Add Delphi support to autowrap

Description

The aim of this project is to enable the D community to write multi operation system GUI application using an IDE. Delphi allows to write GUI application for Windows / MacOS, Android and iOS using a single code line. It has a highly sophisticated UI toolkit (FireMonkey) while UIs can be easily clicked together. Delphi has a a free community version (with restrictions also free for commercial projects). In addition it integrates very well with the different stores (Microsoft Store, Android Playstore, ...).

By adding support for Delphi to autowrap, D classes and their methods / attributes can be directly called from Delphi code (e.g. Button handlers) as if they were written in Delphi.

Example: A dub project has a dependency to autowrap and has the targetType dynamicLibrary. It has a module lib.d with this coding:

module lib;

import autowrap.delphi;

class Foo
{
    void bar(int i)
    {
        return i;
    }
}

mixin(
    wrapDelphi(
        Modules(
            Module("lib")
        ),
        OutputFolder("includes"),
        LibraryName("dmodules"),
    )
);

Command dub build will create a file dmodules.so and also a file includes/lib.pas. In Delphi the folder includes is known. lib.pas contains a Delphi class Foo which will forward all method calls, attribute read / writes,... to the D code within dmodules.so.

What are rough milestones of this project?

Generate Delphi wrapper code for D classes / functions
Get Windows applications running
Get Android applications running
Get MacOS applications running
Get iOS applications running

How does this project help the D community?

Finally it would be possible to write GUI applications for Windows / MacOS and the mobile world in a straight forward way. Just use a very thin Delphi layer and call directly into D classes.

Known issues

Delphi cannot resolve circular references. Developer is forced to write code without circular references or in some cases resolve them using forward declarations.
D does not allow writing files (pascal wrapper files) during compile time. A workaround could be the usage of dub postGenerate hook. https://github.com/symmetryinvestments/autowrap/issues/250

Recommended skills

Delphi

(If applicable, e.g. GSoC/SAoC)

What can students expect to get out of doing this project?

Point of Contact

## References https://github.com/symmetryinvestments/autowrap/issues/249

dlang / project-ideas