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
|
// Copyright 2017 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
package com.yahoo.searchlib.rankingexpression.rule;
import com.google.common.collect.ImmutableList;
import com.yahoo.searchlib.rankingexpression.Reference;
import com.yahoo.searchlib.rankingexpression.evaluation.Context;
import com.yahoo.searchlib.rankingexpression.evaluation.MapContext;
import com.yahoo.searchlib.rankingexpression.evaluation.Value;
import com.yahoo.tensor.TensorType;
import com.yahoo.tensor.evaluation.TypeContext;
import java.util.Collections;
import java.util.Deque;
import java.util.List;
import java.util.function.DoubleBinaryOperator;
import java.util.function.DoubleUnaryOperator;
/**
* A free, parametrized function
*
* @author bratseth
*/
public class LambdaFunctionNode extends CompositeNode {
private final ImmutableList<String> arguments;
private final ExpressionNode functionExpression;
public LambdaFunctionNode(List<String> arguments, ExpressionNode functionExpression) {
// TODO: Verify that the function only accesses the given arguments
this.arguments = ImmutableList.copyOf(arguments);
this.functionExpression = functionExpression;
}
@Override
public List<ExpressionNode> children() {
return Collections.singletonList(functionExpression);
}
@Override
public CompositeNode setChildren(List<ExpressionNode> children) {
if ( children.size() != 1)
throw new IllegalArgumentException("A lambda function must have a single child expression");
return new LambdaFunctionNode(arguments, children.get(0));
}
@Override
public String toString(SerializationContext context, Deque<String> path, CompositeNode parent) {
return ("f(" + commaSeparated(arguments) + ")(" + functionExpression.toString(context, path, this)) + ")";
}
private String commaSeparated(List<String> list) {
StringBuilder b = new StringBuilder();
for (String element : list)
b.append(element).append(",");
if (b.length() > 0)
b.setLength(b.length()-1);
return b.toString();
}
@Override
public TensorType type(TypeContext<Reference> context) {
return TensorType.empty; // by definition - no nested lambdas
}
/** Evaluate this in a context which must have the arguments bound */
@Override
public Value evaluate(Context context) {
return functionExpression.evaluate(context);
}
/**
* Returns this as a double unary operator
*
* @throws IllegalStateException if this has more than one argument
*/
public DoubleUnaryOperator asDoubleUnaryOperator() {
if (arguments.size() > 1)
throw new IllegalStateException("Cannot apply " + this + " as a DoubleUnaryOperator: " +
"Must have at most one argument " + " but has " + arguments);
return new DoubleUnaryLambda();
}
/**
* Returns this as a double binary operator
*
* @throws IllegalStateException if this has more than two arguments
*/
public DoubleBinaryOperator asDoubleBinaryOperator() {
if (arguments.size() > 2)
throw new IllegalStateException("Cannot apply " + this + " as a DoubleBinaryOperator: " +
"Must have at most two argument " + " but has " + arguments);
return new DoubleBinaryLambda();
}
private class DoubleUnaryLambda implements DoubleUnaryOperator {
@Override
public double applyAsDouble(double operand) {
MapContext context = new MapContext();
if (arguments.size() > 0)
context.put(arguments.get(0), operand);
return evaluate(context).asDouble();
}
@Override
public String toString() {
return LambdaFunctionNode.this.toString();
}
}
private class DoubleBinaryLambda implements DoubleBinaryOperator {
@Override
public double applyAsDouble(double left, double right) {
MapContext context = new MapContext();
if (arguments.size() > 0)
context.put(arguments.get(0), left);
if (arguments.size() > 1)
context.put(arguments.get(1), right);
return evaluate(context).asDouble();
}
@Override
public String toString() {
return LambdaFunctionNode.this.toString();
}
}
}
|
