flex ☆

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Description:
Fast Lexical Analyzer, generates Scanners (tokenizers)

Type: Formula | Latest Version: 2.6.4@0 | Tracked Since: Oct 15, 2025

Links: Homepage | formulae.brew.sh

Category: Developer tools

Tags: lexer parser compiler code-generation scanning

Install: brew install flex

About:
Flex is a fast lexical analyzer generator that converts formal specifications of patterns into a C/C++ program for recognizing tokens in input text. It is widely used in compiler construction to build scanners that process source code, configuration files, and log data. Its main value proposition is high performance and seamless integration with parser generators like Yacc/Bison.

Key Features:

Generates highly efficient C/C++ scanners from pattern specifications
Supports start conditions and regular expression extensions for complex parsing
Seamless integration with Yacc/Bison and other parser generators
Cross-platform with extensive compatibility and mature community support

Use Cases:

Building lexical analyzers for custom programming languages
Parsing structured text formats like logs, configs, and data files
Tokenizing input for compilers and interpreters

Alternatives:

re2c – Generates C-based scanners from regular expressions; focuses on embedding regex directly in source code rather than separate spec files
ANTLR – Full parser generator with lexer and parser combined; supports multiple target languages but heavier than flex/bison workflow

Version History

Detected	Version	Rev	Change	Commit
Oct 15, 2025 5:02pm		2	VERSION_BUMP	ea0f373d
Sep 14, 2025 6:33am		2	VERSION_BUMP	77b4d8df