Chevrotain

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

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

Try it online

Features

• Lexer engine based on RexExps.

  • Supports Token location tracking.
  • Supports Token skipping (whitespace/comments/...)
  • Allows prioritising shorter matches (Keywords vs Identifiers).
  • No code generation The Lexer does not require any code generation phase.

• Parsing DSL for creating the parsing rules.

  • No code generation - the DSL is just javascript not a new external language, what is written is what will be run, this speeds up development, makes debugging trivial and provides great flexibility for inserting custom actions into the grammar.
  • Strong Error Recovery capabilities based on Antlr3's algorithms.
  • Automatic lookahead calculation for LL(1) grammars.
  • In addition custom lookahead logic can be provided explicitly.
  • Backtracking support.

• High performance see:

  • performance comparison
  • and on jsPerf

• Grammar Introspection, the grammar's structure is known and exposed this can be used to implement features such as automatically generated syntax diagrams or Syntactic error recovery.

• Well tested with ~100% code coverage

Installation

• npm: npm install chevrotain
• Bower bower install chevrotain
• or download directly from github releases:
  • the 'chevrotain-binaries-...' files contain the compiled javascript code.

Getting Started

Online version

Related Repos

Runnable (and debuggable) examples:

• Json Parser
• Simple Calculator
• ECMAScript5 Parser
• Lexer advanced features

Documentation

• Latest released version's HTML docs

  • Parsing DSL

• Annotated source code (dev version):

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

• The aggregated Typescript definitions :

  • chevrotain.d.ts (dev version)
  • Also packaged in both the github and npm releases.

Dependencies

Only a single dependency to lodash.

Compatibility

The Generated artifact(chevrotain.js) should run on any modern Javascript ES5.1 runtime.

• The CI build runs the tests under Node.js.
• Additionally local testing is done on latest versions of Chrome/Firefox/IE.
• The dependency to lodash is imported via UMD, in order to make chevrotain.js portable to multiple environments.