components/dom_distiller/core/page_features.cc

   1 // Copyright 2015 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "components/dom_distiller/core/page_features.h"
   6
   7 #include <string>
   8
   9 #include "base/json/json_reader.h"
  10 #include "third_party/re2/re2/re2.h"
  11
  12 namespace dom_distiller {
  13 /* This code needs to derive features in the same way and order in which they
  14  * are derived when training the model. Parts of that code are reproduced in the
  15  * comments below.
  16  */
  17
  18 namespace {
  19 std::string GetLastSegment(const std::string& path) {
  20   // return re.search('[^/]*\/?$', path).group(0)
  21   if (path.size() == 0)
  22     return "";
  23   size_t start = path.rfind("/", path.size() - 1);
  24   return start == std::string::npos ? "" : path.substr(start + 1);
  25 }
  26
  27 int CountMatches(const std::string& s, const std::string& p) {
  28   // return len(re.findall(p, s))
  29   re2::StringPiece sp(s);
  30   re2::RE2 regexp(p);
  31   int count = 0;
  32   while (re2::RE2::FindAndConsume(&sp, regexp))
  33     count++;
  34   return count;
  35 }
  36
  37 int GetWordCount(const std::string& s) {
  38   return CountMatches(s, "\\w+");
  39 }
  40
  41 bool Contains(const std::string& n, const std::string& h) {
  42   return h.find(n) != std::string::npos;
  43 }
  44
  45 bool EndsWith(const std::string& t, const std::string& s) {
  46   return s.size() >= t.size() &&
  47          s.compare(s.size() - t.size(), std::string::npos, t) == 0;
  48 }
  49 }
  50
  51 int kDerivedFeaturesCount = 29;
  52
  53 std::vector<double> CalculateDerivedFeatures(bool isOGArticle,
  54                                              const GURL& url,
  55                                              double numElements,
  56                                              double numAnchors,
  57                                              double numForms,
  58                                              const std::string& innerText,
  59                                              const std::string& textContent,
  60                                              const std::string& innerHTML) {
  61   // In the training pipeline, the strings are explicitly encoded in utf-8 (as
  62   // they are here).
  63   const std::string& path = url.path();
  64   int innerTextWords = GetWordCount(innerText);
  65   int textContentWords = GetWordCount(textContent);
  66   int innerHTMLWords = GetWordCount(innerHTML);
  67   std::vector<double> features;
  68   // 'opengraph', opengraph,
  69   features.push_back(isOGArticle);
  70   // 'forum', 'forum' in path,
  71   features.push_back(Contains("forum", path));
  72   // 'index', 'index' in path,
  73   features.push_back(Contains("index", path));
  74   // 'view', 'view' in path,
  75   features.push_back(Contains("view", path));
  76   // 'asp', '.asp' in path,
  77   features.push_back(Contains(".asp", path));
  78   // 'phpbb', 'phpbb' in path,
  79   features.push_back(Contains("phpbb", path));
  80   // 'php', path.endswith('.php'),
  81   features.push_back(EndsWith(".php", path));
  82   // 'pathlength', len(path),
  83   features.push_back(path.size());
  84   // 'domain', len(path) < 2,
  85   features.push_back(path.size() < 2);
  86   // 'pathcomponents', CountMatches(path, r'\/.'),
  87   features.push_back(CountMatches(path, "\\/."));
  88   // 'slugdetector', CountMatches(path, r'[^\w/]'),
  89   features.push_back(CountMatches(path, "[^\\w/]"));
  90   // 'pathnumbers', CountMatches(path, r'\d+'),
  91   features.push_back(CountMatches(path, "\\d+"));
  92   // 'lastSegmentLength', len(GetLastSegment(path)),
  93   features.push_back(GetLastSegment(path).size());
  94   // 'formcount', numForms,
  95   features.push_back(numForms);
  96   // 'anchorcount', numAnchors,
  97   features.push_back(numAnchors);
  98   // 'elementcount', numElements,
  99   features.push_back(numElements);
 100   // 'anchorratio', float(numAnchors) / max(1, numElements),
 101   features.push_back(double(numAnchors) / std::max<double>(1, numElements));
 102   // 'innertextlength', len(innerText),
 103   features.push_back(innerText.size());
 104   // 'textcontentlength', len(textContent),
 105   features.push_back(textContent.size());
 106   // 'innerhtmllength', len(innerHTML),
 107   features.push_back(innerHTML.size());
 108   // 'innertextlengthratio', float(len(innerText)) / max(1, len(innerHTML)),
 109   features.push_back(double(innerText.size()) /
 110                      std::max<double>(1.0, innerHTML.size()));
 111   // 'textcontentlengthratio', float(len(textContent)) / max(1, len(innerHTML)),
 112   features.push_back(double(textContent.size()) /
 113                      std::max<double>(1.0, innerHTML.size()));
 114   // 'innertexttextcontentlengthratio',
 115   // float(len(innerText)) / max(1, len(textContent)),
 116   features.push_back(double(innerText.size()) /
 117                      std::max<double>(1.0, textContent.size()));
 118   // 'innertextwordcount', innerTextWords,
 119   features.push_back(innerTextWords);
 120   // 'textcontentwordcount', textContentWords,
 121   features.push_back(textContentWords);
 122   // 'innerhtmlwordcount', innerHTMLWords,
 123   features.push_back(innerHTMLWords);
 124   // 'innertextwordcountratio', float(innerTextWords) / max(1, innerHTMLWords),
 125   features.push_back(double(innerTextWords) /
 126                      std::max<int>(1.0, innerHTMLWords));
 127   // 'textcontentwordcountratio',
 128   // float(textContentWords) / max(1, innerHTMLWords),
 129   features.push_back(double(textContentWords) /
 130                      std::max<int>(1.0, innerHTMLWords));
 131   // 'innertexttextcontentwordcountratio',
 132   // float(innerTextWords) / max(1, textContentWords),
 133   features.push_back(double(innerTextWords) /
 134                      std::max<int>(1.0, textContentWords));
 135   return features;
 136 }
 137
 138 std::vector<double> CalculateDerivedFeaturesFromJSON(
 139     const base::Value* stringified_json) {
 140   std::string stringified;
 141   if (!stringified_json->GetAsString(&stringified)) {
 142     return std::vector<double>();
 143   }
 144
 145   scoped_ptr<base::Value> json(base::JSONReader::Read(stringified));
 146   if (!json) {
 147     return std::vector<double>();
 148   }
 149
 150   const base::DictionaryValue* dict;
 151   if (!json->GetAsDictionary(&dict)) {
 152     return std::vector<double>();
 153   }
 154
 155   bool isOGArticle = false;
 156   std::string url, innerText, textContent, innerHTML;
 157   double numElements = 0.0, numAnchors = 0.0, numForms = 0.0;
 158
 159   if (!(dict->GetBoolean("opengraph", &isOGArticle) &&
 160         dict->GetString("url", &url) &&
 161         dict->GetDouble("numElements", &numElements) &&
 162         dict->GetDouble("numAnchors", &numAnchors) &&
 163         dict->GetDouble("numForms", &numForms) &&
 164         dict->GetString("innerText", &innerText) &&
 165         dict->GetString("textContent", &textContent) &&
 166         dict->GetString("innerHTML", &innerHTML))) {
 167     return std::vector<double>();
 168   }
 169
 170   GURL parsed_url(url);
 171   if (!parsed_url.is_valid()) {
 172     return std::vector<double>();
 173   }
 174
 175   return CalculateDerivedFeatures(isOGArticle, parsed_url, numElements,
 176                                   numAnchors, numForms, innerText, textContent,
 177                                   innerHTML);
 178 }
 179 }