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package bjc.utils.patterns;
import java.util.function.*;
import bjc.functypes.*;
/**
* Represents a pattern matcher against a series of patterns.
*
* @author Ben Culkin
*
* @param <ReturnType> The type returned from matching the patterns.
* @param <InputType> The type to match against.
*/
@FunctionalInterface
public interface PatternMatcher<ReturnType, InputType> {
/**
* Match an input object against a set of patterns.
*
* @param input The object to match against.
*
* @return The result of matching against the object.
*
* @throws NonExhaustiveMatch If none of the patterns in this set match
*/
ReturnType matchFor(InputType input) throws NonExhaustiveMatch;
/**
* Create a pattern matcher against a static set of patterns.
*
* @param <RetType> The type returned from matching the patterns.
* @param <InpType> The type to match against.
*
* @param patterns The set of patterns to match on.
*
* @return A pattern matcher which matches on the given patterns.
*/
@SafeVarargs
static <RetType, InpType> PatternMatcher<RetType, InpType> matchingOn(
ComplexPattern<RetType, ?, InpType>... patterns) {
return new SimplePatternMatcher<>(patterns);
}
/**
* Create a pattern matcher from a handler function.
*
* @param <RetType> The type returned by the matcher.
* @param <InpType> The type to match against.
*
* @param handler The handler function.
*
* @return A pattern matcher defined by the given handler.
*/
static <RetType, InpType> PatternMatcher<RetType, InpType> from(
ThrowFunction<InpType, RetType, NonExhaustiveMatch> handler) {
return new FunctionalPatternMatcher<>(handler);
}
/**
* Create a pattern matcher which applies a transform to its input.
*
* @param <NewInput> The new input type to use.
* @param transformer The function to convert from the new input to the old input.
*
* @return A pattern matcher which takes values of the new type instead.
*/
default <NewInput> PatternMatcher<ReturnType, NewInput> transformInput(
Function<NewInput, InputType> transformer) {
return from(inp -> matchFor(transformer.apply(inp)));
}
/**
* Create a pattern matcher which applies a transform to its output.
*
* @param <NewOutput> The new output type to use.
*
* @param transformer The function to convert from the new output to the old output.
*
* @return A pattern matcher which takes values of the new type instead.
*/
default <NewOutput> PatternMatcher<NewOutput, InputType> transformOutput(
Function<ReturnType, NewOutput> transformer) {
return from(inp -> transformer.apply(matchFor(inp)));
}
}
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