Use lambdas for generating static data for QStringLiteral

This means it will work on C++0x compilers that support lambdas (all
of them once they've completed supporting the functionality). Olivier
had the idea and the initial code.

Change-Id: I11ef7da4058ed18f4ea99ada070891a68ed54f55
Reviewed-on: http://codereview.qt.nokia.com/1380
Reviewed-by: Qt Sanity Bot <qt_sanity_bot@ovi.com>
Reviewed-by: Olivier Goffart <olivier.goffart@nokia.com>

1 files changed, 33 insertions, 26 deletions

diff --git a/src/corelib/tools/qstring.h b/src/corelib/tools/qstring.h
index de973a82fb..2251b64430 100644
--- a/src/corelib/tools/qstring.h
+++ b/src/corelib/tools/qstring.h
@@ -96,28 +96,16 @@ template<int N> struct QConstStringDataPtr
     const QConstStringData<N> *ptr;
 };
 
-#if defined(Q_CC_GNU)
-// We need to create a QStringData in the .rodata section of memory
-// and the only way to do that is to create a "static const" variable.
-// To do that, we need the __extension__ {( )} trick which only GCC supports
-
-# if defined(Q_COMPILER_UNICODE_STRINGS)
+#if defined(Q_COMPILER_UNICODE_STRINGS)
 template<int n> struct QConstStringData
 {
     const QStringData str;
     const char16_t data[n];
     operator const QStringData &() const { return str; }
 };
+#define QT_QSTRING_UNICODE_MARKER   u""
 
-# define QStringLiteral(str) \
-    __extension__ ({ \
-        enum { Size = sizeof(u"" str)/2 }; \
-        static const QConstStringData<Size> qstring_literal = \
-        { { Q_REFCOUNT_INITIALIZER(-1), Size -1, 0, 0, { 0 } }, u"" str }; \
-        QConstStringDataPtr<Size> holder = { &qstring_literal }; \
-        holder; })
-
-# elif defined(Q_OS_WIN) || (defined(__SIZEOF_WCHAR_T__) && __SIZEOF_WCHAR_T__ == 2) || defined(WCHAR_MAX) && (WCHAR_MAX - 0 < 65536)
+#elif defined(Q_OS_WIN) || (defined(__SIZEOF_WCHAR_T__) && __SIZEOF_WCHAR_T__ == 2) || defined(WCHAR_MAX) && (WCHAR_MAX - 0 < 65536)
 // wchar_t is 2 bytes
 template<int n> struct QConstStringData
 {
@@ -125,26 +113,45 @@ template<int n> struct QConstStringData
     const wchar_t data[n];
     operator const QStringData &() const { return str; }
 };
-# define QStringLiteral(str) \
+#define QT_QSTRING_UNICODE_MARKER   L""
+
+#else
+template<int n> struct QConstStringData
+{
+    const QStringData str;
+    const ushort data[n];
+    operator const QStringData &() const { return str; }
+};
+#endif
+
+#if defined(QT_QSTRING_UNICODE_MARKER)
+# if defined(Q_COMPILER_LAMBDA)
+#  define QStringLiteral(str) ([]() { \
+        enum { Size = sizeof(QT_QSTRING_UNICODE_MARKER str)/2 }; \
+        static const QConstStringData<Size> qstring_literal = \
+        { { Q_REFCOUNT_INITIALIZER(-1), Size -1, 0, 0, { 0 } }, QT_QSTRING_UNICODE_MARKER str }; \
+        QConstStringDataPtr<Size> holder = { &qstring_literal }; \
+    return holder; }())
+
+# elif defined(Q_CC_GNU)
+// We need to create a QStringData in the .rodata section of memory
+// and the only way to do that is to create a "static const" variable.
+// To do that, we need the __extension__ {( )} trick which only GCC supports
+
+#  define QStringLiteral(str) \
     __extension__ ({ \
-        enum { Size = sizeof(L"" str)/2 }; \
+        enum { Size = sizeof(QT_QSTRING_UNICODE_MARKER str)/2 }; \
         static const QConstStringData<Size> qstring_literal = \
-        { { Q_REFCOUNT_INITIALIZER(-1), Size -1, 0, 0, { 0 } }, L"" str }; \
+        { { Q_REFCOUNT_INITIALIZER(-1), Size -1, 0, 0, { 0 } }, QT_QSTRING_UNICODE_MARKER str }; \
         QConstStringDataPtr<Size> holder = { &qstring_literal }; \
         holder; })
 # endif
 #endif
 
 #ifndef QStringLiteral
-// not GCC, or GCC in C++98 mode with 4-byte wchar_t
+// no lambdas, not GCC, or GCC in C++98 mode with 4-byte wchar_t
 // fallback, uses QLatin1String as next best options
 
-template<int n> struct QConstStringData
-{
-    const QStringData str;
-    const ushort data[n];
-    operator const QStringData &() const { return str; }
-};
 # define QStringLiteral(str) QLatin1String(str)
 #endif
 
@@ -576,7 +583,7 @@ public:
     template <int n>
     inline QString(const QConstStringData<n> &dd) : d(const_cast<QStringData *>(&dd.str)) {}
     template <int N>
-    inline QString(QConstStringDataPtr<N> dd) : d(const_cast<QStringData *>(&dd.ptr->str)) {}
+    Q_DECL_CONSTEXPR inline QString(QConstStringDataPtr<N> dd) : d(const_cast<QStringData *>(&dd.ptr->str)) {}
 
 private:
 #if defined(QT_NO_CAST_FROM_ASCII) && !defined(Q_NO_DECLARED_NOT_DEFINED)