Chevrotain

Chevrotain is a JavaScript parsing DSL for building High Performance LL(k) Parsers with optional fault-tolerant capabilities.

Chevrotain is NOT a parser generator. It solves the same kind of problems as a parser generator, just without any code generation phase.

---> Try it online <---

Features

1. Lexer Engine based on Regular Expressions.

   • Full Token position information.
   • Token skipping (whitespace/comments/...).
   • Prioritise shorter matches (Keywords vs Identifiers).
   • Multiple Lexer Modes depending on the context.
   • Tokens Grouping.
   • Different Token types for balancing performance, memory usage and ease of use.
   • No code generation The Lexer does not require any code generation phase.

2. Parsing DSL.

   • LL(k) grammars support.
   • Error Reporting with full location information.
   • Strong Error Recovery/Fault-Tolerance capabilities based on Antlr3's algorithms.
   • Supports gates/predicates.
   • Backtracking support.
   • Grammar Inheritance.
   • Multiple starting rules.
   • Parametrized Rules.
   • No code generation.
     • The DSL is just JavaScript, not an external language.
     • The grammar is directly debuggable as plain JavaScript source.
     • Short feedback loops.
     • Allows great flexibility for inserting custom Parser actions

3. High Performance.

4. Railroad Diagrams Generation.

5. Grammar Reflection/Introspection.

   • The Grammar's structure is known and exposed at runtime.
   • Can be used to implement advanced features such as dynamically generated syntax diagrams or Syntactic error recovery.

6. Well tested with ~100% code coverage, Unit & Integration tests

Installation

• npm: npm install chevrotain
• Browser: The npm package contains Chevrotain as concatenated and minified files ready for use in a browser. These can also be accessed directly via UNPKG in a script tag.
  • Latest:
    • https://unpkg.com/chevrotain/lib/chevrotain.js
    • https://unpkg.com/chevrotain/lib/chevrotain.min.js
  • Explicit version number:
    • https://unpkg.com/chevrotain@0.15.0/lib/chevrotain.js
    • https://unpkg.com/chevrotain@0.15.0/lib/chevrotain.min.js

Getting Started

Online tutorial

• Step #1 - Building a Lexer: online version / written version.
• Step #2 - Building a Parser: online version / written version.
• Step #3 - Adding actions to the Parser: online version / written version.
• Step #4 - Fault tolerance and Error recovery: online version / written version.

Documentation

• Sample Grammars

• Other Examples

• FAQ

• Token Types Docs

• HTML docs

  • The Parsing DSL Docs

• The d.ts TypeScript definitions

Dependencies

None.

Compatibility

Chevrotain should run on any modern JavaScript ES5.1 runtime.

• The CI build runs the tests under:

  • Node.js (0.12 / 4 / 6).
  • Latest stable: Chrome, FireFox, IE Edge, IE 11 and Safari 9.

• Uses UMD to work with common module loaders (browser global / amd / commonjs).

Contributions

Contributions are greatly appreciated. See CONTRIBUTING.md for details