css_summarizer_base.h

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/*
 * Copyright 2013 Google Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http:///www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */


#ifndef NET_INSTAWEB_REWRITER_PUBLIC_CSS_SUMMARIZER_BASE_H_
#define NET_INSTAWEB_REWRITER_PUBLIC_CSS_SUMMARIZER_BASE_H_

#include <vector>

#include "net/instaweb/rewriter/public/resource_slot.h"
#include "net/instaweb/rewriter/public/rewrite_filter.h"
#include "pagespeed/kernel/base/basictypes.h"
#include "pagespeed/kernel/base/scoped_ptr.h"
#include "pagespeed/kernel/base/string.h"
#include "pagespeed/kernel/base/string_util.h"
#include "pagespeed/kernel/html/html_element.h"

namespace Css {

class Stylesheet;

}  

namespace net_instaweb {

class AbstractMutex;
class HtmlCharactersNode;
class RewriteContext;
class RewriteDriver;
class Statistics;
class Variable;

class CssSummarizerBase : public RewriteFilter {
 public:
  static const char kNumCssUsedForCriticalCssComputation[];
  static const char kNumCssNotUsedForCriticalCssComputation[];

  explicit CssSummarizerBase(RewriteDriver* driver);
  virtual ~CssSummarizerBase();

  static void InitStats(Statistics* statistics);

 protected:
  enum SummaryState {
    kSummaryOk,

    kSummaryStillPending,

    kSummaryCssParseError,

    kSummaryResourceCreationFailed,

    kSummaryInputUnavailable,

    kSummarySlotRemoved,
  };

  struct SummaryInfo {
    SummaryInfo()
        : state(kSummaryStillPending),
          is_external(false),
          is_inside_noscript(false) {}

    GoogleString data;

    SummaryState state;

    GoogleString location;

    GoogleString base;

    GoogleString media_from_html;

    GoogleString rel;

    bool is_external;

    bool is_inside_noscript;
  };

  virtual GoogleString CacheKeySuffix() const;

  virtual bool MustSummarize(HtmlElement* element) const {
    return true;
  }

  virtual void Summarize(Css::Stylesheet* stylesheet,
                         GoogleString* out) const = 0;

  virtual void RenderSummary(int pos,
                             HtmlElement* element,
                             HtmlCharactersNode* char_node,
                             bool* is_element_deleted);

  virtual void WillNotRenderSummary(int pos,
                                    HtmlElement* element,
                                    HtmlCharactersNode* char_node);

  virtual void SummariesDone();

  int NumStyles() const { return static_cast<int>(summaries_.size()); }

  const SummaryInfo& GetSummaryForStyle(int pos) const {
    return summaries_.at(pos);
  }

  virtual void StartDocumentImpl();
  virtual void EndDocument();
  virtual void StartElementImpl(HtmlElement* element);
  virtual void Characters(HtmlCharactersNode* characters);
  virtual void EndElementImpl(HtmlElement* element);
  virtual void RenderDone();

  virtual RewriteContext* MakeRewriteContext();

 private:
  class Context;

  void Clear();

  void ReportSummariesDone();

  void StartInlineRewrite(HtmlElement* style, HtmlCharactersNode* text);

  void StartExternalRewrite(HtmlElement* link, HtmlElement::Attribute* src,
                            StringPiece rel);

  Context* CreateContextAndSummaryInfo(const HtmlElement* element,
                                       bool external,
                                       const ResourceSlotPtr& slot,
                                       const GoogleString& location,
                                       StringPiece base_for_resources,
                                       StringPiece rel);

  ResourceSlotPtr MakeSlotForInlineCss(HtmlCharactersNode* char_node);

  std::vector<SummaryInfo> summaries_;

  scoped_ptr<AbstractMutex> progress_lock_;
  int outstanding_rewrites_; 
  bool saw_end_of_document_; 
  std::vector<int> canceled_summaries_; 

  HtmlElement* style_element_; 

  Variable* num_css_used_for_critical_css_computation_;
  Variable* num_css_not_used_for_critical_css_computation_;

  
};

}  

#endif