1 files changed, 470 insertions, 0 deletions
diff --git a/dom/base/nsTextFragment.cpp b/dom/base/nsTextFragment.cpp
new file mode 100644
index 0000000000..260e254bed
--- /dev/null
+++ b/dom/base/nsTextFragment.cpp
@@ -0,0 +1,470 @@
+/* -*- 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
+
+/*
+ * 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
+
+  return FirstNon8BitUnvectorized(str, end);
+}
+
+bool
+nsTextFragment::SetTo(const char16_t* aBuffer, int32_t aLength, bool aUpdateBidi)
+{
+  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)
+{
+  // 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);
+  }
+
+  // Should we optimize for aData.Length() == 0?
+
+  CheckedUint32 length = mState.mLength;
+  length += aLength;
+
+  if (!length.isValid()) {
+    return false;
+  }
+
+  if (mState.mIs2b) {
+    length *= sizeof(char16_t);
+    if (!length.isValid()) {
+      return false;
+    }
+
+    // Already a 2-byte string so the result will be too
+    char16_t* buff = static_cast<char16_t*>(realloc(m2b, length.value()));
+    if (!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
+    length *= sizeof(char16_t);
+    if (!length.isValid()) {
+      return false;
+    }
+
+    // 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(length.value()));
+    if (!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
+  char* buff;
+  if (mState.mInHeap) {
+    buff = static_cast<char*>(realloc(const_cast<char*>(m1b), length.value()));
+    if (!buff) {
+      return false;
+    }
+  }
+  else {
+    buff = static_cast<char*>(malloc(length.value()));
+    if (!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) {
+    const char16_t* cp = aBuffer;
+    const char16_t* end = cp + aLength;
+    while (cp < end) {
+      char16_t ch1 = *cp++;
+      uint32_t utf32Char = ch1;
+      if (NS_IS_HIGH_SURROGATE(ch1) &&
+          cp < end &&
+          NS_IS_LOW_SURROGATE(*cp)) {
+        char16_t ch2 = *cp++;
+        utf32Char = SURROGATE_TO_UCS4(ch1, ch2);
+      }
+      if (UTF32_CHAR_IS_BIDI(utf32Char) || IsBidiControlRTL(utf32Char)) {
+        mState.mIsBidi = true;
+        break;
+      }
+    }
+  }
+}