/// <summary>
/// Deal with a special case for an index redirection where we are looking for
/// an integer or some simply type. There is only one very special case where this
/// shows up. Unlikely to be used by physics, actually. :-) The second case we
/// handle is dealing with != for two object compares.
/// </summary>
/// <param name="expression"></param>
/// <returns></returns>
protected override Expression VisitBinary(BinaryExpression expression)
{
//
// If we are comparing a "new" against a null, then we don't support that.
//
if (expression.Left.IsNull() || expression.Right.IsNull())
{
Expression nonNull = expression.Left.IsNull() ? expression.Right : expression.Left;
if (nonNull.NodeType == ExpressionType.New)
{
throw new InvalidOperationException(string.Format("Doing a null comparison to a temporary object created in the query is very likely to generate incorrect code - not supported ({0})", expression.ToString()));
}
}
// If this is an array index, then...
if (expression.NodeType == ExpressionType.ArrayIndex && expression.IsLeafType())
{
var rootExpr = expression.Left as MemberExpression;
if (rootExpr != null)
{
return Expression.ArrayIndex(VisitExpressionImplemented(rootExpr), expression.Right);
}
}
// If this is a comparison, and these are objects that have indicies (in whatever we are looping through)...
if (expression.NodeType == ExpressionType.Equal || expression.NodeType == ExpressionType.NotEqual)
{
// Are we pointing to something we can deal with?
var indexLeft = ExtractIndexReference(expression.Left);
if (indexLeft != null)
{
var indexRight = ExtractIndexReference(expression.Right);
if (indexRight != null)
{
if (expression.NodeType == ExpressionType.NotEqual)
{
return Expression.NotEqual(indexLeft, indexRight);
} else
{
return Expression.Equal(indexLeft, indexRight);
}
}
}
}
return base.VisitBinary(expression);
}
