BGEX Compiler

0.0.26 verified Fri May 01 auth: no javascript

BGEX (Better Grammar EXtractor) is a language and compiler for defining and generating context-free grammar parsers. v0.0.26 compiles BGEX source into TypeScript parsers that export typed AST nodes. It relies on TypeScript >=5.0 as a peer dependency. Differentiators include native ESM, full TypeScript support, and lightweight output with no runtime dependencies.

Common errors

error TypeError: compile is not a function ↓

cause Importing default export instead of named export.

fix

Use import { compile } from 'bgex-compiler' instead of import compile from 'bgex-compiler'.

error Error: Invalid grammar: unexpected token at line 1 ↓

cause Grammar string contains trailing spaces or CRLF line endings.

fix

Trim input and replace \r\n with \n before passing to compile().

error Cannot find module 'bgex-compiler' or its corresponding type declarations. ↓

cause TypeScript project not configured for ESM or missing module resolution.

fix

Ensure tsconfig.json has 'moduleResolution': 'node16' or 'bundler' and 'module': 'ESNext'.

error SyntaxError: Named export 'compile' not found. The requested module 'bgex-compiler' is a CommonJS module. ↓

cause Running in CJS context; bgex-compiler is ESM-only.

fix

Set package.json type: 'module' or use dynamic import().

Warnings

breaking API changed in v0.0.20: compile() now returns an object with parse() instead of direct function. ↓

fix Update to use const parser = compile(grammar); const ast = parser.parse(input);

gotcha Grammar line endings must be Unix-style LF; Windows CRLF causes parse errors. ↓

fix Convert input to LF before passing to compile().

deprecated The 'grammar' option in compile() is deprecated; pass grammar string directly. ↓

fix Use compile(grammar) instead of compile({ grammar }).

gotcha Compiled parsers are not serializable; cannot be passed across worker threads. ↓

fix Recompile grammar in each worker.

Install

npm install bgex-compiler

yarn add bgex-compiler

pnpm add bgex-compiler

Imports

compile

wrong

const compile = require('bgex-compiler')

correct

import { compile } from 'bgex-compiler'

ESM-only package; CommonJS require is unsupported.

type ASTNode

import type { ASTNode } from 'bgex-compiler'

parse
```
import { parse } from 'bgex-compiler'
```

Quickstart

Shows how to define a simple arithmetic grammar and parse an input string into an AST using BGEX.

import { compile, parse } from 'bgex-compiler';

const grammar = `
  expr = term ('+' term)*
  term = factor ('*' factor)*
  factor = '(' expr ')' | NUMBER
  NUMBER = [0-9]+
`;

const parser = compile(grammar);
const ast = parser.parse('3+4*5');
console.log(ast);
// Example output: { type: 'expr', left: { type: 'term', ... }, right: ... }