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/*
* Copyright 2016 Federico Tomassetti
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.github.javaparser.symbolsolver.logic;
import com.github.javaparser.resolution.MethodUsage;
import com.github.javaparser.resolution.declarations.ResolvedReferenceTypeDeclaration;
import com.github.javaparser.resolution.types.ResolvedType;
import java.lang.reflect.Method;
import java.lang.reflect.Parameter;
import java.util.Arrays;
import java.util.List;
import java.util.Optional;
import java.util.Set;
import java.util.stream.Collectors;
/**
* @author Federico Tomassetti
*/
public final class FunctionalInterfaceLogic {
private FunctionalInterfaceLogic() {
// prevent instantiation
}
/**
* Get the functional method defined by the type, if any.
*/
public static Optional<MethodUsage> getFunctionalMethod(ResolvedType type) {
if (type.isReferenceType() && type.asReferenceType().getTypeDeclaration().isInterface()) {
return getFunctionalMethod(type.asReferenceType().getTypeDeclaration());
} else {
return Optional.empty();
}
}
/**
* Get the functional method defined by the type, if any.
*/
public static Optional<MethodUsage> getFunctionalMethod(ResolvedReferenceTypeDeclaration typeDeclaration) {
//We need to find all abstract methods
Set<MethodUsage> methods = typeDeclaration.getAllMethods().stream()
.filter(m -> m.getDeclaration().isAbstract())
// Remove methods inherited by Object:
// Consider the case of Comparator which define equals. It would be considered a functional method.
.filter(m -> !declaredOnObject(m))
.collect(Collectors.toSet());
if (methods.size() == 1) {
return Optional.of(methods.iterator().next());
} else {
return Optional.empty();
}
}
public static boolean isFunctionalInterfaceType(ResolvedType type) {
return getFunctionalMethod(type).isPresent();
}
private static String getSignature(Method m) {
return String.format("%s(%s)", m.getName(), String.join(", ", Arrays.stream(m.getParameters()).map(p -> toSignature(p)).collect(Collectors.toList())));
}
private static String toSignature(Parameter p) {
return p.getType().getCanonicalName();
}
private static List<String> OBJECT_METHODS_SIGNATURES = Arrays.stream(Object.class.getDeclaredMethods())
.map(method -> getSignature(method))
.collect(Collectors.toList());
private static boolean declaredOnObject(MethodUsage m) {
return OBJECT_METHODS_SIGNATURES.contains(m.getDeclaration().getSignature());
}
}
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