gradle-master/subprojects/tooling-api-builders/src/main/java/org/gradle/tooling/internal/provider/runner/OperationDependenciesResolver.java
/*
 * Copyright 2018 the original author or authors.
 *
 * 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 org.gradle.tooling.internal.provider.runner;

import org.gradle.execution.plan.Node;
import org.gradle.tooling.internal.protocol.events.InternalOperationDescriptor;

import java.util.ArrayList;
import java.util.LinkedHashSet;
import java.util.List;
import java.util.Objects;
import java.util.Set;

import static java.util.stream.Collectors.toCollection;

class OperationDependenciesResolver {

    private final List<OperationDependencyLookup> lookups = new ArrayList<>();

    void addLookup(OperationDependencyLookup lookup) {
        lookups.add(lookup);
    }

    Set<InternalOperationDescriptor> resolveDependencies(Node node) {
        return node.getDependencySuccessors().stream()
            .map(this::lookupExistingOperationDescriptor)
            .filter(Objects::nonNull)
            .collect(toCollection(LinkedHashSet::new));
    }

    private InternalOperationDescriptor lookupExistingOperationDescriptor(Node node) {
        return lookups.stream()
            .map(entry -> entry.lookupExistingOperationDescriptor(node))
            .filter(Objects::nonNull)
            .findFirst()
            .orElse(null);
    }

}
