public override void VisitBinaryExpression(SqlParser.Expressions.BinaryExpression binaryExpression)
{
binaryExpression.Left.Accept(this);
binaryExpression.Right.Accept(this);
var rightExpression = PopStack();
var leftExpression = PopStack();
var expression = BinaryUtils.CreateBinaryExpression(leftExpression, rightExpression, binaryExpression.Type);
AddExpressionToStack(expression);
}
private VisitResult VisitBinaryExpression_Internal(SqlParser.Expressions.BinaryExpression binaryExpression)
{
var leftResult = VisitInternal(binaryExpression.Left);
//Left result should only contain: '%text' or 'text'
if (leftResult.StartsWith && !leftResult.WildcardOnly)
{
throw new SqlErrorException("Like expression can only support starts with ('text%'), ends with ('%text') and contains ('%text%') at this time");
}
var rightResult = VisitInternal(binaryExpression.Right);
//Right result should only contain 'text%' or 'text'
if (rightResult.EndsWith && !rightResult.WildcardOnly)
{
throw new SqlErrorException("Like expression can only support starts with ('text%'), ends with ('%text') and contains ('%text%') at this time");
}
if (binaryExpression.Type != BinaryType.Add)
{
throw new SqlErrorException("Like expression can only do string concatination at this time");
}
//If one of the results are null, they have been removed since they were just '%'
//We only return the other result since concat is not required
if (leftResult.Expression == null)
{
return(rightResult);
}
//Remove empty strings that was just for wildcarding
if (leftResult.WildcardOnly && rightResult.WildcardOnly)
{
return(new VisitResult()
{
EndsWith = true,
StartsWith = true,
WildcardOnly = true,
Expression = Expression.Constant("")
});
}
else if (leftResult.WildcardOnly)
{
return(new VisitResult()
{
EndsWith = true,
StartsWith = rightResult.StartsWith,
Expression = rightResult.Expression
});
}
else if (rightResult.WildcardOnly)
{
return(new VisitResult()
{
StartsWith = true,
Expression = leftResult.Expression,
EndsWith = leftResult.EndsWith
});
}
var expression = BinaryUtils.CreateBinaryExpression(leftResult.Expression, rightResult.Expression, BinaryType.Add);
return(new VisitResult()
{
StartsWith = rightResult.StartsWith || rightResult.WildcardOnly,
EndsWith = leftResult.EndsWith || leftResult.WildcardOnly,
Expression = expression
});
}
