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Pattern match predicates


\begin{verbsyntax}\onerule{PatternMatchStatement}{Variable ('~' \vert 'matches' \vert 'instanceof' \vert '!~') Pattern} \end{verbsyntax}

As predicates, pattern match statements on rule test nodes (rule test variables) are allowed. A variable is linked to a pattern with the tokens ~, matches, or instanceof. The pattern match statement succeeds if the variable has the form of the pattern. If a variable is linked to a pattern with !~ the pattern match statement succeeds if the variable has not the form of the pattern.
\begin{examplefoot}N ~ Block // node N matches type Block N instanceof Block //... ... matches type Block N !~ Block // node N is not of type Block \end{examplefoot}

In rule transformations pattern matching is not allowed.


 
Uwe Assmann
1998-12-22