public EvaluatorJava(String ExpressionJava)
{
Stack <ExpressionJava> expressionStack = new Stack <ExpressionJava>();
foreach (String token in ExpressionJava.Split(' '))
{
if (token.Equals("+"))
{
ExpressionJava subExpression = new PlusJava(expressionStack.Pop(), expressionStack.Pop());
expressionStack.Push(subExpression);
}
else if (token.Equals("-"))
{
// it's necessary to remove first the right operand from the stack
ExpressionJava right = expressionStack.Pop();
// ..and then the left one
ExpressionJava left = expressionStack.Pop();
ExpressionJava subExpression = new MinusJava(left, right);
expressionStack.Push(subExpression);
}
else
{
expressionStack.Push(new VariableJava(token));
}
}
syntaxTree = expressionStack.Pop();
}
public MinusJava(ExpressionJava left, ExpressionJava right)
{
leftOperand = left;
rightOperand = right;
}
