content: /*
   * Licensed to the Apache Software Foundation (ASF) under one or more
   * contributor license agreements.  See the NOTICE file distributed with
   * this work for additional information regarding copyright ownership.
   * The ASF licenses this file to You 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 org.apache.commons.io.input;
  
  import java.io.IOException;
  import java.io.InputStream;
  import java.nio.ByteBuffer;
  import java.nio.CharBuffer;
  import java.nio.charset.CharacterCodingException;
  import java.nio.charset.Charset;
  import java.nio.charset.CharsetEncoder;
  import java.nio.charset.CoderResult;
  import java.nio.charset.CodingErrorAction;
  
  /**
   * {@link InputStream} implementation that can read from String, StringBuffer,
   * StringBuilder or CharBuffer.
   * <p>
   * <strong>Note:</strong> Supports {@link #mark(int)} and {@link #reset()}.
   *
   * @since 2.2
   */
  public class CharSequenceInputStream extends InputStream {
  
      private final CharsetEncoder encoder;
      private final CharBuffer cbuf;
      private final ByteBuffer bbuf;
  
      private int mark;
      
      /**
       * Constructor.
       * 
       * @param s the input character sequence
       * @param charset the character set name to use
       * @param bufferSize the buffer size to use.
       */
      public CharSequenceInputStream(final CharSequence s, final Charset charset, int bufferSize) {
          super();
          this.encoder = charset.newEncoder()
              .onMalformedInput(CodingErrorAction.REPLACE)
              .onUnmappableCharacter(CodingErrorAction.REPLACE);
          this.bbuf = ByteBuffer.allocate(bufferSize);
          this.bbuf.flip();
          this.cbuf = CharBuffer.wrap(s);
          this.mark = -1;
      }
  
      /**
       * Constructor, calls {@link #CharSequenceInputStream(CharSequence, Charset, int)}.
       * 
       * @param s the input character sequence
       * @param charset the character set name to use
       * @param bufferSize the buffer size to use.
       */
      public CharSequenceInputStream(final CharSequence s, final String charset, int bufferSize) {
          this(s, Charset.forName(charset), bufferSize);
      }
  
      /**
       * Constructor, calls {@link #CharSequenceInputStream(CharSequence, Charset, int)}
       * with a buffer size of 2048.
       * 
       * @param s the input character sequence
       * @param charset the character set name to use
       */
      public CharSequenceInputStream(final CharSequence s, final Charset charset) {
          this(s, charset, 2048);
      }
  
      /**
       * Constructor, calls {@link #CharSequenceInputStream(CharSequence, String, int)}
       * with a buffer size of 2048.
       * 
       * @param s the input character sequence
       * @param charset the character set name to use
       */
      public CharSequenceInputStream(final CharSequence s, final String charset) {
          this(s, charset, 2048);
      }
  
      /**
       * Fills the byte output buffer from the input char buffer.
       * 
       * @throws CharacterCodingException
       *             an error encoding data
       */
      private void fillBuffer() throws CharacterCodingException {
          this.bbuf.compact();
          CoderResult result = this.encoder.encode(this.cbuf, this.bbuf, true);
          if (result.isError()) {
              result.throwException();
          }
          this.bbuf.flip();
      }
      
      @Override
      public int read(byte[] b, int off, int len) throws IOException {
          if (b == null) {
              throw new NullPointerException("Byte array is null");
          }
          if (len < 0 || (off + len) > b.length) {
              throw new IndexOutOfBoundsException("Array Size=" + b.length +
                      ", offset=" + off + ", length=" + len);
          }
          if (len == 0) {
              return 0; // must return 0 for zero length read
          }
          if (!this.bbuf.hasRemaining() && !this.cbuf.hasRemaining()) {
              return -1;
          }
          int bytesRead = 0;
          while (len > 0) {
              if (this.bbuf.hasRemaining()) {
                  int chunk = Math.min(this.bbuf.remaining(), len);
                  this.bbuf.get(b, off, chunk);
                  off += chunk;
                  len -= chunk;
                  bytesRead += chunk;
              } else {
                  fillBuffer();
                  if (!this.bbuf.hasRemaining() && !this.cbuf.hasRemaining()) {
                      break;
                  }
              }
          }
          return bytesRead == 0 && !this.cbuf.hasRemaining() ? -1 : bytesRead;
      }
  
      @Override
      public int read() throws IOException {
          for (;;) {
              if (this.bbuf.hasRemaining()) {
                  return this.bbuf.get() & 0xFF;
              } else {
                  fillBuffer();
                  if (!this.bbuf.hasRemaining() && !this.cbuf.hasRemaining()) {
                      return -1;
                  }
              }
          }
      }
  
      @Override
      public int read(byte[] b) throws IOException {
          return read(b, 0, b.length);
      }
  
      @Override
      public long skip(long n) throws IOException {
          int skipped = 0;
          while (n > 0 && this.cbuf.hasRemaining()) {
              this.cbuf.get();
              n--;
              skipped++;
          }
          return skipped;
      }
  
      @Override
      public int available() throws IOException {
          return this.cbuf.remaining();
      }
  
      @Override
      public void close() throws IOException {
      }
  
      /**
       * {@inheritDoc}
       * @param readlimit max read limit (ignored)
       */
      @Override
      public synchronized void mark(int readlimit) {
          this.mark = this.cbuf.position();
      }
  
      @Override
      public synchronized void reset() throws IOException {
          if (this.mark != -1) {
              this.cbuf.position(this.mark);
              this.mark = -1;
          }
      }
  
      @Override
      public boolean markSupported() {
          return true;
      }
      
  }
  