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

/*
 * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
 *           (C) 2004-2005 Allan Sandfeld Jensen (kde@carewolf.com)
 * Copyright (C) 2006, 2007 Nicholas Shanks (webkit@nickshanks.com)
 * Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013 Apple Inc.
 * All rights reserved.
 * Copyright (C) 2007 Alexey Proskuryakov <ap@webkit.org>
 * Copyright (C) 2007, 2008 Eric Seidel <eric@webkit.org>
 * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved.
 * (http://www.torchmobile.com/)
 * Copyright (c) 2011, Code Aurora Forum. All rights reserved.
 * Copyright (C) Research In Motion Limited 2011. All rights reserved.
 * Copyright (C) 2012 Google Inc. All rights reserved.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public License
 * along with this library; see the file COPYING.LIB.  If not, write to
 * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
 * Boston, MA 02110-1301, USA.
 */

#include "core/css/PageRuleCollector.h"

#include <algorithm>
#include "core/css/CSSPropertyValueSet.h"
#include "core/css/StyleRule.h"
#include "core/style/ComputedStyle.h"

namespace blink {

static inline bool ComparePageRules(const StyleRulePage* r1,
                                    const StyleRulePage* r2) {
  return r1->Selector()->Specificity() < r2->Selector()->Specificity();
}

bool PageRuleCollector::IsLeftPage(const ComputedStyle* root_element_style,
                                   int page_index) const {
  bool is_first_page_left = false;
  DCHECK(root_element_style);
  if (!root_element_style->IsLeftToRightDirection())
    is_first_page_left = true;

  return (page_index + (is_first_page_left ? 1 : 0)) % 2;
}

bool PageRuleCollector::IsFirstPage(int page_index) const {
  // FIXME: In case of forced left/right page, page at index 1 (not 0) can be
  // the first page.
  return (!page_index);
}

String PageRuleCollector::PageName(int /* pageIndex */) const {
  // FIXME: Implement page index to page name mapping.
  return "";
}

PageRuleCollector::PageRuleCollector(const ComputedStyle* root_element_style,
                                     int page_index)
    : is_left_page_(IsLeftPage(root_element_style, page_index)),
      is_first_page_(IsFirstPage(page_index)),
      page_name_(PageName(page_index)) {}

void PageRuleCollector::MatchPageRules(RuleSet* rules) {
  if (!rules)
    return;

  rules->CompactRulesIfNeeded();
  HeapVector<Member<StyleRulePage>> matched_page_rules;
  MatchPageRulesForList(matched_page_rules, rules->PageRules(), is_left_page_,
                        is_first_page_, page_name_);
  if (matched_page_rules.IsEmpty())
    return;

  std::stable_sort(matched_page_rules.begin(), matched_page_rules.end(),
                   ComparePageRules);

  for (unsigned i = 0; i < matched_page_rules.size(); i++)
    result_.AddMatchedProperties(&matched_page_rules[i]->Properties());
}

static bool CheckPageSelectorComponents(const CSSSelector* selector,
                                        bool is_left_page,
                                        bool is_first_page,
                                        const String& page_name) {
  for (const CSSSelector* component = selector; component;
       component = component->TagHistory()) {
    if (component->Match() == CSSSelector::kTag) {
      const AtomicString& local_name = component->TagQName().LocalName();
      DCHECK_NE(local_name, CSSSelector::UniversalSelectorAtom());
      if (local_name != page_name)
        return false;
    }

    CSSSelector::PseudoType pseudo_type = component->GetPseudoType();
    if ((pseudo_type == CSSSelector::kPseudoLeftPage && !is_left_page) ||
        (pseudo_type == CSSSelector::kPseudoRightPage && is_left_page) ||
        (pseudo_type == CSSSelector::kPseudoFirstPage && !is_first_page)) {
      return false;
    }
  }
  return true;
}

void PageRuleCollector::MatchPageRulesForList(
    HeapVector<Member<StyleRulePage>>& matched_rules,
    const HeapVector<Member<StyleRulePage>>& rules,
    bool is_left_page,
    bool is_first_page,
    const String& page_name) {
  for (unsigned i = 0; i < rules.size(); ++i) {
    StyleRulePage* rule = rules[i];

    if (!CheckPageSelectorComponents(rule->Selector(), is_left_page,
                                     is_first_page, page_name))
      continue;

    // If the rule has no properties to apply, then ignore it.
    const CSSPropertyValueSet& properties = rule->Properties();
    if (properties.IsEmpty())
      continue;

    // Add this rule to our list of matched rules.
    matched_rules.push_back(rule);
  }
}

}  // namespace blink