[core] add the ability to stringy numbers as hex

src/mbgl/util/string.cpp

@@ -15,6 +15,25 @@ std::string toString(double num, bool decimal) {
 std::string toString(long double num, bool decimal) {
     return dtoa(num, decimal);
 }
+
+namespace {
+
+template <typename T>
+std::string toPaddedHex(T x) {
+    std::string result;
+    result.resize(sizeof(T) * 2);
+    for (int index = sizeof(T) * 2 - 1; index >= 0; index--) {
+        const int digit = x & 0x0F;
+        result[index] = '0' + digit + (digit > 9 ? 39 : 0);
+        x >>= 4;
+    }
+    return result;
+}
+
+}
+
+std::string toHex(size_t value) {
+    return toPaddedHex(value);
 }
 
 } // namespace util