std::istringstream usage in StringUtilities::DecodeRml makes customizing String type impossible

[eugeneko]

Until these changes, it was possible to use any string type in RmlUI as long as it had standard interface (e.g. EASTL).
Now, it is impossible because std::istringstream cannot accept anything but std::string.

I am not saying that you should stop using std::istringstream, but maybe RmlUI needs a customization point to initialize std::istringstream with arbitrary string type.

[mikke89]

Ah, I see. As far as I can tell, the istream is only used to convert from hex-encoded number in a string to an integer. Maybe there are other approaches to consider? std::stoi possibly, or some scan-function?

[rokups]

I always use good old sscanf. Not something "modern C++" would advise, but rooted in reality at least 😁

[mikke89]

Yeah, I don't mind sscanf in this case. I think std::stoi throws, which might be problematic. PR incoming from any of you? :)

[rokups]

@gleblebedev i guess you have this worked out in your branch already?

[gleblebedev]

Yep:

					{
						String tmp = s.substr(start, j);
						const char* begin = tmp.c_str();
						char* end;
						uint32_t code_point = strtoul(begin, &end, 16);
						result += ToUTF8(static_cast<Character>(code_point));
						i = start + (end - begin) + 1;
						continue;
					}

and

					if (j > 0 && s[start + j] == ';')
					{
						String tmp = s.substr(start, j);
						const char* begin = tmp.c_str();
						char* end;
						uint32_t code_point = strtoul(begin, &end, 10);
						result += ToUTF8(static_cast<Character>(code_point));
						i = start + (end - begin) + 1;
						continue;
					}

[gleblebedev]

@mikke89 if it looks ok I can make a PR later

[mikke89]

@gleblebedev Yup, looks like a good approach. Would be nice with some error handling back, checking for zero and ULONG_MAX seems sufficient. Might need adjustments to handle cases where long is 64-bit as well.

[gleblebedev]

@mikke89 is � not a valid symbol? Or what do you mean by checking for zero?

[gleblebedev]

Ha, github converted the html unicode symbol into symbol.

[mikke89]

I'm just looking over this, zero is returned if conversion can not be performed: https://en.cppreference.com/w/cpp/string/byte/strtoul.

[gleblebedev]

#475