protected virtual Expression VisitOuterJoined(DbOuterJoinedExpression outer)
{
Expression test = Visit(outer.Test);
Expression expression = Visit(outer.Expression);
return(UpdateOuterJoined(outer, test, expression));
}
protected DbOuterJoinedExpression UpdateOuterJoined(DbOuterJoinedExpression outer,
Expression test, Expression expression)
{
if (test != outer.Test || expression != outer.Expression)
{
return(new DbOuterJoinedExpression(test, expression));
}
return(outer);
}
public static DbProjectionExpression AddOuterJoinTest(this DbProjectionExpression proj)
{
string colName = proj.Select.Columns.GetAvailableColumnName("Test");
DbSelectExpression newSource = proj.Select.AddColumn(new DbColumnDeclaration(colName, Expression.Constant(1, typeof(int?))));
Expression newProjector =
new DbOuterJoinedExpression(
new DbColumnExpression(typeof(int?), null, newSource.Alias, colName),
proj.Projector
);
return new DbProjectionExpression(newSource, newProjector, proj.Aggregator);
}
public static DbProjectionExpression AddOuterJoinTest(this DbProjectionExpression proj)
{
string colName = proj.Select.Columns.GetAvailableColumnName("Test");
DbSelectExpression newSource = proj.Select.AddColumn(new DbColumnDeclaration(colName, Expression.Constant(1, typeof(int?))));
Expression newProjector =
new DbOuterJoinedExpression(
new DbColumnExpression(typeof(int?), null, newSource.Alias, colName),
proj.Projector
);
return(new DbProjectionExpression(newSource, newProjector, proj.Aggregator));
}
protected override Expression VisitOuterJoined(DbOuterJoinedExpression outer)
{
Expression expr = this.Visit(outer.Expression);
DbColumnExpression column = (DbColumnExpression)outer.Test;
ParameterExpression reader;
int iOrdinal;
if (this.scope.TryGetValue(column, out reader, out iOrdinal))
{
return(Expression.Condition(
Expression.Call(reader, "IsDbNull", null, Expression.Constant(iOrdinal)),
Expression.Constant(outer.Type.CreateInstance(), outer.Type),
expr
));
}
return(expr);
}
protected DbOuterJoinedExpression UpdateOuterJoined(DbOuterJoinedExpression outer,
Expression test, Expression expression)
{
if (test != outer.Test || expression != outer.Expression)
return new DbOuterJoinedExpression(test, expression);
return outer;
}
protected virtual Expression VisitOuterJoined(DbOuterJoinedExpression outer)
{
Expression test = Visit(outer.Test);
Expression expression = Visit(outer.Expression);
return UpdateOuterJoined(outer, test, expression);
}
internal static Expression BindMember(Expression source, MemberInfo member)
{
switch (source.NodeType)
{
case (ExpressionType)DbExpressionType.Entity:
DbEntityExpression ex = (DbEntityExpression)source;
var result = BindMember(ex.Expression, member);
MemberExpression mex = result as MemberExpression;
if (mex != null && mex.Expression == ex.Expression && mex.Member == member)
{
return(Expression.MakeMemberAccess(source, member));
}
return(result);
case ExpressionType.Convert:
UnaryExpression ux = (UnaryExpression)source;
return(BindMember(ux.Operand, member));
case ExpressionType.MemberInit:
MemberInitExpression min = (MemberInitExpression)source;
for (int i = 0, n = min.Bindings.Count; i < n; i++)
{
MemberAssignment assign = min.Bindings[i] as MemberAssignment;
if (assign != null && MembersMatch(assign.Member, member))
{
return(assign.Expression);
}
}
break;
case ExpressionType.New:
NewExpression nex = (NewExpression)source;
if (nex.Members != null)
{
for (int i = 0, n = nex.Members.Count; i < n; i++)
{
if (MembersMatch(nex.Members[i], member))
{
return(nex.Arguments[i]);
}
}
}
else if (nex.Type.IsGenericType && nex.Type.GetGenericTypeDefinition() == typeof(Grouping <,>))
{
if (member.Name == "Key")
{
return(nex.Arguments[0]);
}
}
break;
case (ExpressionType)DbExpressionType.Projection:
// member access on a projection turns into a new projection w/ member access applied
DbProjectionExpression proj = (DbProjectionExpression)source;
Expression newProjector = BindMember(proj.Projector, member);
return(new DbProjectionExpression(proj.Select, newProjector));
case (ExpressionType)DbExpressionType.OuterJoined:
DbOuterJoinedExpression oj = (DbOuterJoinedExpression)source;
Expression em = BindMember(oj.Expression, member);
if (em is DbColumnExpression)
{
return(em);
}
return(new DbOuterJoinedExpression(oj.Test, em));
case ExpressionType.Conditional:
ConditionalExpression cex = (ConditionalExpression)source;
return(Expression.Condition(cex.Test, BindMember(cex.IfTrue, member), BindMember(cex.IfFalse, member)));
case ExpressionType.Constant:
ConstantExpression con = (ConstantExpression)source;
Type memberType = TypeHelper.GetMemberType(member);
if (con.Value == null)
{
return(Expression.Constant(GetDefault(memberType), memberType));
}
else
{
return(Expression.Constant(GetValue(con.Value, member), memberType));
}
}
return(Expression.MakeMemberAccess(source, member));
}
