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UniCC is a universal LALR(1) parser generator, targetting C, C++, Python, JavaScript, JSON and XML.


UniCC (UNIversal Compiler-Compiler) is a LALR(1) parser generator.

It compiles an augmented grammar definition into a program source code that parses the described grammar. Because UniCC is intended to be target-language independent, it can be configured via template definition files to emit parsers in almost any programming language.

UniCC comes with out of the box support for the programming languages C, C++, Python (both 2.x and 3.x) and JavaScript. Parsers can also be generated into JSON and XML.

UniCC can generate both scanner-less and scanner-mode parsers. The more powerful scanner-less parsing is the default, and allows to break the barrier between the grammar and its tokens, so tokens are under full control of the context-free grammar. Scanner-less parsing requires that the provided grammar is internally rewritten according to whitespace and lexeme settings.


This is the full definition of a four-function arithmetic syntax including their integer calculation semantics (in C).

#!language      "C";	// <- target language!

#whitespaces    ' \t';
#lexeme         int;
#default action [* @@ = @1 *];

#left           '+' '-';
#left           '*' '/';

//Defining the grammar
calc$           : expr           [* printf( "= %d\n", @expr ) *]

expr            : expr '+' expr  [* @@ = @1 + @3 *]
                | expr '-' expr  [* @@ = @1 - @3 *]
                | expr '*' expr  [* @@ = @1 * @3 *]
                | expr '/' expr  [* @@ = @1 / @3 *]
                | '(' expr ')'   [* @@ = @2 *]
                | int

int             : '0-9'          [* @@ = @1 - '0' *]
                | int '0-9'      [* @@ = @int * 10 + @2 - '0' *]

To build and run this example, do

$ unicc expr.par
$ cc -o expr expr.c
$ ./expr -sl
= 23

More real-world examples for parsers implemented with UniCC are xpl, rapidbatch and ViUR logics or can be found in the examples-folder.


UniCC provides the following features and tools:

  • Grammars are expressed in a powerful Backus-Naur-style meta language
  • Generates parsers in C, C++, Python, JavaScript, JSON and XML
  • Scanner-less and scanner-mode parser construction supported
  • Build-in full Unicode processing
  • Grammar prototyping features, virtual productions and anonymous nonterminals
  • Abstract syntax tree notation features
  • Semantically determined symbols
  • Standard LALR(1) conflict resolution
  • Platform-independent (console-based)


The UniCC User's Manual is the official standard documentation of the UniCC Parser Generator. Download it for free here.


On Linux and OS X, UniCC can be build and installed like any GNU-style program, with

make install

Previously, the Phorward Toolkit must be compiled and installed, because UniCC depends on it.

Windows users may download the pre-built setup package that can be found on the Phorward download server at


Contributions, ideas, concepts and code is always welcome. Please feel free to contact me if you have any questions.


UniCC is developed and maintained by Jan Max Meyer, Phorward Software Technologies.


This software is an open source project released under the terms and conditions of the 3-clause BSD license. See the LICENSE file for more information.

Copyright (C) 2006-2019 by Phorward Software Technologies, Jan Max Meyer.

You may use, modify and distribute this software under the terms and conditions of the 3-clause BSD license. The full license terms can be obtained from the file LICENSE.

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