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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 2015 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.annotations.VisibleForTesting;
import com.google.common.base.Splitter;
import com.google.common.base.Strings;
import com.google.common.collect.BiMap;
import com.google.common.collect.HashBiMap;
import com.google.common.collect.ImmutableMap;
import com.google.javascript.jscomp.base.format.SimpleFormat;
import java.util.LinkedHashMap;
import java.util.Map;

/** A utility class for generating and parsing id mappings held by {@link ReplaceIdGenerators}. */
public final class IdMappingUtil {

  @VisibleForTesting static final char NEW_LINE = '\n';

  private static final Splitter LINE_SPLITTER = Splitter.on(NEW_LINE).omitEmptyStrings();

  // Prevent instantiation.
  private IdMappingUtil() {}

  /**
   * @return The serialize map of generators and their ids and their replacements.
   */
  static String generateSerializedIdMappings(Map> idGeneratorMaps) {
    StringBuilder sb = new StringBuilder();
    for (Map.Entry> replacements : idGeneratorMaps.entrySet()) {
      if (!replacements.getValue().isEmpty()) {
        sb.append('[').append(replacements.getKey()).append(']').append(NEW_LINE).append(NEW_LINE);

        for (Map.Entry replacement : replacements.getValue().entrySet()) {
          sb.append(replacement.getKey())
              .append(':')
              .append(replacement.getValue())
              .append(NEW_LINE);
        }
        sb.append(NEW_LINE);
      }
    }
    return sb.toString();
  }

  /**
   * The expected format looks like this:
   *
   * [generatorName1] someId1:someFile:theLine:theColumn ...
   *
   * 
[[generatorName2] someId2:someFile:theLine:theColumn] ...
   *
   * 
The returned data is grouped by generator name (the map key). The inner map provides
   * mappings from id to content (file, line and column info). In a glimpse, the structure is {@code
   * Map>}.
   *
   * @throws IllegalArgumentException malformed input where there it 1) has duplicate generator
   * name, or 2) the line has no ':' for id and its content.
   */
  public static Map> parseSerializedIdMappings(String idMappings) {
    if (Strings.isNullOrEmpty(idMappings)) {
      return ImmutableMap.of();
    }

    Map> resultMap = new LinkedHashMap<>();
    BiMap currentSectionMap = null;

    int lineIndex = 0;
    for (String line : LINE_SPLITTER.split(idMappings)) {
      lineIndex++;
      if (line.isEmpty()) {
        continue;
      }
      if (line.charAt(0) == '[') {
        String currentSection = line.substring(1, line.length() - 1);
        currentSectionMap = resultMap.get(currentSection);
        if (currentSectionMap == null) {
          currentSectionMap = HashBiMap.create();
          resultMap.put(currentSection, currentSectionMap);
        } else {
          throw new IllegalArgumentException(
              SimpleFormat.format(
                  "Cannot parse id map: %s\n Line: $s, lineIndex: %s",
                  idMappings, line, lineIndex));
        }
      } else {
        int split = line.indexOf(':');
        if (split != -1) {
          String name = line.substring(0, split);
          String location = line.substring(split + 1);
          currentSectionMap.put(name, location);
        } else {
          throw new IllegalArgumentException(
              SimpleFormat.format(
                  "Cannot parse id map: %s\n Line: $s, lineIndex: %s",
                  idMappings, line, lineIndex));
        }
      }
    }
    return resultMap;
  }
}