QStringBuilder: add support for char16_t{,*,[]}

[ChangeLog][QtCore][QStringBuilder] Added support for char16_t
characters and strings.

Change-Id: Iee727f07226f2a326ae0df28d44930336cd8f71e
Reviewed-by: Milian Wolff <milian.wolff@kdab.com>
Reviewed-by: Olivier Goffart (Woboq GmbH) <ogoffart@woboq.com>
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>

3 files changed, 95 insertions, 1 deletions

diff --git a/src/corelib/tools/qstringbuilder.cpp b/src/corelib/tools/qstringbuilder.cpp
index 8300da30c2..37b0e08caf 100644
--- a/src/corelib/tools/qstringbuilder.cpp
+++ b/src/corelib/tools/qstringbuilder.cpp
@@ -74,8 +74,9 @@ QT_BEGIN_NAMESPACE
 
     \list
     \li QString, QStringRef,
-    \li QChar, QCharRef, QLatin1Char,
+    \li QChar, QCharRef, QLatin1Char, (since 5.10:) \c char16_t,
     \li QLatin1String,
+    \li (since 5.10:) \c{const char16_t[]} (\c{u"foo"}),
     \li QByteArray, \c char, \c{const char[]}.
     \endlist
 
diff --git a/src/corelib/tools/qstringbuilder.h b/src/corelib/tools/qstringbuilder.h
index 5c6d990314..e9ca2245ba 100644
--- a/src/corelib/tools/qstringbuilder.h
+++ b/src/corelib/tools/qstringbuilder.h
@@ -187,6 +187,18 @@ template <> struct QConcatenable<char> : private QAbstractConcatenable
     { *out++ = c; }
 };
 
+#if defined(Q_COMPILER_UNICODE_STRINGS)
+template <> struct QConcatenable<char16_t> : private QAbstractConcatenable
+{
+    typedef char16_t type;
+    typedef QString ConvertTo;
+    enum { ExactSize = true };
+    static Q_DECL_CONSTEXPR int size(char16_t) { return 1; }
+    static inline void appendTo(char16_t c, QChar *&out)
+    { *out++ = c; }
+};
+#endif
+
 template <> struct QConcatenable<QLatin1Char>
 {
     typedef QLatin1Char type;
@@ -325,6 +337,46 @@ template <> struct QConcatenable<char *> : QConcatenable<const char*>
     typedef char *type;
 };
 
+#if defined(Q_COMPILER_UNICODE_STRINGS)
+template <int N> struct QConcatenable<const char16_t[N]> : private QAbstractConcatenable
+{
+    using type = const char16_t[N];
+    using ConvertTo = QString;
+    enum { ExactSize = true };
+    static int size(const char16_t[N]) { return N - 1; }
+    static void appendTo(const char16_t a[N], QChar *&out)
+    {
+        memcpy(out, a, (N - 1) * sizeof(char16_t));
+        out += N - 1;
+    }
+};
+
+template <int N> struct QConcatenable<char16_t[N]> : QConcatenable<const char16_t[N]>
+{
+    using type = char16_t[N];
+};
+
+template <> struct QConcatenable<const char16_t *> : private QAbstractConcatenable
+{
+    using type = const char16_t *;
+    using ConvertTo = QString;
+    enum { ExactSize = true };
+    static int size(const char16_t *a) { return QStringView(a).length(); };
+    static inline void QT_ASCII_CAST_WARN appendTo(const char16_t *a, QChar *&out)
+    {
+        if (!a)
+            return;
+        while (*a)
+            *out++ = *a++;
+    }
+};
+
+template <> struct QConcatenable<char16_t *> : QConcatenable<const char16_t*>
+{
+    typedef char16_t *type;
+};
+#endif // UNICODE_STRINGS
+
 template <> struct QConcatenable<QByteArray> : private QAbstractConcatenable
 {
     typedef QByteArray type;
diff --git a/tests/auto/corelib/tools/qstringbuilder/qstringbuilder1/stringbuilder.cpp b/tests/auto/corelib/tools/qstringbuilder/qstringbuilder1/stringbuilder.cpp
index 32fb321931..4f7b05530c 100644
--- a/tests/auto/corelib/tools/qstringbuilder/qstringbuilder1/stringbuilder.cpp
+++ b/tests/auto/corelib/tools/qstringbuilder/qstringbuilder1/stringbuilder.cpp
@@ -64,6 +64,11 @@ template <> QString toQString(const QLatin1String &l) { return l; }
 template <> QString toQString(const QLatin1Char &l) { return QChar(l); }
 template <> QString toQString(const QChar &c) { return c; }
 template <> QString toQString(const QChar::SpecialCharacter &c) { return QChar(c); }
+#ifdef Q_COMPILER_UNICODE_STRINGS
+template <> QString toQString(char16_t * const &p) { return QStringView(p).toString(); }
+template <size_t N> QString toQString(const char16_t (&a)[N]) { return QStringView(a).toString(); }
+template <> QString toQString(const char16_t &c) { return QChar(c); }
+#endif
 
 template <typename T> QByteArray toQByteArray(const T &t);
 
@@ -82,6 +87,12 @@ void runScenario()
     QLatin1Char lchar('c');
     QChar qchar(lchar);
     QChar::SpecialCharacter special(QChar::Nbsp);
+#ifdef Q_COMPILER_UNICODE_STRINGS
+    char16_t u16char = UNICODE_LITERAL[0];
+    char16_t u16chararray[] = { u's', 0xF6, u'm', 0xEB, u' ', u'l', 0xEF, u't', 0xEB, u'r', 0xE4, u'l', 0x00 };
+    QCOMPARE(QStringView(u16chararray), QStringView(UNICODE_LITERAL));
+    char16_t *u16charstar = u16chararray;
+#endif
 
 #define CHECK(QorP, a1, a2) \
     do { \
@@ -101,6 +112,9 @@ void runScenario()
     CHECK(P, l1string, qchar);
     CHECK(P, l1string, special);
     CHECK(P, l1string, QStringLiteral(LITERAL));
+    CHECK(Q, l1string, u16char);
+    CHECK(Q, l1string, u16chararray);
+    CHECK(Q, l1string, u16charstar);
 
     CHECK(P, string, string);
     CHECK(P, string, stringref);
@@ -108,26 +122,53 @@ void runScenario()
     CHECK(P, string, qchar);
     CHECK(P, string, special);
     CHECK(P, string, QStringLiteral(LITERAL));
+    CHECK(Q, string, u16char);
+    CHECK(Q, string, u16chararray);
+    CHECK(Q, string, u16charstar);
 
     CHECK(P, stringref, stringref);
     CHECK(P, stringref, lchar);
     CHECK(P, stringref, qchar);
     CHECK(P, stringref, special);
     CHECK(P, stringref, QStringLiteral(LITERAL));
+    CHECK(Q, stringref, u16char);
+    CHECK(Q, stringref, u16chararray);
+    CHECK(Q, stringref, u16charstar);
 
     CHECK(P, lchar, lchar);
     CHECK(P, lchar, qchar);
     CHECK(P, lchar, special);
     CHECK(P, lchar, QStringLiteral(LITERAL));
+    CHECK(Q, lchar, u16char);
+    CHECK(Q, lchar, u16chararray);
+    CHECK(Q, lchar, u16charstar);
 
     CHECK(P, qchar, qchar);
     CHECK(P, qchar, special);
     CHECK(P, qchar, QStringLiteral(LITERAL));
+    CHECK(Q, qchar, u16char);
+    CHECK(Q, qchar, u16chararray);
+    CHECK(Q, qchar, u16charstar);
 
     CHECK(P, special, special);
     CHECK(P, special, QStringLiteral(LITERAL));
+    CHECK(Q, special, u16char);
+    CHECK(Q, special, u16chararray);
+    CHECK(Q, special, u16charstar);
 
     CHECK(P, QStringLiteral(LITERAL), QStringLiteral(LITERAL));
+    CHECK(Q, QStringLiteral(LITERAL), u16char);
+    CHECK(Q, QStringLiteral(LITERAL), u16chararray);
+    CHECK(Q, QStringLiteral(LITERAL), u16charstar);
+
+    // CHECK(Q, u16char, u16char);             // BUILTIN <-> BUILTIN cat't be overloaded
+    // CHECK(Q, u16char, u16chararray);
+    // CHECK(Q, u16char, u16charstar);
+
+    // CHECK(Q, u16chararray, u16chararray);   // BUILTIN <-> BUILTIN cat't be overloaded
+    // CHECK(Q, u16chararray, u16charstar);
+
+    // CHECK(Q, u16charstar, u16charstar);     // BUILTIN <-> BUILTIN cat't be overloaded
 
 #undef DO