ResourceTableChunk.java

/*
 * Copyright 2016 Google Inc. 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.devrel.gmscore.tools.apk.arsc;

import com.google.common.base.Preconditions;

import java.nio.ByteBuffer;
import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.Map;

import javax.annotation.Nullable;

/**
 * Represents a resource table structure. Its sub-chunks contain:
 *
 * <ul>
 * <li>A {@link StringPoolChunk} containing all string values in the entire resource table. It does
 *    not, however, contain the names of entries or type identifiers.
 * <li>One or more {@link PackageChunk}.
 * </ul>
 */
public final class ResourceTableChunk extends ChunkWithChunks {

  /** A string pool containing all string resource values in the entire resource table. */
  private StringPoolChunk stringPool;

  /** The packages contained in this resource table. */
  private final Map<String, PackageChunk> packages = new HashMap<>();

  protected ResourceTableChunk(ByteBuffer buffer, @Nullable Chunk parent) {
    super(buffer, parent);
    // packageCount. We ignore this, because we already know how many chunks we have.
    Preconditions.checkState(buffer.getInt() >= 1, "ResourceTableChunk package count was < 1.");
  }

  @Override
  protected void init(ByteBuffer buffer) {
    super.init(buffer);
    packages.clear();
    for (Chunk chunk : getChunks().values()) {
      if (chunk instanceof PackageChunk) {
        PackageChunk packageChunk = (PackageChunk) chunk;
        packages.put(packageChunk.getPackageName(), packageChunk);
      } else  if (chunk instanceof StringPoolChunk) {
        stringPool = (StringPoolChunk) chunk;
      }
    }
    Preconditions.checkNotNull(stringPool, "ResourceTableChunk must have a string pool.");
  }

  /** Returns the string pool containing all string resource values in the resource table. */
  public StringPoolChunk getStringPool() {
    return stringPool;
  }

  /** Returns the package with the given {@code packageName}. Else, returns null. */
  @Nullable
  public PackageChunk getPackage(String packageName) {
    return packages.get(packageName);
  }

  /** Returns the packages contained in this resource table. */
  public Collection<PackageChunk> getPackages() {
    return Collections.unmodifiableCollection(packages.values());
  }

  @Override
  protected Type getType() {
    return Chunk.Type.TABLE;
  }

  @Override
  protected void writeHeader(ByteBuffer output) {
    super.writeHeader(output);
    output.putInt(packages.size());
  }
}