QUrl: port percent-decoding to char16_t

Port decode() to take a QStringView to isolate callers from char16_t.
Have it return qsizetype instead of int. Use QChar* as output pointer
internally, to avoid more casts.

Change-Id: Ia388361a281ee97c41b01d8e6fe2c00801d988c4
Reviewed-by: Lars Knoll <[email protected]>

src/corelib/io/qurlrecode.cpp

@@ -481,7 +481,7 @@ static int recode(QString &result, const ushort *begin, const ushort *end, QUrl:
  * needs to be decoded.
  */
 #ifdef __SSE2__
-static bool simdCheckNonEncoded(ushort *&output, const ushort *&input, const ushort *end)
+static bool simdCheckNonEncoded(QChar *&output, const char16_t *&input, const char16_t *end)
 {
 #  ifdef __AVX2__
     const __m256i percents256 = _mm256_broadcastw_epi16(_mm_cvtsi32_si128('%'));
@@ -561,8 +561,8 @@ static bool simdCheckNonEncoded(...)
     \since 5.0
     \internal
 
-    This function decodes a percent-encoded string located from \a begin to \a
-    end, by appending each character to \a appendTo. It returns the number of
+    This function decodes a percent-encoded string located in \a in
+    by appending each character to \a appendTo. It returns the number of
     characters appended. Each percent-encoded sequence is decoded as follows:
 
     \list
@@ -578,18 +578,22 @@ static bool simdCheckNonEncoded(...)
     The input should also be a valid percent-encoded sequence (the output of
     qt_urlRecode is always valid).
 */
-static int decode(QString &appendTo, const ushort *begin, const ushort *end)
+static qsizetype decode(QString &appendTo, QStringView in)
 {
+    const char16_t *begin = in.utf16();
+    const char16_t *end = begin + in.size();
+
     // fast check whether there's anything to be decoded in the first place
-    const ushort *input = reinterpret_cast<const ushort*>(QtPrivate::qustrchr(QStringView(begin, end), '%'));
+    const char16_t *input = QtPrivate::qustrchr(in, '%');
+
     if (Q_LIKELY(input == end))
         return 0;           // nothing to do, it was already decoded!
 
     // detach
     const int origSize = appendTo.size();
     appendTo.resize(origSize + (end - begin));
-    ushort *output = reinterpret_cast<ushort *>(appendTo.begin()) + origSize;
-    memcpy(static_cast<void *>(output), static_cast<const void *>(begin), (input - begin) * sizeof(ushort));
+    QChar *output = appendTo.data() + origSize;
+    memcpy(static_cast<void *>(output), static_cast<const void *>(begin), (input - begin) * sizeof(QChar));
     output += input - begin;
 
     while (input != end) {
@@ -604,15 +608,15 @@ static int decode(QString &appendTo, const ushort *begin, const ushort *end)
         }
 
         ++input;
-        *output++ = decodeNibble(input[0]) << 4 | decodeNibble(input[1]);
-        if (output[-1] >= 0x80)
+        *output++ = QChar::fromUcs2(decodeNibble(input[0]) << 4 | decodeNibble(input[1]));
+        if (output[-1].unicode() >= 0x80)
             output[-1] = QChar::ReplacementCharacter;
         input += 2;
 
         // search for the next percent, copying from input to output
         if (simdCheckNonEncoded(output, input, end)) {
             while (input != end) {
-                ushort uc = *input;
+                const char16_t uc = *input;
                 if (uc == '%')
                     break;
                 *output++ = uc;
@@ -621,7 +625,7 @@ static int decode(QString &appendTo, const ushort *begin, const ushort *end)
         }
     }
 
-    int len = output - reinterpret_cast<ushort *>(appendTo.begin());
+    const qsizetype len = output - appendTo.begin();
     appendTo.truncate(len);
     return len - origSize;
 }
@@ -673,7 +677,7 @@ qt_urlRecode(QString &appendTo, const QChar *begin, const QChar *end,
 {
     uchar actionTable[sizeof defaultActionTable];
     if (encoding == QUrl::FullyDecoded) {
-        return decode(appendTo, reinterpret_cast<const ushort *>(begin), reinterpret_cast<const ushort *>(end));
+        return int(decode(appendTo, QStringView{begin, end}));
     }
 
     memcpy(actionTable, defaultActionTable, sizeof actionTable);