<< metafront >>

Tired of shift/reduce errors?
Then shift to metafront and reduce development time!

EXTENSIBLE PARSING & TRANSFORMATION

We present the metafront tool for specifying flexible, safe, and efficient syntactic transformations between languages defined by context-free grammars. The transformations are guaranteed to terminate and to map grammatically legal input to grammatically legal output.

We rely on a novel parser algorithm, specificity parsing, that is designed to support gradual extensions of a grammar by allowing productions to remain in a natural style and by statically reporting ambiguities and errors in terms of individual productions as they are being added.

Our tool may be used as a parser generator in which the resulting parser automatically supports a flexible, safe, and efficient macro processor, or as an extensible lightweight compiler generator for domain-specific languages. We show substantial examples of both kinds.

LANGUAGE EXAMPLES

Lambda: [ Id | Lambda ] (test.lambda)
- LambdaNum extension: [ LambdaNum ] (test.lambda_num)
- LambdaBool extension: [ LambdaBool ] (test.lambda_bool)
Java: [ JavaLex | Java ] (test.java)
- ForEach extension: [ ForEach ] (test.foreach)
- ForEach extension: [ Reserve ] (test.reserve)

TRANSFORMATION EXAMPLES

Lambda: [ LambdaNum2Lambda | LambdaBool2LambdaNum ]
Java: [ ForEach2Java | Reserve2Java ]

DOWNLOAD PROTOTYPE

metafront.tgz [213K ".jar" + examples] (written by Claus Brabrand)

The metafront tool uses the software packages:

automaton.jar; the dk.brics.automaton package (written by Anders Møller); and
JFlex.jar; the JFlex Java Scanner Generator.

Example usage:

% cd metafront/
% setenv METAFRONT=$pwd          // base metafront directory
% cd examples/Lambda/
% java ../../metafront -s Exp LambdaBool2LambdaNum.x test/test.lambda_bool

RESEARCH PAPERS

"The metafront System: Extensible Parsing & Transformation" [ bibtex ]
by Claus Brabrand, Michael I. Schwartzbach, and Mads Vanggaard
LDTA 2003, Warsaw, Poland. [ Powerpoint ]

"Growing Languages with Metamorphic Syntax Macros" [ bibtex ]
by Claus Brabrand and Michael I. Schwartzbach
PEPM 2002, Portland, Oregon, USA. [ PowerPoint ]

The metafront tool is currently being developed at BRICS.

Maintained by Claus Brabrand