Json parse_number()

in GomokuServer/GomokuServer/json11.cpp [573:622]

• 40 lines of code
• 19 McCabe index (conditional complexity)

    Json parse_number() {
        size_t start_pos = i;

        if (str[i] == '-')
            i++;

        // Integer part
        if (str[i] == '0') {
            i++;
            if (in_range(str[i], '0', '9'))
                return fail("leading 0s not permitted in numbers");
        } else if (in_range(str[i], '1', '9')) {
            i++;
            while (in_range(str[i], '0', '9'))
                i++;
        } else {
            return fail("invalid " + esc(str[i]) + " in number");
        }

        if (str[i] != '.' && str[i] != 'e' && str[i] != 'E'
                && (i - start_pos) <= static_cast<size_t>(std::numeric_limits<int>::digits10)) {
            return std::atoi(str.c_str() + start_pos);
        }

        // Decimal part
        if (str[i] == '.') {
            i++;
            if (!in_range(str[i], '0', '9'))
                return fail("at least one digit required in fractional part");

            while (in_range(str[i], '0', '9'))
                i++;
        }

        // Exponent part
        if (str[i] == 'e' || str[i] == 'E') {
            i++;

            if (str[i] == '+' || str[i] == '-')
                i++;

            if (!in_range(str[i], '0', '9'))
                return fail("at least one digit required in exponent");

            while (in_range(str[i], '0', '9'))
                i++;
        }

        return std::strtod(str.c_str() + start_pos, nullptr);
    }