DataInputStream.java

/*
 * Copyright 2010 Google Inc.
 * 
 * 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 java.io;

import com.google.gwt.corp.compatibility.Numbers;

public class DataInputStream extends InputStream implements DataInput {

  private final InputStream is;
  
  public DataInputStream(final InputStream is) {
    this.is = is;
  }
  
  @Override
  public int read() throws IOException {
    return is.read();
  }

  public boolean readBoolean() throws IOException {
    return readByte() != 0;
  }

  public byte readByte() throws IOException {
    int i = read();
    if (i == -1) {
      throw new EOFException();
    }
    return (byte) i;
  }

  public char readChar() throws IOException {
    int a = is.read();
    int b = readUnsignedByte();
    return (char) ((a << 8) | b);
  }

  public double readDouble() throws IOException {
    throw new RuntimeException("readDouble");
  }

  public float readFloat() throws IOException {
    return Numbers.intBitsToFloat(readInt());
  }

  public void readFully(byte[] b) throws IOException {
    readFully(b, 0, b.length);
  }

  public void readFully(byte[] b, int off, int len) throws IOException {
    while (len > 0) {
      int count = is.read(b, off, len);
      if (count <= 0) {
        throw new EOFException();
      }
      off += count;
      len -= count;
    }
  }

  public int readInt() throws IOException {
    int a = is.read();
    int b = is.read();
    int c = is.read();
    int d = readUnsignedByte();
    return (a << 24) | (b << 16) | (c << 8) | d;
  }

  public String readLine() throws IOException {
    throw new RuntimeException("readline NYI");
  }

  public long readLong() throws IOException {
    long a = readInt();
    long b = readInt() & 0x0ffffffff;
    return (a << 32) | b;
  }

  public short readShort() throws IOException {
    int a = is.read();
    int b = readUnsignedByte();
    return (short) ((a << 8) | b);
  }

  public String readUTF() throws IOException {
    int bytes = readUnsignedShort();
    StringBuilder sb = new StringBuilder();
    
    while (bytes > 0) {
      bytes -= readUtfChar(sb);
    }
    
    return sb.toString();
  }

  private int readUtfChar(StringBuilder sb) throws IOException {
    int a = readUnsignedByte();
    if ((a & 0x80) == 0) {
      sb.append((char) a);
      return 1;
    }
    if ((a & 0xe0) == 0xb0) {
      int b = readUnsignedByte();
      sb.append((char)(((a& 0x1F) << 6) | (b & 0x3F)));
      return 2;
    }
    if ((a & 0xf0) == 0xe0) {
      int b = is.read();
      int c = readUnsignedByte();
      sb.append((char)(((a & 0x0F) << 12) | ((b & 0x3F) << 6) | (c & 0x3F)));
      return 3;
    }
    throw new UTFDataFormatException();
  }

  public int readUnsignedByte() throws IOException {
    int i = read();
    if (i == -1) {
      throw new EOFException();
    }
    return i;
  }

  public int readUnsignedShort() throws IOException {
    int a = is.read();
    int b = readUnsignedByte();
    return ((a << 8) | b);
  }

  public int skipBytes(int n) throws IOException {
    // note: This is actually a valid implementation of this method, rendering it quite useless...
    return 0;
  }

}