Arithmetica.MathExpressionTokenizer.Tokenize C# (CSharp) Метод

        public TokenStream Tokenize(string source)
        {
            List<Token> tokens = new List<Token>();
            using (StringReader reader = new StringReader(source))
            {
                while (true)
                {
                    // Peek at the next value in the string.
                    if (reader.Peek() == -1)
                    {
                        break;
                    }
                    char value = (char)reader.Peek();

                    // Is the value numeric?
                    if (char.IsDigit(value))
                    {
                        tokens.Add(this.ParseNumber(reader));
                    }
                    // Is this a letter?
                    else if (char.IsLetter(value))
                    {
                        tokens.Add(this.ParseWord(reader));
                    }
                    // Left parenthesis?
                    else if (value == '(')
                    {
                        reader.Read();
                        tokens.Add(new Token(TokenType.OpeningParenthesis, '('));
                    }
                    // Left parenthesis?
                    else if (value == ')')
                    {
                        reader.Read();
                        tokens.Add(new Token(TokenType.ClosingParenthesis, ')'));
                    }
                    // Separator?
                    else if(value == ',')
                    {
                        reader.Read();
                        tokens.Add(new Token(TokenType.Separator, ','));
                    }
                    else if (char.IsWhiteSpace(value))
                    {
                        reader.Read();
                        continue;
                    }
                    else
                    {
                        reader.Read(); // Consume the character.
                        if (_operations.Contains(value))
                        {
                            // This is an arithmetic operation.
                            TokenType operation = TokenType.Unknown;
                            switch (value)
                            {
                                case '+': operation = TokenType.Addition; break;
                                case '-': operation = TokenType.Subtraction; break;
                                case '*': operation = TokenType.Multiplication; break;
                                case '/': operation = TokenType.Division; break;
                                case '%': operation = TokenType.Modulus; break;
                                case '^': operation = TokenType.Exponentiation; break;
                            }
                            if (operation != TokenType.Unknown)
                            {
                                tokens.Add(new Token(operation, value));
                            }
                        }
                        else
                        {
                            // We don't know how to process this token.
                            string message = string.Format("Unknown token '{0}' in expression.", value);
                            throw new MathExpressionException("Invalid expression.", message);
                        }
                    }
                }
            }
            return new TokenStream(tokens, TokenNotation.Infix);
        }