|
|
Java example source code file (FastStringBuffer.java)
This example Java source code file (FastStringBuffer.java) is included in the alvinalexander.com
"Java Source Code
Warehouse" project. The intent of this project is to help you "Learn
Java by Example" TM.
Learn more about this Java project at its project page.
The FastStringBuffer.java Java example source code
/*
* reserved comment block
* DO NOT REMOVE OR ALTER!
*/
/*
* Copyright 1999-2004 The Apache Software Foundation.
*
* 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.
*/
/*
* $Id: FastStringBuffer.java,v 1.2.4.1 2005/09/15 08:15:44 suresh_emailid Exp $
*/
package com.sun.org.apache.xml.internal.utils;
/**
* Bare-bones, unsafe, fast string buffer. No thread-safety, no
* parameter range checking, exposed fields. Note that in typical
* applications, thread-safety of a StringBuffer is a somewhat
* dubious concept in any case.
* <p>
* Note that Stree and DTM used a single FastStringBuffer as a string pool,
* by recording start and length indices within this single buffer. This
* minimizes heap overhead, but of course requires more work when retrieving
* the data.
* <p>
* FastStringBuffer operates as a "chunked buffer". Doing so
* reduces the need to recopy existing information when an append
* exceeds the space available; we just allocate another chunk and
* flow across to it. (The array of chunks may need to grow,
* admittedly, but that's a much smaller object.) Some excess
* recopying may arise when we extract Strings which cross chunk
* boundaries; larger chunks make that less frequent.
* <p>
* The size values are parameterized, to allow tuning this code. In
* theory, Result Tree Fragments might want to be tuned differently
* from the main document's text.
* <p>
* %REVIEW% An experiment in self-tuning is
* included in the code (using nested FastStringBuffers to achieve
* variation in chunk sizes), but this implementation has proven to
* be problematic when data may be being copied from the FSB into itself.
* We should either re-architect that to make this safe (if possible)
* or remove that code and clean up for performance/maintainability reasons.
* <p>
*/
public class FastStringBuffer
{
// If nonzero, forces the inial chunk size.
/**/static final int DEBUG_FORCE_INIT_BITS=0;
// %BUG% %REVIEW% *****PROBLEM SUSPECTED: If data from an FSB is being copied
// back into the same FSB (variable set from previous variable, for example)
// and blocksize changes in mid-copy... there's risk of severe malfunction in
// the read process, due to how the resizing code re-jiggers storage. Arggh.
// If we want to retain the variable-size-block feature, we need to reconsider
// that issue. For now, I have forced us into fixed-size mode.
static final boolean DEBUG_FORCE_FIXED_CHUNKSIZE=true;
/** Manifest constant: Suppress leading whitespace.
* This should be used when normalize-to-SAX is called for the first chunk of a
* multi-chunk output, or one following unsuppressed whitespace in a previous
* chunk.
* @see #sendNormalizedSAXcharacters(org.xml.sax.ContentHandler,int,int)
*/
public static final int SUPPRESS_LEADING_WS=0x01;
/** Manifest constant: Suppress trailing whitespace.
* This should be used when normalize-to-SAX is called for the last chunk of a
* multi-chunk output; it may have to be or'ed with SUPPRESS_LEADING_WS.
*/
public static final int SUPPRESS_TRAILING_WS=0x02;
/** Manifest constant: Suppress both leading and trailing whitespace.
* This should be used when normalize-to-SAX is called for a complete string.
* (I'm not wild about the name of this one. Ideas welcome.)
* @see #sendNormalizedSAXcharacters(org.xml.sax.ContentHandler,int,int)
*/
public static final int SUPPRESS_BOTH
= SUPPRESS_LEADING_WS | SUPPRESS_TRAILING_WS;
/** Manifest constant: Carry trailing whitespace of one chunk as leading
* whitespace of the next chunk. Used internally; I don't see any reason
* to make it public right now.
*/
private static final int CARRY_WS=0x04;
/**
* Field m_chunkBits sets our chunking strategy, by saying how many
* bits of index can be used within a single chunk before flowing over
* to the next chunk. For example, if m_chunkbits is set to 15, each
* chunk can contain up to 2^15 (32K) characters
*/
int m_chunkBits = 15;
/**
* Field m_maxChunkBits affects our chunk-growth strategy, by saying what
* the largest permissible chunk size is in this particular FastStringBuffer
* hierarchy.
*/
int m_maxChunkBits = 15;
/**
* Field m_rechunkBits affects our chunk-growth strategy, by saying how
* many chunks should be allocated at one size before we encapsulate them
* into the first chunk of the next size up. For example, if m_rechunkBits
* is set to 3, then after 8 chunks at a given size we will rebundle
* them as the first element of a FastStringBuffer using a chunk size
* 8 times larger (chunkBits shifted left three bits).
*/
int m_rebundleBits = 2;
/**
* Field m_chunkSize establishes the maximum size of one chunk of the array
* as 2**chunkbits characters.
* (Which may also be the minimum size if we aren't tuning for storage)
*/
int m_chunkSize; // =1<<(m_chunkBits-1);
/**
* Field m_chunkMask is m_chunkSize-1 -- in other words, m_chunkBits
* worth of low-order '1' bits, useful for shift-and-mask addressing
* within the chunks.
*/
int m_chunkMask; // =m_chunkSize-1;
/**
* Field m_array holds the string buffer's text contents, using an
* array-of-arrays. Note that this array, and the arrays it contains, may be
* reallocated when necessary in order to allow the buffer to grow;
* references to them should be considered to be invalidated after any
* append. However, the only time these arrays are directly exposed
* is in the sendSAXcharacters call.
*/
char[][] m_array;
/**
* Field m_lastChunk is an index into m_array[], pointing to the last
* chunk of the Chunked Array currently in use. Note that additional
* chunks may actually be allocated, eg if the FastStringBuffer had
* previously been truncated or if someone issued an ensureSpace request.
* <p>
* The insertion point for append operations is addressed by the combination
* of m_lastChunk and m_firstFree.
*/
int m_lastChunk = 0;
/**
* Field m_firstFree is an index into m_array[m_lastChunk][], pointing to
* the first character in the Chunked Array which is not part of the
* FastStringBuffer's current content. Since m_array[][] is zero-based,
* the length of that content can be calculated as
* (m_lastChunk<> m_chunkBits;
if (m_lastChunk == 0 && m_innerFSB != null)
{
// Replace this FSB with the appropriate inner FSB, truncated
m_innerFSB.setLength(l, this);
}
else
{
m_firstFree = l & m_chunkMask;
// There's an edge case if l is an exact multiple of m_chunkBits, which risks leaving
// us pointing at the start of a chunk which has not yet been allocated. Rather than
// pay the cost of dealing with that in the append loops (more scattered and more
// inner-loop), we correct it here by moving to the safe side of that
// line -- as we would have left the indexes had we appended up to that point.
if(m_firstFree==0 && m_lastChunk>0)
{
--m_lastChunk;
m_firstFree=m_chunkSize;
}
}
}
/**
* Subroutine for the public setLength() method. Deals with the fact
* that truncation may require restoring one of the innerFSBs
*
* NEEDSDOC @param l
* NEEDSDOC @param rootFSB
*/
private final void setLength(int l, FastStringBuffer rootFSB)
{
m_lastChunk = l >>> m_chunkBits;
if (m_lastChunk == 0 && m_innerFSB != null)
{
m_innerFSB.setLength(l, rootFSB);
}
else
{
// Undo encapsulation -- pop the innerFSB data back up to root.
// Inefficient, but attempts to keep the code simple.
rootFSB.m_chunkBits = m_chunkBits;
rootFSB.m_maxChunkBits = m_maxChunkBits;
rootFSB.m_rebundleBits = m_rebundleBits;
rootFSB.m_chunkSize = m_chunkSize;
rootFSB.m_chunkMask = m_chunkMask;
rootFSB.m_array = m_array;
rootFSB.m_innerFSB = m_innerFSB;
rootFSB.m_lastChunk = m_lastChunk;
// Finally, truncate this sucker.
rootFSB.m_firstFree = l & m_chunkMask;
}
}
/**
* Note that this operation has been somewhat deoptimized by the shift to a
* chunked array, as there is no factory method to produce a String object
* directly from an array of arrays and hence a double copy is needed.
* By using ensureCapacity we hope to minimize the heap overhead of building
* the intermediate StringBuffer.
* <p>
* (It really is a pity that Java didn't design String as a final subclass
* of MutableString, rather than having StringBuffer be a separate hierarchy.
* We'd avoid a <strong>lot of double-buffering.)
*
* @return the contents of the FastStringBuffer as a standard Java string.
*/
public final String toString()
{
int length = (m_lastChunk << m_chunkBits) + m_firstFree;
return getString(new StringBuffer(length), 0, 0, length).toString();
}
/**
* Append a single character onto the FastStringBuffer, growing the
* storage if necessary.
* <p>
* NOTE THAT after calling append(), previously obtained
* references to m_array[][] may no longer be valid....
* though in fact they should be in this instance.
*
* @param value character to be appended.
*/
public final void append(char value)
{
char[] chunk;
// We may have preallocated chunks. If so, all but last should
// be at full size.
boolean lastchunk = (m_lastChunk + 1 == m_array.length);
if (m_firstFree < m_chunkSize) // Simplified test single-character-fits
chunk = m_array[m_lastChunk];
else
{
// Extend array?
int i = m_array.length;
if (m_lastChunk + 1 == i)
{
char[][] newarray = new char[i + 16][];
System.arraycopy(m_array, 0, newarray, 0, i);
m_array = newarray;
}
// Advance one chunk
chunk = m_array[++m_lastChunk];
if (chunk == null)
{
// Hierarchical encapsulation
if (m_lastChunk == 1 << m_rebundleBits
&& m_chunkBits < m_maxChunkBits)
{
// Should do all the work of both encapsulating
// existing data and establishing new sizes/offsets
m_innerFSB = new FastStringBuffer(this);
}
// Add a chunk.
chunk = m_array[m_lastChunk] = new char[m_chunkSize];
}
m_firstFree = 0;
}
// Space exists in the chunk. Append the character.
chunk[m_firstFree++] = value;
}
/**
* Append the contents of a String onto the FastStringBuffer,
* growing the storage if necessary.
* <p>
* NOTE THAT after calling append(), previously obtained
* references to m_array[] may no longer be valid.
*
* @param value String whose contents are to be appended.
*/
public final void append(String value)
{
if (value == null)
return;
int strlen = value.length();
if (0 == strlen)
return;
int copyfrom = 0;
char[] chunk = m_array[m_lastChunk];
int available = m_chunkSize - m_firstFree;
// Repeat while data remains to be copied
while (strlen > 0)
{
// Copy what fits
if (available > strlen)
available = strlen;
value.getChars(copyfrom, copyfrom + available, m_array[m_lastChunk],
m_firstFree);
strlen -= available;
copyfrom += available;
// If there's more left, allocate another chunk and continue
if (strlen > 0)
{
// Extend array?
int i = m_array.length;
if (m_lastChunk + 1 == i)
{
char[][] newarray = new char[i + 16][];
System.arraycopy(m_array, 0, newarray, 0, i);
m_array = newarray;
}
// Advance one chunk
chunk = m_array[++m_lastChunk];
if (chunk == null)
{
// Hierarchical encapsulation
if (m_lastChunk == 1 << m_rebundleBits
&& m_chunkBits < m_maxChunkBits)
{
// Should do all the work of both encapsulating
// existing data and establishing new sizes/offsets
m_innerFSB = new FastStringBuffer(this);
}
// Add a chunk.
chunk = m_array[m_lastChunk] = new char[m_chunkSize];
}
available = m_chunkSize;
m_firstFree = 0;
}
}
// Adjust the insert point in the last chunk, when we've reached it.
m_firstFree += available;
}
/**
* Append the contents of a StringBuffer onto the FastStringBuffer,
* growing the storage if necessary.
* <p>
* NOTE THAT after calling append(), previously obtained
* references to m_array[] may no longer be valid.
*
* @param value StringBuffer whose contents are to be appended.
*/
public final void append(StringBuffer value)
{
if (value == null)
return;
int strlen = value.length();
if (0 == strlen)
return;
int copyfrom = 0;
char[] chunk = m_array[m_lastChunk];
int available = m_chunkSize - m_firstFree;
// Repeat while data remains to be copied
while (strlen > 0)
{
// Copy what fits
if (available > strlen)
available = strlen;
value.getChars(copyfrom, copyfrom + available, m_array[m_lastChunk],
m_firstFree);
strlen -= available;
copyfrom += available;
// If there's more left, allocate another chunk and continue
if (strlen > 0)
{
// Extend array?
int i = m_array.length;
if (m_lastChunk + 1 == i)
{
char[][] newarray = new char[i + 16][];
System.arraycopy(m_array, 0, newarray, 0, i);
m_array = newarray;
}
// Advance one chunk
chunk = m_array[++m_lastChunk];
if (chunk == null)
{
// Hierarchical encapsulation
if (m_lastChunk == 1 << m_rebundleBits
&& m_chunkBits < m_maxChunkBits)
{
// Should do all the work of both encapsulating
// existing data and establishing new sizes/offsets
m_innerFSB = new FastStringBuffer(this);
}
// Add a chunk.
chunk = m_array[m_lastChunk] = new char[m_chunkSize];
}
available = m_chunkSize;
m_firstFree = 0;
}
}
// Adjust the insert point in the last chunk, when we've reached it.
m_firstFree += available;
}
/**
* Append part of the contents of a Character Array onto the
* FastStringBuffer, growing the storage if necessary.
* <p>
* NOTE THAT after calling append(), previously obtained
* references to m_array[] may no longer be valid.
*
* @param chars character array from which data is to be copied
* @param start offset in chars of first character to be copied,
* zero-based.
* @param length number of characters to be copied
*/
public final void append(char[] chars, int start, int length)
{
int strlen = length;
if (0 == strlen)
return;
int copyfrom = start;
char[] chunk = m_array[m_lastChunk];
int available = m_chunkSize - m_firstFree;
// Repeat while data remains to be copied
while (strlen > 0)
{
// Copy what fits
if (available > strlen)
available = strlen;
System.arraycopy(chars, copyfrom, m_array[m_lastChunk], m_firstFree,
available);
strlen -= available;
copyfrom += available;
// If there's more left, allocate another chunk and continue
if (strlen > 0)
{
// Extend array?
int i = m_array.length;
if (m_lastChunk + 1 == i)
{
char[][] newarray = new char[i + 16][];
System.arraycopy(m_array, 0, newarray, 0, i);
m_array = newarray;
}
// Advance one chunk
chunk = m_array[++m_lastChunk];
if (chunk == null)
{
// Hierarchical encapsulation
if (m_lastChunk == 1 << m_rebundleBits
&& m_chunkBits < m_maxChunkBits)
{
// Should do all the work of both encapsulating
// existing data and establishing new sizes/offsets
m_innerFSB = new FastStringBuffer(this);
}
// Add a chunk.
chunk = m_array[m_lastChunk] = new char[m_chunkSize];
}
available = m_chunkSize;
m_firstFree = 0;
}
}
// Adjust the insert point in the last chunk, when we've reached it.
m_firstFree += available;
}
/**
* Append the contents of another FastStringBuffer onto
* this FastStringBuffer, growing the storage if necessary.
* <p>
* NOTE THAT after calling append(), previously obtained
* references to m_array[] may no longer be valid.
*
* @param value FastStringBuffer whose contents are
* to be appended.
*/
public final void append(FastStringBuffer value)
{
// Complicating factor here is that the two buffers may use
// different chunk sizes, and even if they're the same we're
// probably on a different alignment due to previously appended
// data. We have to work through the source in bite-sized chunks.
if (value == null)
return;
int strlen = value.length();
if (0 == strlen)
return;
int copyfrom = 0;
char[] chunk = m_array[m_lastChunk];
int available = m_chunkSize - m_firstFree;
// Repeat while data remains to be copied
while (strlen > 0)
{
// Copy what fits
if (available > strlen)
available = strlen;
int sourcechunk = (copyfrom + value.m_chunkSize - 1)
>>> value.m_chunkBits;
int sourcecolumn = copyfrom & value.m_chunkMask;
int runlength = value.m_chunkSize - sourcecolumn;
if (runlength > available)
runlength = available;
System.arraycopy(value.m_array[sourcechunk], sourcecolumn,
m_array[m_lastChunk], m_firstFree, runlength);
if (runlength != available)
System.arraycopy(value.m_array[sourcechunk + 1], 0,
m_array[m_lastChunk], m_firstFree + runlength,
available - runlength);
strlen -= available;
copyfrom += available;
// If there's more left, allocate another chunk and continue
if (strlen > 0)
{
// Extend array?
int i = m_array.length;
if (m_lastChunk + 1 == i)
{
char[][] newarray = new char[i + 16][];
System.arraycopy(m_array, 0, newarray, 0, i);
m_array = newarray;
}
// Advance one chunk
chunk = m_array[++m_lastChunk];
if (chunk == null)
{
// Hierarchical encapsulation
if (m_lastChunk == 1 << m_rebundleBits
&& m_chunkBits < m_maxChunkBits)
{
// Should do all the work of both encapsulating
// existing data and establishing new sizes/offsets
m_innerFSB = new FastStringBuffer(this);
}
// Add a chunk.
chunk = m_array[m_lastChunk] = new char[m_chunkSize];
}
available = m_chunkSize;
m_firstFree = 0;
}
}
// Adjust the insert point in the last chunk, when we've reached it.
m_firstFree += available;
}
/**
* @return true if the specified range of characters are all whitespace,
* as defined by XMLCharacterRecognizer.
* <p>
* CURRENTLY DOES NOT CHECK FOR OUT-OF-RANGE.
*
* @param start Offset of first character in the range.
* @param length Number of characters to send.
*/
public boolean isWhitespace(int start, int length)
{
int sourcechunk = start >>> m_chunkBits;
int sourcecolumn = start & m_chunkMask;
int available = m_chunkSize - sourcecolumn;
boolean chunkOK;
while (length > 0)
{
int runlength = (length <= available) ? length : available;
if (sourcechunk == 0 && m_innerFSB != null)
chunkOK = m_innerFSB.isWhitespace(sourcecolumn, runlength);
else
chunkOK = com.sun.org.apache.xml.internal.utils.XMLCharacterRecognizer.isWhiteSpace(
m_array[sourcechunk], sourcecolumn, runlength);
if (!chunkOK)
return false;
length -= runlength;
++sourcechunk;
sourcecolumn = 0;
available = m_chunkSize;
}
return true;
}
/**
* @param start Offset of first character in the range.
* @param length Number of characters to send.
* @return a new String object initialized from the specified range of
* characters.
*/
public String getString(int start, int length)
{
int startColumn = start & m_chunkMask;
int startChunk = start >>> m_chunkBits;
if (startColumn + length < m_chunkMask && m_innerFSB == null) {
return getOneChunkString(startChunk, startColumn, length);
}
return getString(new StringBuffer(length), startChunk, startColumn,
length).toString();
}
protected String getOneChunkString(int startChunk, int startColumn,
int length) {
return new String(m_array[startChunk], startColumn, length);
}
/**
* @param sb StringBuffer to be appended to
* @param start Offset of first character in the range.
* @param length Number of characters to send.
* @return sb with the requested text appended to it
*/
StringBuffer getString(StringBuffer sb, int start, int length)
{
return getString(sb, start >>> m_chunkBits, start & m_chunkMask, length);
}
/**
* Internal support for toString() and getString().
* PLEASE NOTE SIGNATURE CHANGE from earlier versions; it now appends into
* and returns a StringBuffer supplied by the caller. This simplifies
* m_innerFSB support.
* <p>
* Note that this operation has been somewhat deoptimized by the shift to a
* chunked array, as there is no factory method to produce a String object
* directly from an array of arrays and hence a double copy is needed.
* By presetting length we hope to minimize the heap overhead of building
* the intermediate StringBuffer.
* <p>
* (It really is a pity that Java didn't design String as a final subclass
* of MutableString, rather than having StringBuffer be a separate hierarchy.
* We'd avoid a <strong>lot of double-buffering.)
*
*
* @param sb
* @param startChunk
* @param startColumn
* @param length
*
* @return the contents of the FastStringBuffer as a standard Java string.
*/
StringBuffer getString(StringBuffer sb, int startChunk, int startColumn,
int length)
{
int stop = (startChunk << m_chunkBits) + startColumn + length;
int stopChunk = stop >>> m_chunkBits;
int stopColumn = stop & m_chunkMask;
// Factored out
//StringBuffer sb=new StringBuffer(length);
for (int i = startChunk; i < stopChunk; ++i)
{
if (i == 0 && m_innerFSB != null)
m_innerFSB.getString(sb, startColumn, m_chunkSize - startColumn);
else
sb.append(m_array[i], startColumn, m_chunkSize - startColumn);
startColumn = 0; // after first chunk
}
if (stopChunk == 0 && m_innerFSB != null)
m_innerFSB.getString(sb, startColumn, stopColumn - startColumn);
else if (stopColumn > startColumn)
sb.append(m_array[stopChunk], startColumn, stopColumn - startColumn);
return sb;
}
/**
* Get a single character from the string buffer.
*
*
* @param pos character position requested.
* @return A character from the requested position.
*/
public char charAt(int pos)
{
int startChunk = pos >>> m_chunkBits;
if (startChunk == 0 && m_innerFSB != null)
return m_innerFSB.charAt(pos & m_chunkMask);
else
return m_array[startChunk][pos & m_chunkMask];
}
/**
* Sends the specified range of characters as one or more SAX characters()
* events.
* Note that the buffer reference passed to the ContentHandler may be
* invalidated if the FastStringBuffer is edited; it's the user's
* responsibility to manage access to the FastStringBuffer to prevent this
* problem from arising.
* <p>
* Note too that there is no promise that the output will be sent as a
* single call. As is always true in SAX, one logical string may be split
* across multiple blocks of memory and hence delivered as several
* successive events.
*
* @param ch SAX ContentHandler object to receive the event.
* @param start Offset of first character in the range.
* @param length Number of characters to send.
* @exception org.xml.sax.SAXException may be thrown by handler's
* characters() method.
*/
public void sendSAXcharacters(
org.xml.sax.ContentHandler ch, int start, int length)
throws org.xml.sax.SAXException
{
int startChunk = start >>> m_chunkBits;
int startColumn = start & m_chunkMask;
if (startColumn + length < m_chunkMask && m_innerFSB == null) {
ch.characters(m_array[startChunk], startColumn, length);
return;
}
int stop = start + length;
int stopChunk = stop >>> m_chunkBits;
int stopColumn = stop & m_chunkMask;
for (int i = startChunk; i < stopChunk; ++i)
{
if (i == 0 && m_innerFSB != null)
m_innerFSB.sendSAXcharacters(ch, startColumn,
m_chunkSize - startColumn);
else
ch.characters(m_array[i], startColumn, m_chunkSize - startColumn);
startColumn = 0; // after first chunk
}
// Last, or only, chunk
if (stopChunk == 0 && m_innerFSB != null)
m_innerFSB.sendSAXcharacters(ch, startColumn, stopColumn - startColumn);
else if (stopColumn > startColumn)
{
ch.characters(m_array[stopChunk], startColumn,
stopColumn - startColumn);
}
}
/**
* Sends the specified range of characters as one or more SAX characters()
* events, normalizing the characters according to XSLT rules.
*
* @param ch SAX ContentHandler object to receive the event.
* @param start Offset of first character in the range.
* @param length Number of characters to send.
* @return normalization status to apply to next chunk (because we may
* have been called recursively to process an inner FSB):
* <dl>
* <dt>0
* <dd>if this output did not end in retained whitespace, and thus whitespace
* at the start of the following chunk (if any) should be converted to a
* single space.
* <dt>SUPPRESS_LEADING_WS
* <dd>if this output ended in retained whitespace, and thus whitespace
* at the start of the following chunk (if any) should be completely
* suppressed.</dd>
* </dd>
* </dl>
* @exception org.xml.sax.SAXException may be thrown by handler's
* characters() method.
*/
public int sendNormalizedSAXcharacters(
org.xml.sax.ContentHandler ch, int start, int length)
throws org.xml.sax.SAXException
{
// This call always starts at the beginning of the
// string being written out, either because it was called directly or
// because it was an m_innerFSB recursion. This is important since
// it gives us a well-known initial state for this flag:
int stateForNextChunk=SUPPRESS_LEADING_WS;
int stop = start + length;
int startChunk = start >>> m_chunkBits;
int startColumn = start & m_chunkMask;
int stopChunk = stop >>> m_chunkBits;
int stopColumn = stop & m_chunkMask;
for (int i = startChunk; i < stopChunk; ++i)
{
if (i == 0 && m_innerFSB != null)
stateForNextChunk=
m_innerFSB.sendNormalizedSAXcharacters(ch, startColumn,
m_chunkSize - startColumn);
else
stateForNextChunk=
sendNormalizedSAXcharacters(m_array[i], startColumn,
m_chunkSize - startColumn,
ch,stateForNextChunk);
startColumn = 0; // after first chunk
}
// Last, or only, chunk
if (stopChunk == 0 && m_innerFSB != null)
stateForNextChunk= // %REVIEW% Is this update really needed?
m_innerFSB.sendNormalizedSAXcharacters(ch, startColumn, stopColumn - startColumn);
else if (stopColumn > startColumn)
{
stateForNextChunk= // %REVIEW% Is this update really needed?
sendNormalizedSAXcharacters(m_array[stopChunk],
startColumn, stopColumn - startColumn,
ch, stateForNextChunk | SUPPRESS_TRAILING_WS);
}
return stateForNextChunk;
}
static final char[] SINGLE_SPACE = {' '};
/**
* Internal method to directly normalize and dispatch the character array.
* This version is aware of the fact that it may be called several times
* in succession if the data is made up of multiple "chunks", and thus
* must actively manage the handling of leading and trailing whitespace.
*
* Note: The recursion is due to the possible recursion of inner FSBs.
*
* @param ch The characters from the XML document.
* @param start The start position in the array.
* @param length The number of characters to read from the array.
* @param handler SAX ContentHandler object to receive the event.
* @param edgeTreatmentFlags How leading/trailing spaces should be handled.
* This is a bitfield contining two flags, bitwise-ORed together:
* <dl>
* <dt>SUPPRESS_LEADING_WS
* <dd>When false, causes leading whitespace to be converted to a single
* space; when true, causes it to be discarded entirely.
* Should be set TRUE for the first chunk, and (in multi-chunk output)
* whenever the previous chunk ended in retained whitespace.</dd>
* <dt>SUPPRESS_TRAILING_WS
* <dd>When false, causes trailing whitespace to be converted to a single
* space; when true, causes it to be discarded entirely.
* Should be set TRUE for the last or only chunk.
* </dd>
* </dl>
* @return normalization status, as in the edgeTreatmentFlags parameter:
* <dl>
* <dt>0
* <dd>if this output did not end in retained whitespace, and thus whitespace
* at the start of the following chunk (if any) should be converted to a
* single space.
* <dt>SUPPRESS_LEADING_WS
* <dd>if this output ended in retained whitespace, and thus whitespace
* at the start of the following chunk (if any) should be completely
* suppressed.</dd>
* </dd>
* </dl>
*
*
* @exception org.xml.sax.SAXException Any SAX exception, possibly
* wrapping another exception.
*/
static int sendNormalizedSAXcharacters(char ch[],
int start, int length,
org.xml.sax.ContentHandler handler,
int edgeTreatmentFlags)
throws org.xml.sax.SAXException
{
boolean processingLeadingWhitespace =
((edgeTreatmentFlags & SUPPRESS_LEADING_WS) != 0);
boolean seenWhitespace = ((edgeTreatmentFlags & CARRY_WS) != 0);
boolean suppressTrailingWhitespace =
((edgeTreatmentFlags & SUPPRESS_TRAILING_WS) != 0);
int currPos = start;
int limit = start+length;
// Strip any leading spaces first, if required
if (processingLeadingWhitespace) {
for (; currPos < limit
&& XMLCharacterRecognizer.isWhiteSpace(ch[currPos]);
currPos++) { }
// If we've only encountered leading spaces, the
// current state remains unchanged
if (currPos == limit) {
return edgeTreatmentFlags;
}
}
// If we get here, there are no more leading spaces to strip
while (currPos < limit) {
int startNonWhitespace = currPos;
// Grab a chunk of non-whitespace characters
for (; currPos < limit
&& !XMLCharacterRecognizer.isWhiteSpace(ch[currPos]);
currPos++) { }
// Non-whitespace seen - emit them, along with a single
// space for any preceding whitespace characters
if (startNonWhitespace != currPos) {
if (seenWhitespace) {
handler.characters(SINGLE_SPACE, 0, 1);
seenWhitespace = false;
}
handler.characters(ch, startNonWhitespace,
currPos - startNonWhitespace);
}
int startWhitespace = currPos;
// Consume any whitespace characters
for (; currPos < limit
&& XMLCharacterRecognizer.isWhiteSpace(ch[currPos]);
currPos++) { }
if (startWhitespace != currPos) {
seenWhitespace = true;
}
}
return (seenWhitespace ? CARRY_WS : 0)
| (edgeTreatmentFlags & SUPPRESS_TRAILING_WS);
}
/**
* Directly normalize and dispatch the character array.
*
* @param ch The characters from the XML document.
* @param start The start position in the array.
* @param length The number of characters to read from the array.
* @param handler SAX ContentHandler object to receive the event.
* @exception org.xml.sax.SAXException Any SAX exception, possibly
* wrapping another exception.
*/
public static void sendNormalizedSAXcharacters(char ch[],
int start, int length,
org.xml.sax.ContentHandler handler)
throws org.xml.sax.SAXException
{
sendNormalizedSAXcharacters(ch, start, length,
handler, SUPPRESS_BOTH);
}
/**
* Sends the specified range of characters as sax Comment.
* <p>
* Note that, unlike sendSAXcharacters, this has to be done as a single
* call to LexicalHandler#comment.
*
* @param ch SAX LexicalHandler object to receive the event.
* @param start Offset of first character in the range.
* @param length Number of characters to send.
* @exception org.xml.sax.SAXException may be thrown by handler's
* characters() method.
*/
public void sendSAXComment(
org.xml.sax.ext.LexicalHandler ch, int start, int length)
throws org.xml.sax.SAXException
{
// %OPT% Do it this way for now...
String comment = getString(start, length);
ch.comment(comment.toCharArray(), 0, length);
}
/**
* Copies characters from this string into the destination character
* array.
*
* @param srcBegin index of the first character in the string
* to copy.
* @param srcEnd index after the last character in the string
* to copy.
* @param dst the destination array.
* @param dstBegin the start offset in the destination array.
* @exception IndexOutOfBoundsException If any of the following
* is true:
* <ul>srcBegin is negative.
* <li>srcBegin is greater than srcEnd
* <li>srcEnd is greater than the length of this
* string
* <li>dstBegin is negative
* <li>dstBegin+(srcEnd-srcBegin) is larger than
* <code>dst.length
* @exception NullPointerException if <code>dst is null
*/
private void getChars(int srcBegin, int srcEnd, char dst[], int dstBegin)
{
// %TBD% Joe needs to write this function. Make public when implemented.
}
/**
* Encapsulation c'tor. After this is called, the source FastStringBuffer
* will be reset to use the new object as its m_innerFSB, and will have
* had its chunk size reset appropriately. IT SHOULD NEVER BE CALLED
* EXCEPT WHEN source.length()==1<<(source.m_chunkBits+source.m_rebundleBits)
*
* NEEDSDOC @param source
*/
private FastStringBuffer(FastStringBuffer source)
{
// Copy existing information into new encapsulation
m_chunkBits = source.m_chunkBits;
m_maxChunkBits = source.m_maxChunkBits;
m_rebundleBits = source.m_rebundleBits;
m_chunkSize = source.m_chunkSize;
m_chunkMask = source.m_chunkMask;
m_array = source.m_array;
m_innerFSB = source.m_innerFSB;
// These have to be adjusted because we're calling just at the time
// when we would be about to allocate another chunk
m_lastChunk = source.m_lastChunk - 1;
m_firstFree = source.m_chunkSize;
// Establish capsule as the Inner FSB, reset chunk sizes/addressing
source.m_array = new char[16][];
source.m_innerFSB = this;
// Since we encapsulated just as we were about to append another
// chunk, return ready to create the chunk after the innerFSB
// -- 1, not 0.
source.m_lastChunk = 1;
source.m_firstFree = 0;
source.m_chunkBits += m_rebundleBits;
source.m_chunkSize = 1 << (source.m_chunkBits);
source.m_chunkMask = source.m_chunkSize - 1;
}
}
Other Java examples (source code examples)
Here is a short list of links related to this Java FastStringBuffer.java source code file:
|
The search page
Other Java source code examples at this package level
Click here to learn more about this project
