PLY is a

parsing Parsing, syntax analysis, or syntactic analysis is a process of analyzing a String (computer science), string of Symbol (formal), symbols, either in natural language, computer languages or data structures, conforming to the rules of a formal gramm ...

tool written purely in Python. It is, in essence, a re-implementation of Lex and

Yacc Yacc (Yet Another Compiler-Compiler) is a computer program for the Unix operating system developed by Stephen C. Johnson. It is a lookahead left-to-right rightmost derivation (LALR) parser generator, generating a LALR parser (the part of a co ...

originally in C-language. It was written by David M. Beazley. PLY uses the same LALR parsing technique as Lex and Yacc. It also has extensive

debugging In engineering, debugging is the process of finding the Root cause analysis, root cause, workarounds, and possible fixes for bug (engineering), bugs. For software, debugging tactics can involve interactive debugging, control flow analysis, Logf ...

and error reporting facilities.

Features

Implemented in Python, it has almost all the features provided by Lex and Yacc. It includes support for empty productions, precedence rules, error recovery, and

ambiguous grammar In computer science, an ambiguous grammar is a context-free grammar for which there exists a string (computer science), string that can have more than one leftmost derivation or parse tree. Every non-empty context-free language admits an ambiguous ...

s. It supports Python 3.

Structure the PLY module

PLY has the following two Python modules which are part of the ply package. *ply.lex - A re-implementation of Lex for lexical analysis *ply.yacc - A re-implementation of

for parser creation

References

{{Authority control Parser generators Python (programming language) software Lexical analysis