Implement heuristics for parsing version number

Similar solution exists in QtHelp module:
QString QHelpDBReader::qtVersionHeuristic() const

Fixes: QTCREATORBUG-26292
Change-Id: I9037785920e25428db0fa7f03f737c5ef66c4ac3
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Eike Ziller <eike.ziller@qt.io>

src/plugins/coreplugin/helpitem.cpp

@@ -29,6 +29,8 @@
 #include <utils/algorithm.h>
 #include <utils/htmldocextractor.h>
 
+#include <QVersionNumber>
+
 using namespace Core;
 
 HelpItem::HelpItem() = default;
@@ -165,31 +167,66 @@ QString HelpItem::extractContent(bool extended) const
     return contents;
 }
 
-static std::pair<QUrl, int> extractVersion(const QUrl &url)
+// The following is only correct under the specific current conditions, and it will
+// always be quite some guessing as long as the version information does not
+// include separators for major vs minor vs patch version.
+static QVersionNumber qtVersionHeuristic(const QString &digits)
+{
+    if (digits.count() > 6 || digits.count() < 3)
+        return {}; // suspicious version number
+
+    for (const QChar &digit : digits)
+        if (!digit.isDigit())
+            return {}; // we should have only digits
+
+    // When we have 3 digits, we split it like: ABC -> A.B.C
+    // When we have 4 digits, we split it like: ABCD -> A.BC.D
+    // When we have 5 digits, we split it like: ABCDE -> A.BC.DE
+    // When we have 6 digits, we split it like: ABCDEF -> AB.CD.EF
+    switch (digits.count()) {
+    case 3:
+        return QVersionNumber(digits.mid(0, 1).toInt(),
+                              digits.mid(1, 1).toInt(),
+                              digits.mid(2, 1).toInt());
+    case 4:
+        return QVersionNumber(digits.mid(0, 1).toInt(),
+                              digits.mid(1, 2).toInt(),
+                              digits.mid(3, 1).toInt());
+    case 5:
+        return QVersionNumber(digits.mid(0, 1).toInt(),
+                              digits.mid(1, 2).toInt(),
+                              digits.mid(3, 2).toInt());
+    case 6:
+        return QVersionNumber(digits.mid(0, 2).toInt(),
+                              digits.mid(2, 2).toInt(),
+                              digits.mid(4, 2).toInt());
+    default:
+        break;
+    }
+    return {};
+}
+
+static std::pair<QUrl, QVersionNumber> extractVersion(const QUrl &url)
 {
     const QString host = url.host();
     const QStringList hostParts = host.split('.');
     if (hostParts.size() == 4 && (host.startsWith("com.trolltech.")
             || host.startsWith("org.qt-project."))) {
-        bool ok = false;
+        const QVersionNumber version = qtVersionHeuristic(hostParts.at(3));
-        // the following is only correct under the specific current conditions, and it will
+        if (!version.isNull()) {
-        // always be quite some guessing as long as the version information does not
-        // include separators for major vs minor vs patch version
-        const int version = hostParts.at(3).toInt(&ok);
-        if (ok) {
             QUrl urlWithoutVersion(url);
             urlWithoutVersion.setHost(hostParts.mid(0, 3).join('.'));
             return {urlWithoutVersion, version};
         }
     }
-    return {url, 0};
+    return {url, {}};
 }
 
 // sort primary by "url without version" and seconday by "version"
 static bool helpUrlLessThan(const QUrl &a, const QUrl &b)
 {
-    const std::pair<QUrl, int> va = extractVersion(a);
+    const std::pair<QUrl, QVersionNumber> va = extractVersion(a);
-    const std::pair<QUrl, int> vb = extractVersion(b);
+    const std::pair<QUrl, QVersionNumber> vb = extractVersion(b);
     const QString sa = va.first.toString();
     const QString sb = vb.first.toString();
     if (sa == sb)
@@ -260,10 +297,10 @@ static const HelpItem::Links getBestLink(const HelpItem::Links &links)
     // This is to ensure that if we succeeded with an ID lookup, and we have e.g. Qt5 and Qt4
     // documentation, that we only return the Qt5 link even though the Qt5 and Qt4 URLs look
     // different.
-    int highestVersion = -1;
+    QVersionNumber highestVersion;
     HelpItem::Link bestLink;
     for (const HelpItem::Link &link : links) {
-        const int version = extractVersion(link.second).second;
+        const QVersionNumber version = extractVersion(link.second).second;
         if (version > highestVersion) {
             highestVersion = version;
             bestLink = link;