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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.*;

/**
 * This class breaks up the character data read from a given Reader into {@link DataEntryToken}s. It
 * distinguishes character sequences that can be interpreted as valid Java identifiers from other
 * character sequences.
 *
 * @author Lars Vandenbergh
 */
public class DataEntryTokenizer {
  private Reader reader;
  private StringBuffer buffer;

  public DataEntryTokenizer(Reader reader) {
    this.reader = reader;
    this.buffer = new StringBuffer();
  }

  public DataEntryToken nextToken() throws IOException {
    StringBuffer tokenString = new StringBuffer(buffer.toString());
    buffer.setLength(0);

    while (true) {
      int i = reader.read();
      if (i < 0) {
        break;
      }

      // Is it part if the current token or the start of a new token?
      char c = (char) i;
      if (tokenString.length() == 0
          || isJavaIdentifierChar(c) == isJavaIdentifierChar(tokenString.charAt(0))) {
        tokenString.append(c);
      } else {
        buffer.append(c);
        break;
      }
    }

    if (tokenString.length() == 0) {
      return null;
    } else {
      DataEntryTokenType tokenType =
          isJavaIdentifierChar(tokenString.charAt(0))
              ? DataEntryTokenType.JAVA_IDENTIFIER
              : DataEntryTokenType.OTHER;

      return new DataEntryToken(tokenString.toString(), tokenType);
    }
  }

  private boolean isJavaIdentifierChar(char c) {
    return Character.isJavaIdentifierPart(c) || c == '.' || c == '-';
  }
}