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
|
// Copyright Yahoo. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
#pragma once
#include "itablefactory.h"
namespace search::fef {
/**
* This factory class is used to instantiate tables based on a function.
* The name of the table specifies the function and arguments to use.
* The following functions are supported:
* - expdecay(w,t) : w * exp(-x/t)
* - loggrowth(w,t,s) : w * log(1 + x/s) + t
* - linear(w,t) : w * x + t
* All functions support an optional last parameter for setting the table size.
**/
class FunctionTableFactory : public ITableFactory
{
public:
struct ParsedName {
vespalib::string type;
std::vector<vespalib::string> args;
ParsedName() noexcept : type(), args() {}
};
/**
* Creates a new factory able to create tables with the given default size.
**/
explicit FunctionTableFactory(size_t defaultTableSize);
/**
* Creates a table where the given name specifies the function and arguments to use.
**/
[[nodiscard]] Table::SP createTable(const vespalib::string & name) const override;
/**
* Parses the given function name and returns true if success.
**/
static bool parseFunctionName(const vespalib::string & name, ParsedName & parsed);
private:
size_t _defaultTableSize;
bool checkArgs(const std::vector<vespalib::string> & args, size_t exp, size_t & tableSize) const;
bool isSupported(const vespalib::string & type) const;
bool isExpDecay(const vespalib::string & type) const { return type == "expdecay"; }
bool isLogGrowth(const vespalib::string & type) const { return type == "loggrowth"; }
bool isLinear(const vespalib::string & type) const { return type == "linear"; }
Table::SP createExpDecay(double w, double t, size_t len) const;
Table::SP createLogGrowth(double w, double t, double s, size_t len) const;
Table::SP createLinear(double w, double t, size_t len) const;
};
}
|
