acornjs/acorn
Acorn
Acorn is a JavaScript parser that converts source text into a structured abstract syntax tree. It follows the ESTree specification to produce a standardized JSON tree format, enabling consistent analysis of code structure and language versions.
The project features a plugin-based grammar extension system that allows the base parser to be extended with custom rules for experimental or non-standard language features. It also includes syntax error recovery, which inserts placeholder nodes into the tree when encountering invalid code to allow parsing to continue.
The toolset covers static analysis and compiler tooling, providing capabilities to traverse syntax trees, track node ancestry, and map tree elements back to their original line and column positions in the source code.
A command line interface is available to process source files and output the resulting syntax tree.
Features
- JavaScript Source Parsers - Provides a high-performance parser that converts JavaScript source code into structured ESTree-compliant data.
- ESTree AST Parsing - Implements a high-performance parser that converts JavaScript source code into abstract syntax trees following the ESTree specification.
- Recursive Descent Parsers - Employs a recursive descent parsing algorithm to transform source code into a structured syntax tree.
- JavaScript Parsers - Provides the underlying parsing engine required for static analysis of JavaScript program logic and architecture.
- Lexical Tokenizers - Includes a lexical tokenizer that converts raw source text into a sequential stream of discrete tokens.
- Grammar Extensions - Offers a modular system for extending the base parser with custom grammar rules to support experimental language features.
- Parser Rule Extensions - Allows adding custom parsing rules via a plugin system to support non-standard syntax and specialized language patterns.
- Visitor Pattern Traversers - Implements a visitor-pattern walker to trigger specific actions when encountering predefined node types during tree traversal.
- Node Metadata Attachments - Attaches line and column metadata to every AST node to map elements back to their original source locations.
- AST Node Location - Allows identifying specific nodes within an AST based on their character offsets or spanning positions.
- Source Text Mapping - Provides mapping of AST nodes back to their exact character offsets and line numbers in the original source text.
- AST Node Location Mapping - Tracks character offsets and line numbers on every tree node to link parsed elements back to the original source text.
- Parsing Recovery - Implements mechanisms to maintain valid syntax tree structures by inserting placeholder nodes when parsing malformed source code.
- Parse Error Reporters - Generates detailed error objects including exact character offsets and line positions for syntax errors.
- Structural Syntax Recovery - Inserts placeholder nodes into the syntax tree when encountering invalid code to allow parsing to continue.
- Syntax Traversal - Provides tools for navigating and inspecting nodes and tokens within a generated syntax tree.
- AST & Language Tools - Small, fast JavaScript parser.
- AST Parsers - Tiny and fast JavaScript parser.
Star history
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