Syntax Definition Formalism (original) (raw)
From Wikipedia, the free encyclopedia
The Syntax Definition Formalism (SDF) 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 SDF3.[1] 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.
Features of SDF:
- Supports the entire range of context-free languages
- Allows modular syntax definitions (grammars can import subgrammars) which enables reuse
- Supports annotations
The following example defines a simple Boolean expression syntax in SDF2:
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
[edit]
- ASF+SDF Meta Environment provides SDF
- RascalMPL
- Spoofax/IMP [1]
- Stratego/XT
- Strafunski
- GNU bison
- ANTLR
- A Quick Introduction to SDF, Visser, J. & Scheerder, J. (2000) CWI
- The Syntax Definition Formalism SDF, Mark van den Brand, Paul Klint, Jurgen Vinju (2007) CWI
- Grammar Deployment Kit
- SdfMetz computes metrics for SDF grammars
- Download SDF from the ASF+SDF Meta Environment homepage