Class InputStreamReader

classpath/java/io/InputStreamReader.java:15–92

import avian.Utf8;

public class InputStreamReader extends Reader {
  private static final int MultibytePadding = 4;

  private final InputStream in;

  public InputStreamReader(InputStream in) {
    this.in = in;
  }

  public InputStreamReader(InputStream in, String encoding)
    throws UnsupportedEncodingException
  {
    this(in);

    if (! encoding.equals("UTF-8")) {
      throw new UnsupportedEncodingException(encoding);
    }    
  }
  
  public int read(char[] b, int offset, int length) throws IOException {
    if (length == 0) {
      return 0;
    }

    byte[] buffer = new byte[length + MultibytePadding];
    int bufferLength = length;
    int bufferOffset = 0;
    while (true) {
      int c = in.read(buffer, bufferOffset, bufferLength);

      if (c <= 0) {
        if (bufferOffset > 0) {
          // if we've reached the end of the stream while trying to
          // read a multibyte character, we still need to return any
          // competely-decoded characters, plus \ufffd to indicate an
          // unknown character
          c = 1;
          while (bufferOffset > 0) {
            char[] buffer16 = Utf8.decode16(buffer, 0, bufferOffset);

            if (buffer16 != null) {
              System.arraycopy(buffer16, 0, b, offset, buffer16.length);
              
              c = buffer16.length + 1;
              break;
            } else {
              -- bufferOffset;
            }
          }

          b[offset + c - 1] = '\ufffd';
        }

        return c;
      }

      bufferOffset += c;