protected Expression Compare(BinaryExpression bop)
{
var e1 = this.SkipConvert(bop.Left);
var e2 = this.SkipConvert(bop.Right);
OuterJoinedExpression oj1 = e1 as OuterJoinedExpression;
OuterJoinedExpression oj2 = e2 as OuterJoinedExpression;
EntityExpression entity1 = oj1 != null ? oj1.Expression as EntityExpression : e1 as EntityExpression;
EntityExpression entity2 = oj2 != null ? oj2.Expression as EntityExpression : e2 as EntityExpression;
bool negate = bop.NodeType == ExpressionType.NotEqual;
// check for outer-joined entity comparing against null. These are special because outer joins have
// a test expression specifically desgined to be tested against null to determine if the joined side exists.
if (oj1 != null && e2.NodeType == ExpressionType.Constant && ((ConstantExpression)e2).Value == null)
{
return(MakeIsNull(oj1.Test, negate));
}
else if (oj2 != null && e1.NodeType == ExpressionType.Constant && ((ConstantExpression)e1).Value == null)
{
return(MakeIsNull(oj2.Test, negate));
}
// if either side is an entity construction expression then compare using its primary key members
if (entity1 != null)
{
return(this.MakePredicate(e1, e2, this.mapping.GetPrimaryKeyMembers(entity1.Entity), negate));
}
else if (entity2 != null)
{
return(this.MakePredicate(e1, e2, this.mapping.GetPrimaryKeyMembers(entity2.Entity), negate));
}
// check for comparison of user constructed type projections
var dm1 = this.GetDefinedMembers(e1);
var dm2 = this.GetDefinedMembers(e2);
if (dm1 == null && dm2 == null)
{
// neither are constructed types
return(bop);
}
if (dm1 != null && dm2 != null)
{
// both are constructed types, so they'd better have the same members declared
HashSet <string> names1 = new HashSet <string>(dm1.Select(m => m.Name));
HashSet <string> names2 = new HashSet <string>(dm2.Select(m => m.Name));
if (names1.IsSubsetOf(names2) && names2.IsSubsetOf(names1))
{
return(MakePredicate(e1, e2, dm1, negate));
}
}
else if (dm1 != null)
{
return(MakePredicate(e1, e2, dm1, negate));
}
else if (dm2 != null)
{
return(MakePredicate(e1, e2, dm2, negate));
}
throw new InvalidOperationException("Cannot compare two constructed types with different sets of members assigned.");
}
protected override Expression VisitEntity(EntityExpression entity)
{
return(this.Visit(entity.Expression));
}
