Pascal Language Server

An LSP server implementation for Pascal variants that are supported by Free Pascal. It uses CodeTools from Lazarus as backend.

https://github.com/Isopod/pascal-language-server notes:

Forked from the original project, but has since been mostly rewritten. This fork adds many new features and fixes several bugs.

Castle Game Engine fork features

Features of Castle Game Engine fork:

• We are a fork of Philip Zander LSP Pascal server

• We contribute back improvements that are not CGE-specific (see e.g. Isopod#1 , Isopod#2 , Isopod#4 ).

• We add capability to configure the LSP server using castle-pasls.ini to:

  • Define Castle Game Engine path that will make pasls aware of CGE units and autocomplete CGE API.
  • Add extra FPC options.
  • Provide custom Lazarus config location (useful if you install Lazarus by fpcupdeluxe but still want pasls to read Lazarus config -- this is optional).
  • Improve debugging by known log filename and more complete JSON logs.

• We can also auto-detect Castle Game Engine path in some situations:

  • If the LSP server binary is distributed in bin of Castle Game Engine.
  • Or if the environment 'CASTLE_ENGINE_PATH` is defined (but note that accessing environment is not possible when this is run by VS Code extension).
  • Or if you're on Unix and using /usr/src/castle-engine/ or /usr/local/src/castle-engine/.

• We also pass Castle Game Engine options that are also passed by CGE build tool like -Mobjfpc -Sm -Sc -Sg -Si -Sh.

• We autodetect OS and CPU harder, and we fix OS=windows to proper win64 or win32 (common mistake, esp. because of genericptr/pasls-vscode#1 ).

Features

• Code completion
• Signature help
• Go to declaration
• Go to definition
• Automatic dependency resolution for .lpk and .lpr files
• Works with include files, as long as they specify {%MainUnit xxx.pas} at the top (just like for Lazarus CodeTools)
• Detection of Castle Game Engine unit paths in a various ways

Building

First, make sure, submodules are loaded:

git submodule update --init --recursive

To compile, open the project file in Lazarus or use the command line:

cd server
lazbuild pasls.lpi

It is recommended to use Free Pascal Compiler version 3.2.0 and Lazarus version 2.0.8 or later, older versions are not officially supported.

Clients

Neovim ≥ 0.5.0

For information on how to use the server from Neovim, see client/nvim.

Emacs

To use the server from lsp-mode in Emacs, install the separate lsp-pascal module. Full example setup of it is documented in Michalis notes about LSP + Pascal.

VS Code

Install the VS Code extension from https://github.com/genericptr/pasls-vscode .

Note that the extension settings expose some additional LSP options not understood by this LSP server. But the basic ones (FPC, Lazarus configs and the executable of LSP server) work completely fine with this LSP server.

Other

Any editor that allows you to add custom LSP configurations should work.

Configuration

In order for the language server to find all the units, it needs to know the following parameters:

• location of the FPC standard library source files
• location of the FPC compiler executable
• location of the Lazarus install directory
• the OS you are compiling for
• the architecture you are compiling for

By default, the server will try to auto-detect these parameters from your Lazarus config. It will search for config files in the following locations (the exact paths will depend on your operating system):

• <User settings directory>/lazarus (e.g. /home/user/.config/lazarus)
• <User home directory>/.lazarus (e.g. /home/user/.lazarus)
• <System settings directory>/lazarus (e.g. /etc/lazarus)
• Custom directory specified in castle-pasls.ini as config in [lazarus] section (see below for example). This is useful in case your Lazarus config is in a special directory, as e.g. usually setup by fpcupdeluxe.

In addition, you can also specify these parameters manually in one of the following ways:

1. Set the environment variables:

   • PP — Path to the FPC compiler executable
   • FPCDIR — Path of the source code of the FPC standard library
   • LAZARUSDIR — Path of your Lazarus installation
   • FPCTARGET — Target OS (e.g. Linux, Darwin, ...)
   • FPCTARGETCPU — Target architecture (e.g. x86_64, AARCH64, ...)

   This overrides auto-detected settings.

2. Or specify the locations via LSP initializationOptions. How this is done will depend on your client. The format is the following:

   {
     "PP": "",
     "FPCDIR": "",
     "LAZARUSDIR": "",
     "FPCTARGET": "",
     "FPCTARGETCPU": ""
   }

   This overrides environment variables.

Extra configuration in LSP initialization options

Additional keys in LSP initialization options can be used to influence the LSP server behavior. See the docs of your LSP client (text editor) to know how to pass initialization options.

• syntaxErrorReportingMode (integer): Determines how to report syntax errors. Syntax errors indicate that CodeTools cannot understand the surrounding Pascal code well enough to provide any code completion.

  • 0 (default): Show an error message. This relies on the LSP client (text editor) handling the window/showMessage message. Support in various text editor:

    • VS Code: works.

    • NeoVim (0.8.0): works, the message is shown for ~1 sec by default.

    • Emacs: works, the message is visible in echo area and the *Messages* buffer. You can filter out useless No completion found messages to make it perfect, see https://github.com/michaliskambi/elisp/blob/master/lsp/kambi-pascal-lsp.el for example.

  • 1: Return a fake completion item with the error message. This works well in VC Code and NeoVim -- while the completion item doesn't really complete anything, but the error message is clearly visible.

  • 2: Return an error to the LSP client. Some LSP clients will just hide the error, but some (like Emacs) will show it clearly and prominently.

Extra configuration in castle-engine/pascal-language-server

The pasls reads configuration file castle-pasls.ini in user config dir to enable some additional features.

Where exactly is the config file?

• On Unix: $HOME/.config/pasls/castle-pasls.ini
• On Windows: C:/Users/<username>/AppData/Local/pasls/castle-pasls.ini
• In general: Uncomment WriteLn('Reading config from ', FileName); in server/castlelsp.pas, run pasls manually, see the output.

Allowed options:

[log]
;; Where to write log (contains DebugLog output, allows to debug how everything in pasls behaves).
;; We will add suffix with process id, like '.pid123' .
;; By default none.
filename=/tmp/pasls-log.txt

;; Whether to dump full JSON request/response contents to log (may be quite long).
;; By default this is false (0), and JSON request/response logs are cut at 2000 characters.
;; You change it to true (1) to have full logs, useful at debugging.
full_json=1

[lazarus]
;; Custom directory with Lazarus config.
;; It should contain files like environmentoptions.xml, fpcdefines.xml .
;; See the log output to know if pasls read successfully XML files from there.
config=/home/michalis/installed/fpclazarus/current/config_lazarus/

[castle]
;; Castle Game Engine location.
;;
;; Set this to make pasls autocomplete CGE API by:
;; 1. knowing paths to all CGE units (derived from this CGE path),
;; 2. using default CGE compilation settings, like -Mobjfpc and -Sh (used by CGE build tool and editor).
;;
;; ( Alternatively to this you can define CASTLE_ENGINE_PATH environment variable,
;; but note that VS Code integration prevents all environment variables from reaching pasls now. )
path=/home/michalis/sources/castle-engine/castle-engine/

[extra_options]
;; Specify as many extra FPC options as you want.
;; Each extra option must have a consecutive number, we start from 1, and stop when
;; an option does not exist (or is an empty string).
option_1=-Fu/home/michalis/sources/castle-engine/castle-engine/tests/code/tester-fpcunit
option_2=-dSOME_DEFINE
option_3=-dSOMETHING_MORE

Roadmap

Wishlist

• Renaming of identifiers
• “Find all references”
• Signature help: Highlight active parameter
• Code formatting?

Known bugs

• Signature help does not show all overloads