// HTMLParser Library $Name: v1_6_20060319 $ - A java-based parser for HTML
// http://sourceforge.org/projects/htmlparser
// Copyright (C) 2004 Derrick Oswald
//
// Revision Control Information
//
// $Source: /cvsroot/htmlparser/htmlparser/src/org/htmlparser/lexer/InputStreamSource.java,v $
// $Author: derrickoswald $
// $Date: 2005/10/25 01:26:09 $
// $Revision: 1.9 $
//
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; either
// version 2.1 of the License, or (at your option) any later version.
//
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
// Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
//
package org.htmlparser.lexer;
import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.UnsupportedEncodingException;
import org.htmlparser.util.EncodingChangeException;
import org.htmlparser.util.ParserException;
/**
* A source of characters based on an InputStream such as from a URLConnection.
*/
public class InputStreamSource
extends
Source
{
/**
* An initial buffer size.
* Has a default value of {16384}.
*/
public static int BUFFER_SIZE = 16384;
/**
* The stream of bytes.
* Set to <code>null</code> when the source is closed.
*/
protected transient InputStream mStream;
/**
* The character set in use.
*/
protected String mEncoding;
/**
* The converter from bytes to characters.
*/
protected transient InputStreamReader mReader;
/**
* The characters read so far.
*/
protected char[] mBuffer;
/**
* The number of valid bytes in the buffer.
*/
protected int mLevel;
/**
* The offset of the next byte returned by read().
*/
protected int mOffset;
/**
* The bookmark.
*/
protected int mMark;
/**
* Create a source of characters using the default character set.
* @param stream The stream of bytes to use.
* @exception UnsupportedEncodingException If the default character set
* is unsupported.
*/
public InputStreamSource (InputStream stream)
throws
UnsupportedEncodingException
{
this (stream, null, BUFFER_SIZE);
}
/**
* Create a source of characters.
* @param stream The stream of bytes to use.
* @param charset The character set used in encoding the stream.
* @exception UnsupportedEncodingException If the character set
* is unsupported.
*/
public InputStreamSource (InputStream stream, String charset)
throws
UnsupportedEncodingException
{
this (stream, charset, BUFFER_SIZE);
}
/**
* Create a source of characters.
* @param stream The stream of bytes to use.
* @param charset The character set used in encoding the stream.
* @param size The initial character buffer size.
* @exception UnsupportedEncodingException If the character set
* is unsupported.
*/
public InputStreamSource (InputStream stream, String charset, int size)
throws
UnsupportedEncodingException
{
if (null == stream)
stream = new Stream (null);
else
// bug #1044707 mark()/reset() issues
if (!stream.markSupported ())
// wrap the stream so we can reset
stream = new Stream (stream);
// else
// just because mark is supported doesn't guarantee
// proper reset operation; there is no call to mark
// in this code, so if reset misbehaves there is an
// appropriate message in setEncoding() to suggest
// wraping it in a Stream.
// This was deemed better than an attempt to call
// reset at this point just to check if we would
// succeed later, or to call mark with an arbitrary
// lookahead size
mStream = stream;
if (null == charset)
{
mReader = new InputStreamReader (stream);
mEncoding = mReader.getEncoding ();
}
else
{
mEncoding = charset;
mReader = new InputStreamReader (stream, charset);
}
mBuffer = new char[size];
mLevel = 0;
mOffset = 0;
mMark = -1;
}
//
// Serialization support
//
/**
* Serialization support.
* @param out Where to write this object.
* @exception IOException If serialization has a problem.
*/
private void writeObject (ObjectOutputStream out)
throws
IOException
{
int offset;
char[] buffer;
if (null != mStream)
{
// remember the offset, drain the input stream, restore the offset
offset = mOffset;
buffer = new char[4096];
while (EOF != read (buffer))
;
mOffset = offset;
}
out.defaultWriteObject ();
}
/**
* Deserialization support.
* @param in Where to read this object from.
* @exception IOException If deserialization has a problem.
*/
private void readObject (ObjectInputStream in)
throws
IOException,
ClassNotFoundException
{
in.defaultReadObject ();
if (null != mBuffer) // buffer is null when destroy's been called
// pretend we're open, mStream goes null when exhausted
mStream = new ByteArrayInputStream (new byte[0]);
}
/**
* Get the input stream being used.
* @return The current input stream.
*/
public InputStream getStream ()
{
return (mStream);
}
/**
* Get the encoding being used to convert characters.
* @return The current encoding.
*/
public String getEncoding ()
{
return (mEncoding);
}
/**
* Begins reading from the source with the given character set.
* If the current encoding is the same as the requested encoding,
* this method is a no-op. Otherwise any subsequent characters read from
* this page will have been decoded using the given character set.<p>
* Some magic happens here to obtain this result if characters have already
* been consumed from this source.
* Since a Reader cannot be dynamically altered to use a different character
* set, the underlying stream is reset, a new Source is constructed
* and a comparison made of the characters read so far with the newly
* read characters up to the current position.
* If a difference is encountered, or some other problem occurs,
* an exception is thrown.
* @param character_set The character set to use to convert bytes into
* characters.
* @exception ParserException If a character mismatch occurs between
* characters already provided and those that would have been returned
* had the new character set been in effect from the beginning. An
* exception is also thrown if the underlying stream won't put up with
* these shenanigans.
*/
public void setEncoding (String character_set)
throws
ParserException
{
String encoding;
InputStream stream;
char[] buffer;
int offset;
char[] new_chars;
encoding = getEncoding ();
if (!encoding.equalsIgnoreCase (character_set))
{
stream = getStream ();
try
{
buffer = mBuffer;
offset = mOffset;
stream.reset ();
try
{
mEncoding = character_set;
mReader = new InputStreamReader (stream, character_set);
mBuffer = new char[mBuffer.length];
mLevel = 0;
mOffset = 0;
mMark = -1;
if (0 != offset)
{
new_chars = new char[offset];
if (offset != read (new_chars))
throw new ParserException ("reset stream failed");
for (int i = 0; i < offset; i++)
if (new_chars[i] != buffer[i])
throw new EncodingChangeException ("character mismatch (new: "
+ new_chars[i]
+ " [0x"
+ Integer.toString (new_chars[i], 16)
+ "] != old: "
+ " [0x"
+ Integer.toString (buffer[i], 16)
+ buffer[i]
+ "]) for encoding change from "
+ encoding
+ " to "
+ character_set
+ " at character offset "
+ i);
}
}
catch (IOException ioe)
{
throw new ParserException (ioe.getMessage (), ioe);
}
}
catch (IOException ioe)
{ // bug #1044707 mark()/reset() issues
throw new ParserException ("Stream reset failed ("
+ ioe.getMessage ()
+ "), try wrapping it with a org.htmlparser.lexer.Stream",
ioe);
}
}
}
/**
* Fetch more characters from the underlying reader.
* Has no effect if the underlying reader has been drained.
* @param min The minimum to read.
* @exception IOException If the underlying reader read() throws one.
*/
protected void fill (int min)
throws
IOException
{
char[] buffer;
int size;
int read;
if (null != mReader) // mReader goes null when it's been sucked dry
{
size = mBuffer.length - mLevel; // available space
if (size < min) // oops, better get some buffer space
{
// unknown length... keep doubling
size = mBuffer.length * 2;
read = mLevel + min;
if (size < read) // or satisfy min, whichever is greater
size = read;
else
min = size - mLevel; // read the max
buffer = new char[size];
}
else
{
buffer = mBuffer;
min = size;
}
// read into the end of the 'new' buffer
read = mReader.read (buffer, mLevel, min);
if (EOF == read)
{
mReader.close ();
mReader = null;
}
else
{
if (mBuffer != buffer)
{ // copy the bytes previously read
System.arraycopy (mBuffer, 0, buffer, 0, mLevel);
mBuffer = buffer;
}
mLevel += read;
}
// todo, should repeat on read shorter than original min
}
}
//
// Reader overrides
//
/**
* Does nothing.
* It's supposed to close the source, but use destroy() instead.
* @exception IOException <em>not used</em>
* @see #destroy
*/
public void close () throws IOException
{
}
/**
* Read a single character.
* This method will block until a character is available,
* an I/O error occurs, or the end of the stream is reached.
* @return The character read, as an integer in the range 0 to 65535
* (<tt>0x00-0xffff</tt>), or {@link #EOF EOF} if the end of the stream has
* been reached
* @exception IOException If an I/O error occurs.
*/
public int read () throws IOException
{
int ret;
if (mLevel - mOffset < 1)
{
if (null == mStream)
throw new IOException ("source is closed");
fill (1);
if (mOffset >= mLevel)
ret = EOF;
else
ret = mBuffer[mOffset++];
}
else
ret = mBuffer[mOffset++];
return (ret);
}
/**
* Read characters into a portion of an array. This method will block
* until some input is available, an I/O error occurs, or the end of the
* stream is reached.
* @param cbuf Destination buffer
* @param off Offset at which to start storing characters
* @param len Maximum number of characters to read
* @return The number of characters read, or {@link #EOF EOF} if the end of
* the stream has been reached
* @exception IOException If an I/O error occurs.
*/
public int read (char[] cbuf, int off, int len) throws IOException
{
int ret;
if (null == mStream)
throw new IOException ("source is closed");
if ((null == cbuf) || (0 > off) || (0 > len))
throw new IOException ("illegal argument read ("
+ ((null == cbuf) ? "null" : "cbuf")
+ ", " + off + ", " + len + ")");
if (mLevel - mOffset < len)
fill (len - (mLevel - mOffset)); // minimum to satisfy this request
if (mOffset >= mLevel)
ret = EOF;
else
{
ret = Math.min (mLevel - mOffset, len);
System.arraycopy (mBuffer, mOffset, cbuf, off, ret);
mOffset += ret;
}
return (ret);
}
/**
* Read characters into an array.
* This method will block until some input is available, an I/O error occurs,
* or the end of the stream is reached.
* @param cbuf Destination buffer.
* @return The number of characters read, or {@link #EOF EOF} if the end of
* the stream has been reached.
* @exception IOException If an I/O error occurs.
*/
public int read (char[] cbuf) throws IOException
{
return (read (cbuf, 0, cbuf.length));
}
/**
* Reset the source.
* Repositions the read point to begin at zero.
* @exception IllegalStateException If the source has been closed.
*/
public void reset ()
throws
IllegalStateException
{
if (null == mStream)
throw new IllegalStateException ("source is closed");
if (-1 != mMark)
mOffset = mMark;
else
mOffset = 0;
}
/**
* Tell whether this source supports the mark() operation.
* @return <code>true</code>.
*/
public boolean markSupported ()
{
return (true);
}
/**
* Mark the present position in the source.
* Subsequent calls to {@link #reset()}
* will attempt to reposition the source to this point.
* @param readAheadLimit <em>Not used.</em>
* @exception IOException If the source is closed.
*
*/
public void mark (int readAheadLimit) throws IOException
{
if (null == mStream)
throw new IOException ("source is closed");
mMark = mOffset;
}
/**
* Tell whether this source is ready to be read.
* @return <code>true</code> if the next read() is guaranteed not to block
* for input, <code>false</code> otherwise.
* Note that returning false does not guarantee that the next read will block.
* @exception IOException If the source is closed.
*/
public boolean ready () throws IOException
{
if (null == mStream)
throw new IOException ("source is closed");
return (mOffset < mLevel);
}
/**
* Skip characters.
* This method will block until some characters are available,
* an I/O error occurs, or the end of the stream is reached.
* <em>Note: n is treated as an int</em>
* @param n The number of characters to skip.
* @return The number of characters actually skipped
* @exception IllegalArgumentException If <code>n</code> is negative.
* @exception IOException If an I/O error occurs.
*/
public long skip (long n)
throws
IOException,
IllegalArgumentException
{
long ret;
if (null == mStream)
throw new IOException ("source is closed");
if (0 > n)
throw new IllegalArgumentException ("cannot skip backwards");
else
{
if (mLevel - mOffset < n)
fill ((int)(n - (mLevel - mOffset))); // minimum to satisfy this request
if (mOffset >= mLevel)
ret = EOF;
else
{
ret = Math.min (mLevel - mOffset, n);
mOffset += ret;
}
}
return (ret);
}
//
// Methods not in your Daddy's Reader
//
/**
* Undo the read of a single character.
* @exception IOException If the source is closed or no characters have
* been read.
*/
public void unread () throws IOException
{
if (null == mStream)
throw new IOException ("source is closed");
if (0 < mOffset)
mOffset--;
else
throw new IOException ("can't unread no characters");
}
/**
* Retrieve a character again.
* @param offset The offset of the character.
* @return The character at <code>offset</code>.
* @exception IOException If the offset is beyond {@link #offset()} or the
* source is closed.
*/
public char getCharacter (int offset) throws IOException
{
char ret;
if (null == mStream)
throw new IOException ("source is closed");
if (offset >= mBuffer.length)
throw new IOException ("illegal read ahead");
else
ret = mBuffer[offset];
return (ret);
}
/**
* Retrieve characters again.
* @param array The array of characters.
* @param offset The starting position in the array where characters are to be placed.
* @param start The starting position, zero based.
* @param end The ending position
* (exclusive, i.e. the character at the ending position is not included),
* zero based.
* @exception IOException If the start or end is beyond {@link #offset()}
* or the source is closed.
*/
public void getCharacters (char[] array, int offset, int start, int end) throws IOException
{
if (null == mStream)
throw new IOException ("source is closed");
System.arraycopy (mBuffer, start, array, offset, end - start);
}
/**
* Retrieve a string.
* @param offset The offset of the first character.
* @param length The number of characters to retrieve.
* @return A string containing the <code>length</code> characters at <code>offset</code>.
* @exception IOException If the offset or (offset + length) is beyond
* {@link #offset()} or the source is closed.
*/
public String getString (int offset, int length) throws IOException
{
String ret;
if (null == mStream)
throw new IOException ("source is closed");
if (offset + length > mBuffer.length)
throw new IOException ("illegal read ahead");
else
ret = new String (mBuffer, offset, length);
return (ret);
}
/**
* Append characters already read into a <code>StringBuffer</code>.
* @param buffer The buffer to append to.
* @param offset The offset of the first character.
* @param length The number of characters to retrieve.
* @exception IOException If the offset or (offset + length) is beyond
* {@link #offset()} or the source is closed.
*/
public void getCharacters (StringBuffer buffer, int offset, int length) throws IOException
{
if (null == mStream)
throw new IOException ("source is closed");
buffer.append (mBuffer, offset, length);
}
/**
* Close the source.
* Once a source has been closed, further {@link #read() read},
* {@link #ready ready}, {@link #mark mark}, {@link #reset reset},
* {@link #skip skip}, {@link #unread unread},
* {@link #getCharacter getCharacter} or {@link #getString getString}
* invocations will throw an IOException.
* Closing a previously-closed source, however, has no effect.
* @exception IOException If an I/O error occurs
*/
public void destroy () throws IOException
{
mStream = null;
if (null != mReader)
mReader.close ();
mReader = null;
mBuffer = null;
mLevel = 0;
mOffset = 0;
mMark = -1;
}
/**
* Get the position (in characters).
* @return The number of characters that have already been read, or
* {@link #EOF EOF} if the source is closed.
*/
public int offset ()
{
int ret;
if (null == mStream)
ret = EOF;
else
ret = mOffset;
return (ret);
}
/**
* Get the number of available characters.
* @return The number of characters that can be read without blocking or
* zero if the source is closed.
*/
public int available ()
{
int ret;
if (null == mStream)
ret = 0;
else
ret = mLevel - mOffset;
return (ret);
}
}