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Pascal Code Formatter (Quadroid JCF Fork)

My hard fork of JEDI Code Formatter CLI from Bee Jay, which itself is a fork of Lazarus JCF, that I slightly improved with better indentation and much needed support for modern Delphi variable declarations. It was really hard to get around in its ancient, complex, and almost completely undocumented code. Still, I managed to implement what I wanted. It’s just hardly can be extended or improved any further given how tricky input source code can be and how difficult it is to target individual edge cases in the AST without breaking something else somewhere. In the future it would be better to switch to a formatter that doesn’t require deep parsing of the source.

(The updated VSCode extension that works with this version is also available, pull request.)

Changes include:

  • Support for Delphi inline variable declarations:

    var I: Integer := 10;

    With type inference:

    var I := 42;

    Inside for statement:

    for var I := Low (myArray) to High (myArray) do

    Source files with inline variables no longer cause formatter to fail.

  • New option IndentCaseLabels to control indentation of case label statements independently from the whole case block. E.g., with IndentCaseLabels set to True (default):

    case i of
  1..9:
    for i := 1 to i do write(i, ',');
  10: begin
    writeln;
    writeln;
  end;
  else
    myProcedure;
end;

    With IndentCaseLabels set to False:

    case i of
1..9:
  for i := 1 to i do write(i, ',');
10: begin
  writeln;
  writeln;
end;
else
  myProcedure;
end;

  • New option IndentMethodParams, so it’s possible to write method parameters like this (IndentMethodParams set to False):

    function myFunction(aParam: string
; aParam2: real): boolean;

    And avoid second line being indented. Otherwise (set to True):

    function myFunction(aParam: string
  ; aParam2: real): boolean;

  • New option IndentInterfaceGuid to prevent interface GUID from being indented. Set to True:

    IFace = interface
  ['{5E3C2BCA-56C8-46DE-959F-338AF5F69C1A}']
  procedure proc;
end;

    Set to False:

    IFace = interface
['{5E3C2BCA-56C8-46DE-959F-338AF5F69C1A}']
  procedure proc;
end;

  • Formatter now correctly processes line endings inside comments and also avoids formatting control statements with comments in-between them.

  • The formatter source code has been processed through the formatter itself to validate correct function “in the wild”.

Unless I forgot something, all my changes are “tagged” with // fix: comments.

Binaries are available. The 64-bit Windows build is from FPC. The 32-bit Windows version is built with Delphi. Other operating systems should build with little to no changes.

How to test:

pascal-format -config=pascal-format.new.cfg -out test.fmt.pas test.pas

TODO: with GUI now removed, debugging parsed AST is impossible, unless doing it by trial and error. The AST view needs to be rewritten to output in textual form, or, better yet, simply remade in LCL (but without Delphi support). Should be fairly simple to do given it’s basically just a tree view on an empty form.

So here it is in case if someone else wants to waste their time and continue trying to make this thing smarter.

Original description follows.

Jedi Code Formatter CLI

I (Bee Jay) took Jedi Code Formatter (JCF) from Lazarus IDE repository and made it as CLI (command line interface) version by removing all the GUI (graphical user interface) parts from the original GUI version. The CLI version can be used as Pascal code formatter in Visual Studio Code, or as backend engine of an online Pascal code beautifier.

Original: a copy (sometimes modified) of r823 jcf2 svn tree: https://jedicodeformat.svn.sourceforge.net/svnroot/jedicodeformat/trunk/CodeFormat/Jcf2

Original author: Anthony Steele.

Original license: MPL 1.1.

How To Build Using Lazarus

  1. You must have Lazarus IDE already installed on your system.
  2. Clone or download this jcf-pascal-format GitHub repo into your own folder.
  3. Start your Lazarus IDE and open pascal_format.lpi project within jcf-pascal-format/App folder.
  4. Build it via Lazarus' Run → Build menu.
  5. Wait while Lazarus is building the JCF project.
  6. Take the executable pascal-format file from jcf-pascal-format folder along with the pascal-format.cfg configuration file.
  7. Just to make sure, test it from Terminal using ./pascal-format -? command. It should show the usage manual.

How To Build Using VS Code

  1. You must have both Free Pascal compiler and VS Code already installed on your system.
  2. Clone or download this jcf-pascal-format GitHub repo into your own folder.
  3. Start your VS Code and open pascal_format.lpi project within jcf-pascal-format/App folder.
  4. Build it via VS Code's Tasks → Run Task... → pascal-format: Build Release menu.
  5. Wait while FPC is building the jcf-pascal-format project.
  6. Open test.pas file from jcf-pascal-format folder.
  7. Test JCF program using Tasks → Run Task... → pascal-format: Test CLI Program menu and you should see the result in the test.pas file.

How To Use jcf-pascal-format in VS Code

  1. Copy the pascal-format and pascal-format.cfg config files into your Pascal workspace folder.
  2. Create a new VS Code task or open the tasks.json if you already have one.
  3. Copy the task example below and paste it into your tasks.json file.
{
  "label"  : "JCF: Beautify Code",
  "type"   : "shell",
  "command": "./pascal-format",
  "args": [
    "${file}",
    "-clarify",
    "-inplace",
    "-config=pascal-format.xml"
  ],
  "presentation": {
    "reveal": "never"
  },
  "problemMatcher": []
},
  1. It's a task to beautify Pascal code.
  2. If you need a task to obfuscate code, simply make another task using the code above, but then change -clarify arg into -obfuscate.
  3. Save your tasks.json. Now you should have new pascal-format's tasks in your tasks list.

The Problem With JCF

Although JCF is a good Pascal code formatter, it has one single problem that quite annoying. JCF requires the code must be compilable which means it has to be a complete program and syntactically correct. JCF will fail on code snippets or wrong code. To make it works on code snippet, it must be put between a begin..end pair and has a correct program header, like this:

program test;

begin
  // put code snippet here
end.

Demo

Here's JCF CLI in action within VS Code (with OmniPascal):

Note: If you're also interested in my other tasks shown in the demo, see my gist about it here.

Hope it's gonna be useful to other Pascal fellows out there. Have fun! 😊