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Core Jackson abstractions, basic JSON streaming API implementation
package com.fasterxml.jackson.core.util;
import java.math.BigDecimal;
import java.util.ArrayList;
import java.util.Arrays;
import com.fasterxml.jackson.core.io.NumberInput;
/**
* TextBuffer is a class similar to {@link StringBuffer}, with
* following differences:
*
* - TextBuffer uses segments character arrays, to avoid having
* to do additional array copies when array is not big enough.
* This means that only reallocating that is necessary is done only once:
* if and when caller
* wants to access contents in a linear array (char[], String).
*
* - TextBuffer can also be initialized in "shared mode", in which
* it will just act as a wrapper to a single char array managed
* by another object (like parser that owns it)
*
* - TextBuffer is not synchronized.
*
*
*/
public final class TextBuffer
{
final static char[] NO_CHARS = new char[0];
/**
* Let's start with sizable but not huge buffer, will grow as necessary
*/
final static int MIN_SEGMENT_LEN = 1000;
/**
* Let's limit maximum segment length to something sensible
* like 256k
*/
final static int MAX_SEGMENT_LEN = 0x40000;
/*
/**********************************************************
/* Configuration:
/**********************************************************
*/
private final BufferRecycler _allocator;
/*
/**********************************************************
/* Shared input buffers
/**********************************************************
*/
/**
* Shared input buffer; stored here in case some input can be returned
* as is, without being copied to collector's own buffers. Note that
* this is read-only for this Object.
*/
private char[] _inputBuffer;
/**
* Character offset of first char in input buffer; -1 to indicate
* that input buffer currently does not contain any useful char data
*/
private int _inputStart;
private int _inputLen;
/*
/**********************************************************
/* Aggregation segments (when not using input buf)
/**********************************************************
*/
/**
* List of segments prior to currently active segment.
*/
private ArrayList _segments;
/**
* Flag that indicates whether _seqments is non-empty
*/
private boolean _hasSegments = false;
// // // Currently used segment; not (yet) contained in _seqments
/**
* Amount of characters in segments in {@link _segments}
*/
private int _segmentSize;
private char[] _currentSegment;
/**
* Number of characters in currently active (last) segment
*/
private int _currentSize;
/*
/**********************************************************
/* Caching of results
/**********************************************************
*/
/**
* String that will be constructed when the whole contents are
* needed; will be temporarily stored in case asked for again.
*/
private String _resultString;
private char[] _resultArray;
/*
/**********************************************************
/* Life-cycle
/**********************************************************
*/
public TextBuffer(BufferRecycler allocator) {
_allocator = allocator;
}
/**
* Method called to indicate that the underlying buffers should now
* be recycled if they haven't yet been recycled. Although caller
* can still use this text buffer, it is not advisable to call this
* method if that is likely, since next time a buffer is needed,
* buffers need to reallocated.
* Note: calling this method automatically also clears contents
* of the buffer.
*/
public void releaseBuffers()
{
if (_allocator == null) {
resetWithEmpty();
} else {
if (_currentSegment != null) {
// First, let's get rid of all but the largest char array
resetWithEmpty();
// And then return that array
char[] buf = _currentSegment;
_currentSegment = null;
_allocator.releaseCharBuffer(BufferRecycler.CHAR_TEXT_BUFFER, buf);
}
}
}
/**
* Method called to clear out any content text buffer may have, and
* initializes buffer to use non-shared data.
*/
public void resetWithEmpty()
{
_inputStart = -1; // indicates shared buffer not used
_currentSize = 0;
_inputLen = 0;
_inputBuffer = null;
_resultString = null;
_resultArray = null;
// And then reset internal input buffers, if necessary:
if (_hasSegments) {
clearSegments();
}
}
/**
* Method called to initialize the buffer with a shared copy of data;
* this means that buffer will just have pointers to actual data. It
* also means that if anything is to be appended to the buffer, it
* will first have to unshare it (make a local copy).
*/
public void resetWithShared(char[] buf, int start, int len)
{
// First, let's clear intermediate values, if any:
_resultString = null;
_resultArray = null;
// Then let's mark things we need about input buffer
_inputBuffer = buf;
_inputStart = start;
_inputLen = len;
// And then reset internal input buffers, if necessary:
if (_hasSegments) {
clearSegments();
}
}
public void resetWithCopy(char[] buf, int start, int len)
{
_inputBuffer = null;
_inputStart = -1; // indicates shared buffer not used
_inputLen = 0;
_resultString = null;
_resultArray = null;
// And then reset internal input buffers, if necessary:
if (_hasSegments) {
clearSegments();
} else if (_currentSegment == null) {
_currentSegment = buf(len);
}
_currentSize = _segmentSize = 0;
append(buf, start, len);
}
public void resetWithString(String value)
{
_inputBuffer = null;
_inputStart = -1;
_inputLen = 0;
_resultString = value;
_resultArray = null;
if (_hasSegments) {
clearSegments();
}
_currentSize = 0;
}
/**
* Helper method used to find a buffer to use, ideally one
* recycled earlier.
*/
private char[] buf(int needed)
{
if (_allocator != null) {
return _allocator.allocCharBuffer(BufferRecycler.CHAR_TEXT_BUFFER, needed);
}
return new char[Math.max(needed, MIN_SEGMENT_LEN)];
}
private void clearSegments()
{
_hasSegments = false;
/* Let's start using _last_ segment from list; for one, it's
* the biggest one, and it's also most likely to be cached
*/
/* 28-Aug-2009, tatu: Actually, the current segment should
* be the biggest one, already
*/
//_currentSegment = _segments.get(_segments.size() - 1);
_segments.clear();
_currentSize = _segmentSize = 0;
}
/*
/**********************************************************
/* Accessors for implementing public interface
/**********************************************************
*/
/**
* @return Number of characters currently stored by this collector
*/
public int size() {
if (_inputStart >= 0) { // shared copy from input buf
return _inputLen;
}
if (_resultArray != null) {
return _resultArray.length;
}
if (_resultString != null) {
return _resultString.length();
}
// local segmented buffers
return _segmentSize + _currentSize;
}
public int getTextOffset() {
/* Only shared input buffer can have non-zero offset; buffer
* segments start at 0, and if we have to create a combo buffer,
* that too will start from beginning of the buffer
*/
return (_inputStart >= 0) ? _inputStart : 0;
}
/**
* Method that can be used to check whether textual contents can
* be efficiently accessed using {@link #getTextBuffer}.
*/
public boolean hasTextAsCharacters()
{
// if we have array in some form, sure
if (_inputStart >= 0 || _resultArray != null) return true;
// not if we have String as value
if (_resultString != null) return false;
return true;
}
public char[] getTextBuffer()
{
// Are we just using shared input buffer?
if (_inputStart >= 0) return _inputBuffer;
if (_resultArray != null) return _resultArray;
if (_resultString != null) {
return (_resultArray = _resultString.toCharArray());
}
// Nope; but does it fit in just one segment?
if (!_hasSegments) return _currentSegment;
// Nope, need to have/create a non-segmented array and return it
return contentsAsArray();
}
/*
/**********************************************************
/* Other accessors:
/**********************************************************
*/
public String contentsAsString()
{
if (_resultString == null) {
// Has array been requested? Can make a shortcut, if so:
if (_resultArray != null) {
_resultString = new String(_resultArray);
} else {
// Do we use shared array?
if (_inputStart >= 0) {
if (_inputLen < 1) {
return (_resultString = "");
}
_resultString = new String(_inputBuffer, _inputStart, _inputLen);
} else { // nope... need to copy
// But first, let's see if we have just one buffer
int segLen = _segmentSize;
int currLen = _currentSize;
if (segLen == 0) { // yup
_resultString = (currLen == 0) ? "" : new String(_currentSegment, 0, currLen);
} else { // no, need to combine
StringBuilder sb = new StringBuilder(segLen + currLen);
// First stored segments
if (_segments != null) {
for (int i = 0, len = _segments.size(); i < len; ++i) {
char[] curr = _segments.get(i);
sb.append(curr, 0, curr.length);
}
}
// And finally, current segment:
sb.append(_currentSegment, 0, _currentSize);
_resultString = sb.toString();
}
}
}
}
return _resultString;
}
public char[] contentsAsArray() {
char[] result = _resultArray;
if (result == null) {
_resultArray = result = resultArray();
}
return result;
}
/**
* Convenience method for converting contents of the buffer
* into a {@link BigDecimal}.
*/
public BigDecimal contentsAsDecimal() throws NumberFormatException
{
// Already got a pre-cut array?
if (_resultArray != null) {
return NumberInput.parseBigDecimal(_resultArray);
}
// Or a shared buffer?
if ((_inputStart >= 0) && (_inputBuffer != null)) {
return NumberInput.parseBigDecimal(_inputBuffer, _inputStart, _inputLen);
}
// Or if not, just a single buffer (the usual case)
if ((_segmentSize == 0) && (_currentSegment != null)) {
return NumberInput.parseBigDecimal(_currentSegment, 0, _currentSize);
}
// If not, let's just get it aggregated...
return NumberInput.parseBigDecimal(contentsAsArray());
}
/**
* Convenience method for converting contents of the buffer
* into a Double value.
*/
public double contentsAsDouble() throws NumberFormatException {
return NumberInput.parseDouble(contentsAsString());
}
/*
/**********************************************************
/* Public mutators:
/**********************************************************
*/
/**
* Method called to make sure that buffer is not using shared input
* buffer; if it is, it will copy such contents to private buffer.
*/
public void ensureNotShared() {
if (_inputStart >= 0) {
unshare(16);
}
}
public void append(char c) {
// Using shared buffer so far?
if (_inputStart >= 0) {
unshare(16);
}
_resultString = null;
_resultArray = null;
// Room in current segment?
char[] curr = _currentSegment;
if (_currentSize >= curr.length) {
expand(1);
curr = _currentSegment;
}
curr[_currentSize++] = c;
}
public void append(char[] c, int start, int len)
{
// Can't append to shared buf (sanity check)
if (_inputStart >= 0) {
unshare(len);
}
_resultString = null;
_resultArray = null;
// Room in current segment?
char[] curr = _currentSegment;
int max = curr.length - _currentSize;
if (max >= len) {
System.arraycopy(c, start, curr, _currentSize, len);
_currentSize += len;
return;
}
// No room for all, need to copy part(s):
if (max > 0) {
System.arraycopy(c, start, curr, _currentSize, max);
start += max;
len -= max;
}
/* And then allocate new segment; we are guaranteed to now
* have enough room in segment.
*/
// Except, as per [Issue-24], not for HUGE appends... so:
do {
expand(len);
int amount = Math.min(_currentSegment.length, len);
System.arraycopy(c, start, _currentSegment, 0, amount);
_currentSize += amount;
start += amount;
len -= amount;
} while (len > 0);
}
public void append(String str, int offset, int len)
{
// Can't append to shared buf (sanity check)
if (_inputStart >= 0) {
unshare(len);
}
_resultString = null;
_resultArray = null;
// Room in current segment?
char[] curr = _currentSegment;
int max = curr.length - _currentSize;
if (max >= len) {
str.getChars(offset, offset+len, curr, _currentSize);
_currentSize += len;
return;
}
// No room for all, need to copy part(s):
if (max > 0) {
str.getChars(offset, offset+max, curr, _currentSize);
len -= max;
offset += max;
}
/* And then allocate new segment; we are guaranteed to now
* have enough room in segment.
*/
// Except, as per [Issue-24], not for HUGE appends... so:
do {
expand(len);
int amount = Math.min(_currentSegment.length, len);
str.getChars(offset, offset+amount, _currentSegment, 0);
_currentSize += amount;
offset += amount;
len -= amount;
} while (len > 0);
}
/*
/**********************************************************
/* Raw access, for high-performance use:
/**********************************************************
*/
public char[] getCurrentSegment()
{
/* Since the intention of the caller is to directly add stuff into
* buffers, we should NOT have anything in shared buffer... ie. may
* need to unshare contents.
*/
if (_inputStart >= 0) {
unshare(1);
} else {
char[] curr = _currentSegment;
if (curr == null) {
_currentSegment = buf(0);
} else if (_currentSize >= curr.length) {
// Plus, we better have room for at least one more char
expand(1);
}
}
return _currentSegment;
}
public char[] emptyAndGetCurrentSegment()
{
// inlined 'resetWithEmpty()'
_inputStart = -1; // indicates shared buffer not used
_currentSize = 0;
_inputLen = 0;
_inputBuffer = null;
_resultString = null;
_resultArray = null;
// And then reset internal input buffers, if necessary:
if (_hasSegments) {
clearSegments();
}
char[] curr = _currentSegment;
if (curr == null) {
_currentSegment = curr = buf(0);
}
return curr;
}
public int getCurrentSegmentSize() { return _currentSize; }
public void setCurrentLength(int len) { _currentSize = len; }
public char[] finishCurrentSegment() {
if (_segments == null) {
_segments = new ArrayList();
}
_hasSegments = true;
_segments.add(_currentSegment);
int oldLen = _currentSegment.length;
_segmentSize += oldLen;
_currentSize = 0;
// Let's grow segments by 50%
int newLen = oldLen + (oldLen >> 1);
if (newLen < MIN_SEGMENT_LEN) {
newLen = MIN_SEGMENT_LEN;
} else if (newLen > MAX_SEGMENT_LEN) {
newLen = MAX_SEGMENT_LEN;
}
char[] curr = carr(newLen);
_currentSegment = curr;
return curr;
}
/**
* Method called to expand size of the current segment, to
* accommodate for more contiguous content. Usually only
* used when parsing tokens like names if even then.
*/
public char[] expandCurrentSegment()
{
final char[] curr = _currentSegment;
// Let's grow by 50%
final int len = curr.length;
// Must grow by at least 1 char, no matter what
int newLen = (len == MAX_SEGMENT_LEN) ? (MAX_SEGMENT_LEN+1) : Math.min(MAX_SEGMENT_LEN, len + (len >> 1));
return (_currentSegment = Arrays.copyOf(curr, newLen));
}
/**
* Method called to expand size of the current segment, to
* accommodate for more contiguous content. Usually only
* used when parsing tokens like names if even then.
*
* @param minSize Required minimum strength of the current segment
*
* @since 2.4.0
*/
public char[] expandCurrentSegment(int minSize) {
char[] curr = _currentSegment;
if (curr.length >= minSize) return curr;
_currentSegment = curr = Arrays.copyOf(curr, minSize);
return curr;
}
/*
/**********************************************************
/* Standard methods:
/**********************************************************
*/
/**
* Note: calling this method may not be as efficient as calling
* {@link #contentsAsString}, since it's not guaranteed that resulting
* String is cached.
*/
@Override public String toString() { return contentsAsString(); }
/*
/**********************************************************
/* Internal methods:
/**********************************************************
*/
/**
* Method called if/when we need to append content when we have been
* initialized to use shared buffer.
*/
private void unshare(int needExtra)
{
int sharedLen = _inputLen;
_inputLen = 0;
char[] inputBuf = _inputBuffer;
_inputBuffer = null;
int start = _inputStart;
_inputStart = -1;
// Is buffer big enough, or do we need to reallocate?
int needed = sharedLen+needExtra;
if (_currentSegment == null || needed > _currentSegment.length) {
_currentSegment = buf(needed);
}
if (sharedLen > 0) {
System.arraycopy(inputBuf, start, _currentSegment, 0, sharedLen);
}
_segmentSize = 0;
_currentSize = sharedLen;
}
/**
* Method called when current segment is full, to allocate new
* segment.
*/
private void expand(int minNewSegmentSize)
{
// First, let's move current segment to segment list:
if (_segments == null) {
_segments = new ArrayList();
}
char[] curr = _currentSegment;
_hasSegments = true;
_segments.add(curr);
_segmentSize += curr.length;
_currentSize = 0;
int oldLen = curr.length;
// Let's grow segments by 50% minimum
int newLen = oldLen + (oldLen >> 1);
if (newLen < MIN_SEGMENT_LEN) {
newLen = MIN_SEGMENT_LEN;
} else if (newLen > MAX_SEGMENT_LEN) {
newLen = MAX_SEGMENT_LEN;
}
_currentSegment = carr(newLen);
}
private char[] resultArray()
{
if (_resultString != null) { // Can take a shortcut...
return _resultString.toCharArray();
}
// Do we use shared array?
if (_inputStart >= 0) {
final int len = _inputLen;
if (len < 1) {
return NO_CHARS;
}
final int start = _inputStart;
if (start == 0) {
return Arrays.copyOf(_inputBuffer, len);
}
return Arrays.copyOfRange(_inputBuffer, start, start+len);
}
// nope, not shared
int size = size();
if (size < 1) {
return NO_CHARS;
}
int offset = 0;
final char[] result = carr(size);
if (_segments != null) {
for (int i = 0, len = _segments.size(); i < len; ++i) {
char[] curr = _segments.get(i);
int currLen = curr.length;
System.arraycopy(curr, 0, result, offset, currLen);
offset += currLen;
}
}
System.arraycopy(_currentSegment, 0, result, offset, _currentSize);
return result;
}
private char[] carr(int len) { return new char[len]; }
}