TextEditor: Improve speed of hash function for font settings

The size of the array is fixed so we can simply use the memory patter as
a hash value.

Change-Id: If86a58b111a07b2bd9cecc12a03d74b93a914159
Task-number: QTCREATORBUG-16419
Reviewed-by: Eike Ziller <eike.ziller@qt.io>
Reviewed-by: David Schulz <david.schulz@theqtcompany.com>

src/libs/utils/sizedarray.h

@@ -108,6 +108,11 @@ public:
         return m_size == 0;
     }
 
+    void fillWithZero()
+    {
+        std::array<T, MaxSize>::fill(T(0));
+    }
+
 private:
     std::uint8_t m_size = 0;
 };

src/plugins/clangcodemodel/clanghighlightingmarksreporter.cpp

@@ -70,6 +70,7 @@ TextEditor::TextStyle toTextStyle(ClangBackEnd::HighlightingType type)
 TextEditor::TextStyles toTextStyles(ClangBackEnd::HighlightingTypes types)
 {
     TextEditor::TextStyles textStyles;
+    textStyles.mixinStyles.fillWithZero();
 
     textStyles.mainStyle = toTextStyle(types.mainHighlightingType);
 

src/plugins/texteditor/fontsettings.cpp

@@ -181,12 +181,9 @@ QTextCharFormat FontSettings::toTextCharFormat(TextStyle category) const
     return tf;
 }
 
-uint qHash(const TextStyles &textStyles)
+uint qHash(TextStyles textStyles)
 {
-    uint hash = qHash(textStyles.mainStyle);
-    for (TextStyle mixinStyle : textStyles.mixinStyles)
-        hash ^= qHash(mixinStyle);
-    return hash;
+    return ::qHash(reinterpret_cast<quint64&>(textStyles));
 }
 
 bool operator==(const TextStyles &first, const TextStyles &second)
@@ -219,7 +216,7 @@ void FontSettings::addMixinStyle(QTextCharFormat &textCharFormat,
     };
 }
 
-QTextCharFormat FontSettings::toTextCharFormat(const TextStyles &textStyles) const
+QTextCharFormat FontSettings::toTextCharFormat(TextStyles textStyles) const
 {
     auto textCharFormatIterator = m_textCharFormatCache.find(textStyles);
     if (textCharFormatIterator != m_textCharFormatCache.end())

src/plugins/texteditor/fontsettings.h

@@ -66,7 +66,7 @@ public:
 
     QVector<QTextCharFormat> toTextCharFormats(const QVector<TextStyle> &categories) const;
     QTextCharFormat toTextCharFormat(TextStyle category) const;
-    QTextCharFormat toTextCharFormat(const TextStyles &textStyles) const;
+    QTextCharFormat toTextCharFormat(TextStyles textStyles) const;
 
     QString family() const;
     void setFamily(const QString &family);