private Tristate EvaluateExpression(ExpressionSyntax expression)
{
expression.Accept(_symbolTracker);
return(_expressionEvaluator.EvaluateExpression(expression));
}
public override SyntaxNode VisitBinaryExpression(BinaryExpressionSyntax node)
{
Tristate leftState = _expressionEvaluator.EvaluateExpression(node.Left);
Tristate rightState = _expressionEvaluator.EvaluateExpression(node.Right);
var left = (ExpressionSyntax)node.Left.Accept(this);
var right = (ExpressionSyntax)node.Right.Accept(this);
if (node.Left != left)
{
node = node.WithLeft(left);
}
if (node.Right != right)
{
node = node.WithRight(right);
}
if (leftState != Tristate.Varying && rightState != Tristate.Varying)
{
return(node);
}
ExpressionSyntax newExpression = null;
if (node.Kind() == SyntaxKind.LogicalAndExpression)
{
if (leftState == Tristate.True)
{
// true && varying == varying
newExpression = right;
}
else if (rightState == Tristate.True)
{
// varying && true == varying
newExpression = left;
}
}
else if (node.Kind() == SyntaxKind.LogicalOrExpression)
{
if (leftState == Tristate.False)
{
// false || varying == varying
newExpression = right;
}
else if (rightState == Tristate.False)
{
// varying || false == varying
newExpression = left;
}
}
if (newExpression != null)
{
return(newExpression
.WithLeadingTrivia(node.GetLeadingTrivia())
.WithTrailingTrivia(node.GetTrailingTrivia()));
}
return(node);
}
