1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
|
module ActiveRelation
class Join < Relation
attr_reader :join_sql, :relation1, :relation2, :predicates
delegate :engine, :to => :relation1
hash_on :relation1
def initialize(join_sql, relation1, relation2 = Nil.new, *predicates)
@join_sql, @relation1, @relation2, @predicates = join_sql, relation1, relation2, predicates
end
def ==(other)
self.class == other.class and
predicates == other.predicates and (
(relation1 == other.relation1 and relation2 == other.relation2) or
(relation2 == other.relation1 and relation1 == other.relation2)
)
end
def attributes
(externalize(relation1).attributes +
externalize(relation2).attributes).collect { |a| a.bind(self) }
end
def prefix_for(attribute)
if relation1[attribute] && !relation2[attribute]
externalize(relation1).prefix_for(attribute)
elsif relation2[attribute] && !relation1[attribute]
externalize(relation2).prefix_for(attribute)
else
if (attribute % relation1[attribute]).size < (attribute % relation2[attribute]).size
externalize(relation1).prefix_for(attribute)
else
externalize(relation2).prefix_for(attribute)
end
end
end
def joins
this_join = [
join_sql,
externalize(relation2).table_sql,
("ON" unless predicates.blank?),
predicates.collect { |p| p.bind(self).to_sql }.join(' AND ')
].compact.join(" ")
[relation1.joins, relation2.joins, this_join].compact.join(" ")
end
def selects
externalize(relation1).selects + externalize(relation2).selects
end
def table_sql
externalize(relation1).table_sql
end
private
def externalize(relation)
Externalizer.new(relation)
end
Externalizer = Struct.new(:relation) do
delegate :engine, :to => :relation
def table_sql
case
when relation.aggregation?
relation.to_sql(Sql::TableReference.new(engine))
when relation.alias?
relation.table_sql + ' AS ' + engine.quote_table_name(relation.alias.to_s)
else
relation.table_sql
end
end
def selects
relation.aggregation?? [] : relation.selects
end
def attributes
relation.aggregation?? relation.attributes.collect(&:to_attribute) : relation.attributes
end
def prefix_for(attribute)
if relation[attribute]
relation.alias?? relation.alias : relation.prefix_for(attribute)
end
end
end
end
end
|
