https://lezer.codemirror.net

Lezer
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The Lezer Parser System

The problem of parsing structured text has resisted one-size-fits all
solutions for over 60 years. Lezer isn't such a solution either, but
it is a very decent parser generator, especially well suited for use
in code editors.

Lezer (the Dutch word for reader, pronounced like "laser") provides a
parser generator that outputs JavaScript modules, which can be loaded
to parse code into a non-abstract syntax tree. This tree can then be
used to do highlighting and basic semantic analysis.

Features

  * Grammar Driven

    Write your grammars declaratively, use a parser generator tool to
    convert it into an efficient parser.

  * Incremental

    Lezer can quickly re-parse documents that were slightly changed
    compared to a previously parsed version by reusing nodes from the
    old parse.

  * Error-Insensitive

    Being designed for the code editor use case, the parser is
    equipped with strategies for recovering from syntax errors, and
    can produce a tree for any input.

  * Fast

    By using the LR parsing algorithm, an efficient tokenizer, and
    data structures optimized for locality, the parser rips through
    its input like an angry wolverine.

  * Lightweight

    The parser generator produces compact parse table files which,
    along with the run-time library, are all you need to ship to
    clients.

  * Memory-Friendly

    The syntax tree representation is designed to be compact, packing
    groups of smaller nodes into arrays of 16-bit numbers.

Grammars

  * C++

  * CSS

  * Clojure

  * HTML

  * Java

  * JavaScript

  * Julia

  * JSON

  * Lezer

  * Markdown

  * PHP

  * Python

  * Rust

  * XML

About

Lezer is open source under an MIT license. It is maintained by the
CodeMirror team.

Lezer is being developed on GitHub. Contributions are welcome.

Discussing the project, or asking questions, is best done on the
forum. Bugs should be reported through the issue tracker. We aim to
be an inclusive, welcoming community. To make that explicit, we have
a code of conduct that applies to communication around the project.

Links

  * Blog post announcing the library
  * Online Lezer sandbox

Sponsors

Tines
Code of Conduct Report an Issue