anko / chevrotain

Javascript parsing DSL

Chevrotain

Chevrotain is a Javascript parsing DSL for building high performance fault-tolerant recursive decent parsers.

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. * 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.
   • Easily debuggable.
   • Short feedback loops.
   • Allows great flexibility for inserting custom Parser actions

3. High performance.

4. Generated Railroad Diagrams.

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 NPMCDN in a script tag.
  • Latest:
    • https://npmcdn.com/chevrotain/lib/chevrotain.js
    • https://npmcdn.com/chevrotain/lib/chevrotain.min.js
  • Explicit version number:
    • https://npmcdn.com/[email protected]/lib/chevrotain.js
    • https://npmcdn.com/[email protected]/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

• FAQ

• Examples Folder

• HTML docs

  • The Parsing DSL Docs

• Annotated source code (dev version):

  • tokens_public.ts
  • lexer_public.ts
  • parser_public.ts
  • gast_public.ts

• The aggregated Typescript definitions :

  • chevrotain.d.ts (latest version)

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 / 5).
  • 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