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ProGuardCORE is a free library to read, analyze, modify, and write Java class files.
There is a newer version: 9.1.6
/*
 * ProGuardCORE -- library to process Java bytecode.
 *
 * Copyright (c) 2002-2020 Guardsquare NV
 *
 * 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 proguard.io;

import java.io.*;
import java.nio.charset.Charset;
import proguard.classfile.*;

/**
 * This {@link DataEntryReader} writes the resource data entries that it reads to a given {@link
 * DataEntryWriter}, updating their contents based on the renamed classes in the given {@link
 * ClassPool}.
 *
 * @author Eric Lafortune
 */
public class DataEntryRewriter extends DataEntryCopier {
  private final ClassPool classPool;
  private final Charset charset;

  /** Creates a new DataEntryRewriter. */
  public DataEntryRewriter(ClassPool classPool, Charset charset, DataEntryWriter dataEntryWriter) {
    super(dataEntryWriter);

    this.classPool = classPool;
    this.charset = charset;
  }

  // Implementations for DataEntryCopier.

  @Override
  protected void copyData(InputStream inputStream, OutputStream outputStream) throws IOException {
    Reader reader = new BufferedReader(new InputStreamReader(inputStream, charset));
    Writer writer = new BufferedWriter(new OutputStreamWriter(outputStream, charset));

    copyData(reader, writer);

    writer.flush();
  }

  /** Copies all data that it can read from the given reader to the given writer. */
  protected void copyData(Reader reader, Writer writer) throws IOException {
    DataEntryTokenizer tokenizer = new DataEntryTokenizer(reader);
    DataEntryToken token;

    // Read all tokens.
    while ((token = tokenizer.nextToken()) != null) {
      String word = token.string;

      // Adapt the word if it is a valid Java identifier.
      if (token.type == DataEntryTokenType.JAVA_IDENTIFIER) {
        word = adaptedWord(word);
      }

      // Write the word.
      writer.write(word);
    }
  }

  // Small utility methods.

  /** Adapts the given word if possible, based on the renamed class names. */
  private String adaptedWord(String word) {
    boolean containsDots = word.indexOf('.') >= 0;

    // Replace dots by forward slashes.
    String className = containsDots ? word.replace('.', TypeConstants.PACKAGE_SEPARATOR) : word;

    // Find the class corresponding to the word.
    Clazz clazz = classPool.getClass(className);
    if (clazz != null) {
      // Update the word if necessary.
      String newClassName = clazz.getName();
      if (!className.equals(newClassName)) {
        // Replace forward slashes by dots.
        word =
            containsDots
                ? newClassName.replace(TypeConstants.PACKAGE_SEPARATOR, '.')
                : newClassName;
      }
    }

    return word;
  }
}