third_party/WebKit/Source/core/css/CSSSelectorList.cpp

/*
 * Copyright (C) 2008, 2012 Apple Inc. All rights reserved.
 * Copyright (C) 2009 Google Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
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 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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#include "core/css/CSSSelectorList.h"

#include <memory>
#include "core/css/parser/CSSParserSelector.h"
#include "platform/wtf/allocator/Partitions.h"
#include "platform/wtf/text/StringBuilder.h"

namespace {
// CSSSelector is one of the top types that consume renderer memory,
// so instead of using the |WTF_HEAP_PROFILER_TYPE_NAME| macro in the
// allocations below, pass this type name constant to allow profiling
// in official builds.
const char kCSSSelectorTypeName[] = "blink::CSSSelector";
}

namespace blink {

CSSSelectorList CSSSelectorList::Copy() const {
  CSSSelectorList list;

  unsigned length = this->ComputeLength();
  list.selector_array_ =
      reinterpret_cast<CSSSelector*>(WTF::Partitions::FastMalloc(
          WTF::Partitions::ComputeAllocationSize(length, sizeof(CSSSelector)),
          kCSSSelectorTypeName));
  for (unsigned i = 0; i < length; ++i)
    new (&list.selector_array_[i]) CSSSelector(selector_array_[i]);

  return list;
}

CSSSelectorList CSSSelectorList::AdoptSelectorVector(
    Vector<std::unique_ptr<CSSParserSelector>>& selector_vector) {
  size_t flattened_size = 0;
  for (size_t i = 0; i < selector_vector.size(); ++i) {
    for (CSSParserSelector* selector = selector_vector[i].get(); selector;
         selector = selector->TagHistory())
      ++flattened_size;
  }
  DCHECK(flattened_size);

  CSSSelectorList list;
  list.selector_array_ = reinterpret_cast<CSSSelector*>(
      WTF::Partitions::FastMalloc(WTF::Partitions::ComputeAllocationSize(
                                      flattened_size, sizeof(CSSSelector)),
                                  kCSSSelectorTypeName));
  size_t array_index = 0;
  for (size_t i = 0; i < selector_vector.size(); ++i) {
    CSSParserSelector* current = selector_vector[i].get();
    while (current) {
      // Move item from the parser selector vector into selector_array_ without
      // invoking destructor (Ugh.)
      CSSSelector* current_selector = current->ReleaseSelector().release();
      memcpy(&list.selector_array_[array_index], current_selector,
             sizeof(CSSSelector));
      WTF::Partitions::FastFree(current_selector);

      current = current->TagHistory();
      DCHECK(!list.selector_array_[array_index].IsLastInSelectorList());
      if (current)
        list.selector_array_[array_index].SetNotLastInTagHistory();
      ++array_index;
    }
    DCHECK(list.selector_array_[array_index - 1].IsLastInTagHistory());
  }
  DCHECK_EQ(flattened_size, array_index);
  list.selector_array_[array_index - 1].SetLastInSelectorList();
  selector_vector.clear();

  return list;
}

unsigned CSSSelectorList::ComputeLength() const {
  if (!selector_array_)
    return 0;
  CSSSelector* current = selector_array_;
  while (!current->IsLastInSelectorList())
    ++current;
  return (current - selector_array_) + 1;
}

void CSSSelectorList::DeleteSelectors() {
  DCHECK(selector_array_);

  bool finished = false;
  for (CSSSelector* s = selector_array_; !finished; ++s) {
    finished = s->IsLastInSelectorList();
    s->~CSSSelector();
  }

  WTF::Partitions::FastFree(selector_array_);
}

String CSSSelectorList::SelectorsText() const {
  StringBuilder result;

  for (const CSSSelector* s = First(); s; s = Next(*s)) {
    if (s != First())
      result.Append(", ");
    result.Append(s->SelectorText());
  }

  return result.ToString();
}

}  // namespace blink