public override IExpression Simplify()
{
IExpression newLeft = left.Simplify();
IExpression newRight = right.Simplify();
ConstantExpression leftConst = newLeft as ConstantExpression;
ConstantExpression rightConst = newRight as ConstantExpression;
NegateExpression leftNegate = newLeft as NegateExpression;
NegateExpression rightNegate = newRight as NegateExpression;
if (leftConst != null && rightConst != null)
{
// two constants; just evaluate it;
if (rightConst.Value == 0)
{
throw new InvalidExpressionException("Divide by zero detected in function");
}
return(new ConstantExpression(leftConst.Value / rightConst.Value));
}
else if (leftConst != null && leftConst.Value == 0)
{
// 0 / y; return 0;
if (rightConst != null && rightConst.Value == 0)
{
throw new InvalidExpressionException("Divide by zero detected in function");
}
return(new ConstantExpression(0));
}
else if (rightConst != null)
{
if (rightConst.Value == 0)
{
// x / 0;
throw new InvalidExpressionException("Divide by zero detected in function");
}
if (rightConst.Value == 1)
{
// x / 1; return x;
return(newLeft);
}
if (rightConst.Value == -1)
{
// x / -1; return -x;
if (leftNegate != null)
{
// x = -u (-x = --u); return u;
return(leftNegate.Child);
}
return(new NegateExpression(newLeft));
}
}
else if (leftNegate != null && rightNegate != null)
{
// -x / -y; return x / y;
return(new DivExpression(leftNegate.Child, rightNegate.Child));
}
// x / y; no simplification
return(new DivExpression(newLeft, newRight));
}
public override IExpression Simplify()
{
IExpression newLeft = left.Simplify();
IExpression newRight = right.Simplify();
ConstantExpression leftConst = newLeft as ConstantExpression;
ConstantExpression rightConst = newRight as ConstantExpression;
NegateExpression leftNegate = newLeft as NegateExpression;
NegateExpression rightNegate = newRight as NegateExpression;
if (leftConst != null && rightConst != null)
{
// two constants; just evaluate it;
return(new ConstantExpression(leftConst.Value + rightConst.Value));
}
else if (leftConst != null && leftConst.Value == 0)
{
// 0 + y; return y;
return(newRight);
}
else if (rightConst != null && rightConst.Value == 0)
{
// x + 0; return x;
return(newLeft);
}
else if (rightNegate != null)
{
// x + -y; return x - y; (this covers -x + -y case too)
return(new SubExpression(newLeft, rightNegate.Child));
}
else if (leftNegate != null)
{
// -x + y; return y - x;
return(new SubExpression(newRight, leftNegate.Child));
}
// x + y; no simplification
return(new AddExpression(newLeft, newRight));
}
public override IExpression Simplify()
{
IExpression newLeft = left.Simplify();
IExpression newRight = right.Simplify();
ConstantExpression leftConst = newLeft as ConstantExpression;
ConstantExpression rightConst = newRight as ConstantExpression;
NegateExpression rightNegate = newRight as NegateExpression;
if (leftConst != null && rightConst != null)
{
// two constants; just evaluate it;
return(new ConstantExpression(leftConst.Value - rightConst.Value));
}
else if (leftConst != null && leftConst.Value == 0)
{
// 0 - y; return -y;
if (rightNegate != null)
{
// y = -u (--u); return u;
return(rightNegate.Child);
}
return(new NegateExpression(newRight));
}
else if (rightConst != null && rightConst.Value == 0)
{
// x - 0; return x;
return(newLeft);
}
else if (rightNegate != null)
{
// x - -y; return x + y;
return(new AddExpression(newLeft, rightNegate.Child));
}
// x - y; no simplification
return(new SubExpression(newLeft, newRight));
}
public override IExpression Simplify()
{
IExpression newLeft = left.Simplify();
IExpression newRight = right.Simplify();
ConstantExpression leftConst = newLeft as ConstantExpression;
ConstantExpression rightConst = newRight as ConstantExpression;
NegateExpression leftNegate = newLeft as NegateExpression;
NegateExpression rightNegate = newRight as NegateExpression;
if (leftConst != null && rightConst != null)
{
// two constants; just evaluate it;
return(new ConstantExpression(leftConst.Value * rightConst.Value));
}
else if (leftConst != null)
{
if (leftConst.Value == 0)
{
// 0 * y; return 0;
return(new ConstantExpression(0));
}
if (leftConst.Value == 1)
{
// 1 * y; return y;
return(newRight);
}
if (leftConst.Value == -1)
{
// -1 * y; return -y
if (rightNegate != null)
{
// y = -u (-y = --u); return u;
return(rightNegate.Child);
}
return(new NegateExpression(newRight));
}
}
else if (rightConst != null)
{
if (rightConst.Value == 0)
{
// x * 0; return 0;
return(new ConstantExpression(0));
}
if (rightConst.Value == 1)
{
// x * 1; return x;
return(newLeft);
}
if (rightConst.Value == -1)
{
// x * -1; return -x;
if (leftNegate != null)
{
// x = -u (-x = --u); return u;
return(leftNegate.Child);
}
return(new NegateExpression(newLeft));
}
}
else if (leftNegate != null && rightNegate != null)
{
// -x * -y; return x * y;
return(new MultExpression(leftNegate.Child, rightNegate.Child));
}
// x * y; no simplification
return(new MultExpression(newLeft, newRight));
}
