tree-sitter-vba

A Tree-sitter grammar for Visual Basic for Applications (VBA).

Fills the gap of the long-missing tree-sitter VBA parser — the only production-ready open-source VBA grammar for tree-sitter.

Features

• ✅ Case-insensitive keywords — VBA is case-insensitive by nature; Sub, sub, and SUB all match correctly
• ✅ Line continuation — supports VBA's _ line continuation character
• ✅ Full VBA statement coverage — Sub/Function/Property, If/ElseIf/Else, For/For Each/While/Do loops, Select Case, With, Dim, Const, Set, GoTo, error handling, file I/O, and more
• ✅ Expression hierarchy — proper operator precedence for arithmetic, comparison, logical, and concatenation operators
• ✅ Pre-built DLL — compiled for Windows with MSVC ABI compatibility (via Zig)

Project Structure

tree-sitter-vba/
├── grammar.js              # Tree-sitter grammar definition
├── src/
│   ├── parser.c            # Generated C parser (1.2M)
│   ├── node-types.json     # AST node type definitions
│   └── grammar.json        # Grammar metadata
├── tree_sitter_vba.dll     # Pre-built Windows DLL (MSVC compatible)
├── sgconfig.yml            # ast-grep custom language config
├── rules/                  # ast-grep search rules
│   └── find_subs.yml       # Example rule: find all Sub procedures
├── test/
│   ├── sample.bas          # Sample VBA test file
│   └── simple.bas          # Simple VBA test file
└── tree-sitter.json        # Tree-sitter configuration

Usage

As a Tree-sitter grammar

# Install the grammar
npm install @arrmee/tree-sitter-vba

# Or generate from source
npx tree-sitter generate
npx tree-sitter build

With Python

import ctypes
from tree_sitter import Language, Parser

lib = ctypes.CDLL('./tree_sitter_vba.dll')
lib.tree_sitter_vba.restype = ctypes.c_void_p
lang = Language(lib.tree_sitter_vba())

parser = Parser(lang)
tree = parser.parse(bytes(code, 'utf-8'))

With C/C++

#include "tree_sitter/api.h"
TSLanguage *tree_sitter_vba();

TSLanguage *vba = tree_sitter_vba();
TSParser *parser = ts_parser_new();
ts_parser_set_language(parser, vba);

With ast-grep (custom language)

# sgconfig.yml
customLanguages:
  vba:
    libraryPath: ./tree_sitter_vba.dll
    extensions:
      - .bas
      - .cls
      - .frm

Building from Source

Prerequisites

• Tree-sitter CLI
• A C compiler (GCC/MinGW, MSVC, or Zig)

Generate & Build

# Generate the C parser from grammar.js
npx tree-sitter generate

# Compile the shared library with Zig (MSVC compatible)
zig cc -shared -O3 -I src src/parser.c -o tree_sitter_vba.dll -target x86_64-windows-msvc

License

GPL-3.0. Derived from Rubberduck VBA ANTLR4 grammar (Copyright Ulrich Wolffgang, Rubberduck Contributors), licensed under GPL-3.0.

Why another VBA parser?

Existing tree-sitter VBA grammars were either:

• Incomplete — only parsing a subset of VBScript (tree-sitter-vbscript)
• Wrong language — targeting VB.NET (tree-sitter-vb-dotnet) which has significant syntax differences from VBA
• Abandoned — started but never reached production quality

This grammar is implemented from scratch based on the Microsoft VBA Language Specification. It was developed using AI-assisted translation with manual validation and extensive testing against real-world VBA codebases.