public static Entity operator /(Entity a, Entity b)
{
var result = new OperatorEntity(Constants.Operators.DIV);
result.Children.Add(a);
result.Children.Add(b);
return(result);
}
public bool IsOperatorEntity(IEnumerable <string> types, out OperatorEntity result)
{
result = null;
var r = this as OperatorEntity;
if (r != null && types.Contains(r.Name))
{
result = r;
return(true);
}
return(false);
}
public bool IsOperatorEntity(out OperatorEntity result)
{
result = null;
var r = this as OperatorEntity;
if (r != null)
{
result = r;
return(true);
}
return(false);
}
public override Entity Eval()
{
VariableEntity va = null, vb = null;
NumberEntity na = null, nb = null;
OperatorEntity oa = null, ob = null;
var a = Children.ElementAt(0).Eval();
var b = Children.ElementAt(1).Eval();
Entity result = this;
if ((a.IsNumberEntity(out na) && b.IsNumberEntity(out nb)))
{
return(EvalNumber(na, nb));
}
if (a.IsVariableEntity(out va) && b.IsVariableEntity(out vb))
{
return(EvalVariable(Name, va, vb));
}
if (Name == Constants.Operators.MUL)
{
return(EvalMultiplicationOperator(a, b));
}
if (Name == Constants.Operators.SUM || Name == Constants.Operators.SUB)
{
return(EvalSumOrSubOperator(Name, a, b));
}
switch (Name)
{
case Constants.Operators.MUL:
return(a * b);
case Constants.Operators.DIV:
return(a / b);
}
return(null);
}
private static Entity EvalSumOrSubOperator(string name, Entity a, Entity b)
{
VariableEntity va = null, vb = null;
NumberEntity na = null, nb = null;
OperatorEntity oa = null, ob = null;
// (x + x2) + 3
// (x + x2) + x5
if ((a.IsOperatorEntity(new string[] { Constants.Operators.SUM, Constants.Operators.SUB }, out oa) || b.IsOperatorEntity(new string[] { Constants.Operators.SUM, Constants.Operators.SUB }, out ob)) &&
((a.IsVariableEntity(out va) || b.IsVariableEntity(out vb)) ||
((a.IsNumberEntity(out na) || b.IsNumberEntity(out nb)))))
{
var children = new List <Entity>();
if (ob != null)
{
children.Add(a);
if (name == Constants.Operators.SUB)
{
ob = (Number.Create(-1) * ob).Eval() as OperatorEntity;
}
var entities = GetSumOrSubEntities(ob);
children.AddRange(GetSumOrSubEntities(ob));
}
else
{
children.AddRange(GetSumOrSubEntities(oa));
if (name == Constants.Operators.SUB)
{
b = (Number.Create(-1) * b).Eval();
}
children.Add(b);
}
var variables = children.Where(_ => _ is VariableEntity).GroupBy(_ => ((VariableEntity)_).Name + ((VariableEntity)_).Pow);
var numbers = children.Where(_ => _ is NumberEntity);
Entity variableEntity = null;
foreach (var grp in variables)
{
Entity subVariableEntity = null;
foreach (var variable in grp)
{
if (subVariableEntity == null)
{
subVariableEntity = variable;
}
else
{
subVariableEntity = (subVariableEntity + variable).Eval();
}
}
if (variableEntity == null)
{
variableEntity = subVariableEntity;
}
else
{
variableEntity = variableEntity + subVariableEntity;
}
}
Entity numberEntity = Number.Create(0);
foreach (var number in numbers)
{
numberEntity = (numberEntity + number).Eval();
}
return(variableEntity + numberEntity);
}
// a == 0 or b == 0
bool isAEmpty = false, isBEmpty = false;
if (a.IsNumberEntity(out na) && (isAEmpty = na.Number.Value == 0) || b.IsNumberEntity(out nb) && (isBEmpty = nb.Number.Value == 0))
{
return(isAEmpty ? b : a);
}
switch (name)
{
case Constants.Operators.SUM:
return(a + b);
default:
return(a - b);
}
}
