boostregex

Boost.Regex is a component of the Boost C++ Libraries that provides a cross-platform regular expression engine for C++. It offers a feature-rich API with support for different character types and a backtracking matching model, making it suitable for complex pattern matching tasks in C++ programs.

The library supports multiple regular expression grammars, with ECMAScript (the default) and optional alternatives such as basic, extended, awk, and grep syntax. Patterns can include typical regex constructs such as quantifiers, alternation, character classes, and capturing groups, and the engine can work with both narrow and wide character inputs.

Core types and algorithms in Boost.Regex include the pattern object boost::regex, and result containers such as boost::smatch, boost::cmatch, and related sub-match types. Matching operations are provided through functions like boost::regex_search, boost::regex_match, and boost::regex_replace, with additional tools such as regex_token_iterator for traversing captures.

Error handling is performed via exceptions such as boost::regex_error when a pattern is invalid or a matching operation fails. The library also exposes options to control syntax and match behavior through various flag types, enabling customization of performance and matching rules.

Relation to other regex facilities: Boost.Regex predates the standard library’s regex support introduced in C++11 and remains a mature alternative in many codebases, especially for projects requiring broader syntax options or compatibility with pre-C++11 code. Boost.Regex is distributed under the Boost Software License and typically requires linking against the Boost.Regex library as part of a Boost installation.