Use QtMiscUtils hex/oct-related helpers

Thanks to Thiago for pointing them out in review.

Change-Id: I14d588a8bd5ba29d43a5daeacfd55d974eb65557
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

src/corelib/io/qsettings.cpp

@@ -751,8 +751,8 @@ StNormal:
                 ch = str.at(i);
                 if (isHexDigit(ch))
                     goto StHexEscape;
-            } else if (isOctalDigit(ch)) {
-                escapeVal = ch - '0';
+            } else if (const int o = fromOct(ch); o != -1) {
+                escapeVal = o;
                 goto StOctEscape;
             } else if (ch == '\n' || ch == '\r') {
                 if (i < str.size()) {
@@ -814,11 +814,9 @@ StHexEscape:
     }
 
     ch = str.at(i);
-    if (ch >= 'a')
-        ch -= 'a' - 'A';
-    if ((ch >= '0' && ch <= '9') || (ch >= 'A' && ch <= 'F')) {
+    if (const int h = fromHex(ch); h != -1) {
         escapeVal <<= 4;
-        escapeVal += QtMiscUtils::fromHex(ch);
+        escapeVal += h;
         ++i;
         goto StHexEscape;
     } else {
@@ -833,9 +831,9 @@ StOctEscape:
     }
 
     ch = str.at(i);
-    if (ch >= '0' && ch <= '7') {
+    if (const int o = fromOct(ch); o != -1) {
         escapeVal <<= 3;
-        escapeVal += ch - '0';
+        escapeVal += o;
         ++i;
         goto StOctEscape;
     } else {

src/corelib/mimetypes/qmimemagicrule.cpp

@@ -148,12 +148,8 @@ static inline QByteArray makePattern(const QByteArray &value)
                 char c = 0;
                 for (int i = 0; i < 2 && p + 1 < e; ++i) {
                     ++p;
-                    if (*p >= '0' && *p <= '9')
-                        c = (c << 4) + *p - '0';
-                    else if (*p >= 'a' && *p <= 'f')
-                        c = (c << 4) + *p - 'a' + 10;
-                    else if (*p >= 'A' && *p <= 'F')
-                        c = (c << 4) + *p - 'A' + 10;
+                    if (const int h = fromHex(*p); h != -1)
+                        c = (c << 4) + h;
                     else
                         continue;
                 }

src/corelib/serialization/qjsonparser.cpp

@@ -780,15 +780,13 @@ bool Parser::parseNumber()
 static inline bool addHexDigit(char digit, char32_t *result)
 {
     *result <<= 4;
-    if (digit >= '0' && digit <= '9')
-        *result |= (digit - '0');
-    else if (digit >= 'a' && digit <= 'f')
-        *result |= (digit - 'a') + 10;
-    else if (digit >= 'A' && digit <= 'F')
-        *result |= (digit - 'A') + 10;
-    else
-        return false;
-    return true;
+    const int h = fromHex(digit);
+    if (h != -1) {
+        *result |= h;
+        return true;
+    }
+
+    return false;
 }
 
 static inline bool scanEscapeSequence(const char *&json, const char *end, char32_t *ch)

src/corelib/serialization/qtextstream.cpp

@@ -1752,13 +1752,10 @@ QTextStreamPrivate::NumberParsingStatus QTextStreamPrivate::getNumber(qulonglong
         // Parse digits
         int ndigits = 0;
         while (getChar(&dig)) {
-            int n = dig.toLower().unicode();
-            if (n >= '0' && n <= '9') {
+            const int h = fromHex(dig.unicode());
+            if (h != -1) {
                 val <<= 4;
-                val += n - '0';
-            } else if (n >= 'a' && n <= 'f') {
-                val <<= 4;
-                val += 10 + (n - 'a');
+                val += h;
             } else {
                 ungetChar(dig);
                 break;