net/instaweb/rewriter/insert_amp_link_filter.cc - incubator-pagespeed-mod - Git at Google

 /*
  * Copyright 2016 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: sjnickerson@google.com (Simon Nickerson)

 #include "net/instaweb/rewriter/public/insert_amp_link_filter.h"

 #include "net/instaweb/rewriter/public/rewrite_driver.h"
 #include "net/instaweb/rewriter/public/rewrite_options.h"
 #include "pagespeed/kernel/base/string_util.h"
 #include "pagespeed/kernel/html/html_element.h"
 #include "pagespeed/kernel/html/html_name.h"
 #include "pagespeed/kernel/http/google_url.h"

 namespace net_instaweb {

 namespace {

 // Attribute name for the AMP <link> tag
 const char kAmpHtmlAttributeName[] = "amphtml";

 // URL fragment names for matching. These are case sensitive.
 const char kAllExceptLeaf[] = "all_except_leaf";
 const char kAllExceptQuery[] = "all_except_query";
 const char kLeafSansQuery[] = "leaf_sans_query";
 const char kLeafWithQuery[] = "leaf_with_query";
 const char kPathNoTrailingSlash[] = "path_no_trailing_slash";
 const char kMaybeTrailingSlash[] = "maybe_trailing_slash";
 const char kMaybeQuery[] = "maybe_query";
 const char kUrlPattern[] = "url";
 const char kTrailingSlash[] = "/";

 GoogleString PathNoTrailingSlash(const GoogleUrl& google_url);
 GoogleString MaybeQuery(const GoogleUrl& google_url);
 GoogleString MaybeTrailingSlash(const GoogleUrl& google_url);
 void AppendUrlFragment(GoogleString* str, const GoogleUrl& google_url,
                           const StringPiece fragment_name);

 }  // namespace

 InsertAmpLinkFilter::InsertAmpLinkFilter(RewriteDriver* rewrite_driver)
     : CommonFilter(rewrite_driver), enabled_(false), amp_link_found_(false) {}

 InsertAmpLinkFilter::~InsertAmpLinkFilter() {}

 void InsertAmpLinkFilter::StartDocumentImpl() { amp_link_found_ = false; }

 void InsertAmpLinkFilter::DetermineEnabled(GoogleString* disabled_reason) {
   const RewriteOptions* options = driver()->options();
   if (options->amp_link_pattern() != "") {
     set_is_enabled(true);
   }
 }

 void InsertAmpLinkFilter::StartElementImpl(HtmlElement* element) {
   if (element->keyword() == HtmlName::kLink &&
       StringCaseEqual(element->AttributeValue(HtmlName::kRel),
                       kAmpHtmlAttributeName)) {
     amp_link_found_ = true;
   }
 }

 void InsertAmpLinkFilter::EndElementImpl(HtmlElement* element) {
   if (is_enabled() && !amp_link_found_ &&
       element->keyword() == HtmlName::kHead) {
     HtmlElement* linkAmphtml = driver()->NewElement(element, HtmlName::kLink);
     driver()->AddAttribute(linkAmphtml, HtmlName::kRel, kAmpHtmlAttributeName);
     driver()->AddAttribute(linkAmphtml, HtmlName::kHref, GetAmpUrl());
     driver()->AppendChild(element, linkAmphtml);
     // We don't want to insert AMP links if there are multiple <head> elements.
     amp_link_found_ = true;
   }
 }

 GoogleString InsertAmpLinkFilter::GetAmpUrl() {
   const char* amp_pattern = driver()->options()->amp_link_pattern().c_str();
   const GoogleUrl& google_url = driver()->google_url();

   GoogleString amp_link;

   // Populate amp_link by iterating through amp_pattern. Characters between "${"
   // and "}" are URL fragment names. Other characters are just copied directly.
   const char* fragment_name_start = nullptr;
   for (const char* p = amp_pattern; *p != '\0'; p++) {
     if (*p == '$' && *(p + 1) == '{') {
       fragment_name_start = p + 2;
     } else if (*p == '}' && fragment_name_start != nullptr) {
       StringPiece fragment_name(fragment_name_start, p - fragment_name_start);
       AppendUrlFragment(&amp_link, google_url, fragment_name);
       fragment_name_start = nullptr;
     } else if (fragment_name_start == nullptr) {
       amp_link += *p;
     }
   }

   if (fragment_name_start != nullptr) {
     // Handle missing closing brace by appending the string literal.
     // The "- 2" is to pick up the "${".
     StrAppend(&amp_link, fragment_name_start - 2);
   }

   return amp_link;
 }

 namespace {

 // Appends a fragment_name extracted from google_url to str.
 void AppendUrlFragment(GoogleString* str, const GoogleUrl& google_url,
                           const StringPiece fragment_name) {
   if (fragment_name == kUrlPattern) {
     StrAppend(str, google_url.Spec());
   } else if (fragment_name == kAllExceptQuery) {
     StrAppend(str, google_url.AllExceptQuery());
   } else if (fragment_name == kAllExceptLeaf) {
     StrAppend(str, google_url.AllExceptLeaf());
   } else if (fragment_name == kLeafSansQuery) {
     StrAppend(str, google_url.LeafSansQuery());
   } else if (fragment_name == kLeafWithQuery) {
     StrAppend(str, google_url.LeafWithQuery());
   } else if (fragment_name == kMaybeQuery) {
     StrAppend(str, MaybeQuery(google_url));
   } else if (fragment_name == kPathNoTrailingSlash) {
     StrAppend(str, PathNoTrailingSlash(google_url));
   } else if (fragment_name == kMaybeTrailingSlash) {
     StrAppend(str, MaybeTrailingSlash(google_url));
   } else {
     // If we couldn't find a match, just append fragment_name between "${" and
     // "}" as it would have appeared in the amp_link_pattern.
     StrAppend(str, "${", fragment_name, "}");
   }
 }

 // Returns the path from google_url without the trailing slash (if present).
 // For example, "http://test.com/a/b/" -> "/a/b"
 GoogleString PathNoTrailingSlash(const GoogleUrl& google_url) {
   GoogleString path =
       StrCat(google_url.PathSansLeaf(), google_url.LeafSansQuery());
   if (EndsInSlash(path)) {
     path.resize(path.size() - 1);
   }
   return path;
 }

 // Returns a trailing slash if the path in the google_url contains a trailing
 // slash. For example, "http://test.com/a/b/" -> "/"
 GoogleString MaybeQuery(const GoogleUrl& google_url) {
   StringPiece query = google_url.Query();
   GoogleString maybe_query = query.empty() ? "" : StrCat("?", query);
   return maybe_query;
 }

 // Returns the query string including a "?" if present, or an empty string
 // if not present. For example, "http://test.com/a/b?p=3" -> "?p=3"
 GoogleString MaybeTrailingSlash(const GoogleUrl& google_url) {
   if (google_url.AllExceptQuery().ends_with(kTrailingSlash)) {
     return kTrailingSlash;
   } else {
     return "";
   }
 }

 }  // namespace

 }  // namespace net_instaweb
	/*
	* Copyright 2016 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: sjnickerson@google.com (Simon Nickerson)

	#include "net/instaweb/rewriter/public/insert_amp_link_filter.h"

	#include "net/instaweb/rewriter/public/rewrite_driver.h"
	#include "net/instaweb/rewriter/public/rewrite_options.h"
	#include "pagespeed/kernel/base/string_util.h"
	#include "pagespeed/kernel/html/html_element.h"
	#include "pagespeed/kernel/html/html_name.h"
	#include "pagespeed/kernel/http/google_url.h"

	namespace net_instaweb {

	namespace {

	// Attribute name for the AMP <link> tag
	const char kAmpHtmlAttributeName[] = "amphtml";

	// URL fragment names for matching. These are case sensitive.
	const char kAllExceptLeaf[] = "all_except_leaf";
	const char kAllExceptQuery[] = "all_except_query";
	const char kLeafSansQuery[] = "leaf_sans_query";
	const char kLeafWithQuery[] = "leaf_with_query";
	const char kPathNoTrailingSlash[] = "path_no_trailing_slash";
	const char kMaybeTrailingSlash[] = "maybe_trailing_slash";
	const char kMaybeQuery[] = "maybe_query";
	const char kUrlPattern[] = "url";
	const char kTrailingSlash[] = "/";

	GoogleString PathNoTrailingSlash(const GoogleUrl& google_url);
	GoogleString MaybeQuery(const GoogleUrl& google_url);
	GoogleString MaybeTrailingSlash(const GoogleUrl& google_url);
	void AppendUrlFragment(GoogleString* str, const GoogleUrl& google_url,
	const StringPiece fragment_name);

	} // namespace

	InsertAmpLinkFilter::InsertAmpLinkFilter(RewriteDriver* rewrite_driver)
	: CommonFilter(rewrite_driver), enabled_(false), amp_link_found_(false) {}

	InsertAmpLinkFilter::~InsertAmpLinkFilter() {}

	void InsertAmpLinkFilter::StartDocumentImpl() { amp_link_found_ = false; }

	void InsertAmpLinkFilter::DetermineEnabled(GoogleString* disabled_reason) {
	const RewriteOptions* options = driver()->options();
	if (options->amp_link_pattern() != "") {
	set_is_enabled(true);
	}
	}

	void InsertAmpLinkFilter::StartElementImpl(HtmlElement* element) {
	if (element->keyword() == HtmlName::kLink &&
	StringCaseEqual(element->AttributeValue(HtmlName::kRel),
	kAmpHtmlAttributeName)) {
	amp_link_found_ = true;
	}
	}

	void InsertAmpLinkFilter::EndElementImpl(HtmlElement* element) {
	if (is_enabled() && !amp_link_found_ &&
	element->keyword() == HtmlName::kHead) {
	HtmlElement* linkAmphtml = driver()->NewElement(element, HtmlName::kLink);
	driver()->AddAttribute(linkAmphtml, HtmlName::kRel, kAmpHtmlAttributeName);
	driver()->AddAttribute(linkAmphtml, HtmlName::kHref, GetAmpUrl());
	driver()->AppendChild(element, linkAmphtml);
	// We don't want to insert AMP links if there are multiple <head> elements.
	amp_link_found_ = true;
	}
	}

	GoogleString InsertAmpLinkFilter::GetAmpUrl() {
	const char* amp_pattern = driver()->options()->amp_link_pattern().c_str();
	const GoogleUrl& google_url = driver()->google_url();

	GoogleString amp_link;

	// Populate amp_link by iterating through amp_pattern. Characters between "${"
	// and "}" are URL fragment names. Other characters are just copied directly.
	const char* fragment_name_start = nullptr;
	for (const char* p = amp_pattern; *p != '\0'; p++) {
	if (p == '$' && (p + 1) == '{') {
	fragment_name_start = p + 2;
	} else if (*p == '}' && fragment_name_start != nullptr) {
	StringPiece fragment_name(fragment_name_start, p - fragment_name_start);
	AppendUrlFragment(&amp_link, google_url, fragment_name);
	fragment_name_start = nullptr;
	} else if (fragment_name_start == nullptr) {
	amp_link += *p;
	}
	}

	if (fragment_name_start != nullptr) {
	// Handle missing closing brace by appending the string literal.
	// The "- 2" is to pick up the "${".
	StrAppend(&amp_link, fragment_name_start - 2);
	}

	return amp_link;
	}

	namespace {

	// Appends a fragment_name extracted from google_url to str.
	void AppendUrlFragment(GoogleString* str, const GoogleUrl& google_url,
	const StringPiece fragment_name) {
	if (fragment_name == kUrlPattern) {
	StrAppend(str, google_url.Spec());
	} else if (fragment_name == kAllExceptQuery) {
	StrAppend(str, google_url.AllExceptQuery());
	} else if (fragment_name == kAllExceptLeaf) {
	StrAppend(str, google_url.AllExceptLeaf());
	} else if (fragment_name == kLeafSansQuery) {
	StrAppend(str, google_url.LeafSansQuery());
	} else if (fragment_name == kLeafWithQuery) {
	StrAppend(str, google_url.LeafWithQuery());
	} else if (fragment_name == kMaybeQuery) {
	StrAppend(str, MaybeQuery(google_url));
	} else if (fragment_name == kPathNoTrailingSlash) {
	StrAppend(str, PathNoTrailingSlash(google_url));
	} else if (fragment_name == kMaybeTrailingSlash) {
	StrAppend(str, MaybeTrailingSlash(google_url));
	} else {
	// If we couldn't find a match, just append fragment_name between "${" and
	// "}" as it would have appeared in the amp_link_pattern.
	StrAppend(str, "${", fragment_name, "}");
	}
	}

	// Returns the path from google_url without the trailing slash (if present).
	// For example, "http://test.com/a/b/" -> "/a/b"
	GoogleString PathNoTrailingSlash(const GoogleUrl& google_url) {
	GoogleString path =
	StrCat(google_url.PathSansLeaf(), google_url.LeafSansQuery());
	if (EndsInSlash(path)) {
	path.resize(path.size() - 1);
	}
	return path;
	}

	// Returns a trailing slash if the path in the google_url contains a trailing
	// slash. For example, "http://test.com/a/b/" -> "/"
	GoogleString MaybeQuery(const GoogleUrl& google_url) {
	StringPiece query = google_url.Query();
	GoogleString maybe_query = query.empty() ? "" : StrCat("?", query);
	return maybe_query;
	}

	// Returns the query string including a "?" if present, or an empty string
	// if not present. For example, "http://test.com/a/b?p=3" -> "?p=3"
	GoogleString MaybeTrailingSlash(const GoogleUrl& google_url) {
	if (google_url.AllExceptQuery().ends_with(kTrailingSlash)) {
	return kTrailingSlash;
	} else {
	return "";
	}
	}

	} // namespace

	} // namespace net_instaweb