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package bjc.utils.patterns;
import bjc.data.*;
/**
* Implements pattern-matching (of a sort) against a collection of patterns.
*
* @author Ben Culkin
*
* @param <ReturnType> The type returned by the pattern.
*/
public class PatternMatcher<ReturnType, InputType>
implements IPatternMatcher<ReturnType, InputType> {
private final ComplexPattern<ReturnType, Object, InputType>[] patterns;
/**
* Create a new pattern matcher.
*
* @param patterns The set of patterns to match against.
*/
@SuppressWarnings("unchecked")
@SafeVarargs
public PatternMatcher(ComplexPattern<ReturnType, ?, InputType>...patterns) {
// Note: this may seem a somewhat questionable cast, but because we never
// actually do anything with the value who has a type matching the second
// parameter, this should be safe
this.patterns = (ComplexPattern<ReturnType, Object, InputType>[]) patterns;
}
@Override
public ReturnType matchFor(InputType input) throws NonExhaustiveMatch {
for (ComplexPattern<ReturnType, Object, InputType> pattern : patterns) {
IPair<Boolean, Object> matches = pattern.matches(input);
if (matches.getLeft()) {
pattern.apply(input, matches.getRight());
}
}
throw new NonExhaustiveMatch("Non-exhaustive match against " + input);
}
}
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