System.Json.JsonReader.ReadNumericLiteral C# (CSharp) Method

		JsonPrimitive ReadNumericLiteral ()
		{
			bool negative = false;
			if (PeekChar () == '-') {
				negative = true;
				ReadChar ();
				if (PeekChar () < 0)
					throw JsonError ("Invalid JSON numeric literal; extra negation");
			}

			int c;
			decimal val = 0;
			int x = 0;
			bool zeroStart = PeekChar () == '0';
			for (; ; x++) {
				c = PeekChar ();
				if (c < '0' || '9' < c)
					break;
				val = val * 10 + (c - '0');
				ReadChar ();
				if (zeroStart && x == 1 && c == '0')
					throw JsonError ("leading multiple zeros are not allowed");
			}

			// fraction

			bool hasFrac = false;
			decimal frac = 0;
			int fdigits = 0;
			if (PeekChar () == '.') {
				hasFrac = true;
				ReadChar ();
				if (PeekChar () < 0)
					throw JsonError ("Invalid JSON numeric literal; extra dot");
				decimal d = 10;
				while (true) {
					c = PeekChar ();
					if (c < '0' || '9' < c)
						break;
					ReadChar ();
					frac += (c - '0') / d;
					d *= 10;
					fdigits++;
				}
				if (fdigits == 0)
					throw JsonError ("Invalid JSON numeric literal; extra dot");
			}
			frac = Decimal.Round (frac, fdigits);

			c = PeekChar ();
			if (c != 'e' && c != 'E') {
				if (!hasFrac) {
					if (negative && int.MinValue <= -val ||
					    !negative && val <= int.MaxValue)
						return new JsonPrimitive ((int) (negative ? -val : val));
					if (negative && long.MinValue <= -val ||
					    !negative && val <= long.MaxValue)
						return new JsonPrimitive ((long) (negative ? -val : val));
				}
				var v = val + frac;
				return new JsonPrimitive (negative ? -v : v);
			}

			// exponent

			ReadChar ();

			int exp = 0;
			if (PeekChar () < 0)
				throw new ArgumentException ("Invalid JSON numeric literal; incomplete exponent");
			bool negexp = false;
			c = PeekChar ();
			if (c == '-') {
				ReadChar ();
				negexp = true;
			}
			else if (c == '+')
				ReadChar ();

			if (PeekChar () < 0)
				throw JsonError ("Invalid JSON numeric literal; incomplete exponent");
			while (true) {
				c = PeekChar ();
				if (c < '0' || '9' < c)
					break;
				exp = exp * 10 + (c - '0');
				ReadChar ();
			}
			// it is messy to handle exponent, so I just use Decimal.Parse() with assured JSON format.
			int [] bits = Decimal.GetBits (val + frac);
			return new JsonPrimitive (new Decimal (bits [0], bits [1], bits [2], negative, (byte) exp));
		}