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

/*
 * (C) 1999-2003 Lars Knoll (knoll@kde.org)
 * Copyright (C) 2004, 2006, 2010, 2012 Apple 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/MediaList.h"

#include "bindings/core/v8/ExceptionState.h"
#include "core/css/CSSStyleSheet.h"
#include "core/css/MediaQuery.h"
#include "core/css/MediaQueryExp.h"
#include "core/css/parser/MediaQueryParser.h"
#include "wtf/text/StringBuilder.h"
#include <memory>

namespace blink {

/* MediaList is used to store 3 types of media related entities which mean the
 * same:
 *
 * Media Queries, Media Types and Media Descriptors.
 *
 * Media queries, as described in the Media Queries Level 3 specification, build
 * on the mechanism outlined in HTML4. The syntax of media queries fit into the
 * media type syntax reserved in HTML4. The media attribute of HTML4 also exists
 * in XHTML and generic XML. The same syntax can also be used inside the @media
 * and @import rules of CSS.
 *
 * However, the parsing rules for media queries are incompatible with those of
 * HTML4 and are consistent with those of media queries used in CSS.
 *
 * HTML5 (at the moment of writing still work in progress) references the Media
 * Queries specification directly and thus updates the rules for HTML.
 *
 * CSS 2.1 Spec (http://www.w3.org/TR/CSS21/media.html)
 * CSS 3 Media Queries Spec (http://www.w3.org/TR/css3-mediaqueries/)
 */

MediaQuerySet::MediaQuerySet() {}

MediaQuerySet::MediaQuerySet(const MediaQuerySet& o)
    : m_queries(o.m_queries.size()) {
  for (unsigned i = 0; i < m_queries.size(); ++i)
    m_queries[i] = o.m_queries[i]->copy();
}

MediaQuerySet* MediaQuerySet::create(const String& mediaString) {
  if (mediaString.isEmpty())
    return MediaQuerySet::create();

  return MediaQueryParser::parseMediaQuerySet(mediaString);
}

MediaQuerySet* MediaQuerySet::createOffMainThread(const String& mediaString) {
  if (mediaString.isEmpty())
    return MediaQuerySet::create();

  return MediaQueryParser::parseMediaQuerySet(mediaString);
}

bool MediaQuerySet::set(const String& mediaString) {
  MediaQuerySet* result = create(mediaString);
  m_queries.swap(result->m_queries);
  return true;
}

bool MediaQuerySet::add(const String& queryString) {
  // To "parse a media query" for a given string means to follow "the parse
  // a media query list" steps and return "null" if more than one media query
  // is returned, or else the returned media query.
  MediaQuerySet* result = create(queryString);

  // Only continue if exactly one media query is found, as described above.
  if (result->m_queries.size() != 1)
    return true;

  MediaQuery* newQuery = result->m_queries[0].release();
  ASSERT(newQuery);

  // If comparing with any of the media queries in the collection of media
  // queries returns true terminate these steps.
  for (size_t i = 0; i < m_queries.size(); ++i) {
    MediaQuery* query = m_queries[i].get();
    if (*query == *newQuery)
      return true;
  }

  m_queries.append(newQuery);
  return true;
}

bool MediaQuerySet::remove(const String& queryStringToRemove) {
  // To "parse a media query" for a given string means to follow "the parse
  // a media query list" steps and return "null" if more than one media query
  // is returned, or else the returned media query.
  MediaQuerySet* result = create(queryStringToRemove);

  // Only continue if exactly one media query is found, as described above.
  if (result->m_queries.size() != 1)
    return true;

  MediaQuery* newQuery = result->m_queries[0].release();
  ASSERT(newQuery);

  // Remove any media query from the collection of media queries for which
  // comparing with the media query returns true.
  bool found = false;
  for (size_t i = 0; i < m_queries.size(); ++i) {
    MediaQuery* query = m_queries[i].get();
    if (*query == *newQuery) {
      m_queries.remove(i);
      --i;
      found = true;
    }
  }

  return found;
}

void MediaQuerySet::addMediaQuery(MediaQuery* mediaQuery) {
  m_queries.append(mediaQuery);
}

String MediaQuerySet::mediaText() const {
  StringBuilder text;

  bool first = true;
  for (size_t i = 0; i < m_queries.size(); ++i) {
    if (!first)
      text.append(", ");
    else
      first = false;
    text.append(m_queries[i]->cssText());
  }
  return text.toString();
}

DEFINE_TRACE(MediaQuerySet) {
  // We don't support tracing of vectors of OwnPtrs (ie.
  // std::unique_ptr<Vector<std::unique_ptr<MediaQuery>>>).
  // Since this is a transitional object we are just ifdef'ing it out when
  // oilpan is not enabled.
  visitor->trace(m_queries);
}

MediaList::MediaList(MediaQuerySet* mediaQueries, CSSStyleSheet* parentSheet)
    : m_mediaQueries(mediaQueries),
      m_parentStyleSheet(parentSheet),
      m_parentRule(nullptr) {}

MediaList::MediaList(MediaQuerySet* mediaQueries, CSSRule* parentRule)
    : m_mediaQueries(mediaQueries),
      m_parentStyleSheet(nullptr),
      m_parentRule(parentRule) {}

void MediaList::setMediaText(const String& value) {
  CSSStyleSheet::RuleMutationScope mutationScope(m_parentRule);

  m_mediaQueries->set(value);

  if (m_parentStyleSheet)
    m_parentStyleSheet->didMutate();
}

String MediaList::item(unsigned index) const {
  const HeapVector<Member<MediaQuery>>& queries = m_mediaQueries->queryVector();
  if (index < queries.size())
    return queries[index]->cssText();
  return String();
}

void MediaList::deleteMedium(const String& medium,
                             ExceptionState& exceptionState) {
  CSSStyleSheet::RuleMutationScope mutationScope(m_parentRule);

  bool success = m_mediaQueries->remove(medium);
  if (!success) {
    exceptionState.throwDOMException(NotFoundError,
                                     "Failed to delete '" + medium + "'.");
    return;
  }
  if (m_parentStyleSheet)
    m_parentStyleSheet->didMutate();
}

void MediaList::appendMedium(const String& medium,
                             ExceptionState& exceptionState) {
  CSSStyleSheet::RuleMutationScope mutationScope(m_parentRule);

  bool success = m_mediaQueries->add(medium);
  if (!success) {
    exceptionState.throwDOMException(
        InvalidCharacterError,
        "The value provided ('" + medium + "') is not a valid medium.");
    return;
  }

  if (m_parentStyleSheet)
    m_parentStyleSheet->didMutate();
}

void MediaList::reattach(MediaQuerySet* mediaQueries) {
  ASSERT(mediaQueries);
  m_mediaQueries = mediaQueries;
}

DEFINE_TRACE(MediaList) {
  visitor->trace(m_mediaQueries);
  visitor->trace(m_parentStyleSheet);
  visitor->trace(m_parentRule);
}

}  // namespace blink