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
|
/********************* */
/*! \file eqc_info.cpp
** \verbatim
** Top contributors (to current version):
** Andrew Reynolds
** This file is part of the CVC4 project.
** Copyright (c) 2009-2019 by the authors listed in the file AUTHORS
** in the top-level source directory) and their institutional affiliations.
** All rights reserved. See the file COPYING in the top-level source
** directory for licensing information.\endverbatim
**
** \brief Implementation of equivalence class info for the theory of strings
**/
#include "theory/strings/eqc_info.h"
#include "theory/strings/theory_strings_utils.h"
#include "theory/strings/word.h"
using namespace std;
using namespace CVC4::context;
using namespace CVC4::kind;
namespace CVC4 {
namespace theory {
namespace strings {
EqcInfo::EqcInfo(context::Context* c)
: d_lengthTerm(c),
d_codeTerm(c),
d_cardinalityLemK(c),
d_normalizedLength(c),
d_prefixC(c),
d_suffixC(c)
{
}
Node EqcInfo::addEndpointConst(Node t, Node c, bool isSuf)
{
// check conflict
Node prev = isSuf ? d_suffixC : d_prefixC;
if (!prev.isNull())
{
Trace("strings-eager-pconf-debug") << "Check conflict " << prev << ", " << t
<< " post=" << isSuf << std::endl;
Node prevC = utils::getConstantEndpoint(prev, isSuf);
Assert(!prevC.isNull());
Assert(prevC.isConst());
if (c.isNull())
{
c = utils::getConstantEndpoint(t, isSuf);
Assert(!c.isNull());
}
Assert(c.isConst());
bool conflict = false;
// if the constant prefixes are different
if (c != prevC)
{
// conflicts between constants should be handled by equality engine
Assert(!t.isConst() || !prev.isConst());
Trace("strings-eager-pconf-debug")
<< "Check conflict constants " << prevC << ", " << c << std::endl;
size_t pvs = Word::getLength(prevC);
size_t cvs = Word::getLength(c);
if (pvs == cvs || (pvs > cvs && t.isConst())
|| (cvs > pvs && prev.isConst()))
{
// If equal length, cannot be equal due to node check above.
// If one is fully constant and has less length than the other, then the
// other will not fit and we are in conflict.
conflict = true;
}
else
{
Node larges = pvs > cvs ? prevC : c;
Node smalls = pvs > cvs ? c : prevC;
if (isSuf)
{
conflict = !Word::hasSuffix(larges, smalls);
}
else
{
conflict = !Word::hasPrefix(larges, smalls);
}
}
if (!conflict && (pvs > cvs || prev.isConst()))
{
// current is subsumed, either shorter prefix or the other is a full
// constant
return Node::null();
}
}
else if (!t.isConst())
{
// current is subsumed since the other may be a full constant
return Node::null();
}
if (conflict)
{
Trace("strings-eager-pconf")
<< "Conflict for " << prevC << ", " << c << std::endl;
std::vector<Node> ccs;
Node r[2];
for (unsigned i = 0; i < 2; i++)
{
Node tp = i == 0 ? t : prev;
if (tp.getKind() == STRING_IN_REGEXP)
{
ccs.push_back(tp);
r[i] = tp[0];
}
else
{
r[i] = tp;
}
}
if (r[0] != r[1])
{
ccs.push_back(r[0].eqNode(r[1]));
}
Assert(!ccs.empty());
Node ret =
ccs.size() == 1 ? ccs[0] : NodeManager::currentNM()->mkNode(AND, ccs);
Trace("strings-eager-pconf")
<< "String: eager prefix conflict: " << ret << std::endl;
return ret;
}
}
if (isSuf)
{
d_suffixC = t;
}
else
{
d_prefixC = t;
}
return Node::null();
}
} // namespace strings
} // namespace theory
} // namespace CVC4
|
