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tenfourfox/dom/base/nsTextFragment.cpp

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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
/*
* A class which represents a fragment of text (eg inside a text
* node); if only codepoints below 256 are used, the text is stored as
* a char*; otherwise the text is stored as a char16_t*
*/
#include "nsTextFragment.h"
#include "nsCRT.h"
#include "nsReadableUtils.h"
#include "nsMemory.h"
#include "nsBidiUtils.h"
#include "nsUnicharUtils.h"
#include "nsUTF8Utils.h"
#include "mozilla/CheckedInt.h"
#include "mozilla/MemoryReporting.h"
#include "mozilla/SSE.h"
#include "nsTextFragmentImpl.h"
#include <algorithm>
#define TEXTFRAG_WHITE_AFTER_NEWLINE 50
#define TEXTFRAG_MAX_NEWLINES 7
// Static buffer used for common fragments
static char* sSpaceSharedString[TEXTFRAG_MAX_NEWLINES + 1];
static char* sTabSharedString[TEXTFRAG_MAX_NEWLINES + 1];
static char sSingleCharSharedString[256];
using mozilla::CheckedUint32;
// static
nsresult
nsTextFragment::Init()
{
// Create whitespace strings
uint32_t i;
for (i = 0; i <= TEXTFRAG_MAX_NEWLINES; ++i) {
sSpaceSharedString[i] = new char[1 + i + TEXTFRAG_WHITE_AFTER_NEWLINE];
sTabSharedString[i] = new char[1 + i + TEXTFRAG_WHITE_AFTER_NEWLINE];
sSpaceSharedString[i][0] = ' ';
sTabSharedString[i][0] = ' ';
uint32_t j;
for (j = 1; j < 1 + i; ++j) {
sSpaceSharedString[i][j] = '\n';
sTabSharedString[i][j] = '\n';
}
for (; j < (1 + i + TEXTFRAG_WHITE_AFTER_NEWLINE); ++j) {
sSpaceSharedString[i][j] = ' ';
sTabSharedString[i][j] = '\t';
}
}
// Create single-char strings
for (i = 0; i < 256; ++i) {
sSingleCharSharedString[i] = i;
}
return NS_OK;
}
// static
void
nsTextFragment::Shutdown()
{
uint32_t i;
for (i = 0; i <= TEXTFRAG_MAX_NEWLINES; ++i) {
delete [] sSpaceSharedString[i];
delete [] sTabSharedString[i];
sSpaceSharedString[i] = nullptr;
sTabSharedString[i] = nullptr;
}
}
nsTextFragment::~nsTextFragment()
{
ReleaseText();
MOZ_COUNT_DTOR(nsTextFragment);
}
void
nsTextFragment::ReleaseText()
{
if (mState.mLength && m1b && mState.mInHeap) {
free(m2b); // m1b == m2b as far as free is concerned
}
m1b = nullptr;
mState.mIsBidi = false;
// Set mState.mIs2b, mState.mInHeap, and mState.mLength = 0 with mAllBits;
mAllBits = 0;
}
nsTextFragment&
nsTextFragment::operator=(const nsTextFragment& aOther)
{
ReleaseText();
if (aOther.mState.mLength) {
if (!aOther.mState.mInHeap) {
m1b = aOther.m1b; // This will work even if aOther is using m2b
}
else {
CheckedUint32 m2bSize = aOther.mState.mLength;
m2bSize *= (aOther.mState.mIs2b ? sizeof(char16_t) : sizeof(char));
m2b = nullptr;
if (m2bSize.isValid()) {
m2b = static_cast<char16_t*>(malloc(m2bSize.value()));
}
if (m2b) {
memcpy(m2b, aOther.m2b, m2bSize.value());
} else {
// allocate a buffer for a single REPLACEMENT CHARACTER
m2b = static_cast<char16_t*>(moz_xmalloc(sizeof(char16_t)));
m2b[0] = 0xFFFD; // REPLACEMENT CHARACTER
mState.mIs2b = true;
mState.mInHeap = true;
mState.mLength = 1;
}
}
if (m1b) {
mAllBits = aOther.mAllBits;
}
}
return *this;
}
static inline int32_t
FirstNon8BitUnvectorized(const char16_t *str, const char16_t *end)
{
typedef Non8BitParameters<sizeof(size_t)> p;
const size_t mask = p::mask();
const uint32_t alignMask = p::alignMask();
const uint32_t numUnicharsPerWord = p::numUnicharsPerWord();
const int32_t len = end - str;
int32_t i = 0;
// Align ourselves to a word boundary.
int32_t alignLen =
std::min(len, int32_t(((-NS_PTR_TO_INT32(str)) & alignMask) / sizeof(char16_t)));
for (; i < alignLen; i++) {
if (str[i] > 255)
return i;
}
// Check one word at a time.
const int32_t wordWalkEnd = ((len - i) / numUnicharsPerWord) * numUnicharsPerWord;
for (; i < wordWalkEnd; i += numUnicharsPerWord) {
const size_t word = *reinterpret_cast<const size_t*>(str + i);
if (word & mask)
return i;
}
// Take care of the remainder one character at a time.
for (; i < len; i++) {
if (str[i] > 255)
return i;
}
return -1;
}
#ifdef MOZILLA_MAY_SUPPORT_SSE2
namespace mozilla {
namespace SSE2 {
int32_t FirstNon8Bit(const char16_t *str, const char16_t *end);
} // namespace SSE2
} // namespace mozilla
#endif
#ifdef TENFOURFOX_VMX
namespace mozilla {
namespace VMX {
int32_t FirstNon8Bit(const char16_t *str, const char16_t *end);
}
}
#endif
/*
* This function returns -1 if all characters in str are 8 bit characters.
* Otherwise, it returns a value less than or equal to the index of the first
* non-8bit character in str. For example, if first non-8bit character is at
* position 25, it may return 25, or for example 24, or 16. But it guarantees
* there is no non-8bit character before returned value.
*/
static inline int32_t
FirstNon8Bit(const char16_t *str, const char16_t *end)
{
#ifdef MOZILLA_MAY_SUPPORT_SSE2
if (mozilla::supports_sse2()) {
return mozilla::SSE2::FirstNon8Bit(str, end);
}
#endif
#ifdef TENFOURFOX_VMX
return mozilla::VMX::FirstNon8Bit(str, end);
#endif
return FirstNon8BitUnvectorized(str, end);
}
bool
nsTextFragment::SetTo(const char16_t* aBuffer, int32_t aLength, bool aUpdateBidi)
{
if (MOZ_UNLIKELY(aLength < 0 || static_cast<uint32_t>(aLength) >
NS_MAX_TEXT_FRAGMENT_LENGTH)) {
return false;
}
ReleaseText();
if (aLength == 0) {
return true;
}
char16_t firstChar = *aBuffer;
if (aLength == 1 && firstChar < 256) {
m1b = sSingleCharSharedString + firstChar;
mState.mInHeap = false;
mState.mIs2b = false;
mState.mLength = 1;
return true;
}
const char16_t *ucp = aBuffer;
const char16_t *uend = aBuffer + aLength;
// Check if we can use a shared string
if (aLength <= 1 + TEXTFRAG_WHITE_AFTER_NEWLINE + TEXTFRAG_MAX_NEWLINES &&
(firstChar == ' ' || firstChar == '\n' || firstChar == '\t')) {
if (firstChar == ' ') {
++ucp;
}
const char16_t* start = ucp;
while (ucp < uend && *ucp == '\n') {
++ucp;
}
const char16_t* endNewLine = ucp;
char16_t space = ucp < uend && *ucp == '\t' ? '\t' : ' ';
while (ucp < uend && *ucp == space) {
++ucp;
}
if (ucp == uend &&
endNewLine - start <= TEXTFRAG_MAX_NEWLINES &&
ucp - endNewLine <= TEXTFRAG_WHITE_AFTER_NEWLINE) {
char** strings = space == ' ' ? sSpaceSharedString : sTabSharedString;
m1b = strings[endNewLine - start];
// If we didn't find a space in the beginning, skip it now.
if (firstChar != ' ') {
++m1b;
}
mState.mInHeap = false;
mState.mIs2b = false;
mState.mLength = aLength;
return true;
}
}
// See if we need to store the data in ucs2 or not
int32_t first16bit = FirstNon8Bit(ucp, uend);
if (first16bit != -1) { // aBuffer contains no non-8bit character
// Use ucs2 storage because we have to
CheckedUint32 m2bSize = aLength;
m2bSize *= sizeof(char16_t);
if (!m2bSize.isValid()) {
return false;
}
m2b = static_cast<char16_t*>(malloc(m2bSize.value()));
if (!m2b) {
return false;
}
memcpy(m2b, aBuffer, m2bSize.value());
mState.mIs2b = true;
if (aUpdateBidi) {
UpdateBidiFlag(aBuffer + first16bit, aLength - first16bit);
}
} else {
// Use 1 byte storage because we can
char* buff = static_cast<char*>(malloc(aLength));
if (!buff) {
return false;
}
// Copy data
LossyConvertEncoding16to8 converter(buff);
copy_string(aBuffer, aBuffer+aLength, converter);
m1b = buff;
mState.mIs2b = false;
}
// Setup our fields
mState.mInHeap = true;
mState.mLength = aLength;
return true;
}
void
nsTextFragment::CopyTo(char16_t *aDest, int32_t aOffset, int32_t aCount)
{
NS_ASSERTION(aOffset >= 0, "Bad offset passed to nsTextFragment::CopyTo()!");
NS_ASSERTION(aCount >= 0, "Bad count passed to nsTextFragment::CopyTo()!");
if (aOffset < 0) {
aOffset = 0;
}
if (uint32_t(aOffset + aCount) > GetLength()) {
aCount = mState.mLength - aOffset;
}
if (aCount != 0) {
if (mState.mIs2b) {
memcpy(aDest, m2b + aOffset, sizeof(char16_t) * aCount);
} else {
const char *cp = m1b + aOffset;
const char *end = cp + aCount;
LossyConvertEncoding8to16 converter(aDest);
copy_string(cp, end, converter);
}
}
}
bool
nsTextFragment::Append(const char16_t* aBuffer, uint32_t aLength, bool aUpdateBidi)
{
if (!aLength) {
return true;
}
// This is a common case because some callsites create a textnode
// with a value by creating the node and then calling AppendData.
if (mState.mLength == 0) {
if (MOZ_UNLIKELY(aLength > INT32_MAX)) {
return false;
}
return SetTo(aBuffer, aLength, aUpdateBidi);
}
// Should we optimize for aData.Length() == 0?
// FYI: Don't use CheckedInt in this method since here is very hot path
// in some performance tests.
if (MOZ_UNLIKELY(NS_MAX_TEXT_FRAGMENT_LENGTH - mState.mLength < aLength)) {
return false; // Would be overflown if we'd keep handling.
}
if (mState.mIs2b) {
size_t size = mState.mLength + aLength;
if (MOZ_UNLIKELY(SIZE_MAX / sizeof(char16_t) < size)) {
return false; // Would be overflown if we'd keep handling.
}
size *= sizeof(char16_t);
// Already a 2-byte string so the result will be too
char16_t* buff = static_cast<char16_t*>(realloc(m2b, size));
if (MOZ_UNLIKELY(!buff)) {
return false;
}
memcpy(buff + mState.mLength, aBuffer, aLength * sizeof(char16_t));
mState.mLength += aLength;
m2b = buff;
if (aUpdateBidi) {
UpdateBidiFlag(aBuffer, aLength);
}
return true;
}
// Current string is a 1-byte string, check if the new data fits in one byte too.
int32_t first16bit = FirstNon8Bit(aBuffer, aBuffer + aLength);
if (first16bit != -1) { // aBuffer contains no non-8bit character
size_t size = mState.mLength + aLength;
if (MOZ_UNLIKELY((SIZE_MAX / sizeof(char16_t)) < size)) {
return false; // Would be overflown if we'd keep handling.
}
size *= sizeof(char16_t);
// The old data was 1-byte, but the new is not so we have to expand it
// all to 2-byte
char16_t* buff = static_cast<char16_t*>(malloc(size));
if (MOZ_UNLIKELY(!buff)) {
return false;
}
// Copy data into buff
LossyConvertEncoding8to16 converter(buff);
copy_string(m1b, m1b+mState.mLength, converter);
memcpy(buff + mState.mLength, aBuffer, aLength * sizeof(char16_t));
mState.mLength += aLength;
mState.mIs2b = true;
if (mState.mInHeap) {
free(m2b);
}
m2b = buff;
mState.mInHeap = true;
if (aUpdateBidi) {
UpdateBidiFlag(aBuffer + first16bit, aLength - first16bit);
}
return true;
}
// The new and the old data is all 1-byte
size_t size = mState.mLength + aLength;
MOZ_ASSERT(sizeof(char) == 1);
char* buff;
if (mState.mInHeap) {
buff = static_cast<char*>(realloc(const_cast<char*>(m1b), size));
if (MOZ_UNLIKELY(!buff)) {
return false;
}
}
else {
buff = static_cast<char*>(malloc(size));
if (MOZ_UNLIKELY(!buff)) {
return false;
}
memcpy(buff, m1b, mState.mLength);
mState.mInHeap = true;
}
// Copy aBuffer into buff.
LossyConvertEncoding16to8 converter(buff + mState.mLength);
copy_string(aBuffer, aBuffer + aLength, converter);
m1b = buff;
mState.mLength += aLength;
return true;
}
/* virtual */ size_t
nsTextFragment::SizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf) const
{
if (Is2b()) {
return aMallocSizeOf(m2b);
}
if (mState.mInHeap) {
return aMallocSizeOf(m1b);
}
return 0;
}
// To save time we only do this when we really want to know, not during
// every allocation
void
nsTextFragment::UpdateBidiFlag(const char16_t* aBuffer, uint32_t aLength)
{
if (mState.mIs2b && !mState.mIsBidi) {
if (HasRTLChars(aBuffer, aLength)) {
mState.mIsBidi = true;
}
}
}
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