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package bjc.utils.patterns;
import java.util.*;
import bjc.data.*;
/**
* A pattern matcher over a mutable set of patterns.
*
* Note that modifying a pattern matcher while it is currently doing pattern
* matching is a wonderful way to cause strange behavior.
*
* @author Ben Culkin
*
* @param <ReturnType> The type returned by the pattern matcher.
* @param <InputType> The type of the input to match against.
*/
public class MutablePatternMatcher<ReturnType, InputType>
implements IPatternMatcher<ReturnType, InputType> {
private final List<ComplexPattern<ReturnType, Object, InputType>> patterns;
/**
* Create a new mutable pattern matcher with no patterns.
*/
public MutablePatternMatcher() {
patterns = new ArrayList<>();
}
/**
* Create a new mutable pattern matcher with the given set of patterns.
*
* @param patterns The set of patterns to match on.
*/
@SuppressWarnings("unchecked")
public MutablePatternMatcher(ComplexPattern<ReturnType, ?, InputType>... patterns) {
this();
for (ComplexPattern<ReturnType, ?, InputType> pattern : 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.add((ComplexPattern<ReturnType, Object, InputType>) pattern);
}
}
@Override
public ReturnType matchFor(InputType input) throws NonExhaustiveMatch {
Iterator<ComplexPattern<ReturnType, Object, InputType>> iterator;
iterator = new NonCMEIterator<>(patterns);
while(iterator.hasNext()) {
ComplexPattern<ReturnType, Object, InputType> pattern = iterator.next();
Pair<Boolean, Object> matches = pattern.matches(input);
matches.doWith((bool, obj) -> {
if (bool) pattern.apply(input, obj);
});
}
throw new NonExhaustiveMatch("Non-exhaustive match against " + input);
}
/**
* Add a pattern to this pattern matcher.
*
* @param pattern The pattern to add.
*
* @return Whether or not the pattern was added.
*/
@SuppressWarnings("unchecked")
public boolean addPattern(ComplexPattern<ReturnType, ?, InputType> pattern) {
return patterns.add((ComplexPattern<ReturnType, Object, InputType>) pattern);
}
/**
* Remove a pattern from this pattern matcher.
*
* @param pattern The pattern to remove.
*
* @return Whether or not the pattern was removed.
*/
public boolean removePattern(ComplexPattern<ReturnType, ?, InputType> pattern) {
return patterns.remove(pattern);
}
}
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