Pascal Language Server
A Language Server implementation for Pascal, for use with a Visual Studio Code client, semantic language features, and Free Pascal Compiler (FPC) diagnostics integration.
Features
- Document Symbols — Navigate declarations within a Pascal source file.
- Diagnostics — Report compiler diagnostics through Free Pascal Compiler (FPC) integration.
- Hover Information — Inspect symbol information by hovering over identifiers.
- Go to Definition — Navigate to symbol declarations.
- Go to Type Definition — Navigate to the definition of a symbol's type.
- Go to Implementation — Navigate to implementations of declared routines or other supported symbols.
- Find References — Locate references to symbols across source files.
Symbol Resolution
The language server parses Pascal declarations and builds a symbol table to support navigation and reference resolution.
Unit dependencies declared through uses clauses are resolved recursively. The server searches for dependencies in the following locations:
- Currently open documents.
- The directory containing the source file.
- Workspace folders.
- Free Pascal Compiler unit search paths configured through
-Fu.
An end-to-end test verifies definition lookup across a chain of dependent Pascal units.
Syntax Highlighting
Syntax highlighting is provided by a custom TextMate grammar:
syntaxes/pascal.tmLanguage.json
The grammar covers Free Pascal syntax, including:
- Type and variable declarations.
- Procedures, functions, and formal parameters.
- Expressions, operators, and function calls.
- Keywords, literals, and identifiers.
- Comments and compiler directives.
The grammar is maintained separately from the language server's parsing and semantic analysis.
Project Structure
.
├── client/
│ └── src/
│ ├── test/ # End-to-end tests
│ └── extension.ts # VS Code language client entry point
├── server/
│ └── src/
│ └── server.ts # Language server entry point
├── syntaxes/
│ └── pascal.tmLanguage.json # TextMate syntax highlighting grammar
└── package.json # Extension manifest and project scripts
Development Setup
Prerequisites
Running the Extension
- Open the project folder in Visual Studio Code.
- Run
npm install in the project root.
- Press
Ctrl+Shift+B to compile the client and server in watch mode.
- Open the Run and Debug view with
Ctrl+Shift+D.
- Select Launch Client from the debug configuration list.
- Press
F5 to launch the Extension Development Host.
- Open a Pascal source file in the development window to test the language features.
Testing
The project includes an end-to-end test for symbol resolution across multiple Pascal units, validating navigation through recursively resolved uses dependencies.
