src/net/instaweb/rewriter/public/js_defer_disabled_filter.h

/*
 * Copyright 2011 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.
 */

// Author: atulvasu@google.com (Atul Vasu)

#ifndef NET_INSTAWEB_REWRITER_PUBLIC_JS_DEFER_DISABLED_FILTER_H_
#define NET_INSTAWEB_REWRITER_PUBLIC_JS_DEFER_DISABLED_FILTER_H_

#include "net/instaweb/rewriter/public/common_filter.h"
#include "pagespeed/kernel/base/basictypes.h"

namespace net_instaweb {

class HtmlElement;
class RewriteDriver;
class Statistics;

// Implements deferring of javascripts into post onload.
// JsDisableFilter moves scripts inside a noscript tag. This
// filter adds a javascript that goes through every noscript
// tag to defer them to be executed at onload of window.
class JsDeferDisabledFilter : public CommonFilter {
 public:
  explicit JsDeferDisabledFilter(RewriteDriver* driver);
  virtual ~JsDeferDisabledFilter();

  virtual void DetermineEnabled(GoogleString* disabled_reason);
  virtual const char* Name() const { return "JsDeferDisabledFilter"; }

  static void InitStats(Statistics* statistics);
  static void Terminate();

  // JsDeferDisableFilter will be no op for the request if ShouldApply returns
  // false.
  static bool ShouldApply(RewriteDriver* driver);

 private:
  virtual void EndDocument();

  virtual void StartDocumentImpl() {}
  virtual void StartElementImpl(HtmlElement* element) {}
  virtual void EndElementImpl(HtmlElement* element) {}

  void InsertJsDeferCode();

  DISALLOW_COPY_AND_ASSIGN(JsDeferDisabledFilter);
};

}  // namespace net_instaweb

#endif  // NET_INSTAWEB_REWRITER_PUBLIC_JS_DEFER_DISABLED_FILTER_H_