com.google.devtools.build.lib.packages.AspectParameters.java Source code

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Here is the source code for com.google.devtools.build.lib.packages.AspectParameters.java

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// Copyright 2015 The Bazel Authors. All rights reserved.
//
// 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.google.devtools.build.lib.packages;

import static com.google.common.collect.Iterables.getOnlyElement;

import com.google.common.collect.ImmutableCollection;
import com.google.common.collect.ImmutableMultimap;
import com.google.common.collect.Multimap;
import java.util.Objects;

/**
 * Objects of this class contain values of some attributes of rules. Used for passing this
 * information to the aspects.
 */
public final class AspectParameters {
    private final ImmutableMultimap<String, String> attributes;

    private AspectParameters(Multimap<String, String> attributes) {
        this.attributes = ImmutableMultimap.copyOf(attributes);
    }

    public static final AspectParameters EMPTY = new AspectParameters.Builder().build();

    /**
     * A builder for @{link {@link AspectParameters} class.
     */
    public static class Builder {
        private final ImmutableMultimap.Builder<String, String> attributes = ImmutableMultimap.builder();

        /**
         * Adds a new pair of attribute-value.
         */
        public Builder addAttribute(String name, String value) {
            attributes.put(name, value);
            return this;
        }

        /**
         * Creates a new instance of {@link AspectParameters} class.
         */
        public AspectParameters build() {
            return new AspectParameters(attributes.build());
        }
    }

    /**
     * Returns collection of values for specified key, or an empty collection if key is missing.
     */
    public ImmutableCollection<String> getAttribute(String key) {
        return attributes.get(key);
    }

    public ImmutableMultimap<String, String> getAttributes() {
        return attributes;
    }

    /**
     * Similar to {@link #getAttribute}}, but asserts that there's only one value for the provided
     * key.
     * Uses Guava's {@link Iterables#getOnlyElement}, which may throw exceptions if there isn't
     * exactly one element.
     */
    public String getOnlyValueOfAttribute(String key) {
        return getOnlyElement(getAttribute(key));
    }

    public boolean isEmpty() {
        return this.equals(AspectParameters.EMPTY);
    }

    @Override
    public boolean equals(Object other) {
        if (this == other) {
            return true;
        }
        if (!(other instanceof AspectParameters)) {
            return false;
        }
        AspectParameters that = (AspectParameters) other;
        return Objects.equals(this.attributes, that.attributes);
    }

    @Override
    public int hashCode() {
        return Objects.hashCode(attributes);
    }

    @Override
    public String toString() {
        return attributes.toString();
    }
}