QTest: Extract Method writePrettyUnicodeChar from toPrettyUnicode

Easier to reason about by separating the concerns into separate
functions.

Pick-to: 6.6 6.5
Change-Id: I34666766ac2879577faea17bbd2b700bcb803f51
Reviewed-by: Jason McDonald <macadder1@gmail.com>

src/testlib/qtestcase.cpp

@@ -1697,37 +1697,24 @@ char *toPrettyCString(const char *p, qsizetype length)
 */
 
 constexpr qsizetype PrettyUnicodeMaxOutputSize = 256;
+// escape sequence, closing quote, the three dots and NUL
+constexpr qsizetype PrettyUnicodeMaxIncrement = sizeof(R"(\uXXXX"...)"); // includes NUL
 
-char *toPrettyUnicode(QStringView string)
+static char *writePrettyUnicodeChar(char16_t ch, char * const buffer)
 {
-    auto p = string.utf16();
+    auto dst = buffer;
-    auto length = string.size();
+    auto first = [&](int n) { Q_ASSERT(dst - buffer == n); return dst; };
-    // keep it simple for the vast majority of cases
+    if (ch < 0x7f && ch >= 0x20 && ch != '\\' && ch != '"') {
-    bool trimmed = false;
+        *dst++ = ch;
-    auto buffer = std::make_unique<char[]>(PrettyUnicodeMaxOutputSize);
+        return first(1);
-    const auto end = p + length;
-    char *dst = buffer.get();
-
-    *dst++ = '"';
-    for ( ; p != end; ++p) {
-        // escape sequence, closing quote, the three dots and NUL
-        constexpr qsizetype MaxIncrement = sizeof(R"(\uXXXX"...)"); // includes NUL
-        if (dst - buffer.get() > PrettyUnicodeMaxOutputSize - MaxIncrement) {
-            trimmed = true;
-            break;
-        }
-
-        if (*p < 0x7f && *p >= 0x20 && *p != '\\' && *p != '"') {
-            *dst++ = *p;
-            continue;
     }
 
     // write as an escape sequence
     *dst++ = '\\';
-        switch (*p) {
+    switch (ch) {
     case 0x22:
     case 0x5c:
-            *dst++ = uchar(*p);
+        *dst++ = uchar(ch);
         break;
     case 0x8:
         *dst++ = 'b';
@@ -1746,11 +1733,32 @@ char *toPrettyUnicode(QStringView string)
         break;
     default:
         *dst++ = 'u';
-            *dst++ = toHexUpper(*p >> 12);
+        *dst++ = toHexUpper(ch >> 12);
-            *dst++ = toHexUpper(*p >> 8);
+        *dst++ = toHexUpper(ch >> 8);
-            *dst++ = toHexUpper(*p >> 4);
+        *dst++ = toHexUpper(ch >> 4);
-            *dst++ = toHexUpper(*p);
+        *dst++ = toHexUpper(ch);
+        return first(6);
     }
+    return first(2);
+}
+
+char *toPrettyUnicode(QStringView string)
+{
+    auto p = string.utf16();
+    auto length = string.size();
+    // keep it simple for the vast majority of cases
+    bool trimmed = false;
+    auto buffer = std::make_unique<char[]>(PrettyUnicodeMaxOutputSize);
+    const auto end = p + length;
+    char *dst = buffer.get();
+
+    *dst++ = '"';
+    for ( ; p != end; ++p) {
+        if (dst - buffer.get() > PrettyUnicodeMaxOutputSize - PrettyUnicodeMaxIncrement) {
+            trimmed = true;
+            break;
+        }
+        dst = writePrettyUnicodeChar(*p, dst);
     }
 
     *dst++ = '"';