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// HTMLParser Library $Name: v1_5 $ - 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/StringSource.java,v $
// $Author: derrickoswald $
// $Date: 2005/05/15 11:49:04 $
// $Revision: 1.4 $
//
// 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.IOException;
import org.htmlparser.util.ParserException;
/**
* A source of characters based on a String.
*/
public class StringSource
extends
Source
{
/**
* The source of characters.
*/
protected String mString;
/**
* The current offset into the string.
*/
protected int mOffset;
/**
* The encoding to report.
* Only used by {@link #getEncoding}.
*/
protected String mEncoding;
/**
* The bookmark.
*/
protected int mMark;
/**
* Construct a source using the provided string.
* Until it is set, the encoding will be reported as ISO-8859-1.
* @param string The source of characters.
*/
public StringSource (String string)
{
this (string, "ISO-8859-1");
}
/**
* Construct a source using the provided string and encoding.
* The encoding is only used by {@link #getEncoding}.
* @param string The source of characters.
* @param character_set The encoding to report.
*/
public StringSource (String string, String character_set)
{
mString = (null == string) ? "" : string;
mOffset = 0;
mEncoding = character_set;
mMark = -1;
}
/**
* Get the encoding being used to convert characters.
* @return The current encoding.
*/
public String getEncoding ()
{
return (mEncoding);
}
/**
* Set the encoding to the given character set.
* This simply sets the encoding reported by {@link #getEncoding}.
* @param character_set The character set to use to convert characters.
* @exception ParserException Not thrown.
*/
public void setEncoding (String character_set)
throws
ParserException
{
mEncoding = character_set;
}
//
// Reader overrides
//
/**
* Does nothing.
* It's supposed to close the source, but use destroy() instead.
* @exception IOException not used
* @see #destroy
*/
public void close () throws IOException
{
}
/**
* Read a single character.
* @return The character read, as an integer in the range 0 to 65535
* (0x00-0xffff), or {@link #EOF EOF} if the source is exhausted.
* @exception IOException If an I/O error occurs.
*/
public int read () throws IOException
{
int ret;
if (null == mString)
throw new IOException ("source is closed");
else if (mOffset >= mString.length ())
ret = EOF;
else
{
ret = mString.charAt (mOffset);
mOffset++;
}
return (ret);
}
/**
* Read characters into a portion of an array.
* @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 source
* is exhausted.
* @exception IOException If an I/O error occurs.
*/
public int read (char[] cbuf, int off, int len) throws IOException
{
int length;
int ret;
if (null == mString)
throw new IOException ("source is closed");
else
{
length = mString.length ();
if (mOffset >= length)
ret = EOF;
else
{
if (len > length - mOffset)
len = length - mOffset;
mString.getChars (mOffset, mOffset + len, cbuf, off);
mOffset += len;
ret = len;
}
}
return (ret);
}
/**
* Read characters into an array.
* @param cbuf Destination buffer.
* @return The number of characters read, or {@link #EOF EOF} if the source
* is exhausted.
* @exception IOException If an I/O error occurs.
*/
public int read (char[] cbuf) throws IOException
{
return (read (cbuf, 0, cbuf.length));
}
/**
* Tell whether this source is ready to be read.
* @return Equivalent to a non-zero {@link #available()}, i.e. there are
* still more characters to read.
* @exception IOException Thrown if the source is closed.
*/
public boolean ready () throws IOException
{
if (null == mString)
throw new IOException ("source is closed");
return (mOffset < mString.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 == mString)
throw new IllegalStateException ("source is closed");
else
if (-1 != mMark)
mOffset = mMark;
else
mOffset = 0;
}
/**
* Tell whether this source supports the mark() operation.
* @return true.
*/
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 Not used.
* @exception IOException Thrown if the source is closed.
*
*/
public void mark (int readAheadLimit) throws IOException
{
if (null == mString)
throw new IOException ("source is closed");
mMark = mOffset;
}
/**
* Skip characters.
* Note: n is treated as an int
* @param n The number of characters to skip.
* @return The number of characters actually skipped
* @exception IllegalArgumentException If n is negative.
* @exception IOException If the source is closed.
*/
public long skip (long n)
throws
IOException,
IllegalArgumentException
{
int length;
long ret;
if (null == mString)
throw new IOException ("source is closed");
if (0 > n)
throw new IllegalArgumentException ("cannot skip backwards");
else
{
length = mString.length ();
if (mOffset >= length)
n = 0L;
else if (n > length - mOffset)
n = length - mOffset;
mOffset += n;
ret = n;
}
return (ret);
}
//
// Methods not in your Daddy's Reader
//
/**
* Undo the read of a single character.
* @exception IOException If no characters have been read or the source is closed.
*/
public void unread () throws IOException
{
if (null == mString)
throw new IOException ("source is closed");
else if (mOffset <= 0)
throw new IOException ("can't unread no characters");
else
mOffset--;
}
/**
* Retrieve a character again.
* @param offset The offset of the character.
* @return The character at offset.
* @exception IOException If the source is closed or an attempt is made to
* read beyond {@link #offset()}.
*/
public char getCharacter (int offset) throws IOException
{
char ret;
if (null == mString)
throw new IOException ("source is closed");
else if (offset >= mOffset)
throw new IOException ("read beyond current offset");
else
ret = mString.charAt (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 source is closed or an attempt is made to
* read beyond {@link #offset()}.
*/
public void getCharacters (char[] array, int offset, int start, int end) throws IOException
{
if (null == mString)
throw new IOException ("source is closed");
else
{
if (end > mOffset)
throw new IOException ("read beyond current offset");
else
mString.getChars (start, end, array, offset);
}
}
/**
* Retrieve a string comprised of characters already read.
* Asking for characters ahead of {@link #offset()} will throw an exception.
* @param offset The offset of the first character.
* @param length The number of characters to retrieve.
* @return A string containing the length characters at offset.
* @exception IOException If the source is closed or an attempt is made to
* read beyond {@link #offset()}.
*/
public String getString (int offset, int length) throws IOException
{
String ret;
if (null == mString)
throw new IOException ("source is closed");
else
{
if (offset + length > mOffset)
throw new IOException ("read beyond end of string");
else
ret = mString.substring (offset, offset + length);
}
return (ret);
}
/**
* Append characters already read into a StringBuffer.
* Asking for characters ahead of {@link #offset()} will throw an exception.
* @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 source is closed or an attempt is made to
* read beyond {@link #offset()}.
*/
public void getCharacters (StringBuilder buffer, int offset, int length) throws IOException
{
if (null == mString)
throw new IOException ("source is closed");
else
{
if (offset + length > mOffset)
throw new IOException ("read beyond end of string");
else
buffer.append (mString.substring (offset, 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 Not thrown
*/
public void destroy () throws IOException
{
mString = null;
}
/**
* 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 == mString)
ret = EOF;
else
ret = mOffset;
return (ret);
}
/**
* Get the number of available characters.
* @return The number of characters that can be read or zero if the source
* is closed.
*/
public int available ()
{
int ret;
if (null == mString)
ret = 0;
else
ret = mString.length () - mOffset;
return (ret);
}
}