protected override SyntaxToken VisitBinary(BinarySyntaxToken token)
{
SyntaxToken left = this.Visit(token.Left);
SyntaxToken right = this.Visit(token.Right);
BinaryOperationType type = token.Type;
if (left.TokenType == SyntaxTokenType.Constant && right.TokenType == SyntaxTokenType.Constant)
{
return this.EvalBinary((ConstantSyntaxToken)left, (ConstantSyntaxToken)right, type);
}
// swap constant to the right
if ((type == BinaryOperationType.Add || type == BinaryOperationType.Multiply) && (left.TokenType == SyntaxTokenType.Constant))
{
SyntaxToken temp = right;
right = left;
left = temp;
}
// add
if (type == BinaryOperationType.Add)
{
if (right.HasValue(0))
{
return left;
}
}
// subtract
else if (type == BinaryOperationType.Subtract)
{
if (right.HasValue(0))
{
return left;
}
if (SyntaxToken.Equals(left, right))
{
return SyntaxToken.Constant(0);
}
}
// multiply
else if (type == BinaryOperationType.Multiply)
{
if (right.HasValue(0))
{
return SyntaxToken.Constant(0);
}
if (right.HasValue(1))
{
return left;
}
if (left.TokenType == SyntaxTokenType.Binary && right.TokenType == SyntaxTokenType.Binary)
{
BinarySyntaxToken bl = (BinarySyntaxToken)left;
BinarySyntaxToken br = (BinarySyntaxToken)right;
if (bl.Type == BinaryOperationType.Power && br.Type == BinaryOperationType.Power && SyntaxToken.Equals(bl.Left, br.Left))
{
return this.Visit(SyntaxToken.Pow(bl.Left, SyntaxToken.Add(bl.Right, br.Right)));
}
}
}
// divide
else if (type == BinaryOperationType.Divide)
{
if (left.HasValue(0))
{
return SyntaxToken.Constant(0);
}
if (SyntaxToken.Equals(left, right))
{
return SyntaxToken.Constant(1);
}
}
// modulus
else if (type == BinaryOperationType.Modulus)
{
if (left.HasValue(0))
{
return SyntaxToken.Constant(0);
}
if (SyntaxToken.Equals(left, right))
{
return SyntaxToken.Constant(0);
}
}
// pow
else if (type == BinaryOperationType.Power)
{
if (right.HasValue(0))
{
return SyntaxToken.Constant(1);
}
if (right.HasValue(1))
{
return left;
}
if (left.HasValue(0))
{
return SyntaxToken.Constant(1);
}
if (left.TokenType == SyntaxTokenType.Binary)
{
BinarySyntaxToken bl = (BinarySyntaxToken)left;
if (bl.Type == BinaryOperationType.Power)
{
return this.Visit(SyntaxToken.Pow(bl.Left, SyntaxToken.Multiply(bl.Right, right)));
}
}
}
return SyntaxToken.Binary(left, right, type);
}
