gradle-master/subprojects/language-native/src/main/java/org/gradle/language/nativeplatform/internal/incremental/TokenLookup.java
/*
 * Copyright 2017 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.language.nativeplatform.internal.incremental;

import com.google.common.collect.LinkedHashMultimap;
import com.google.common.collect.Multimap;
import org.gradle.language.nativeplatform.internal.Expression;

import java.util.Collection;
import java.util.Collections;
import java.util.HashSet;
import java.util.Set;

/**
 * Captures the intermediate states during the resolution of macro #include directives, to short-circuit work that has already been done.
 */
class TokenLookup {
    private Set<Expression> broken;
    private Multimap<Expression, Expression> tokensFor;

    boolean isUnresolved(Expression expression) {
        return broken != null && broken.contains(expression);
    }

    void unresolved(Expression expression) {
        if (broken == null) {
            broken = new HashSet<Expression>();
        }
        broken.add(expression);
    }

    Collection<Expression> tokensFor(Expression expression) {
        if (tokensFor == null) {
            return Collections.emptyList();
        }
        return tokensFor.get(expression);
    }

    void addTokensFor(Expression expression, Expression tokens) {
        if (tokensFor == null) {
            tokensFor = LinkedHashMultimap.create();
        }
        tokensFor.put(expression, tokens);
    }

    boolean hasTokensFor(Expression expression) {
        return tokensFor != null && tokensFor.containsKey(expression);
    }
}
