Test distillability without JavaScript

third_party/WebKit/Source/core/dom/DocumentStatisticsCollector.cpp

+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "config.h"
+#include "DocumentStatisticsCollector.h"
+
+#include "core/HTMLNames.h"
+#include "core/css/CSSComputedStyleDeclaration.h"
+#include "core/editing/EphemeralRange.h"
+#include "core/editing/iterators/TextIterator.h"
+#include "core/editing/iterators/WordAwareIterator.h"
+#include "core/html/HTMLHeadElement.h"
+#include "core/inspector/ConsoleMessage.h"
+#include "platform/text/TextBreakIterator.h"
+#include "public/platform/WebDistillability.h"
+#include "wtf/text/StringBuilder.h"
+
+using namespace WTF;
+using namespace Unicode;
+
+namespace blink {
+
+using namespace HTMLNames;
+
+namespace {
+
+unsigned trimmedTextContentLength(Element& root)
+{
+    // TODO(wychen): count the length without allocating the string.
+    return root.textContent().stripWhiteSpace().length();

[dglazkov, 2015/10/22 16:30:31]

The TODO needs to be addressed before landing.

[wychen, 2015/10/23 02:51:30]

Will do.

+}
+
+unsigned innerTextLength(Element& root)
+{
+    unsigned length = 0;
+    EphemeralRange range = EphemeralRange::rangeOfContents(root);
+    TextIteratorAlgorithm<EditingStrategy> it(range.startPosition(), range.endPosition(), TextIteratorForInnerText);
+    for (; !it.atEnd(); it.advance()) {
+        length += it.length();
+    }
+    return length;
+}
+
+class ExtractFeatureWalker {

[dglazkov, 2015/10/22 16:30:31]

This can just be a separate class, no need to hide it. Will likely need a
different name then.

[wychen, 2015/10/23 02:51:30]

Do you mean creating new cpp/h files for this class in WebKit/Source/core/dom/?
I don't understand why hiding it is not a good idea. This class is only used
here.

Or merging it with class DocumentStatisticsCollector?

+public:
+    ExtractFeatureWalker(Document& document, WebDistillabilityFeatures& features) :
+        m_document(document),
+        m_features(features)
+    {
+        unlikelyCandidates = {"banner", "combx", "comment", "community", "disqus", "extra", "foot", "header", "menu", "related", "remark", "rss", "share", "shoutbox", "sidebar", "skyscraper", "sponsor", "ad-break", "agegate", "pagination", "pager", "popup"};

[dglazkov, 2015/10/22 16:30:31]

Should these be static? Why initialize them in constructor?

[wychen, 2015/10/23 02:51:30]

Made static.

+        okMaybeItsACandidate = {"and", "article", "body", "column", "main", "shadow"};
+    }
+
+    bool isVisible(Element& elem)
+    {
+        RefPtr<CSSStyleDeclaration> style =
+            m_document.domWindow()->getComputedStyle(&elem, String());
+        return !(
+            style->getPropertyValue("display") == "none"
+            || style->getPropertyValue("visibility") == "hidden"
+            || style->getPropertyValue("opacity") == "0"
+        );
+    }
+
+    bool matchName(Element& elem, const std::vector<String>& words)
+    {
+        String hay = elem.getClassAttribute().lower() + " " + elem.getIdAttribute().lower();

[dglazkov, 2015/10/22 16:30:31]

We have lots of style machinery to do this correctly. Please look over
StyleResolver and friends. Now that you're in Blink, you no longer need to treat
that machinery as opaque.

[wychen, 2015/10/23 02:51:30]

Could you elaborate how to use StyleResolver to improve this?

+        for (const String& word: words) {
+            if (hay.find(word)) {
+                return true;
+            }
+        }
+        return false;
+    }
+
+    void walk()
+    {
+        walk(*m_document.body(), false);
+    }
+
+private:
+    void walk(Element& root, bool underLi = false)
+    {
+        for (Node& node : NodeTraversal::childrenOf(root)) {
+            if (node.isTextNode()) {
+                String text = toText(node).data();
+                m_features.textContentLength += text.length();
+                continue;
+            }
+            if (!node.isElementNode()) {
+                continue;
+            }
+
+            m_features.numElements++;
+            Element& element = toElement(node);
+            if (element.hasTagName(aTag)) {
+                m_features.numAnchors++;
+            } else if (element.hasTagName(formTag)) {
+                m_features.numForms++;
+            } else if (element.hasTagName(inputTag)) {
+                if (element.getAttribute("type").lower() == "text") {
+                    m_features.numTextInput++;
+                } else if (element.getAttribute("type").lower() == "pasword") {
+                    m_features.numPasswordInput++;
+                }
+            } else if (element.hasTagName(pTag) || element.hasTagName(preTag)) {
+                m_features.numPPRE++;
+                if (!underLi && isVisible(element)
+                    && (!matchName(element, unlikelyCandidates) || matchName(element, okMaybeItsACandidate))) {
+                    unsigned len = trimmedTextContentLength(element);
+                    if (len >= 140) {
+                        m_features.mozScore += sqrt(len - 140);
+                    }
+                    m_features.mozScoreAllSqrt += sqrt(len);
+                    m_features.mozScoreAllLinear += len;
+                }
+            }
+            walk(element, element.hasTagName(liTag) || underLi);
+        }
+    }
+
+    std::vector<String> unlikelyCandidates, okMaybeItsACandidate;
+    Document& m_document;
+    WebDistillabilityFeatures& m_features;
+};
+
+bool hasOGArticle(const Element& head)
+{
+    for (const Node& node : NodeTraversal::childrenOf(head)) {

[dglazkov, 2015/10/22 16:30:31]

If you're traversing things in the method above, might as well do this in there,
too.

[wychen, 2015/10/23 02:51:30]

hasOGArticle traverses head, while walk() traverses body, so I've moved this as
a separate member function of ExtractFeatureWalker.

+        if (!node.isElementNode())
+            continue;
+        const Element& element = toElement(node);
+        if (!element.hasTagName(metaTag))
+            continue;
+        if ((element.getAttribute("name") == ("og:type")) || (element.getAttribute("property") == ("og:type"))) {
+            WTF::CString content = element.getAttribute("content").upper().utf8();
+            if ((content) == "ARTICLE") {
+                return true;
+            }
+        }
+    }
+    return false;
+};
+
+} // namespace
+
+DocumentStatisticsCollector::DocumentStatisticsCollector()
+    : m_readyToCollect(false)
+{
+}
+
+WebDistillabilityFeatures DocumentStatisticsCollector::collectStatistics(Document& document)
+{
+    WebDistillabilityFeatures features({0});
+    if (!m_readyToCollect)
+        return features;
+
+    if (!document.frame() || !document.frame()->isMainFrame())
+        return features;
+
+    if (!document.hasFinishedParsing())
+        return features;
+
+    ASSERT(document.body());
+
+    // First, traverse the DOM tree and collect statistics.
+    ExtractFeatureWalker walker(document, features);
+    walker.walk();
+
+    // Next, traverse the Layout tree and collect statistics on innerText length.
+    features.innerTextLength += innerTextLength(*document.body());
+
+    features.openGraph = hasOGArticle(*document.head());
+
+    // The following DISTILLER_NDEBUG section would be gone when landing.
+#ifndef DISTILLER_NDEBUG
+    StringBuilder message;
+    message.append("openGraph: ");
+    message.appendNumber(features.openGraph);
+    message.append(", numElements: ");
+    message.appendNumber(features.numElements);
+    message.append(", numAnchors: ");
+    message.appendNumber(features.numAnchors);
+    message.append(", numForms: ");
+    message.appendNumber(features.numForms);
+    message.append(", numTextInput: ");
+    message.appendNumber(features.numTextInput);
+    message.append(", numPasswordInput: ");
+    message.appendNumber(features.numPasswordInput);
+    message.append(", numPPRE: ");
+    message.appendNumber(features.numPPRE);
+    message.append(", innerTextLength: ");
+    message.appendNumber(features.innerTextLength);
+    message.append(", textContentLength: ");
+    message.appendNumber(features.textContentLength);
+    message.append(", mozScore: ");
+    message.appendNumber(features.mozScore);
+    message.append(", mozScoreAllSqrt: ");
+    message.appendNumber(features.mozScoreAllSqrt);
+    message.append(", mozScoreAllLinear: ");
+    message.appendNumber(features.mozScoreAllLinear);
+
+    RefPtrWillBeRawPtr<ConsoleMessage> consoleMessage = ConsoleMessage::create(ConsoleAPIMessageSource, DebugMessageLevel, message.toString());
+    document.addConsoleMessage(consoleMessage);
+#endif
+
+    return features;
+}
+
+}