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chevrotain
chevrotain/lib/chevrotain

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Readme

Chevrotain

Introduction

Chevrotain is a very fast and feature rich Parser Building Toolkit for JavaScript. It can be used to build parsers/compilers/interpreters for various use cases ranging from simple configuration files, to full fledged programing languages.

A more in depth description of Chevrotain can be found in this great article on: Parsing in JavaScript: Tools and Libraries.

It is important to note that Chevrotain is NOT a parser generator. It solves the same kind of problems as a parser generator, just without any code generation. Chevrotain Grammars are pure code which can be created/debugged/edited as any other pure code without requiring any new tools or processes.

TLDR

Features

Parsing DSL.
- LL(k) grammars support.
- Useable from JavaScript / TypeScript / CoffeeScript.
- Separation of grammar and semantics.
- Customizable 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.
- Parameterized Rules.
- Syntactic Content Assist.
- 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.
- Custom APIs.
Lexer Engine
- Based on Regular Expressions.
- Full position information tracking (lines/columns/offsets).
- Token skipping (whitespace/comments/...).
- Prioritise longest match (Keywords vs Identifiers).
- Multiple Lexer Modes depending on the context.
- Tokens Grouping.
- Custom Token patterns(none RegExp) support
- No code generation The Lexer does not require any code generation phase.
High Performance.
Railroad Diagrams Generation.
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.
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@3.6.1/lib/chevrotain.js
  - https://unpkg.com/chevrotain@3.6.1/lib/chevrotain.min.js

Documentation & Resources

Getting Started Tutorial.
Sample Grammars.
FAQ.
Other Examples.
HTML API docs.
- The Parsing DSL Docs.

Dependencies

There is a single dependency to regexp-to-ast library. This dependency is included in the bundled artifacts, for ease of consumption in browsers.

Compatibility

Chevrotain runs on any modern JavaScript ES5.1 runtime.

The CI build runs the tests under:
- Node.js (6 / 8 / 10).
- Latest stable: Chrome, FireFox, Safari, IE Edge and IE 11.
Uses UMD to work with common module loaders (browser global / amd / commonjs).

Contributions

Contributions are greatly appreciated. See CONTRIBUTING.md for details.

Where used

Some interesting samples: