はじめに
この拡張モジュールは、 実験的 なものです。この拡張モジュールの動作・ 関数名・その他ドキュメントに書かれている事項は、予告なく、将来的な PHP のリリースにおいて変更される可能性があります。 このモジュールは自己責任で使用してください。
Lexer analysis is a process of splitting a character sequence into a list of lexemes. The lexeme list can be then used for the syntax analysis against a formal grammar. These operations are also known as lexing and parsing. This documentation doesn't aim to provide an exhaustive information on lexing and parsing. Good information in this regard is available on the numerous resources on the net. Several usage examples are included, to show the functionality. The extension is useful for PHP programmers both willing to learn or to utilize parsing and lexing. State machines and grammar parsing don't have to be implemented manually, these complex tasks are taken away by parle. Thanks to that, the development can be focused on the actual problem solving.
The common use case for parle is, when a data format is too complex to be handled by the regex matching with PCRE. The practical application is herewith wide. Be it a specific data format, a behavior modification of existing functions, even an own programming language and beyond. The helper methods such as Parle\Lexer::dump() to inspect the generated state machine, or Parle\Parser::dump() to inspect the generated grammar, are useful. The method Parle\Parser::trace() can also be used to track the parsing operation.