);
  end;
end;

procedure TParserContext.ClearStack;
begin
  if Failed then
    ClearLastError();
  try
    FStack.Clear();
  except
    on e: Exception do
    SetLastError('Internal error:' + e.Message);
  end;
end;

//###########################################################################
// TCustomParser
//###########################################################################

constructor TCustomParser.Create(const ParseContext: TParserContext);
begin
  inherited Create;
  FContext := ParseContext;
end;

function TCustomParser.Parse: boolean;
begin
  result := false;
  SetLastErrorF('No parser implemented for class %s',[ClassName]);
end;

procedure TCustomParser.SetContext(const NewContext: TParserContext);
begin
  FContext := NewContext;
end;

end.

Generic protect for FPC/Lazarus

June 30, 2019 Leave a comment

Freepascal is not frequently mentioned on my blog. I have written about it from time to time, not always in a positive light though. Just to be clear, FPC (the compiler) is fantastic; it was one particular fork of Lazarus I had issues with, involving a license violation.

On the whole, freepascal and Lazarus is capable of great things. There are a few quirks here and there (if not oddities) that prevents mass adoption (the excessive use of include-files to “fake” partial classes being one), but as object-pascal compilers go, Freepascal is a battle-hardened, production ready system.

It’s been Linux in particular that I have used Freepascal on. In 2015 Hydro Oil wanted to move their back-end from Windows to Linux, and I spent a few months converting windows-only services into Linux daemons.

Today I find myself converting parts of the toolkit I came up with to Oxygene, but that’s a post for another day.

Generic protect

If you work a lot with multithreaded code, the unit im posting here might come in handy. Long story short: sharing composite objects between threads and the main process, always means extra scaffolding. You have to make sure you don’t access the list (or it’s elements) at the same time as another thread for example. To ensure this you can either use a critical-section, or you can deliver the data with a synchronized call. This is more or less universal for all languages, no matter if you are using Oxygene, C/C++, C# or Delphi.

When this unit came into being, I was doing quite elaborate classes with a lot of lists. These classes could not share ancestor, or I could have gotten away with just one locking mechanism. Instead I had to implement the same boilerplate code over and over again.

The unit below makes insulating (or protecting) classes easier. It essentially envelopes whatever class-instance you feed it, and returns the proxy object. Whenever you want to access your instance, you have to unlock it first or use a synchronizer (see below).

Works in both Freepascal and Delphi

The unit works for both Delphi and Freepascal, but there is one little difference. For some reason Freepascal does not support anonymous procedures, so we compensate and use inline-procedures instead. While not a huge deal, I really hope the FPC team add anonymous procedures, it makes life a lot easier for generics based code. Async programming without anonymous procedures is highly impractical too.

So if you are in Delphi you can write:

var
 lValue: TProtectedValue;
 lValue.Synchronize( procedure (var Value: integer)
 begin
   Value := Value * 12;
 end);

But under Freepascal you must resort to:

var
 lValue: TProtectedValue;

procedure _UpdateValue(var Data: integer);
begin
 Data := Data * 12;
end;

begin
  lValue.Synchronize(@_UpdateValue);
end;

On small examples like these, the benefit of this style of coding might be lost; but if you suddenly have 40-50 lists that needs to be shared between 100-200 active threads, it will be a time saver!

You can also use it on intrinsic datatypes:

lazarus

OK, here we go:

unit safeobjects;

// 	SafeObjects
//	==========================================================================
//	Written by Jon-Lennart Aasenden
//	Copyright Quartex Components LTD, all rights reserved
//
//	This unit is a part of the QTX Patreon Library
//
//	NOTES ABOUT FREEPASCAL:
//	=======================
//	Freepascal does not allow anonymous procedures, which means we must
//	resort to inline procedures instead:
//
// 	Where we in Delphi could write the following for an atomic,
//	thread safe alteration:
//
// var
// 	LValue: TProtectedValue;
//
//	LValue.Synchronize( procedure (var Value: integer)
//	begin
//		Value := Value * 12;
//	end);
//
//	Freepascal demands that we use an inline procedure instead, which
//  is more or less the same code, just organized slightly differently.
//
// var
// 	LValue: TProtectedValue;
//
//  procedure _UpdateValue(var Data: integer);
//  begin
//  	Data := Data * 12;
//  end;
//
// begin
//	LValue.Synchronize(@_UpdateValue);
// end;
//
//
//
//

{$mode DELPHI}
{$H+}

interface

uses
  {$IFDEF FPC}
  SysUtils,
  Classes,
  SyncObjs,
  Generics.Collections;
	{$ELSE}
  System.SysUtils,
  System.Classes,
  System.SyncObjs,
  System.Generics.Collections;
  {$ENDIF}

type

  {$DEFINE INHERIT_FROM_CRITICALSECTION}

  TProtectedValueAccessRights = set of (lvRead, lvWrite);

  EProtectedValue = class(exception);
  EProtectedObject = class(exception);

  (* Thread safe intrinsic datatype container.
     When sharing values between processes, use this class
     to make read/write access safe and protected. *)

  {$IFDEF INHERIT_FROM_CRITICALSECTION}
  TProtectedValue = class(TCriticalSection)
  {$ELSE}
  TProtectedValue = class(TObject)
  {$ENDIF}
  strict private
    {$IFNDEF INHERIT_FROM_CRITICALSECTION}
    FLock: TCriticalSection;
    {$ENDIF}
    FData: T;
    FOptions: TProtectedValueAccessRights;
  strict protected
    function GetValue: T;virtual;
    procedure SetValue(Value: T);virtual;
    function GetAccessRights: TProtectedValueAccessRights;
    procedure SetAccessRights(Rights: TProtectedValueAccessRights);
  public
    type
  		{$IFDEF FPC}
      TProtectedValueEntry = procedure (var Data: T);
  		{$ELSE}
      TProtectedValueEntry = reference to procedure (var Data: T);
      {$ENDIF}
  public
    constructor Create(Value: T); overload; virtual;
    constructor Create(Value: T; const Access: TProtectedValueAccessRights); overload; virtual;
    constructor Create(const Access: TProtectedValueAccessRights); overload; virtual;
    destructor Destroy;override;

    {$IFNDEF INHERIT_FROM_CRITICALSECTION}
    procedure Enter;
    procedure Leave;
    {$ENDIF}
    procedure Synchronize(const Entry: TProtectedValueEntry);

    property AccessRights: TProtectedValueAccessRights read GetAccessRights;
    property Value: T read GetValue write SetValue;
  end;

  (* Thread safe object container.
     NOTE #1: This object container **CREATES** the instance and maintains it!
              Use Edit() to execute a protected block of code with access
              to the object.

     Note #2: SetValue() does not overwrite the object reference, but
              attempts to perform TPersistent.Assign(). If the instance
              does not inherit from TPersistent an exception is thrown. *)
  TProtectedObject = class(TObject)
  strict private
    FData:      T;
    FLock:      TCriticalSection;
    FOptions:   TProtectedValueAccessRights;
  strict protected
    function    GetValue: T;virtual;
    procedure   SetValue(Value: T);virtual;
    function    GetAccessRights: TProtectedValueAccessRights;
    procedure   SetAccessRights(Rights: TProtectedValueAccessRights);
  public
    type
			{$IFDEF FPC}
      TProtectedObjectEntry = procedure (const Data: T);
	    {$ELSE}
      TProtectedObjectEntry = reference to procedure (const Data: T);
      {$ENDIF}
  public
    property    Value: T read GetValue write SetValue;
    property    AccessRights: TProtectedValueAccessRights read GetAccessRights;

    function    Lock: T;
    procedure   Unlock;
    procedure   Synchronize(const Entry: TProtectedObjectEntry);

    Constructor Create(const AOptions: TProtectedValueAccessRights = [lvRead,lvWrite]); virtual;
    Destructor  Destroy; override;
  end;

  (* TProtectedObjectList:
     This is a thread-safe object list implementation.
     It works more or less like TThreadList, except it deals with objects *)
  TProtectedObjectList = class(TInterfacedPersistent)
  strict private
    FObjects: TObjectList;
    FLock: TCriticalSection;
  strict protected
    function GetEmpty: boolean;virtual;
    function GetCount: integer;virtual;

    (* QueryObject Proxy: TInterfacedPersistent allows us to
       act as a proxy for QueryInterface/GetInterface. Override
       and provide another child instance here to expose
       interfaces from that instread *)
  protected
    function GetOwner: TPersistent;override;

  public
    type
      {$IFDEF FPC}
      TProtectedObjectListProc = procedure (Item: TObject; var Cancel: boolean);
      {$ELSE}
      TProtectedObjectListProc = reference to procedure (Item: TObject; var Cancel: boolean);
      {$ENDIF}
  public
    constructor Create(OwnsObjects: Boolean = true); virtual;
    destructor  Destroy; override;

    function    Contains(Instance: TObject): boolean; virtual;
    function    Enter: TObjectList; virtual;
    Procedure   Leave; virtual;
    Procedure   Clear; virtual;

    procedure   ForEach(const CB: TProtectedObjectListProc); virtual;

    Property    Count: integer read GetCount;
    Property    Empty: boolean read GetEmpty;
  end;

implementation

//############################################################################
//  TProtectedObjectList
//############################################################################

constructor TProtectedObjectList.Create(OwnsObjects: Boolean = True);
begin
  inherited Create;
  FObjects := TObjectList.Create(OwnsObjects);
  FLock := TCriticalSection.Create;
end;

destructor TProtectedObjectList.Destroy;
begin
  FLock.Enter;
  FObjects.Free;
  FLock.Free;
  inherited;
end;

procedure TProtectedObjectList.Clear;
begin
  FLock.Enter;
  try
    FObjects.Clear;
  finally
    FLock.Leave;
  end;
end;

function TProtectedObjectList.GetOwner: TPersistent;
begin
  result := NIL;
end;

procedure TProtectedObjectList.ForEach(const CB: TProtectedObjectListProc);
var
  LItem:  TObject;
  LCancel:  Boolean;
begin
	LCancel := false;
  if assigned(CB) then
  begin
    FLock.Enter;
    try
    	{$HINTS OFF}
      for LItem in FObjects do
      begin
        LCancel := false;
        CB(LItem, LCancel);
        if LCancel then
        	break;
      end;
      {$HINTS ON}
    finally
      FLock.Leave;
    end;
  end;
end;

function TProtectedObjectList.Contains(Instance: TObject): boolean;
begin
  result := false;
  if assigned(Instance) then
  begin
    FLock.Enter;
    try
      result := FObjects.Contains(Instance);
    finally
      FLock.Leave;
    end;
  end;
end;

function TProtectedObjectList.GetCount: integer;
begin
  FLock.Enter;
  try
    result :=FObjects.Count;
  finally
    FLock.Leave;
  end;
end;

function TProtectedObjectList.GetEmpty: Boolean;
begin
  FLock.Enter;
  try
    result := FObjects.Count<1;
  finally
    FLock.Leave;
  end;
end;

function TProtectedObjectList.Enter: TObjectList;
begin
  FLock.Enter;
  result := FObjects;
end;

procedure TProtectedObjectList.Leave;
begin
  FLock.Leave;
end;

//############################################################################
//  TProtectedObject
//############################################################################

constructor TProtectedObject.Create(const AOptions: TProtectedValueAccessRights = [lvRead, lvWrite]);
begin
  inherited Create;
  FLock := TCriticalSection.Create;
  FLock.Enter();
  try
  	FOptions := AOptions;
  	FData := T.Create;
  finally
    FLock.Leave();
  end;
end;

destructor TProtectedObject.Destroy;
begin
	FData.free;
  FLock.Free;
  inherited;
end;

function TProtectedObject.GetAccessRights: TProtectedValueAccessRights;
begin
  FLock.Enter;
  try
    result := FOptions;
  finally
    FLock.Leave;
  end;
end;

procedure TProtectedObject.SetAccessRights(Rights: TProtectedValueAccessRights);
begin
  FLock.Enter;
  try
    FOptions := Rights;
  finally
    FLock.Leave;
  end;
end;

function TProtectedObject.Lock: T;
begin
  FLock.Enter;
  result := FData;
end;

procedure TProtectedObject.Unlock;
begin
  FLock.Leave;
end;

procedure TProtectedObject.Synchronize(const Entry: TProtectedObjectEntry);
begin
  if assigned(Entry) then
  begin
    FLock.Enter;
    try
      Entry(FData);
    finally
      FLock.Leave;
    end;
  end;
end;

function TProtectedObject.GetValue: T;
begin
  FLock.Enter;
  try
    if (lvRead in FOptions) then
    	result := FData
  	else
    	raise EProtectedObject.CreateFmt('%s:Read not allowed error',[classname]);
  finally
    FLock.Leave;
  end;
end;

procedure TProtectedObject.SetValue(Value: T);
begin
  FLock.Enter;
  try
    if (lvWrite in FOptions) then
    begin
      if (TObject(FData) is TPersistent)
      or (TObject(FData).InheritsFrom(TPersistent)) then
      	TPersistent(FData).Assign(TPersistent(Value))
    	else
      	raise EProtectedObject.CreateFmt
        	('Locked object assign failed, %s does not inherit from %s',
        	[TObject(FData).ClassName,'TPersistent']);

    end else
    raise EProtectedObject.CreateFmt('%s:Write not allowed error',[classname]);
  finally
    FLock.Leave;
  end;
end;

//############################################################################
//  TProtectedValue
//############################################################################

Constructor TProtectedValue.Create(const Access: TProtectedValueAccessRights);
begin
  inherited Create;
  {$IFNDEF INHERIT_FROM_CRITICALSECTION}
  FLock := TCriticalSection.Create;
  {$ENDIF}
  FOptions := Access;
end;

constructor TProtectedValue.Create(Value: T);
begin
  inherited Create;
  {$IFNDEF INHERIT_FROM_CRITICALSECTION}
  FLock := TCriticalSection.Create;
  {$ENDIF}
  FOptions := [lvRead, lvWrite];
  FData := Value;
end;

constructor TProtectedValue.Create(Value: T; const Access: TProtectedValueAccessRights);
begin
  inherited Create;
  {$IFNDEF INHERIT_FROM_CRITICALSECTION}
  FLock := TCriticalSection.Create;
  {$ENDIF}
  FOptions := Access;
  FData := Value;
end;

Destructor TProtectedValue.Destroy;
begin
  {$IFNDEF INHERIT_FROM_CRITICALSECTION}
  FLock.Free;
  {$ENDIF}
  inherited;
end;

function TProtectedValue.GetAccessRights: TProtectedValueAccessRights;
begin
  Enter();
  try
    result := FOptions;
  finally
    Leave();
  end;
end;

procedure TProtectedValue.SetAccessRights(Rights: TProtectedValueAccessRights);
begin
  Enter();
  try
    FOptions := Rights;
  finally
    Leave();
  end;
end;

{$IFNDEF INHERIT_FROM_CRITICALSECTION}
procedure TProtectedValue.Enter;
begin
  FLock.Enter;
end;

procedure TProtectedValue.Leave;
begin
  FLock.Leave;
end;
{$ENDIF}

procedure TProtectedValue.Synchronize(const Entry: TProtectedValueEntry);
begin
  if assigned(Entry) then
  Begin
    Enter();
    try
      Entry(FData);
    finally
      Leave();
    end;
  end;
end;

function TProtectedValue.GetValue: T;
begin
  Enter();
  try
    if (lvRead in FOptions) then
    	result := FData
    else
    	raise EProtectedValue.CreateFmt('%s: Read not allowed error', [Classname]);
  finally
    Leave();
  end;
end;

procedure TProtectedValue.SetValue(Value: T);
begin
  Enter();
  try
    if (lvWrite in FOptions) then
    	FData:=Value
    else
    	raise EProtectedValue.CreateFmt('%s: Write not allowed error', [Classname]);
  finally
    Leave();
  end;
end;

end.

Quartex Desktop: a brief look at the API

June 29, 2019 Leave a comment

The Quartex Media Desktop (codename Amibian.js) has gotten a lot of cool attention lately. But telling people why it’s so awesome is not always easy. Not everyone is a software developer, and even then – very few Oxygene, Lazarus or Delphi developers have my level of background into HTML5/JS. Not that I have some hidden talent others lack, but rather that I have spent years working on this particular hybrid technology. And summing it all up is a tall order.

qtx

The Quartex Media Desktop has come a long way

Once in a while I post a few words about why the desktop matters, and why the system is going to be very important for developers and users alike. It’s growing at a rapid pace, with more and more of the underlying mechanics surfacing. I mean, me spending a month solving god knows how much – don’t mean a thing to users that just was a cool desktop. Some frankly don’t care how it works at all.

Well, in this post I will talk about The Desktop API and how it works. This is more practical information – and its the information that will help you when you start coding applications meant to integrate closely with the system.

The visual desktop

The desktop, despite being a pretty front end, serves no purpose right? Well you could not be more wrong, because there are layers of code beneath the pretty exterior that is unique to the world of JavaScript. But before we dig into that, lets have a look at how the desktop is organized.

desktop_layout

The desktop organization is very simple, but highly effective

System Menu

The Quartex Media Desktop (nicknamed “Amibian.js”) follows a long tradition where a small part of the display is always occupied by a system-menu. The menu, once learned is a powerful tool. One that will help you navigate around the system faster.

Menu app-region

The system menu is also capable of hosting smaller, helper applications. The main menu reserves a small region for such apps, simply called the menu app region. This region can stretch depending on it’s content. But such mini-apps are expected with use as little space as possible, with a hard limit of 300 pixels each.

Amibian.js ships with two standard menu apps, those are integral to the system and cannot be deleted, only disabled.

  • Time and date
  • Account name and IP address

Icon Dock

The Icon dock should be no stranger. Ubuntu Linux has a similar dock (albeit on the left side of the display), and in Windows you can create as many docking regions as you see fit. So a good docking bar is a good thing.

The purpose is to have your favorite applications readily available when you login to your system.

There is not that much to write about the icon-dock. You can edit the list of items there and change other options in the preferences. The dock can alight to the right, the left and even to the bottom of the screen.

The first button on the dock, will always be a quick-link to the preferences display. Instead of isolating preferences outside the desktop, as a separate process. I have made it intrinsic. So clicking on the Preferences button will slide the desktop out of view, and the preferences screen into view.

prefsview

The preferences view is still under construction, but its always the first item on the dock

Hosted Software

After this quick tour of the superficial, visual layer of the desktop, you could be forgiven for thinking this is all there is too it. Perhaps you imagine that “starting a program” is just loading stuff into frames and making it look like windows?

Actually, its a lot more elaborate that!

The purpose of the Quartex Media Desktop is to provide developers with common grounds. The market is filled with these juiced up, blinged to the hilt, superficial and outright fraudulent “web desktops”. Any idiot can sit down and make a website that looks like a desktop. Which is also why these desktop’s can do much beyond their initial programming.

You also have companies like CodeStamp that use native languages like C/C++ to create a custom server which deals with the grunt-work. Something I find amusing, but mostly sad. They have spent a fortune re-inventing technology that was made available 20 years ago, and that has been in use ever since.

The problem with these companies is that they are dinosaurs. I could have finished Quartex Media Desktop in a few months if I used Delphi or C++ builder. What CodeStamp have missed, is that their so-called revolutionary idea has been active and running for close to 20 years in the Delphi community. We are falling over each other in options for web desktops. I can have a fully fledged, theme based desktop up and running in less than a work day — with kick ass, llvm optimized, bug free code compiled for Windows, Linux and OS X.

The challenge, which is where the true values exists, is to get rid of native code. To write not just the client (desktop) in JavaScript, but beyond all — to write the entire back-end as Javascript! Only then do we have a truly portable and truly scalable platform to build on.

Amibian.js is designed to deal with 4 types of executables:

  • Local web applications
  • Remote web applications
  • LDEF bytecode binaries
  • Server-side shell

Let’s look at the first two since these fall into the category of “hosted applications”.

A hosted application is a normal web app that can run anywhere. It can be a simple website if you like. And like i mentioned above, external resources are always executed within the safe confounds of an iFrame.

Amibian.js allows hosted applications to call system functions that the desktop exposes. But in order for that to happen, the application must first complete a security process. But once the application is recognized and known (a process known as hand-shaking), the hosted application can integrate tightly with the desktop – so tight that it becomes indistinguishable from a local application.

But more importantly: communication between the desktop and a hosted application, is exclusively through messages. The hosted application cannot call potentially dangerous code, neither directly or indirectly. The methods it can call is held in check by the security policy for that program, which is under your control. So a bit of thought has gone into this work.

The desktop API

Behind the sweet exterior of our desktop, there are practically thousands of functions. And we must not forget that the back-end servers (Quartex Media Desktop is a distributed, clustered system).

Some of the functions a hosted-program can call, might actually exist on the server. So the desktop will accept the call, but relay that call to the back-end. When the call finishes, the response is likewise routed back to the application that initiated it.

desktop_comm

For example, if a hosted application wants to display a “load-file requester”, it would call a function named ShowRequesterFile(). This is a proxy method in the public framework that constructs a message for you, and then send that message to the desktop (browsers use pipes internally).

opendialog

A hosted application calling the ShowRequesterFile() API method. The desktop will go into modal mode and show the requester, just like you would expect from a native application

The desktop receives the message and executes the code designated for it. This involves setting the screen into modal mode, and show the “open file” dialog. When the user selects a file and the dialog closes, the result is shipped back to the application. The hosted application itself is never in direct contact with the filesystem. That is an important distinction.

Also, like mentioned earlier – some of the functions exposed by the public framework, is not a part of the desktop at all. The code to enumerate files and folders is not a part of the HTML5 code (obviously). So the desktop relay such calls to the back-end server(s) and further relay the response when that arrives.

System services

In my next article on the Quartex Media Desktop, we will have a peek at the system services and some of the functions they expose.

Raspberry PI 4 at last!

June 25, 2019 2 comments

It was with astonishment that I opened up my browser this morning to read some daily IT news, only to discover that the Raspberry PI v4 has finally arrived! And boy what a landslide update to the 3.x family it is!

Three times the fun

There are plenty of sites that entertains page-up and page-down with numbers, but I will save all that for an article where I have the physical kit in my posession. But looking at the preliminaries I think it’s safe to say that we are looking at a solid 3x the speed of the older yet capable PI 3b+.

Raspberry-Pi-4-4

The PI returns, and what a joy it is!

While the 3x speed boost is enough to bump the SoC up, from entertaining to serious for business applications – it’s ultimately the memory footprint that will make all the difference. While the Raspberry PI is probably the most loved SBC (single board computer) of all time, it’s always been cut short due to lack of memory. 512 megabyte can only do so much in 2019, and even the slimmest of Linux distributions quickly consumes more ram that older versions could supply.

VideoCore 6, two screens and 4k video

The new model ships in three different configurations, with 1, 2 and 4 gigabytes of ram respectively. I strongly urge people to get the 4Gb version, because with that amount of memory coupled with a good solid-state-disk, means you can enable a proper swap-partition. No matter how fast a SoC might be, without memory to compliment it – the system simply wont be able to deliver on its potential. But with 4Gb, a nice solid state disk (just use a SSD-To-USB with one of the sexy new USB 3.x ports) and you are looking at an OK mini-computer capable of most desktop applications.

I have to admit I never expected the PI to ship with support for two monitors, but lo-and-behold, the board has two mini-hdmi out ports! The board is also fitted with the VideCore 6 rather than VideoCore 4.

Not missing the boat with Oxygene and Elements

One of the most frustrating episodes in the history of Delphi, is that we never got a Delphi edition that could target Raspberry PI (or ARM-Linux in general). It was especially frustrating since Allen Bauer actually demonstrated Delphi generating code that ran on a PI in 2012. The result of not directly supporting the PI, even on service level without a UI layer – is that Delphi developers have missed the IOT market completely.

Before Delphi developers missed the IOT revolution, Delphi also missed out on iOS and Android. By the time Delphi developers could target any of these platforms, the market was completely saturated, and all opportunities to make money was long gone. In other words, Delphi has missed the boat on 3 revolutionary platforms in a row. Something which is borderline unforgivable.

The good news though is that Oxygene, the object-pascal compiler from RemObjects, supports the Raspberry PI SoC. I have yet to test this on v4, but since the PI v4 is 100% backwards compatible I don’t see any reason why there should be any issues. The code generated by Oxygene is not bound to just the PI either. As long as it runs on a debian based distro, it should run just fine on most ARM-Linux SoC’s that have working drivers.

And like I have written about elsewhere, you can also compile for WebAssembly, running either in node.js or in the browser — so there are plenty of ways to get your products over!

Stay tuned for the lineup

This week im going to do a lot of testing on various ARM devices to find out just how many SBC’s Oxygene can target, starting with the ODroid N2. But for Raspberry PI, that should be a slam-dunk. Meaning that object-pascal developers can finally make use of affordable off-the-shelves parts in their hardware projects.

As of writing im preparing the various boards I will be testing. We have the PI 3b+, the Tinkerboard from ASUS, NanoPI, Dragonboard, Odroid XU4 – and the latest power-board, the ODroid N2. Out of these offerings only the N2 is en-par with the Raspberry PI v4, although I suspect the Videocore 6 GPU will outperform the Mali G52.

Hydra now supports Freepascal and Java

June 15, 2019 2 comments

In case you guys missed it, RemObjects Hydra 6.2 now supports FreePascal!

This means that you can now use forms and units from .net and Java from your Freepascal applications – and (drumroll) also mix and match between Delphi, .net, Java and FPC modules! So if you see something cool that Freepascal lacks, just slap it in a Hydra module and you can use it across language barriers.

I have used Hydra for years with Delphi, and being able to use .net forms and components in Delphi is pretty awesome. It’s also a great framework for building modular applications that are easier to manage.

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Being able to tap into Freepascal is a great feature. Or the other way around, with Freepascal showing forms from Delphi, .net or Java.

For example, if you are moving to Freepascal, you can isolate the forms or controls that are not available under Freepascal in a Hydra module, and voila – you can gradually migrate.

If you are moving to Oxygene Pascal the same applies, you can implement the immediate logic under .net, and then import and use the parts that can’t easily be ported (or that you want to wait with).

The best of four worlds — You gotta love that!

Check out Hydra here:

https://hydra.remobjects.com/hydra/whatsnew/default.aspx

 

RemObjects VCL, mind blown!

June 12, 2019 12 comments

For a guy that spends most of his time online, and can talk for hours about the most nerdy topics known to mankind – being gobsmacked and silenced is a rare event. But this morning that was exactly what happened.

Now, Marc Hoffman has blogged regularly over the years regarding the evolution of the RemObjects toolchain; explaining how they decoupled the parts that make up a programming language, such as syntax, rtl and target, but I must admit haven’t really digested the full implications of that work.

Like most developers I have kept my eyes on the parts relevant for me, like the Remoting SDK, Data Abstract and Javascript support. Before I worked at Embarcadero I pretty much spent 10 years contracting -and building Smart Mobile Studio on the side together with the team at The Smart Company Inc.

xo

Smart Pascal gained support for RemObjects SDK servers quite early

Since both the Remoting SDK and Data Abstract were part of our toolbox as Delphi developers, those were naturally more immediate than anything else. We also added support for RemObjects Remoting SDK inside Smart Mobile Studio, so that people could call existing services from their Javascript applications.

Oxygene then

Like most Delphi developers I remember testing Oxygene Pascal when I bought Delphi 2005. Back then Oxygene was licensed by Borland under the “Prism” name and represented their take on dot net support. I was very excited when it came out, but since my knowledge of the dot net framework was nil, I was 100% relient on the documentation.

In many ways Oxygene was a victim of Rad Studio’s abhorrent help-file system. Documentation for Rad Studio (especially Delphi) up to that point had been exemplary since Delphi 4; but by the time Rad Studio 2005 came out, the bloat had reached epic levels. Even for me as a die-hard Delphi fanatic, Delphi 2005 and 2006 was a tragic experience.

image

Removing Oxygene was a monumental mistake

I mean, when it takes 15 minutes (literally) just to open the docs, then learning a whole new programming paradigm under those conditions was quite frankly impossible. Like most Delphi developers I was used to Delphi 7 style documentation, where the docs were not just reference material – but actually teaches you the language itself.

In the end Oxygene remained very interesting, but with a full time job, deadlines and kids to take care of, I stuck to what I knew – namely the VCL.

Oxygene today

Just like Delphi has evolved and improved radically since 2005, Oxygene has likewise evolved above and beyond its initial form. Truth be told, we copied a lot of material from Oxygene when we made Smart Pascal, so I feel strangely at home with Oxygene even after a couple of days. The documentation for Oxygene Pascal (and Elements as a whole) is very good: https://docs.elementscompiler.com/Oxygene/

But Oxygene Pascal, while the obvious “first stop” for Delphi developers looking to expand their market impact, is more than “just a language”. It’s a language that is a part of a growing family of languages that RemObjects support and evolve.

As of writing RemObjects offers the following languages. So even if you don’t have a background in Delphi, or perhaps migrated from Delphi to C# years ago – RemObjects will have solutions and benefits to offer:

  • Oxygene (object pascal)
  • C#
  • Swift
  • Java
water

Water is a sexy, slim new IDE for RemObjects languages on Windows. For the OS X version you want to download Fire.

And here is the cool thing: when you hear “Java” you automatically expect that you are bound hands and feet to the Java runtime-libraries right? Same also with C#, you expect C# to be purely limited to the dot-net framework. And if you like me dabbed in Oxygene back in 2005-2006, you probably think Oxygene is purely a dot-net adapted version of Object Pascal right? But RemObjects have turned that on it’s head!

Remember the decoupling I mentioned at the beginning of this post? What that means in practical terms is that they have separated each language into three distinct parts:

  1. The syntax
  2. The RTL
  3. The target

What this means, is that you can pick your own combinations!

Let’s say you are coming from Delphi. You have 20 years of Object Pascal experience under your belt, and while you dont mind learning new things – Object Pascal is where you will be most productive.

Well in that case picking Oxygene Pascal covers the syntax part. But you don’t have to use the dot-net framework if you don’t want to. You can mix and match these 3 parts as you see fit! Let’s look at some combinations you could pick:

  • Oxygene Pascal -> dot net framework -> CIL
  • Oxygene Pascal -> “VCL” -> CIL
  • Oxygene Pascal -> “VCL” -> WinAPI
  • Oxygene Pascal -> “VCL” -> WebAssembly

(*) The “VCL” here is a compatibility RTL closely modeled on the Freepascal LCL and Delphi VCL. This is written from scratch and contains no proprietary code. It is purely to get people productive faster.

The whole point of this tripartite decoupling is to allow developers to maximize the value of their existing skill-set. If you know Object Pascal then that is a natural starting point for you. If you know the VCL then obviously the VCL compatibility RTL is going to help you become productive much faster than calling WinAPI on C level. But you can, if you like, go all native. And you can likewise ignore native and opt for WebAssembly.

Sound cool? Indeed it is! But it gets better, let’s look at some of the targets:

  • Microsoft Windows
  • Apple OS X
  • Apple iOS
  • Apple WatchOS
  • Android
  • Android wearables
  • Linux x86 / 64
  • Linux ARM
  • tvOS
  • WebAssembly
  • * dot-net
  • * Java

In short: Pick the language you want, pick the RTL or framework you want, pick the target you want — and start coding!

(*) dot-net and Java are not just frameworks, they are also targets since they are Virtual Machines. WebAssembly also fall under the VM category, although the virtual machine there is bolted into Chrome and Firefox (also node.js).

Some example code

Webassembly is something that interest me more than native these days. Sure I love the speed that native has to offer, but since Javascript has become “the defacto universal platform”, and since most of my work privately is done in Javascript – it seems like the obvious place to start.

Webassembly is a bit like Javascript was 10 years ago. I remember it was a bit of a shock coming from Delphi. We had just created Smart Mobile Studio, and suddenly we realized that the classes and object the browser had to offer were close to barren. We were used to the VCL after all. So my work there was basically to implement something with enough similarity to the VCL to be familiar to to Delphi developer, without wandering too far away from established JS standards.

Webassembly is roughly in the same ballpark. Webassembly is just a runtime engine. It doesn’t give you all those nice and helpful classes out of the box. You are expected to either write that yourself – or (as luck would have it) rely on what language vendors provide.

RemObjects have a lot to offer here, because their “Delphi VCL” compatibility RTL compiles just fine for Webassembly. There is no form designer though, but I haven’t used a form designer in years. I prefer to do everything in code because that’s ultimately what works when your codebase grows large enough anyways. Even my Delphi projects are done mainly as raw code, because I like to have the option to compile with Freepascal and Lazarus.

My first test code for Oxygene Pascal with Webassembly as the target is thus very bare-bone. If there is something that has bugged me to no end, it’s that bloody HTML5 canvas. It’s a powerful thing, but it’s also overkill for per-pixel operations. So I figured that a nice, ad-hoc DIB (device independent bitmap) class will do wonders.

Note: Oxygene supports pointers, even under WebAssembly (!), but out of old habit I have avoided it. I want my code to compile for all the targets, without marking a class as “unsafe” in the dot-net paradigm. So I have avoided pointers and just use offsets instead.

namespace qtxlib;

interface

type

  // in-memory pixel format
  TPixelFormat = public (
      pf8bit  = 0,  //___8 -- palette indexed
      pf15bit = 1,  //_555 -- 15 bit encoded
      pf16bit = 2,  //_565 -- 16 bit encoded
      pf24bit = 3,  //_888 -- 24 bit native
      pf32bit = 4   //888A -- 32 bit native
      );

  TPixelBuffer = public class
  private
    FPixels:  array of Byte;
    FDepthLUT: array of Integer;
    FScanLUT: array of Integer;
    FStride:  Integer;
    FWidth:   Integer;
    FHeight:  Integer;
    FBytes:   Integer;
    FFormat:  TPixelFormat;
  protected
    function  CalcStride(const Value, PixelByteSize, AlignSize: Integer): Integer;
    function  GetEmpty: Boolean;
  public
    property  Width: Integer read FWidth;
    property  Height: Integer read FHeight;
    property  Stride: Integer read FStride;
    property  &Empty: Boolean read GetEmpty;
    property  BufferSize: Integer read FBytes;
    property  PixelFormat: TPixelFormat read FFormat;
    property  Buffer[const index: Integer]: Byte read (FPixels[&index]) write (FPixels[&index]);

    function  OffsetForPixel(const dx, dy: Integer): Integer;
    procedure Alloc(NewWidth, NewHeight: Integer; const PxFormat: TPixelFormat);
    procedure Release();

    function Read(Offset: Integer; ByteLength: Integer): array of Byte;
    procedure Write(Offset: Integer; const Data: array of Byte);

    constructor Create; virtual;

    finalizer;
    begin
      if not GetEmpty() then
        Release();
    end;
end;

TColorMixer = public class
end;

TPainter = public class
private
  FBuffer:    TPixelBuffer;
public
  property    PixelBuffer: TPixelBuffer read FBuffer;

  constructor Create(const PxBuffer: TPixelBuffer); virtual;
end;

implementation

//##################################################################################
// TPainter
//##################################################################################

constructor TPainter.Create(const PxBuffer: TPixelBuffer);
begin
  inherited Create();
  if PxBuffer  nil then
    FBuffer := PxBuffer
  else
    raise new Exception("Pixelbuffer cannot be NIL error");
end;

//##################################################################################
// TPixelBuffer
//##################################################################################

constructor TPixelBuffer.Create;
begin
  inherited Create();
  FDepthLUT := [1, 2, 2, 3, 4];
end;

function TPixelBuffer.GetEmpty: Boolean;
begin
  result := length(FPixels) = 0;
end;

function TPixelBuffer.OffsetForPixel(const dx, dy: integer): Integer;
begin
  if length(FPixels) > 0 then
  begin
    result := dy * FStride;
    inc(result, dx * FDepthLUT[FFormat]);
  end;
end;

procedure TPixelBuffer.Write(Offset: Integer; const Data: array of Byte);
begin
  for each el in Data do
  begin
    FPixels[Offset] := el;
    inc(Offset);
  end;
end;

function TPixelBuffer.Read(Offset: Integer; ByteLength: Integer): array of Byte;
begin
  result := new Byte[ByteLength];
  var xOff := 0;
  while ByteLength > 0 do
  begin
    result[xOff] := FPixels[Offset];
    dec(ByteLength);
    inc(Offset);
    inc(xOff);
  end;
end;

procedure TPixelBuffer.Alloc(NewWidth, NewHeight: Integer; const PxFormat: TPixelFormat);
begin
  if not GetEmpty() then
    Release();

  if NewWidth < 1 then
    raise new Exception("Invalid width error");

  if NewHeight  0 then
    result := ( (Result + AlignSize) - xFetch );
end;

end.

This code is just meant to give you a feel for the dialect. I have used a lot of “Delphi style” coding here, so chances are you will hardly see any difference bar namespaces and a funny looking property declaration.

Stay tuned for more posts as I explore the different aspects of Oxygene and webassembly in the days to come 🙂

RemObjects Remoting SDK?

June 3, 2019 Leave a comment

Reading this you could be forgiven for thinking that I must promote RemObjects products, It’s my job now right? Well yes, but also no.

dataabstract-illustration-rework-ro-1100The thing is, I’m really not “traveling salesman” material by any stretch of the imagination. My tolerance for bullshit is ridiculously low, and being practical of nature I loath fancy products that cost a fortune yet deliver nothing but superficial fluff.

The reasons I went to work at RemObjects are many, but most of all it’s because I have been an avid supporter of their products since they launched. I have used and seen their products in action under intense pressure, and I have come to put some faith in their solutions.

Trying to describe what it’s like to write servers that should handle thousands of active user “with or without” RemObjects Remoting SDK is exhausting, because you end up sounding like a fanatic. Having said that, I feel comfortable talking about the products because I speak from experience.

I will try to outline some of the benefits here, but you really should check it out yourself. You can download a trial directly here: https://www.remotingsdk.com/ro/

Remoting framework, what’s that?

RemObjects Remoting framework (or “RemObjects SDK” as it was called earlier) is a framework for writing large-scale RPC (remote procedure call) servers and services. Unlike the typical solutions available for Delphi and C++ builder, including those from Embarcadero I might add, RemObjects framework stands out because it distinguishes between transport, host and message-format – and above all, it’s sheer quality and ease of use.

compo

RemObjects Remoting SDK ships with a rich selection of channels and message formats

This separation between transport, host and message-format makes a lot of sense, because the parameters and data involved in calling a server-method, shouldn’t really be affected by how it got there.

And this is where the fun begins because the framework offers you a great deal of different server types (channels) and you can put together some interesting combinations by just dragging and dropping components.

How about JSON over email? Or XML over pipes?

The whole idea here is that you don’t have to just work with one standard (and pay through the nose for the privilege). You can mix and match from a rich palette of transport mediums and message-formats and instead focus on your job; to deliver a kick-ass product.

And should you need something special that isn’t covered by the existing components, inheriting out your own channel or message classes is likewise a breeze. For example, Andre Mussche have some additional components on GitHub that adds a WebSocket server and client. So there is a lot of room for expanding and building on the foundation provided by RemObjects.

And this is where RemObjects has the biggest edge (imho), namely that their solutions shaves weeks if not months off your development time. And the central aspect of that is their integrated service designer.

Integration into the Delphi IDE

Dropping components on a form is all good and well, but the moment you start coding services that deploy complex data-types (records or structures) the amount of boilerplate code can become overwhelming.

The whole point of a remoting framework is that it should expose your services to the world. Someone working in .net or Java on the other side of the planet should be able to connect, consume and invoke your services. And for that to happen every minute detail of your service has to follow standards.

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The RemObjects Service Builder integrates directly into the Delphi IDE

When you install RemObjects SDK, it also integrates into the Delphi IDE. And one of the features it integrates is a complete, separate service designer. The designer can also be used outside of the Delphi IDE, but I cannot underline enough how handy it is to be able to design your services visually, right there and then, in the Delphi IDE.

This designer doesn’t just help you design your service description (RemObjects has their own RODL file-format, which is a bit like a Microsoft WSDL file), the core purpose is to auto-generate all the boilerplate code for you — directly into your Delphi project (!)

So instead of you having to spend a week typing boilerplate code for your killer solution, you get to focus on implementing the actual methods (which is what you are supposed to be doing in the first place).

DLL services, code re-use and multi-tenancy

The idea of multi-tenancy is an interesting one. One that I talked about with regards to Rad-Server both in Oslo and London before christmas. But Rad-Server is not the only system that allows for multi-tenancy. I was doing multi-tenancy with RemObjects SDK some 14 years ago (if not earlier).

Remember how I said the framework distinguishes between transport, message and host? That last bit, namely host, is going to change how you write applications.

When you install the framework, it registers a series of custom project types inside the Delphi IDE. So if you want to create a brand new RemObjects SDK server project, you can just do that via the ordinary File->New->Other menu option.

One of the project types is called a DLL Server. Which literally means you get to isolate a whole service library inside a single DLL file! You can then load in this DLL file and call the functions from other projects. And that is, ultimately, the fundamental principle for multi-tenancy.

And no, you don’t have to compile your project with external packages for this to work. The term “dll-server” can also be a bit confusing, because we are not compiling a network server into a DLL file, we are placing the code for a service into a DLL file. I used this project type to isolate common code, so I wouldn’t have to copy unit-files all over the place when delivering the same functionality.

It’s also a great way to save money. Don’t want to pay for that new upgrade? Happy with the database components you have? Isolate them in a DLL-Server and continue to use the code from your new Delphi edition. I have Delphi XE3 Database components running inside a RemObjects DLL-Server that I use from Delphi XE 10.3.

project_types

DLL server is awesome and elegantly solves real-life problems out of the box

In my example I was doing business-logic for our biggest customers. Each of them used the same database, but they way they registered data was different. The company I worked for had bought up these projects (and thus their customers with them), and in order to keep the customers happy we couldn’t force them to re-code their systems to match ours. So we had to come up with a way to upgrade our technology without forcing a change on them.

The first thing I did was to create a “DLL server” that dealt with the database. It exposed methods like openTable(), createInvoice(), getInvoiceById() and so on. All the functions I would need to work with the data without getting my fingers dirty with SQL outside the DLL. So all the nitty gritty of SQL components, queries and whatnot was neatly isolated in that DLL file.

I then created separate DLL-Server projects for each customer, implemented their service interfaces identical to their older API. These DLL’s directly referenced the database library for authentication and doing the actual work.

62174838_10156255134895906_9195165500563259392_n

When integrated with the IDE, you are greeted with a nice welcome window when you start Delphi. Here you can open examples or check out the documentation

Finally, I wrapped it all up in a traditional Windows system service, which contained two different server-channels and the message formats they needed. When the service was started it would simply load in the DLL’s and manually register their services and types with the central channel — and voila, it worked like a charm!

Rock solid

Some 10 years after I delivered the RemObjects based solution outlined above, I got a call from my old employer. They had been victim of a devastating cyber attack. I got a bit anxious as he went on and on about damages and costs, fearing that I had somehow contributed to the situation.

targets

But it turned out he called to congratulate me! Out of all the services in their server-park, mine were the only ones left standing when the dust settled.

The RemObjects payload balancer had correctly dealt with both DDOS and brute force attacks, and the hackers were left wanting at the gates.

New job, new office, new adventures

May 12, 2019 5 comments

It’s been roughly 4 weeks since I posted a status report on Amibian.js. I normally keep people up-to-date on facebook (the “Amiga Disrupt” and also “Delphi Developer” groups). It’s been a very hectic month so I fully understand that people are asking. So let’s look at where the project is at and where we are on the time-line.

For those that might not know, I decided to leave Embarcadero a couple of months ago. I will be working out may before I move on. I wanted to write about that myself in a clean fashion, but sadly the news broke on Facebook prematurely.

Long story short, I have been very fortunate to work at Embarcadero. I am not leaving because there is anything wrong or something like that. I was hired as SC for the EMEA regions, which basically made me the support and presenter for most of europe, parts of asia and the middle east. It’s been a great adventure, but ultimately I had to admit that my passion is coding and community work. Sales is a very important part of any company, but it’s not really my cup of tea; my passion has always been research and development.

So, come first of June and I start in a new position at RemObjects. A company that has deep roots with Delphi and C++ builder users – and a company that continues to produce a wealth of high-quality, high-performance frameworks for Delphi and C++ builder. RemObjects also has a strong focus on modern languages, and have a strong portfolio of new and exciting compilers and languages to offer. The Oxygene compiler should be no stranger to Delphi developers, a powerful object-pascal dialect that can target a variety of platforms and chipsets.

Since compiler technology and run-time systems has been my main focus for well over a decade now, I feel RemObjects is a better match.

Quartex Components

Quartex Components has been an officially registered Norwegian company for a while now, so perhaps not news. What is news is that it’s now directly connected with the development of the Quartex Media Desktop (codename “Amibian.js”). While Amibian.js is an open source endeavour, there will be both free and commercial products running on top of that platform. I have written at length about Cloud Forge in the past, so I wont re-hash that again. But 2020 will see a paradigm shift in how teams and companies approach software development.

quartex

Company logo professionally milled and on its way to my new office

I will also, once there is more time, continue to sell and support software license components.

Quartex Media Desktop

The “Amibian.js” project is moving along nicely. The deadline is Q4 2019, but im hoping to wrap up the core functionality before that. So we are on track and kicking ass 🙂

amibian_01

More and more elaborate functionality is being implemented for the desktop

Here is an overview of work done this month:

  • TSystemService application type has been created (node.js)
    • TApplication now holds IPC functions (inter process communication)
    • Running child processes + sending messages is now simplicity itself
    • Database drivers are 90% done. Delete() and DeleteTable() functionality needs to be implemented in a uniform way
  • Authentication is now a separate service
    • Service database layer is finished (using SQLite3 driver by default)
    • Authentication protocol has been designed
    • Server protocol and JSON message envelopes are done
    • Presently working on the client interface
  • LDEF bytecode assembler has been improved
    • Faster symbolic lookup
    • Smarter register recognition
    • Early support for stack-frames
    • Fixed bug in parser (comma-list parse)
  • QTX framework has seen a lot of work
    • Large parts of the RTL sub-strata has been implemented
    • UTF16 codec implemented
    • QTX versions of common controls:
      • TQTXButton
      • TQTXLabel
      • TQTXToolbar
        • TQTXToolButton
        • TQTXToolSeparator
        • TQTXToolElement
      • TQTXPanel
      • TQTXCheckBox
      • .. and much, much more
  • Desktop changes
    • Link Maker functionality has been added
    • Handshake process between desktop and child app now runs on a separate timer, ensuring better conformity and a more robust initialization
    • The Quartex Editor control has been optimized
      • All redraw calls are now synchronized
      • Canvas is created on demand, avoids flicker during initial redraw
      • Support for DEL key + behavior
      • Gutter is now rendered to an offscreen bitmap and blitted into the control’s canvas. The gutter is only fully rendered when cursor forces the view to change

I will continue to keep everyone up to date about the project. As you can understand, its a bit hectic right now so please be patient – it is turning into an EPIC environment!

Understanding a stack

May 9, 2019 Leave a comment

The concept of stacks is an old one, and together with linked-lists and queues – these form the most fundamental programming concepts a developer needs to master.

But, the stack most people use today in languages like object pascal and C++ are not actual stacks; they are more like “conveniently repurposed lists“. Not a huge issue I agree, but the misconception is enough to cause confusion when people dive into low-level programming.

Adventures in assembly-land

stackishIt might seem odd to focus on something as trivial as a stack, but I have my reasons. A friend of mine who is a brilliant coder with plenty of large projects behind him recently decided to have a go at assembly coding. He was doing fine and everything was great, until he started pushing and popping  things off the stack.

After a little chat I realized that the problem was not his code, but rather how he viewed the stack. He was used to high-level versions of stacks, which in most cases are just lists storing arbitrary sized data – so he was looking at the stack as a TList<item> expecting similar behavior. Superficially a real-stack and a list-stack work the same if all you do is clean push and pop operations, but the moment you start designing a stack-scheme and push more elaborate constructs (stack-frames), things can go wrong really fast.

The nature of a real stack

A “real” stack that is a part of a hardware SOC (system on a chip) has nothing to do with lists. It’s actually a solid chunk of memory with a register to keep track of an offset into this memory block.

Let’s for sake of argument say you have 4k of stack space right? It’s clean and contains nothing, so the SP (stack pointer, or offset) is zero. What happens when you push something to the stack? for example:

push EDX

The code above simply writes the content of the EDX register to whatever offset the SP contains. It then updates the SP with the size of the data (EDX is a 32bit register, so the SP is incremented by a longword or 4 bytes). In Delphi pseudocode what happens is something like:

var LAddr := FStackBuffer;
inc(LAddr, SP);
PLongword(LAddr)^ := EDX;
inc(SP, SizeOf(EDX));

The thing about a stack is that it doesn’t manage data-length for you. And that is a big difference to remember. It will push or pop data based on the size of the source (in this case the 32bit EDX register) you use.

If you push 1024 bytes of data to a list based stack, the list keeps track of the size and data for you. So when you pop the data from the stack, you get back that data regardless. But a “real” stack couldn’t care less — which is also why it’s so easy to screw up an entire program if you make a mistake.

In short: The length of what you push – must be matched when you pop the data back (!) If you push a longword, you MUST pop a longword later.

Benefits of a real stack

call stackThe benefit is that the cost of storing values on a stack is almost zero in terms of cpu operations. A list based stack is more expensive; it will allocate memory for a record-item to hold the information about the data, then it will allocate memory to hold the actual data (depends on the type naturally) and finally copy the data into the newly allocated buffer. Hundreds if not thousands of instructions can be involved here.

A real stack will just write whatever you pushed directly into the stack-memory at whatever offset SP is at. Once written it will add the length of the write to the SP – and that’s it! So it’s one of the oldest and fastest mechanisms for lining up data in a predictable way.

Again the rules are simple: when you pop something off the stack, the size must match whatever you used to push it there. So if you pushed a longword (EDX) you also have to make sure you use a 32-bit target when you pop the value back. If you use RDX, which is 64 bit then you will essentially steal 4 bytes from something else using that stack – and all hell will break loose down the line.

Stack schemes and frames

Im not going to dig too deeply into stack-frames here, but instead write a few words about stack-schemes and using the stack to persist data your code relies on. The lines blur between those two topics anyways.

The SP (stack pointer) is not just a simple offset you can read, you can also write and change it (it also serves as a pointer). You can also read from whatever memory the SP is pointing at without polling any data from the stack.

What language developers usually do, is that they design entire structures on the stack that are, when you get into the nitty-gritty, “offset based records”. For example, lets say you have a record that looks like this:

type
PMyRecord ) ^TMyRecord;
TMyRecord = record
  first: Pointer;
  second: integer;
  Third: array[0..255] of longword;
end;

Instead of allocating conventional ram to hold that record, people push it to the stack and then use offsets to read and update the values there. A bit like a super global variable if you like. This is why when you disassemble code, you find stuff like:

mov EDX, (SP)+4

If the above record was on the stack, that pseudo code would move the field “second” into the EDX register. Because that field is 4 bytes from the stack start (providing SP points to zero).

Every programming language has a stack scheme to keep track of things. Local variables, global variables, class instances, type RTTI — most of these things are allocated in conventional ram – but there is a “program record” on the stack that makes it easy to access that information quickly.

This “moving a whole record onto the stack” is basically what a stack-frame is all about. It used to be a very costly affair with a heavy cpu speed penalty. If you look in your Delphi compiler options you will see that there is a checkbox regarding this very topic. Delphi can be told to avoid stack-frames and do register allocation instead, which was super quick compared to stack-frames – but CPU’s today are largely optimized for stack-frame allocation as default, so I doubt there is much to gain by this in 2019.

Note: A stack frame is much more, but its out of scope for this post. Google it for more info.

To sum up

When doing high-level coding you don’t really need to bother with the nuances between a TStack<item> and a “real” stack. But if you plan on digging deeper and learning a few lines of assembly – learning the differences is imperative. Its boring stuff but as fundamental as wheels on a bicycle. There is no way to avoid it, so might as well jump in.

In its absolute raw form, here is roughly the same functionality for Delphi. This was written on the fly in 2 minutes while on the road, so its purely to give you a rough idea of behavior. I would add a secondary field to keep track of the end (next insertion point), that way SP can be changed without overwriting data on new pushes.

And yes, wrapping this in a TObject utterly defeats the purpose of low-level coding, but hopefully it gives you some idea of the differences 🙂

stack_01

stack_02