com.google.common.css.compiler.passes.ConstantDefinitions.java Source code

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Here is the source code for com.google.common.css.compiler.passes.ConstantDefinitions.java

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/*
 * Copyright 2009 Google Inc.
 *
 * 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.common.css.compiler.passes;

import com.google.common.collect.LinkedListMultimap;
import com.google.common.collect.ListMultimap;
import com.google.common.collect.Maps;
import com.google.common.collect.Multimap;
import com.google.common.css.compiler.ast.CssDefinitionNode;

import java.util.List;
import java.util.Map;

/**
 * A container for GSS constant definitions, since a constant could be
 * defined multiple times in the tree, this class has two set of interfaces
 * that can be used to get either all definitions of a constant or only last
 * definition of a constant.
 *
 * @author oana@google.com (Oana Florescu)
 */
public class ConstantDefinitions {
    private final Map<String, CssDefinitionNode> constants = Maps.newHashMap();

    private final ListMultimap<String, CssDefinitionNode> constantsMultimap = LinkedListMultimap.create();

    Map<String, CssDefinitionNode> getConstants() {
        return constants;
    }

    public Multimap<String, CssDefinitionNode> getConstantMultimap() {
        return constantsMultimap;
    }

    /**
     * Returns the last definition of a constant. Callers should not attempt to
     * modify the returned value.
     * 
     * @return definition node or {@code null} if the constant is not defined
     */
    public CssDefinitionNode getConstantDefinition(String constant) {
        return constants.get(constant);
    }

    /**
     * Returns all definitions of a constant.
     *
     * @return collection of definition node or empty collection if the
     * constant is not defined
     */
    public List<CssDefinitionNode> getConstantDefinitions(String constant) {
        return constantsMultimap.get(constant);
    }

    /**
     * Adds a constant definition to this css tree.
     *
     * Note that a constant may be defined multiple times in the tree. For the
     * compact representation of the tree, all references to a constant will be
     * replaced with the same value: the last one specified in the stylesheet
     * (to ignore the definitions in inactive condition blocks the
     * {@code EliminateConditionalNodes} compiler pass needs to be run first).
     */
    public void addConstantDefinition(CssDefinitionNode definition) {
        constants.put(definition.getName().getValue(), definition);
        constantsMultimap.put(definition.getName().getValue(), definition);
    }

    /**
     * @return the iterable of names of all defined constants
     */
    public Iterable<String> getConstantsNames() {
        return constants.keySet();
    }
}