insert_dns_prefetch_filter.h

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/*
 * Copyright 2012 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_INSERT_DNS_PREFETCH_FILTER_H_
#define NET_INSTAWEB_REWRITER_PUBLIC_INSERT_DNS_PREFETCH_FILTER_H_

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

namespace net_instaweb {

class FlushEarlyInfo;
class RewriteDriver;

class InsertDnsPrefetchFilter : public CommonFilter {
 public:
  explicit InsertDnsPrefetchFilter(RewriteDriver* driver);
  virtual ~InsertDnsPrefetchFilter();

  virtual void StartDocumentImpl();
  virtual void EndDocument();
  virtual void StartElementImpl(HtmlElement* element);
  virtual void EndElementImpl(HtmlElement* element);

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

 private:
  void Clear();

  void MarkAlreadyInHead(HtmlElement::Attribute* urlattr);

  bool IsDomainListStable(const FlushEarlyInfo& flush_early_info) const;
  void DebugPrint(const char* msg);

  bool dns_prefetch_inserted_;

  bool in_head_;

  StringSet domains_to_ignore_;

  StringSet domains_in_body_;

  StringVector dns_prefetch_domains_;

  bool user_agent_supports_dns_prefetch_;

  
};

}  

#endif