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-rw-r--r--dom/base/nsTextFragment.cpp538
1 files changed, 538 insertions, 0 deletions
diff --git a/dom/base/nsTextFragment.cpp b/dom/base/nsTextFragment.cpp
new file mode 100644
index 0000000000..5cba2577b8
--- /dev/null
+++ b/dom/base/nsTextFragment.cpp
@@ -0,0 +1,538 @@
+/* -*- 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 "nsBidiUtils.h"
+#include "nsUnicharUtils.h"
+#include "mozilla/CheckedInt.h"
+#include "mozilla/MemoryReporting.h"
+#include "mozilla/SSE.h"
+#include "mozilla/ppc.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 namespace mozilla;
+
+// 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.mIs2b) {
+ NS_RELEASE(m2b);
+ } else if (mState.mLength && m1b && mState.mInHeap) {
+ free(const_cast<char*>(m1b));
+ }
+
+ 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) {
+ MOZ_ASSERT(!aOther.mState.mIs2b);
+ m1b = aOther.m1b;
+ } else if (aOther.mState.mIs2b) {
+ m2b = aOther.m2b;
+ NS_ADDREF(m2b);
+ } else {
+ m1b = static_cast<char*>(malloc(aOther.mState.mLength));
+ if (m1b) {
+ memcpy(const_cast<char*>(m1b), aOther.m1b, aOther.mState.mLength);
+ } else {
+ // allocate a buffer for a single REPLACEMENT CHARACTER
+ m2b = nsStringBuffer::Alloc(sizeof(char16_t) * 2).take();
+ if (!m2b) {
+ MOZ_CRASH("OOM!");
+ }
+ char16_t* data = static_cast<char16_t*>(m2b->Data());
+ data[0] = 0xFFFD; // REPLACEMENT CHARACTER
+ data[1] = char16_t(0);
+ mState.mIs2b = true;
+ mState.mInHeap = true;
+ mState.mLength = 1;
+ return *this;
+ }
+ }
+
+ mAllBits = aOther.mAllBits;
+ }
+
+ return *this;
+}
+
+static inline int32_t FirstNon8BitUnvectorized(const char16_t* str,
+ const char16_t* end) {
+ using p = Non8BitParameters<sizeof(size_t)>;
+ 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;
+}
+
+#if defined(MOZILLA_MAY_SUPPORT_SSE2)
+# include "nsTextFragmentGenericFwd.h"
+#endif
+
+#ifdef __powerpc__
+namespace mozilla {
+namespace VMX {
+int32_t FirstNon8Bit(const char16_t* str, const char16_t* end);
+} // namespace VMX
+} // namespace mozilla
+#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::FirstNon8Bit<xsimd::sse2>(str, end);
+ }
+#elif defined(__powerpc__)
+ if (mozilla::supports_vmx()) {
+ return mozilla::VMX::FirstNon8Bit(str, end);
+ }
+#endif
+
+ return FirstNon8BitUnvectorized(str, end);
+}
+
+bool nsTextFragment::SetTo(const char16_t* aBuffer, uint32_t aLength,
+ bool aUpdateBidi, bool aForce2b) {
+ if (MOZ_UNLIKELY(aLength > NS_MAX_TEXT_FRAGMENT_LENGTH)) {
+ return false;
+ }
+
+ if (aForce2b && mState.mIs2b && !m2b->IsReadonly()) {
+ uint32_t storageSize = m2b->StorageSize();
+ uint32_t neededSize = aLength * sizeof(char16_t);
+ if (!neededSize) {
+ if (storageSize < AutoStringDefaultStorageSize) {
+ // If we're storing small enough nsStringBuffer, let's preserve it.
+
+ static_cast<char16_t*>(m2b->Data())[0] = char16_t(0);
+ mState.mLength = 0;
+ mState.mIsBidi = false;
+ return true;
+ }
+ } else if ((neededSize < storageSize) &&
+ ((storageSize / 2) <
+ (neededSize + AutoStringDefaultStorageSize))) {
+ // Don't try to reuse the existing nsStringBuffer, if it would have
+ // lots of unused space.
+
+ memcpy(m2b->Data(), aBuffer, neededSize);
+ static_cast<char16_t*>(m2b->Data())[aLength] = char16_t(0);
+ mState.mLength = aLength;
+ mState.mIsBidi = false;
+ if (aUpdateBidi) {
+ UpdateBidiFlag(aBuffer, aLength);
+ }
+ return true;
+ }
+ }
+
+ ReleaseText();
+
+ if (aLength == 0) {
+ return true;
+ }
+
+ char16_t firstChar = *aBuffer;
+ if (!aForce2b && 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 (!aForce2b &&
+ 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 = aForce2b ? 0 : FirstNon8Bit(ucp, uend);
+
+ if (first16bit != -1) { // aBuffer contains no non-8bit character
+ // Use ucs2 storage because we have to
+ CheckedUint32 m2bSize = CheckedUint32(aLength) + 1;
+ if (!m2bSize.isValid()) {
+ return false;
+ }
+ m2bSize *= sizeof(char16_t);
+ if (!m2bSize.isValid()) {
+ return false;
+ }
+
+ m2b = nsStringBuffer::Alloc(m2bSize.value()).take();
+ if (!m2b) {
+ return false;
+ }
+ memcpy(m2b->Data(), aBuffer, aLength * sizeof(char16_t));
+ static_cast<char16_t*>(m2b->Data())[aLength] = char16_t(0);
+
+ 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
+ LossyConvertUtf16toLatin1(Span(aBuffer, aLength), Span(buff, aLength));
+ m1b = buff;
+ mState.mIs2b = false;
+ }
+
+ // Setup our fields
+ mState.mInHeap = true;
+ mState.mLength = aLength;
+
+ return true;
+}
+
+void nsTextFragment::CopyTo(char16_t* aDest, uint32_t aOffset,
+ uint32_t aCount) {
+ const CheckedUint32 endOffset = CheckedUint32(aOffset) + aCount;
+ if (!endOffset.isValid() || endOffset.value() > GetLength()) {
+ aCount = mState.mLength - aOffset;
+ }
+
+ if (aCount) {
+ if (mState.mIs2b) {
+ memcpy(aDest, Get2b() + aOffset, sizeof(char16_t) * aCount);
+ } else {
+ const char* cp = m1b + aOffset;
+ ConvertLatin1toUtf16(Span(cp, aCount), Span(aDest, aCount));
+ }
+ }
+}
+
+bool nsTextFragment::Append(const char16_t* aBuffer, uint32_t aLength,
+ bool aUpdateBidi, bool aForce2b) {
+ 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) {
+ return SetTo(aBuffer, aLength, aUpdateBidi, aForce2b);
+ }
+
+ // 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 (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 + 1;
+ if (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
+ nsStringBuffer* buff = nullptr;
+ nsStringBuffer* bufferToRelease = nullptr;
+ if (m2b->IsReadonly()) {
+ buff = nsStringBuffer::Alloc(size).take();
+ if (!buff) {
+ return false;
+ }
+ bufferToRelease = m2b;
+ memcpy(static_cast<char16_t*>(buff->Data()), m2b->Data(),
+ mState.mLength * sizeof(char16_t));
+ } else {
+ buff = nsStringBuffer::Realloc(m2b, size);
+ if (!buff) {
+ return false;
+ }
+ }
+
+ char16_t* data = static_cast<char16_t*>(buff->Data());
+ memcpy(data + mState.mLength, aBuffer, aLength * sizeof(char16_t));
+ mState.mLength += aLength;
+ m2b = buff;
+ data[mState.mLength] = char16_t(0);
+
+ NS_IF_RELEASE(bufferToRelease);
+
+ 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 = aForce2b ? 0 : FirstNon8Bit(aBuffer, aBuffer + aLength);
+
+ if (first16bit != -1) { // aBuffer contains no non-8bit character
+ size_t size = mState.mLength + aLength + 1;
+ if (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
+ nsStringBuffer* buff = nsStringBuffer::Alloc(size).take();
+ if (!buff) {
+ return false;
+ }
+
+ // Copy data into buff
+ char16_t* data = static_cast<char16_t*>(buff->Data());
+ ConvertLatin1toUtf16(Span(m1b, mState.mLength), Span(data, mState.mLength));
+
+ memcpy(data + mState.mLength, aBuffer, aLength * sizeof(char16_t));
+ mState.mLength += aLength;
+ mState.mIs2b = true;
+
+ if (mState.mInHeap) {
+ free(const_cast<char*>(m1b));
+ }
+ data[mState.mLength] = char16_t(0);
+ 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 (!buff) {
+ return false;
+ }
+ } else {
+ buff = static_cast<char*>(malloc(size));
+ if (!buff) {
+ return false;
+ }
+
+ memcpy(buff, m1b, mState.mLength);
+ mState.mInHeap = true;
+ }
+
+ // Copy aBuffer into buff.
+ LossyConvertUtf16toLatin1(Span(aBuffer, aLength),
+ Span(buff + mState.mLength, aLength));
+
+ m1b = buff;
+ mState.mLength += aLength;
+
+ return true;
+}
+
+/* virtual */
+size_t nsTextFragment::SizeOfExcludingThis(
+ mozilla::MallocSizeOf aMallocSizeOf) const {
+ if (Is2b()) {
+ return m2b->SizeOfIncludingThisIfUnshared(aMallocSizeOf);
+ }
+
+ 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(Span(aBuffer, aLength))) {
+ mState.mIsBidi = true;
+ }
+ }
+}
+
+bool nsTextFragment::TextEquals(const nsTextFragment& aOther) const {
+ if (!Is2b()) {
+ // We're 1-byte.
+ if (!aOther.Is2b()) {
+ nsDependentCSubstring ourStr(Get1b(), GetLength());
+ return ourStr.Equals(
+ nsDependentCSubstring(aOther.Get1b(), aOther.GetLength()));
+ }
+
+ // We're 1-byte, the other thing is 2-byte. Instead of implementing a
+ // separate codepath for this, just use our code below.
+ return aOther.TextEquals(*this);
+ }
+
+ nsDependentSubstring ourStr(Get2b(), GetLength());
+ if (aOther.Is2b()) {
+ return ourStr.Equals(
+ nsDependentSubstring(aOther.Get2b(), aOther.GetLength()));
+ }
+
+ // We can't use EqualsASCII here, because the other string might not
+ // actually be ASCII. Just roll our own compare; do it in the simple way.
+ // Bug 1532356 tracks not having to roll our own.
+ if (GetLength() != aOther.GetLength()) {
+ return false;
+ }
+
+ const char16_t* ourChars = Get2b();
+ const char* otherChars = aOther.Get1b();
+ for (uint32_t i = 0; i < GetLength(); ++i) {
+ if (ourChars[i] != static_cast<char16_t>(otherChars[i])) {
+ return false;
+ }
+ }
+
+ return true;
+}
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