foonathan/lexy

Health v2 · maintenance only

Flags: no_readme

Adoption not part of the score

1254 stars · 84 forks observed · 2026-08-28

What it is AI-extracted, prompt v1, taxonomy v1, 2026-08-30, confidence not recorded

lexy is a parser combinator library for C++17 and onwards that lets you define grammars directly in C++ as a DSL. It generates hand-written-style recursive descent parsers with full control over backtracking and lookahead, without external grammar files.

Use cases

• parse structured text formats like IPv4 addresses or config files in C++
• write a DSL or expression parser without a parser generator
• replace hand-written recursive descent parsers with declarative grammar rules
• build a compiler or interpreter front-end in C++
• parse custom file formats with precise control over backtracking and error reporting

When to choose

• you want parser combinator flexibility embedded directly in C++ code
• you need fine-grained control over parsing behavior, backtracking, and lookahead
• you want good error reporting and tracing for grammar debugging
• you prefer no external grammar files or code generation steps

When to avoid

• you need a table-driven parser generator like yacc/ANTLR with automatic ambiguity resolution
• your project targets C++ standards older than C++17
• you need parsing in a language other than C++

Facets

library · maturity active

parser parsers developer-tools programming-languages cpp cross-platform parser-combinators parsing-dsl recursive-descent c++17 header-only

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