Construct a string converter by name

Add a constructor, that allows constructing a string converter by
name. This is required in some cases and also makes it possible to
(in the future) extend the API to 3rd party encodings.

Also add a name() accessor.

Change-Id: I606d6ce9405ee967f76197b803615e27c5b001cf
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

src/corelib/text/qstringconverter.cpp

@@ -1441,15 +1441,46 @@ static qsizetype toLatin1Len(qsizetype l) { return l + 1; }
 
 const QStringConverter::Interface QStringConverter::encodingInterfaces[QStringConverter::LastEncoding + 1] =
 {
-    { QUtf8::convertToUnicode, fromUtf8Len, QUtf8::convertFromUnicode, toUtf8Len },
-    { fromUtf16, fromUtf16Len, toUtf16, toUtf16Len },
-    { fromUtf16LE, fromUtf16Len, toUtf16LE, toUtf16Len },
-    { fromUtf16BE, fromUtf16Len, toUtf16BE, toUtf16Len },
-    { fromUtf32, fromUtf32Len, toUtf32, toUtf32Len },
-    { fromUtf32LE, fromUtf32Len, toUtf32LE, toUtf32Len },
-    { fromUtf32BE, fromUtf32Len, toUtf32BE, toUtf32Len },
-    { fromLatin1, fromLatin1Len, toLatin1, toLatin1Len },
-    { fromLocal8Bit, fromUtf8Len, toLocal8Bit, toUtf8Len }
+    { "UTF-8", QUtf8::convertToUnicode, fromUtf8Len, QUtf8::convertFromUnicode, toUtf8Len },
+    { "UTF-16", fromUtf16, fromUtf16Len, toUtf16, toUtf16Len },
+    { "UTF-16LE", fromUtf16LE, fromUtf16Len, toUtf16LE, toUtf16Len },
+    { "UTF-16BE", fromUtf16BE, fromUtf16Len, toUtf16BE, toUtf16Len },
+    { "UTF-32", fromUtf32, fromUtf32Len, toUtf32, toUtf32Len },
+    { "UTF-32LE", fromUtf32LE, fromUtf32Len, toUtf32LE, toUtf32Len },
+    { "UTF-32BE", fromUtf32BE, fromUtf32Len, toUtf32BE, toUtf32Len },
+    { "ISO-8859-1", fromLatin1, fromLatin1Len, toLatin1, toLatin1Len },
+    { "Locale", fromLocal8Bit, fromUtf8Len, toLocal8Bit, toUtf8Len }
 };
 
+// match names case insensitive and skipping '-' and '_'
+static bool nameMatch(const char *a, const char *b)
+{
+    while (*a && *b) {
+        if (*a == '-' || *a == '_') {
+            ++a;
+            continue;
+        }
+        if (*b == '-' || *b == '_') {
+            ++b;
+            continue;
+        }
+        if (toupper(*a) != toupper(*b))
+            return false;
+        ++a;
+        ++b;
+    }
+    return !*a && !*b;
+}
+
+QStringConverter::QStringConverter(const char *name)
+    : iface(nullptr)
+{
+    for (int i = 0; i < LastEncoding + 1; ++i) {
+        if (nameMatch(encodingInterfaces[i].name, name)) {
+            iface = encodingInterfaces + i;
+            break;
+        }
+    }
+}
+
 QT_END_NAMESPACE

src/corelib/text/qstringconverter.h

@@ -132,18 +132,23 @@ protected:
         using DecoderFn = QChar * (*)(QChar *out, const char *in, qsizetype length, State *state);
         using LengthFn = qsizetype (*)(qsizetype inLength);
         using EncoderFn = char * (*)(char *out, QStringView in, State *state);
+        const char *name = nullptr;
         DecoderFn toUtf16 = nullptr;
         LengthFn toUtf16Len = nullptr;
         EncoderFn fromUtf16 = nullptr;
         LengthFn fromUtf16Len = nullptr;
     };
 
+    QSTRINGCONVERTER_CONSTEXPR QStringConverter()
+        : iface(nullptr)
+    {}
     QSTRINGCONVERTER_CONSTEXPR QStringConverter(Encoding encoding, Flags f)
         : iface(&encodingInterfaces[int(encoding)]), state(f)
     {}
     QSTRINGCONVERTER_CONSTEXPR QStringConverter(const Interface *i)
         : iface(i)
     {}
+    QStringConverter(const char *name);
 
 public:
     bool isValid() const { return iface != nullptr; }
@@ -154,6 +159,9 @@ public:
     }
     bool hasError() const { return state.invalidChars != 0; }
 
+    const char *name() const
+    { return isValid() ? iface->name : nullptr; }
+
 protected:
     const Interface *iface;
     State state;
@@ -168,9 +176,15 @@ protected:
         : QStringConverter(i)
     {}
 public:
+    QSTRINGCONVERTER_CONSTEXPR QStringEncoder()
+        : QStringConverter()
+    {}
     QSTRINGCONVERTER_CONSTEXPR QStringEncoder(Encoding encoding, Flags flags = Flag::Default)
         : QStringConverter(encoding, flags)
     {}
+    QStringEncoder(const char *name)
+        : QStringConverter(name)
+    {}
 
 #if defined(QT_USE_FAST_OPERATOR_PLUS) || defined(QT_USE_QSTRINGBUILDER)
     template<typename T>
@@ -231,6 +245,12 @@ public:
     QSTRINGCONVERTER_CONSTEXPR QStringDecoder(Encoding encoding, Flags flags = Flag::Default)
         : QStringConverter(encoding, flags)
     {}
+    QSTRINGCONVERTER_CONSTEXPR QStringDecoder()
+        : QStringConverter()
+    {}
+    QStringDecoder(const char *name)
+        : QStringConverter(name)
+    {}
 
 #if defined(QT_USE_FAST_OPERATOR_PLUS) || defined(QT_USE_QSTRINGBUILDER)
     template<typename T>

tests/auto/corelib/text/qstringconverter/tst_qstringconverter.cpp

@@ -39,6 +39,8 @@ class tst_QStringConverter : public QObject
 private slots:
     void threadSafety();
 
+    void constructByName();
+
     void convertUtf8();
 
     void nonFlaggedCodepointFFFF() const;
@@ -59,6 +61,31 @@ private slots:
     void utfHeaders();
 };
 
+void tst_QStringConverter::constructByName()
+{
+    QStringDecoder decoder("UTF-8");
+    QVERIFY(decoder.isValid());
+    QVERIFY(!strcmp(decoder.name(), "UTF-8"));
+    decoder = QStringDecoder("XXX");
+    QVERIFY(!decoder.isValid());
+    decoder = QStringDecoder("ISO-8859-1");
+    QVERIFY(decoder.isValid());
+    QVERIFY(!strcmp(decoder.name(), "ISO-8859-1"));
+    decoder = QStringDecoder("UTF-16LE");
+    QVERIFY(decoder.isValid());
+    QVERIFY(!strcmp(decoder.name(), "UTF-16LE"));
+
+    decoder = QStringDecoder("utf8");
+    QVERIFY(decoder.isValid());
+    QVERIFY(!strcmp(decoder.name(), "UTF-8"));
+    decoder = QStringDecoder("iso8859-1");
+    QVERIFY(decoder.isValid());
+    QVERIFY(!strcmp(decoder.name(), "ISO-8859-1"));
+    decoder = QStringDecoder("utf-16");
+    QVERIFY(decoder.isValid());
+    QVERIFY(!strcmp(decoder.name(), "UTF-16"));
+}
+
 void tst_QStringConverter::convertUtf8()
 {
     QFile file(QFINDTESTDATA("utf8.txt"));