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
|
/********************* */
/*! \file cache.h
** \verbatim
** Original author: Morgan Deters <mdeters@cs.nyu.edu>
** Major contributors: none
** Minor contributors (to current version): none
** This file is part of the CVC4 project.
** Copyright (c) 2009-2013 New York University and The University of Iowa
** See the file COPYING in the top-level source directory for licensing
** information.\endverbatim
**
** \brief A generic Cache<> template class for use by functions that
** walk the Node DAG and want to cache results for sub-DAGs
**
** A generic Cache<> template class for use by functions that walk
** the Node DAG and want to cache results for sub-DAGs.
**/
#include "cvc4_private.h"
#ifndef __CVC4__CACHE_H
#define __CVC4__CACHE_H
#include <utility>
#include <functional>
namespace CVC4 {
/**
* A generic implementation of a cache for functions that walk the
* Node DAG performing a computation and want to cache some or all
* computations.
*/
template <class T, class U, class Hasher = std::hash<T> >
class Cache {
typedef std::hash_map<T, U, Hasher> Map;
Map d_map;
std::vector<T> d_current;
typename Map::iterator d_result;
// disallow copy/assignment
Cache(const Cache&) CVC4_UNUSED;
Cache& operator=(const Cache&) CVC4_UNUSED;
public:
typedef T key_type;
typedef U value_type;
typedef Hasher hash_function;
/**
* Makes it easy and error-free to use a Cache<> in a function.
*/
class Scope {
Cache& d_cache;
bool d_fired;
public:
Scope(Cache<T, U, Hasher>& cache, const T& elt) throw(AssertionException) :
d_cache(cache),
d_fired(d_cache.computing(elt)) {
}
~Scope() {
if(!d_fired) {
d_cache();// pop stack
}
}
operator bool() throw() {
return d_fired;
}
const U& get() throw(AssertionException) {
Assert(d_fired, "nothing in cache");
return d_cache.get();
}
U& operator()(U& computed) throw(AssertionException) {
Assert(!d_fired, "can only cache a computation once");
d_fired = true;
return d_cache(computed);
}
const U& operator()(const U& computed) throw(AssertionException) {
Assert(!d_fired, "can only cache a computation once");
d_fired = true;
return d_cache(computed);
}
};/* class Cache::Scope */
Cache() {}
bool computing(const T& elt) {
d_result = d_map.find(elt);
bool found = (d_result != d_map.end());
if(!found) {
d_current.push_back(elt);
}
return found;
}
const U& get() {
Assert(d_result != d_map.end());
return (*d_result).second;
}
// cache nothing (just pop)
void operator()() {
d_current.pop_back();
}
U& operator()(U& result) {
d_map.insert(d_current.back(), result);
d_current.pop_back();
return result;
}
const U& operator()(const U& result) {
d_map.insert(std::make_pair(d_current.back(), result));
d_current.pop_back();
return result;
}
};/* class Cache<> */
}/* CVC4 namespace */
#endif /* __CVC4__CACHE_H */
|
