parboiled2 - A macro-based PEG parser generator for Scala 2.10+

•    Scala

parboiled2 is a Scala 2.11+ library enabling lightweight and easy-to-use, yet powerful, fast and elegant parsing of arbitrary input text. It implements a macro-based parser generator for Parsing Expression Grammars (PEGs), which runs at compile time and translates a grammar rule definition (written in an internal Scala DSL) into corresponding JVM bytecode.PEGs are an alternative to Context-Free Grammars (CFGs) for formally specifying syntax, they make a good replacement for regular expressions and have some advantages over the "traditional" way of building parsers via CFGs (like not needing a separate lexer/scanner phase).

language - A fast PEG parser written in JavaScript with first class errors

•    Objective-J

Language.js is an experimental new parser based on PEG (Parsing Expression Grammar), with the special addition of the "naughty OR" operator to handle errors in a unique new way. It makes use of memoization to achieve linear time parsing speed, and support for automatic cut placement is coming to maintain mostly constant space as well (for a discussion of cut operators see: www.ialab.cs.tsukuba.ac.jp/~mizusima/publications/paste513-mizushima.pdf). The most unique addition Language.js makes to PEG is how it handles errors. No parse ever fails in Language.js, instead SyntaxErrorNodes are placed into the resultant tree. This makes it trivial to do things like write syntax highlighters that have live error reporting. This also means that Language.js is very competent at handling multiple errors (as opposed to aborting on the first one that is reached).

eu.h8me.Parsing - (G)LR parsing/lexing library for .NET

Library implementing a regular expression based lexer and LR(1) based parser generator, using inline code to define lexer and grammar rules. The generated parser uses a GLR parsing engine to allow for ambiguous grammars.

csstree - A tool set for working with CSS including fast detailed parser, walker, generator and lexer based on W3C specs and browser implementations

•    Javascript

CSSTree is a tool set to work with CSS, including fast detailed parser (string->AST), walker (AST traversal), generator (AST->string) and lexer (validation and matching) based on knowledge of spec and browser implementations. The main goal is to be efficient and W3C spec compliant, with focus on CSS analyzing and source-to-source transforming tasks. NOTE: The project is in alpha stage since some parts need further improvements, AST format and API are subjects to change. However it's stable enough and used by packages like CSSO (CSS minifier) and SVGO (SVG optimizer) in production.

rust-peg - Parsing Expression Grammar (PEG) parser generator for Rust

•    Rust

This is a simple parser generator based on Parsing Expression Grammars. Please see the release notes for updates.

PEGTL - Parsing Expression Grammar Template Library

•    C++

The Parsing Expression Grammar Template Library (PEGTL) is a zero-dependency C++ header-only parser combinator library for creating parsers according to a Parsing Expression Grammar (PEG). Grammars are written as regular C++ code, created with template programming (not template meta programming), i.e. nested template instantiations that naturally correspond to the inductive definition of PEGs (and other parser-combinator approaches).

esprima - ECMAScript parsing infrastructure for multipurpose analysis

•    TypeScript

Esprima (esprima.org, BSD license) is a high performance, standard-compliant ECMAScript parser written in ECMAScript (also popularly known as JavaScript). Esprima is created and maintained by Ariya Hidayat, with the help of many contributors. Esprima can be used to perform lexical analysis (tokenization) or syntactic analysis (parsing) of a JavaScript program.

neotoma - Erlang library and packrat parser-generator for parsing expression grammars.

•    Erlang

Neotoma is a packrat parser-generator for Erlang for Parsing Expression Grammars (PEGs). It consists of a parsing-combinator library with memoization routines, a parser for PEGs, and a utility to generate parsers from PEGs. It is inspired by treetop, a Ruby library with similar aims, and parsec, the parser-combinator library for Haskell. Neotoma is licensed under the MIT License (see LICENSE).

lark - A modern parsing library for Python, implementing Earley & LALR(1) and an easy interface

•    Python

Beginners: Lark is not just another parser. It can parse any grammar you throw at it, no matter how complicated or ambiguous, and do so efficiently. It also constructs a parse-tree for you, without additional code on your part. Experts: Lark lets you choose between Earley and LALR(1), to trade-off power and speed. It also contains a CYK parser and experimental features such as a contextual-lexer.

treetop - A Ruby-based parsing DSL based on parsing expression grammars.

•    Ruby

Languages can be split into two components, their syntax and their semantics. It's your understanding of English syntax that tells you the stream of words "Sleep furiously green ideas colorless" is not a valid sentence. Semantics is deeper. Even if we rearrange the above sentence to be "Colorless green ideas sleep furiously", which is syntactically correct, it remains nonsensical on a semantic level. With Treetop, you'll be dealing with languages that are much simpler than English, but these basic concepts apply. Your programs will need to address both the syntax and the semantics of the languages they interpret. Treetop equips you with powerful tools for each of these two aspects of interpreter writing. You'll describe the syntax of your language with a parsing expression grammar. From this description, Treetop will generate a Ruby parser that transforms streams of characters written into your language into abstract syntax trees representing their structure. You'll then describe the semantics of your language in Ruby by defining methods on the syntax trees the parser generates.

ANLP - Another .NET Lexer Parser

•    Silverlight

This project aims to have a lexer/parser working in Silverlight and help people to write their own grammar and make the lexer/parser available in Silverlight.

Lexical Analyzer and Parser Generator

•    Java

Lapg is the combined lexical analyzer and parser generator, which converts a description for a context-free LALR grammar into source file to parse the grammar. Generates code for Java, Javascript, C, C++ and C#.

parsekit - Objective-C Tokenizer and Parser Generator. Supports Grammars.

•    Objective-C

Objective-C Tokenizer and Parser Generator. Supports Grammars.

pigeon - Command pigeon generates parsers in Go from a PEG grammar.

•    Go

The pigeon command generates parsers based on a parsing expression grammar (PEG). Its grammar and syntax is inspired by the PEG.js project, while the implementation is loosely based on the parsing expression grammar for C# 3.0 article. It parses Unicode text encoded in UTF-8. See the godoc page for detailed usage. Also have a look at the Pigeon Wiki for additional information about Pigeon and PEG in general.

Tree-sitter - An incremental parsing system for programmings tools

•    Rust

Tree-sitter is a parser generator tool and an incremental parsing library. It can build a concrete syntax tree for a source file and efficiently update the syntax tree as the source file is edited. It is robust and parse any programming language. It is enough to provide useful results even in the presence of syntax errors.

peg - Peg, Parsing Expression Grammar, is an implementation of a Packrat parser generator.

•    Go

Peg, Parsing Expression Grammar, is an implementation of a Packrat parser generator. A Packrat parser is a descent recursive parser capable of backtracking. The generated parser searches for the correct parsing of the input.

pyparsing

•    Python

The pyparsing module is an alternative approach to creating and executing simple grammars, vs. the traditional lex/yacc approach, or the use of regular expressions. The pyparsing module provides a library of classes that client code uses to construct the grammar directly in Python code. The Python representation of the grammar is quite readable, owing to the self-explanatory class names, and the use of '+', '|' and '^' operator definitions.

parsimonious - The fastest pure-Python PEG parser I can muster

•    Python

Parsimonious aims to be the fastest arbitrary-lookahead parser written in pure Python—and the most usable. It's based on parsing expression grammars (PEGs), which means you feed it a simplified sort of EBNF notation. Parsimonious was designed to undergird a MediaWiki parser that wouldn't take 5 seconds or a GB of RAM to do one page, but it's applicable to all sorts of languages. You can have forward references and even right recursion; it's all taken care of by the grammar compiler. The first rule is taken to be the default start symbol, but you can override that.

OILexer

•    CSharp

OILexer is a LL parser generator for C# aimed at simple language parsing for language enthusiasts. Does not use recursive descent or bottom-up parsing methods, but rather, a top-down deterministic model is employed. This is a portion of the Abstraction Project.

tsdoc - A doc comment standard for the TypeScript language

•    TypeScript

We are developing a library package @microsoft/tsdoc that provides an open source reference implementation of a parser. Using this library is an easy way to ensure that your tool is 100% compatible with the standard. These are just examples. Many other tools in today's web developer community want to interact with TypeScript doc comments. Each of these tools accepts a syntax that is loosely based on JSDoc, but encounters frustrating incompatibilities when attempting to coexist with other parsers.