public override Expression GetDerivation(string parameter)
{
if (this.Operands.Count == 0)
{
return(new ConstantExpression(0));
}
if (this.Operands.Count == 1)
{
return(this.Operands.Single().GetDerivation(parameter));
}
Expression exp1 = this.Operands.First();
Expression exp2 = this.Operands.Count == 2 ? this.Operands[1] : new MultiplyExpression(
this.Operands.Skip(1).ToList());
var e = new AddExpression(new List <Expression>
{
new MultiplyExpression(new List <Expression> {
exp1.GetDerivation(parameter), exp2
}),
new MultiplyExpression(new List <Expression> {
exp1, exp2.GetDerivation(parameter)
}),
}).Normalize();
return(e);
}
private Expression expr1(int priority)
{
Expression retVal;
Expression right;
if (priority >= 0)
{
retVal = expr1(priority - 1);
}
else
{
return(factor());
}
while (inPriority(lookAhead.TokenType, priority))
{
switch (lookAhead.TokenType)
{
case '+':
accept();
right = expr1(priority - 1);
retVal = new AddExpression(new List <Expression> {
retVal, right
});
break;
case '-':
accept();
right = expr1(priority - 1);
retVal = new AddExpression(new List <Expression> {
retVal, new MultiplyExpression(
new List <Expression> {
new ConstantExpression(-1),
right
}
)
});
break;
case '*':
accept();
right = expr1(priority - 1);
retVal = new MultiplyExpression(new List <Expression> {
retVal, right
});
break;
default:
return(retVal);
}
}
return(retVal);
}
public override Expression Normalize()
{
if (Normalized)
{
return(this);
}
var middle = operands.Select(_ => _.Normalize()).Where(_ => {
if (_ is ConstantExpression)
{
if ((_ as ConstantExpression).Constant == 0)
{
return(false);
}
}
return(true);
});
double constant = 0;
var normalized = new List <Expression>();
foreach (var operand in middle)
{
if (operand is ConstantExpression)
{
constant += operand.Calculate(null);
}
else if (operand is AddExpression)
{
foreach (var c in (operand as AddExpression).operands.OfType <ConstantExpression>())
{
constant += c.Constant;
}
normalized.AddRange((operand as AddExpression).operands.Where(_ => !(_ is ConstantExpression)));
}
else
{
normalized.Add(operand);
}
}
if (constant != 0)
{
normalized.Add(new ConstantExpression(constant));
}
normalized = normalized.OrderBy(_ => _, CompareExpression.Instance).ToList();
var normalized2 = new List <Expression>();
Expression lastExpression = null;
foreach (var expression in normalized)
{
if (lastExpression != null && !(lastExpression is ConstantExpression) && !(expression is ConstantExpression))
{
var operand1 = GetExpressionParametersMultiplied(lastExpression);
var operand2 = GetExpressionParametersMultiplied(expression);
if (operand1.Equals(operand2))
{
var constantd = GetExpressionConstant(lastExpression) + GetExpressionConstant(expression);
if (constantd == 0)
{
lastExpression = null;
}
else if (constantd == 1)
{
lastExpression = operand1;
}
else
{
var expressionOperands = new List <Expression>();
expressionOperands.Add(new ConstantExpression(constantd));
if (operand1 is ParameterExpression)
{
expressionOperands.Add(operand1);
}
else
{
expressionOperands.AddRange((operand1 as MultiplyExpression).Operands);
}
lastExpression = new MultiplyExpression(expressionOperands);
lastExpression.Normalized = true;
}
continue;
}
}
if (lastExpression != null)
{
normalized2.Add(lastExpression);
}
lastExpression = expression;
}
if (lastExpression != null)
{
normalized2.Add(lastExpression);
}
if (normalized2.Count() == 1)
{
return(normalized2.Single());
}
if (normalized2.Count() == 0)
{
return(new ConstantExpression(0));
}
var exp = new AddExpression(normalized2);
exp.Normalized = true;
return(exp);
}