qstringbuilder: make it work for the char % string case

src/libs/utils/qstringbuilder.cpp

@@ -53,7 +53,7 @@
     smaller chunks.
 
     Contrary to \c QLatin1String, a \c QLatin1Literal can retrieve its size
-    int \i{O(1)}.
+    without iterating over the literal.
 
     \ingroup tools
     \ingroup shared
@@ -127,5 +127,7 @@
  
    Creates a helper object containing both parameters. 
 
-   This is the main function to build up 
+   This is the main function to build up complex QStringBuilder objects from
+   smaller QStringBuilder objects.
 */
+

src/libs/utils/qstringbuilder.h

@@ -46,14 +46,18 @@
 
 #include <string.h>
 
+// Using this relies on chaning the QString::QString(QChar *, int)
+// constructor to allocated an unitialized string of the given size.
+//#define USE_CHANGED_QSTRING 1
+
 class QLatin1Literal
 {
 public:
     template <int N>
     QLatin1Literal(const char (&str)[N]) : m_size(N - 1), m_data(str) {}
 
-    int size() const { return m_size; }
-    const char *data() const { return m_data; }
+    inline int size() const { return m_size; }
+    inline const char *data() const { return m_data; }
 
     void append(QChar *&out) const
     {
@@ -64,13 +68,18 @@ public:
 
     operator QString() const
     {
+#ifdef USE_CHANGED_QSTRING
+        QString s(m_size, QChar(-1));
+#else
         QString s;
         s.resize(m_size);
+#endif
         QChar *d = s.data();
         append(d);
         return s;
     }
 
+
 private:
     const int m_size;
     const char *m_data;
@@ -84,8 +93,12 @@ public:
 
     operator QString() const
     {
+#ifdef USE_CHANGED_QSTRING
+        QString s(this->size(), QChar(-1));
+#else
         QString s;
         s.resize(this->size());
+#endif
         QChar *d = s.data();
         this->append(d);
         return s;
@@ -115,35 +128,42 @@ private:
 };
 
 
-template <>
-class QStringBuilder<char>
-{
-public:
-    QStringBuilder(char c_) : c(c_) {}
+template <typename A>
+int qStringBuilderSize(const A a) { return a.size(); }
 
-    inline int size() const { return 1; }
-    inline void append(QChar *&out) const { *out++ = QLatin1Char(c); }
-
-private:
-    const char c;
-};
+inline int qStringBuilderSize(const char) { return 1; }
 
 
+template <typename A>
+inline void qStringBuilderAppend(const A a, QChar *&out) { a.append(out); }
 
-template <class A, class B>
+inline void qStringBuilderAppend(char c, QChar *&out) { *out++ = QLatin1Char(c); }
+
+
+template <typename A, typename B>
 class QStringBuilderPair
 {
 public:
     QStringBuilderPair(A a_, B b_) : a(a_), b(b_) {}
-    inline int size() const { return a.size() + b.size(); }
-    inline void append(QChar *&out) const { a.append(out); b.append(out); }
+
+    inline int size() const
+    {
+        return qStringBuilderSize(a) + qStringBuilderSize(b);
+    }
+
+    inline void append(QChar *&out) const
+    {
+        qStringBuilderAppend(a, out);
+        qStringBuilderAppend(b, out);
+    }
+
 private:
     A a;
     B b;
 };
 
 
-template <class A, class B>
+template <typename A, typename B>
 QStringBuilder< QStringBuilderPair<A, B> >
 operator%(const A &a, const B &b)
 {
@@ -176,31 +196,5 @@ operator%(const QString &a, const QString &b)
         QStringBuilder<QString> > (a, b);
 }
 
-// char related specializations
-
-template <class A>
-inline QStringBuilder< QStringBuilderPair<A, QStringBuilder<char> > >
-operator%(const A &a, char b)
-{
-    return QStringBuilderPair<A, QStringBuilder<char> > (a, b);
-}
-
-template <class B>
-inline QStringBuilder< QStringBuilderPair<QStringBuilder<char>, B> >
-operator%(char a, const B &b)
-{
-    return QStringBuilderPair<QStringBuilder<QString>, B> (a, b);
-}
-
-inline QStringBuilder<
-    QStringBuilderPair<QStringBuilder<QString>, QStringBuilder<char> >
->
-operator%(const QString &a, char b)
-{
-    return QStringBuilderPair<
-               QStringBuilder<QString>, QStringBuilder<char>
-           > (a, b);
-}
-
 
 #endif // QSTRINGBUILDER_H

tests/benchmarks/qstringbuilder/main.cpp

@@ -1,12 +1,15 @@
 
+#include "qstringbuilder.h"
+
 #include <QDebug>
 #include <QString>
 
-#include "../../../src/libs/utils/qstringbuilder.h"
-
 #include <qtest.h>
 
 
+#define COMPARE(a, b) QCOMPARE(a, b)
+//#define COMPARE(a, b)
+
 class tst_qstringbuilder : public QObject
 {
     Q_OBJECT
@@ -20,14 +23,18 @@ private slots:
     void b_2_l1literal();
     void b_3_l1literal();
     void b_4_l1literal();
+    void b_5_l1literal();
     void b_string_4_char();
+    void b_char_string_char();
 
     // QString based for comparison
     void s_separator() { qDebug() << "\n-------- QString based ---------"; }
     void s_2_l1string();
     void s_3_l1string();
     void s_4_l1string();
+    void s_5_l1string();
     void s_string_4_char();
+    void s_char_string_char();
 
 private:
     const QLatin1Literal l1literal;
@@ -48,28 +55,42 @@ void tst_qstringbuilder::b_2_l1literal()
 {
     QString result;
     QBENCHMARK { result = l1literal % l1literal; }
-    QCOMPARE(result, l1string + l1string);
+    COMPARE(result, l1string + l1string);
 }
 
 void tst_qstringbuilder::b_3_l1literal()
 {
     QString result;
     QBENCHMARK { result = l1literal % l1literal % l1literal; }
-    QCOMPARE(result, l1string + l1string + l1string);
+    COMPARE(result, l1string + l1string + l1string);
 }
 
 void tst_qstringbuilder::b_4_l1literal()
 {
     QString result;
     QBENCHMARK { result = l1literal % l1literal % l1literal % l1literal; }
-    QCOMPARE(result, l1string + l1string + l1string + l1string);
+    COMPARE(result, l1string + l1string + l1string + l1string);
+}
+
+void tst_qstringbuilder::b_5_l1literal()
+{
+    QString result;
+    QBENCHMARK { result = l1literal % l1literal % l1literal % l1literal %l1literal; }
+    COMPARE(result, l1string + l1string + l1string + l1string + l1string);
 }
 
 void tst_qstringbuilder::b_string_4_char()
 {
     QString result;
-    QBENCHMARK { result = string + achar + achar + achar; }
-    QCOMPARE(result, QString(string % achar % achar % achar));
+    QBENCHMARK { result = string + achar + achar + achar + achar; }
+    COMPARE(result, QString(string % achar % achar % achar % achar));
+}
+
+void tst_qstringbuilder::b_char_string_char()
+{
+    QString result;
+    QBENCHMARK { result = achar + string + achar; }
+    COMPARE(result, QString(achar % string % achar));
 }
 
 
@@ -77,28 +98,42 @@ void tst_qstringbuilder::s_2_l1string()
 {
     QString result;
     QBENCHMARK { result = l1string + l1string; }
-    QCOMPARE(result, QString(l1literal % l1literal));
+    COMPARE(result, QString(l1literal % l1literal));
 }
 
 void tst_qstringbuilder::s_3_l1string()
 {
     QString result;
     QBENCHMARK { result = l1string + l1string + l1string; }
-    QCOMPARE(result, QString(l1literal % l1literal % l1literal));
+    COMPARE(result, QString(l1literal % l1literal % l1literal));
 }
 
 void tst_qstringbuilder::s_4_l1string()
 {
     QString result;
     QBENCHMARK { result = l1string + l1string + l1string + l1string; }
-    QCOMPARE(result, QString(l1literal % l1literal % l1literal % l1literal));
+    COMPARE(result, QString(l1literal % l1literal % l1literal % l1literal));
+}
+
+void tst_qstringbuilder::s_5_l1string()
+{
+    QString result;
+    QBENCHMARK { result = l1string + l1string + l1string + l1string + l1string; }
+    COMPARE(result, QString(l1literal % l1literal % l1literal % l1literal % l1literal));
 }
 
 void tst_qstringbuilder::s_string_4_char()
 {
     QString result;
-    QBENCHMARK { result = string + achar + achar + achar; }
-    QCOMPARE(result, QString(string % achar % achar % achar));
+    QBENCHMARK { result = string + achar + achar + achar + achar; }
+    COMPARE(result, QString(string % achar % achar % achar % achar));
+}
+
+void tst_qstringbuilder::s_char_string_char()
+{
+    QString result;
+    QBENCHMARK { result = achar + string + achar; }
+    COMPARE(result, QString(achar % string % achar));
 }
 
 QTEST_MAIN(tst_qstringbuilder)

tests/benchmarks/qstringbuilder/qstringbuilder.pro

@@ -1,12 +1,12 @@
 load(qttest_p4)
 TEMPLATE = app
 TARGET = tst_qstringbuilder
-DEPENDPATH += .
-INCLUDEPATH += .
+STRINGBUILDERDIR = ../../../src/libs/utils
+INCLUDEPATH += $$STRINGBUILDERDIR
 
 QT -= gui
 
 CONFIG += release
 
 # Input
-SOURCES += main.cpp
+SOURCES += main.cpp $$STRINGBUILDERDIR/qstringbuilder.cpp