-
Notifications
You must be signed in to change notification settings - Fork 6
/
LetBindToLeftJoin.java
178 lines (153 loc) · 5.87 KB
/
LetBindToLeftJoin.java
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
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
/*
* [New BSD License]
* Copyright (c) 2011-2012, Brackit Project Team <info@brackit.org>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* * Neither the name of the Brackit Project Team nor the
* names of its contributors may be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
* ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
package org.brackit.xquery.compiler.optimizer.walker.topdown;
import org.brackit.xquery.atomic.Bool;
import org.brackit.xquery.atomic.QNm;
import org.brackit.xquery.compiler.AST;
import org.brackit.xquery.compiler.XQ;
import org.brackit.xquery.util.Cmp;
/**
* @author Sebastian Baechle
*
*/
public class LetBindToLeftJoin extends AggFunChecker {
@Override
protected AST visit(AST node) {
if (node.getType() != XQ.LetBind) {
return node;
}
AST bindingExpr = node.getChild(1);
if (bindingExpr.getType() != XQ.PipeExpr) {
return node;
}
return convertToLeftJoin(node);
}
private AST convertToLeftJoin(AST let) {
AST insertJoinAfter = let.getParent();
// use a trivial empty pipeline as left input
// and use the constant boolean value "true" as
// left join key expression
AST leftIn = new AST(XQ.Start);
AST lend = new AST(XQ.End);
lend.addChild(new AST(XQ.Bool, Bool.TRUE));
leftIn.addChild(lend);
// copy the nested pipeline as right input
AST rightIn = let.getChild(1).getChild(0).copyTree();
// locate end of the nested pipeline
// and create a copy of the return expression
AST righInEnd = rightIn;
while (righInEnd.getType() != XQ.End) {
righInEnd = righInEnd.getLastChild();
}
AST letReturn = righInEnd.getChild(0).copyTree();
// replace the return expression with a constant
// boolean value "true" as right join key expression
righInEnd.replaceChild(0, new AST(XQ.Bool, Bool.TRUE));
// the post join pipeline uses a let-binding
// for the original return expression
// and then groups the let-bound return values
// (only the binding of the final let will be used)
AST post = new AST(XQ.Start);
AST letVarBinding = let.getChild(0).copyTree();
// TODO fix cardinality of binding if necessary
AST rlet = new AST(XQ.LetBind);
rlet.addChild(letVarBinding);
rlet.addChild(letReturn);
QNm letVar = (QNm) letVarBinding.getChild(0).getValue();
AST groupBy = createGroupBy(letVar, let);
rlet.addChild(groupBy);
post.addChild(rlet);
// finally assemble left join
AST ljoin = createJoin(leftIn, rightIn, post, let.getLastChild().copyTree());
// we must not sort if result is directly aggregated
boolean skipSort = (groupBy.getChild(1).getChild(0).getType() != XQ.SequenceAgg);
if (skipSort) {
ljoin.setProperty("skipSort", Boolean.TRUE);
}
int replaceAt = insertJoinAfter.getChildCount() - 1;
insertJoinAfter.replaceChild(replaceAt, ljoin);
snapshot();
refreshScopes(insertJoinAfter, true);
return insertJoinAfter;
}
private AST createJoin(AST leftIn, AST rightIn, AST post, AST out) {
AST ljoin = new AST(XQ.Join);
ljoin.setProperty("leftJoin", Boolean.TRUE);
ljoin.setProperty("cmp", Cmp.eq);
ljoin.setProperty("GCmp", false);
ljoin.addChild(leftIn);
ljoin.addChild(rightIn);
ljoin.addChild(post);
ljoin.addChild(out);
return ljoin;
}
private AST createGroupBy(QNm letVar, AST letBind) {
int aggType = XQ.SequenceAgg;
Var var = findScope(letBind).localBindings().get(0);
VarRef refs = findVarRefs(var, letBind.getLastChild());
if (refs == null) {
// TODO Unused variable???? SingleAgg OK but currently causes errors
// in GroupByAggregates....
// aggType = XQ.SingleAgg;
} else if (refs.next != null) {
// TODO optimize me
} else {
AST p = refs.ref.getParent();
if (p.getType() == XQ.FunctionCall) {
QNm fun = (QNm) p.getValue();
for (int i = 0; i < aggFuns.length; i++) {
QNm aggFun = aggFuns[i];
if (fun.atomicCmp(aggFun) == 0) {
replaceRef(p, letVar);
aggType = aggFunMap[i];
break;
}
}
}
}
AST groupBy = new AST(XQ.GroupBy);
groupBy.setProperty("sequential", Boolean.TRUE);
AST aggSpec = new AST(XQ.AggregateSpec);
aggSpec.addChild(new AST(XQ.VariableRef, letVar));
aggSpec.addChild(createBinding(letVar, aggType));
groupBy.addChild(aggSpec);
AST dftAgg = new AST(XQ.DftAggregateSpec);
dftAgg.addChild(new AST(XQ.SingleAgg));
groupBy.addChild(dftAgg);
groupBy.addChild(new AST(XQ.End));
return groupBy;
}
private AST createBinding(QNm name, int type) {
AST agg = new AST(XQ.AggregateBinding);
AST binding = new AST(XQ.TypedVariableBinding);
binding.addChild(new AST(XQ.Variable, name));
agg.addChild(binding);
agg.addChild(new AST(type));
return agg;
}
}