Syntax Definition Formalism
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 . These operate using the SGLR (Scannerless GLR parser). An SDF parser outputs parse trees or, in the case of ambiguities, parse forests.
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 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[]
See also[]
- GNU bison
- ANTLR
References[]
Further reading[]
- 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
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