/// <summary>
/// Calculates value of the expression of many variables.
/// </summary>
/// <param name="variables">Variables</param>
/// <returns>Value of the expression</returns>
public double Calculate(params Var[] variables)
{
Stack stack = new Stack();
foreach (Token t in reversePolishNotation)
{
if (t.Type == TokenType.Number)
{
stack.Push(t);
}
else if (t.Type == TokenType.Operator)
{
string operand1Str = stack.Pop().Lexeme.Replace(',', '.');
string operand2Str = stack.Pop().Lexeme.Replace(',', '.');
double operand1 = double.Parse(operand1Str, CultureInfo.InvariantCulture);
double operand2 = double.Parse(operand2Str, CultureInfo.InvariantCulture);
double smallResult = operators[t.Lexeme](operand1, operand2);
stack.Push(new Token(smallResult.ToString(CultureInfo.InvariantCulture), TokenType.Number));
}
else if (t.Type == TokenType.Function)
{
string operandStr = stack.Pop().Lexeme.Replace(',', '.');
double operand = double.Parse(operandStr, CultureInfo.InvariantCulture);
double smallResult = functions[t.Lexeme](operand);
stack.Push(new Token(smallResult.ToString(CultureInfo.InvariantCulture), TokenType.Number));
}
else if (t.Type == TokenType.Constant)
{
double constant = constants[t.Lexeme];
stack.Push(new Token(constant.ToString(CultureInfo.InvariantCulture), TokenType.Number));
}
else if (t.Type == TokenType.Variable)
{
Token smallToken = new Token();
foreach (Var variable in variables)
{
if (t.Lexeme == variable.Name)
{
smallToken = new Token(variable.Value.ToString(CultureInfo.InvariantCulture), TokenType.Number);
break;
}
}
stack.Push(smallToken);
}
else
{
throw new ArgumentException("Bad expression string.");
}
}
double result = double.Parse(stack.Pop().Lexeme, CultureInfo.InvariantCulture);
return result;
}
/// <summary>
/// Adds a token to the top of stack.
/// </summary>
/// <param name="t">Token to add</param>
public void Push(Token t)
{
tokens.Add(t);
}
/// <summary>
/// Parses a string of characters and converts it to sequence of tokens.
/// </summary>
/// <returns>Sequence of tokens</returns>
private List<Token> GetTokens(string expression)
{
List<Token> tokens = new List<Token>();
bool isError;
bool success;
for (int i = 0; i < expression.Length; ++i)
{
isError = true;
success = false;
string number = "";
double num;
while (double.TryParse(expression[i].ToString(CultureInfo.InvariantCulture), System.Globalization.NumberStyles.Number, CultureInfo.InvariantCulture, out num) || expression[i] == '.')
{
if (expression[i] == '.')
{
number += ".";
}
else
{
number += num.ToString(CultureInfo.InvariantCulture);
}
if (i < expression.Length - 1)
{
++i;
}
else break;
}
if (number != "")
{
Token t = new Token(number, TokenType.Number);
tokens.Add(t);
success = true;
isError = false;
number = "";
}
foreach (string s in operators.Keys)
{
if (expression[i].ToString(CultureInfo.InvariantCulture) == s)
{
if (isUnaryOparator(tokens))
{
expression = expression.Insert(i, "0");
--i;
}
else
{
Token t = new Token(expression[i].ToString(CultureInfo.InvariantCulture), TokenType.Operator);
tokens.Add(t);
}
success = true;
isError = false;
break;
}
}
foreach (string s in functions.Keys)
{
if (success)
{
break;
}
string function = "";
int k = i;
for (int j = 0; j < s.Length; ++j)
{
if (s[j] == expression[k])
{
function += expression[k];
}
if (k < expression.Length - 1)
{
++k;
}
else break;
}
if (function == s)
{
Token t = new Token(function, TokenType.Function);
tokens.Add(t);
isError = false;
success = true;
i += function.Length - 1;
break;
}
}
foreach (string s in constants.Keys)
{
if (success)
{
break;
}
string constant = "";
int k = i;
for (int j = 0; j < s.Length; ++j)
{
if (s[j] == expression[k])
{
constant += expression[k];
}
if (k < expression.Length - 1)
{
++k;
}
else break;
}
if (constant == s)
{
Token t = new Token(constant, TokenType.Constant);
tokens.Add(t);
isError = false;
success = true;
i += constant.Length - 1;
break;
}
}
foreach (char c in variables)
{
if (success)
{
break;
}
if (expression[i] == c)
{
Token t = new Token(expression[i].ToString(CultureInfo.InvariantCulture), TokenType.Variable);
tokens.Add(t);
isError = false;
success = true;
break;
}
}
if (isError)
{
throw new ArgumentException("Bad expression string.");
}
}
return tokens;
}
