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
|
// Copyright 2017 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
package com.yahoo.searchdefinition.expressiontransforms;
import com.yahoo.searchdefinition.RankProfile;
import com.yahoo.searchlib.rankingexpression.RankingExpression;
import com.yahoo.searchlib.rankingexpression.rule.CompositeNode;
import com.yahoo.searchlib.rankingexpression.rule.ExpressionNode;
import com.yahoo.searchlib.rankingexpression.rule.FunctionNode;
import com.yahoo.searchlib.rankingexpression.rule.ReferenceNode;
import com.yahoo.searchlib.rankingexpression.transform.ExpressionTransformer;
/**
* Transforms function nodes to reference nodes if a macro shadows a built-in function.
* This has the effect of allowing macros to redefine built-in functions.
* Another effect is that we can more or less add built-in functions over time
* without fear of breaking existing users' macros with the same name.
*
* However, there is a (largish) caveat. If a user has a macro with a certain number
* of arguments, and we add in a built-in function with a different arity,
* this will cause parse errors as the Java parser gives precedence to
* built-in functions.
*
* @author lesters
*/
public class MacroShadower extends ExpressionTransformer<RankProfileTransformContext> {
@Override
public RankingExpression transform(RankingExpression expression, RankProfileTransformContext context) {
String name = expression.getName();
ExpressionNode node = expression.getRoot();
ExpressionNode result = transform(node, context);
return new RankingExpression(name, result);
}
@Override
public ExpressionNode transform(ExpressionNode node, RankProfileTransformContext context) {
if (node instanceof FunctionNode)
return transformFunctionNode((FunctionNode) node, context);
if (node instanceof CompositeNode)
return transformChildren((CompositeNode)node, context);
return node;
}
private ExpressionNode transformFunctionNode(FunctionNode function, RankProfileTransformContext context) {
String name = function.getFunction().toString();
RankProfile.Macro macro = context.rankProfile().getMacros().get(name);
if (macro == null) {
return transformChildren(function, context);
}
int functionArity = function.getFunction().arity();
int macroArity = macro.getFormalParams() != null ? macro.getFormalParams().size() : 0;
if (functionArity != macroArity) {
return transformChildren(function, context);
}
ReferenceNode node = new ReferenceNode(name, function.children(), null);
return transformChildren(node, context);
}
}
|
