- Syntax Definition Formalism
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The Syntax Definition Formalism (SDF for short) is a metasyntax used to define context-free grammars: that is, a formal way to describe formal languages. It can express the entire range of context-free grammars. Its current version is SDF2. A parser and parser generator for SDF specifications are provided as part of the free ASF+SDF Meta Environment. These operate using the SGLR (Scannerless GLR parser). An SDF parser outputs parse trees or, in the case of ambiguities, parse forests.
Contents
Overview
Features of SDF:
- Supports the entire range of context-free languages
- Allows modular syntax definitions (grammars can import subgrammars) which enables reuse
- Supports annotations
Examples
The following example defines a simple Boolean expression syntax:
module basic/Booleans exports sorts Boolean context-free start-symbols Boolean context-free syntax "true" -> Boolean "false" -> Boolean lhs:Boolean "|" rhs:Boolean -> Boolean {left} lhs:Boolean "&" rhs:Boolean -> Boolean {left} "not" "(" Boolean ")" -> Boolean "(" Boolean ")" -> Boolean context-free priorities Boolean "&" Boolean -> Boolean > Boolean "|" Boolean -> Boolean
Program analysis and transformation systems using SDF
- ASF+SDF Meta Environment provides SDF
- RascalMPL
- Spoofax/IMP [1]
- Stratego/XT
- Strafunski
See also
Further reading
External links
- Grammar Deployment Kit
- SdfMetz computes metrics for SDF grammars
- Download SDF from the ASF+SDF Meta Environment homepage
Categories:- Parser generators
- Extensible syntax programming languages
- Programming language implementation
- Computer science stubs
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