XDL Language Server and VS Code Extension

Version: 1.0 Date: November 2025 Status: Complete ✅

Overview

XDL includes a full-featured Language Server Protocol (LSP) implementation and VS Code extension, providing modern IDE features for XDL development.

Features

Language Server (xdl-lsp)

The XDL Language Server provides:

Feature Description
Document Sync Full text synchronization with incremental updates
Diagnostics Real-time syntax error reporting
Completion Auto-completion for keywords, functions, procedures, system variables
Hover Documentation on hover for 100+ built-in functions
Go to Definition Jump to function/procedure/variable definitions
Find References Find all uses of a symbol
Document Symbols Outline view of functions, procedures, and variables
Semantic Tokens Enhanced syntax highlighting beyond TextMate grammar

VS Code Extension (vscode-xdl)

The extension provides:

  • Syntax Highlighting: Full TextMate grammar for XDL syntax
  • Language Configuration: Brackets, comments, folding, indentation
  • File Associations: .xdl and .pro file extensions
  • Commands: Restart server, run file
  • LSP Integration: All language server features

Installation

Building the Language Server 

# Build in release mode
cargo build -p xdl-lsp --release

# Binary location
./target/release/xdl-lsp.exe   # Windows
./target/release/xdl-lsp       # Linux/macOS

Installing the VS Code Extension 

# Navigate to extension directory
cd vscode-xdl

# Install dependencies
npm install

# Compile TypeScript
npm run compile

# Package extension
npx vsce package

# Install the .vsix file
code --install-extension xdl-language-0.1.0.vsix

Configuration

The extension can be configured via VS Code settings:

Setting Type Default Description
xdl.lsp.enabled boolean true Enable/disable the language server
xdl.lsp.path string "" Path to xdl-lsp executable (leave empty for bundled/PATH)
xdl.trace.server string "off" Trace level: off, messages, verbose

LSP Server Architecture

Components 

xdl-lsp/
├── src/
│   ├── main.rs           # Entry point with tracing setup
│   ├── server.rs         # Tower-lsp LanguageServer implementation
│   ├── document.rs       # Document state with ropey text handling
│   ├── diagnostics.rs    # Parse error to LSP diagnostic conversion
│   ├── symbols.rs        # Symbol table with 100+ builtins
│   ├── completion.rs     # Completion provider
│   ├── hover.rs          # Hover information provider
│   ├── goto.rs           # Go-to-definition and references
│   ├── semantic_tokens.rs # Semantic token provider
│   └── utils.rs          # Position/offset utilities

Dependencies

  • tower-lsp: LSP protocol implementation
  • tokio: Async runtime
  • ropey: Efficient text rope for document handling
  • dashmap: Concurrent hash map for document storage
  • xdl-parser: XDL parsing for AST analysis

VS Code Extension Architecture

Components 

vscode-xdl/
├── src/
│   └── extension.ts      # LSP client and command handlers
├── syntaxes/
│   └── xdl.tmLanguage.json  # TextMate grammar
├── package.json          # Extension manifest
├── language-configuration.json  # Language settings
└── tsconfig.json         # TypeScript configuration

TextMate Grammar Scopes

Scope Elements
comment.line.semicolon.xdl ; line comments
string.quoted.single.xdl Single-quoted strings
string.quoted.double.xdl Double-quoted strings
constant.numeric.* Numbers (integer, float, hex, octal, binary)
keyword.control.xdl Control flow (IF, FOR, WHILE, etc.)
keyword.other.xdl Declarations (FUNCTION, PRO, etc.)
keyword.operator.* Operators (AND, OR, EQ, +, -, etc.)
variable.language.system.xdl System variables (!PI, !DPI, etc.)
entity.name.function.xdl Function/procedure names
support.function.builtin.xdl Built-in functions (100+)
support.function.procedure.xdl Built-in procedures (50+)

Supported Built-in Functions

The LSP provides hover documentation and completion for:

Mathematical Functions

SIN, COS, TAN, ASIN, ACOS, ATAN, SINH, COSH, TANH, SQRT, EXP, ALOG, ALOG10, ABS, CEIL, FLOOR, ROUND, FIX, FLOAT, DOUBLE, COMPLEX, IMAGINARY, CONJ

Array Functions

FINDGEN, INDGEN, DINDGEN, BINDGEN, LINDGEN, FLTARR, DBLARR, INTARR, BYTARR, LONARR, STRARR, COMPLEXARR, MAKE_ARRAY, REPLICATE, WHERE, N_ELEMENTS, SIZE, REFORM, TRANSPOSE, REVERSE, SHIFT, ROTATE, SORT, UNIQ

Statistics

TOTAL, MEAN, MEDIAN, VARIANCE, STDDEV, MIN, MAX, MOMENT, CORRELATE, HISTOGRAM

String Functions

STRLEN, STRMID, STRPOS, STRTRIM, STRUPCASE, STRLOWCASE, STRING, STRSPLIT, STRJOIN, STRCMP, BYTE

I/O Functions

PRINT, PRINTF, WRITEF, WRITEU, READF, READU, OPENR, OPENW, OPENU, CLOSE, FREE_LUN, GET_LUN, POINT_LUN, READ_ASCII, READ_CSV, READ_BINARY, DIALOG_PICKFILE

System Functions

SYSTIME, FILEPATH, FILE_TEST, FILE_INFO, FILE_SEARCH, FILE_LINES, FILE_BASENAME, FILE_DIRNAME, GETENV, SETENV, SPAWN

Graphics Procedures

PLOT, OPLOT, PLOTS, CONTOUR, SURFACE, SHADE_SURF, TV, TVSCL, WINDOW, WSET, WSHOW, WDELETE, DEVICE, ERASE, XYOUTS, AXIS, POLYFILL, CURSOR

System Variables

The LSP recognizes XDL system variables (prefixed with !):

Variable Description
!PI Pi (single precision)
!DPI Pi (double precision)
!E Euler’s number
!RADEG Radians to degrees conversion factor
!DTOR Degrees to radians conversion factor
!NULL Null value
!TRUE Boolean true
!FALSE Boolean false
!VERSION XDL version information
!DIR XDL installation directory
!PATH Search path for procedures
!PROMPT Command prompt string
!QUIET Suppress informational messages

Commands

VS Code Commands

Command Description
XDL: Restart Language Server Restart the LSP server
XDL: Run Current File Execute the current XDL file

Troubleshooting

Language Server Not Starting

  1. Check that xdl-lsp is in your PATH or configure xdl.lsp.path
  2. View the Output panel (View > Output > XDL Language Server)
  3. Set xdl.trace.server to verbose for detailed logs

Syntax Highlighting Not Working

  1. Ensure file has .xdl or .pro extension
  2. Check that language mode is set to “XDL” in status bar
  3. Try reloading the VS Code window

Diagnostics Not Appearing

  1. Verify the LSP server is running (check Output panel)
  2. Ensure the file is saved (diagnostics update on save)
  3. Check for valid XDL syntax

Development

Building from Source 

# Clone repository
git clone https://github.com/TuringWorks/xdl
cd xdl

# Build LSP server
cargo build -p xdl-lsp --release

# Build VS Code extension
cd vscode-xdl
npm install
npm run compile

Running Tests 

# LSP server tests
cargo test -p xdl-lsp

# Extension compile check
cd vscode-xdl && npm run compile

Future Enhancements

  • Code formatting
  • Rename symbol
  • Code actions (quick fixes)
  • Workspace symbol search
  • Call hierarchy
  • Type hierarchy
  • Inlay hints
  • Folding ranges from AST