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Syntax Definition Formalism

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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.

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 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

  • ASF+SDF Meta Environment provides SDF
  • RascalMPL
  • Spoofax/IMP [2]
  • Stratego/XT
  • Strafunski

    • References

    Syntax Definition Formalism Wikipedia
    (Text) CC BY-SA