[fpc-devel] First pas2js public release

[Benito van der Zander]

Hi,

>
> Naturally, any memory pointer operation is not possible in Javascript. 
> Code that relies on this will not work.


it would be great, if pointers were added.


One trick would be to wrap every variable that is accessed by a pointer 
in an array (or object).  The array can then be used as reference.

For example:

var a: integer;
       b: pinteger;

begin

      a := 10;
      b := @a;
      b^ := 11;
      writeln(a);
      writeln(b^);

end;

becomes

      var a,b
      a = [10]
      b = a
      b[0] = 11;
      alert(a[0])
      alert(b[0])


For pointer arithmetic or pointers inside array elements, it would need 
an additional index:

For example:

var a: integer = 10;
     ar: array[0..1] of integer = (1,2);
     b: pinteger;

begin
      b := @a;
      b^ := 11;
      b := @ar[1]
      b^ := 12;
      dec(b);
      b^ := 13;
end;

becomes

      var a,b,bi,ar
      a = [10]
      ar = [1,2]
      b = a; bi = 0
      b[bi] = 11;
      b = ar; bi = 1
      b[bi] = 12;
      bi--;
      b[bi] = 13;

It does not cover pointers of mixed sizes (e.g. getting a pbyte of an 
integer, or converting double to int64), but the most common things 
should work. pchars should probably get special treatment, too. When it 
is not modified, there is no need to wrap a string in an array, but just 
keep a string reference plus index. Perhaps there need to be two type of 
pchars, readonly and writeable. Only writeable need wrapping.

And then there needs to be some kind of static analysis that only wraps 
those variables/fields in arrays whose address is actually taken anywhere.


Best,
Benito



Am 16.12.2017 um 17:36 schrieb Michael Van Canneyt:
>
> Hello fellow Pascal enthousiasts,
>
> It is with great pleasure that I can finally announce the first publicly
> available version of pas2js. A "beta" version, version 0.8.39.
> The endpoint (for the time being) of nearly 10 years of (slow) 
> development.
>
> pas2js is a Object Pascal to Javascript transpiler. It compiles Object
> pascal, and emits Javascript. The javascript is usable in the browser, 
> and
> in Node.js.
>
> It is open source, and part of FPC/Lazarus. This makes Free Pascal a 
> full-stack development environment for Web Development:
> You can use it to program the server and the browser alike, all from 
> within
> the environment you love so much :)
>
> What does pas2js include ?
> --------------------------
>
> * On the language level:
>
> It supports basically Delphi 7 syntax, interfaces excepted.
> Naturally, any memory pointer operation is not possible in Javascript. 
> Code that relies on this will not work.
>
> This is just the first version, we of course want to add the same 
> language features that exist in Delphi and FPC today.
>
> * On the runtime level:
>
> Beside the compiler itself, there is a basic Object Pascal RTL, and 
> several units from the FPC Packages are also available:
>
> system
> sysutils
> Math
> strutils
> rtlconst
> classes
> contnrs
> DB (yes, TDataset)
> fpcunit testsuite
> custapp
> restconnection
> js (javascript system objects)
> web (browser provided objects)
> libjquery (jquery is available too)
> nodejs (basic node runtime environment)
> typeinfo
> objpas
> browserconsole (support for writeln)
> dateutils
> browserapp
> nodejsapp
>
> * Debugging:
>
> Obviously, the browser debugger can be used to debug the Javascript.
> But there is more: the compiler can emit a source map, and this means 
> that
> if the browser finds the source file, it will display the original source
> file instead of the javascript. You can debug Object pascal in the 
> browser.
>
> * Demoes ?
>
> The package has several demoes, including FPReport, TDataset, JQuery and
> Bootstrap.
>
> * Documentation  ?
>
> As befits an open source project, docs are lagging behind :/
>
> But a WIKI page has been started, it will be expanded as time permits:
>
> http://wiki.freepascal.org/pas2js
>
> * Sources ?
>
> The pas2js compiler sources and RTL sources have been checked in in 
> FPC's subversion repository. The page describes where to find it in SVN.
>
> * Binaries ?
>
> A snapshot is available:
> http://www.freepascal.org/~michael/pas2js/pas2js-demo-0.8.39.zip
>
> * Reporting bugs ?
>
> The FPC bugtracker has now a 'pas2js' project, it can be used to report
> bugs.
>
> * Can you help ?
>
> Yes, of course. There is still a lot of work to be done. Feel free to 
> contact me or Mattias Gaertner with questions.
>
> What about Lazarus ?
> --------------------
>
> Lazarus "understands" the extensions to object pascal (for importing 
> Javascript
> classes) that were borrowed from the JVM version of the compiler, so the
> code completion will continue to work.
>
> Using the pre-compiler command, CTRL-F9 just works. On error, you will be
> shown the error location etc.
>
> Further and deeped integration of pas2js into lazarus is expected. In 
> the first place, IDE integration. Later on, a real widget set for the 
> browser can (and hopefully will) be created.
>
> But that is not all !
> ---------------------
>
> In the very near future, a major Delphi component vendor will announce a
> complete package for RAD web development in the Delphi IDE. The 
> expectation is that later on, the exact same components will be usable 
> in Lazarus. In essence, the component developer has created a complete 
> browser
> widgetset. More than 100 controls are available.
>
> Using this, you can design a web application as you design a desktop app;
> Fully RAD, as you are used to. But even more, you can bind controls on 
> a form to existing tags in a web page, thus preserving the style in 
> the web page.
>
> The first demoes for a selected audience have evoked very positive 
> feedback
> indeed.
>
> All this is based on pas2js.
>
> As soon as I receive permission, I will announce here where it becomes
> available.
>
> Lastly!
> -------
>
> On a more personal note, I wish to explicitly thank Mattias Gaertner 
> for finally
> finishing what has been started a long time ago.
>
> Without him, none of this would have been possible.
>
> The same is true for Detlef Overbeek, editor of Blaise Pascal magazine,
> without his moral and financial help, it would have taken many more 
> years to
> finish this.
>
> It is - for me - a long standing dream finally come true.
>
> Enjoy !
>
> Michael.
> _______________________________________________
> fpc-devel maillist  - fpc-devel at lists.freepascal.org
> http://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-devel

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