private ICommand MakeAddCommand(string target, string source, int number)
{
IExpression add = new BinaryArithmeticExpression(new VariableExpression(source), new ConstantExpression(number), ArithmeticOperator.Add);
ICommand set = new SetCommand(target, add);
return(set);
}
public void EvaluateDivideExpression()
{
ConstantExpression leftExpression = new ConstantExpression(4);
ConstantExpression rightExpression = new ConstantExpression(2);
BinaryArithmeticExpression expression = new BinaryArithmeticExpression(leftExpression, rightExpression, ArithmeticOperator.Divide);
Assert.AreEqual(2.0, expression.Evaluate(null));
}
public void EvaluateMultiplyExpression()
{
ConstantExpression leftExpression = new ConstantExpression(3);
ConstantExpression rightExpression = new ConstantExpression(2);
BinaryArithmeticExpression expression = new BinaryArithmeticExpression(leftExpression, rightExpression, ArithmeticOperator.Multiply);
Assert.AreEqual(6, expression.Evaluate(null));
}
public void EvaluateSubtractExpression()
{
ConstantExpression leftExpression = new ConstantExpression(1);
ConstantExpression rightExpression = new ConstantExpression(2);
BinaryArithmeticExpression expression = new BinaryArithmeticExpression(leftExpression, rightExpression, ArithmeticOperator.Subtract);
Assert.AreEqual(-1, expression.Evaluate(null));
}
public void CreateBinaryArithmeticExpression()
{
ConstantExpression leftExpression = new ConstantExpression(1);
ConstantExpression rightExpression = new ConstantExpression(2);
BinaryArithmeticExpression expression = new BinaryArithmeticExpression(leftExpression, rightExpression, ArithmeticOperator.Add);
Assert.AreEqual(leftExpression, expression.LeftExpression);
Assert.AreEqual(rightExpression, expression.RightExpression);
Assert.AreEqual(ArithmeticOperator.Add, expression.Operator);
}
public void ParseAndEvaluateMultiplyExpression()
{
Parser parser = new Parser("2*3");
IExpression expression = parser.ParseExpression();
Assert.IsNotNull(expression);
Assert.IsInstanceOfType(expression, typeof(BinaryArithmeticExpression));
BinaryArithmeticExpression multexpr = (BinaryArithmeticExpression)expression;
Assert.AreEqual(ArithmeticOperator.Multiply, multexpr.Operator);
Assert.AreEqual(6, multexpr.Evaluate(null));
Assert.IsNull(parser.ParseExpression());
}
public void ParseAndEvaluateAddExpression()
{
Parser parser = new Parser("1+2");
IExpression expression = parser.ParseExpression();
Assert.IsNotNull(expression);
Assert.IsInstanceOfType(expression, typeof(BinaryArithmeticExpression));
BinaryArithmeticExpression addexpr = (BinaryArithmeticExpression)expression;
Assert.AreEqual(ArithmeticOperator.Add, addexpr.Operator);
Assert.AreEqual(3, addexpr.Evaluate(null));
Assert.IsNull(parser.ParseExpression());
}
private IExpression ParseFactorExpression()
{
IExpression expression = this.ParseSimpleExpression();
Token token = this.NextToken();
while (token != null && token.TokenType == TokenType.Operator)
{
if (token.Value.Equals("*") || token.Value.Equals("/"))
{
ArithmeticOperator oper = token.Value.Equals("*") ? ArithmeticOperator.Multiply : ArithmeticOperator.Divide;
expression = new BinaryArithmeticExpression(expression, this.ParseSimpleExpression(), oper);
token = this.NextToken();
continue;
}
break;
}
this.PushToken(token);
return(expression);
}
public IExpression ParseExpression()
{
IExpression expression = this.ParseFactorExpression();
Token token = this.NextToken();
while (token != null && token.TokenType == TokenType.Operator)
{
if (token.Value.Equals("+") || token.Value.Equals("-"))
{
ArithmeticOperator oper = token.Value.Equals("+") ? ArithmeticOperator.Add : ArithmeticOperator.Subtract;
expression = new BinaryArithmeticExpression(expression, this.ParseFactorExpression(), oper);
token = this.NextToken();
continue;
}
break;
}
this.PushToken(token);
return(expression);
}
