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Closure Compiler is a JavaScript optimizing compiler. It parses your JavaScript, analyzes it, removes dead code and rewrites and minimizes what's left. It also checks syntax, variable references, and types, and warns about common JavaScript pitfalls. It is used in many of Google's JavaScript apps, including Gmail, Google Web Search, Google Maps, and Google Docs.

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/*
 * Copyright 2011 The Closure Compiler 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 com.google.javascript.jscomp;

import com.google.common.base.Preconditions;
import com.google.common.collect.ArrayListMultimap;
import com.google.common.collect.Maps;
import com.google.common.collect.Multimap;
import com.google.javascript.rhino.Node;
import com.google.javascript.rhino.jstype.JSType;
import com.google.javascript.rhino.jstype.SimpleReference;
import com.google.javascript.rhino.jstype.SimpleSlot;
import com.google.javascript.rhino.jstype.StaticScope;
import com.google.javascript.rhino.jstype.StaticSymbolTable;

import java.util.Collections;
import java.util.Map;

/**
 * A symbol table for references that are removed by preprocessor passes
 * (like {@code ProcessClosurePrimitives}).
 *
 * @author [email protected] (Nick Santos)
 */
final class PreprocessorSymbolTable
    implements StaticScope,
               StaticSymbolTable {

  /**
   * All preprocessor symbols are globals.
   */
  private final Map symbols = Maps.newHashMap();

  private final Multimap refs =
      ArrayListMultimap.create();

  private final Node root;

  PreprocessorSymbolTable(Node root) {
    this.root = root;
  }

  @Override
  public Node getRootNode() { return root; }

  @Override
  public JSType getTypeOfThis() { return null; }

  @Override
  public StaticScope getParentScope() { return null; }

  @Override
  public SimpleSlot getSlot(String name) {
    return symbols.get(name);
  }

  @Override
  public SimpleSlot getOwnSlot(String name) {
    return getSlot(name);
  }

  @Override
  public Iterable getReferences(SimpleSlot symbol) {
    return Collections.unmodifiableCollection(refs.get(symbol.getName()));
  }

  @Override
  public Iterable getAllSymbols() {
    return Collections.unmodifiableCollection(symbols.values());
  }

  @Override
  public StaticScope getScope(SimpleSlot slot) {
    return this;
  }

  void addReference(Node node) {
    String name = node.getQualifiedName();
    Preconditions.checkNotNull(name);

    if (!symbols.containsKey(name)) {
      symbols.put(name, new SimpleSlot(name, null, true));
    }

    refs.put(name, new Reference(symbols.get(name), node));
  }

  static final class Reference extends SimpleReference {
    Reference(SimpleSlot symbol, Node node) {
      super(symbol, node);
    }
  }
}