cprover
string_constraint.cpp
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1 /*******************************************************************\
2 
3 Module: String solver
4 
5 Author: Diffblue Ltd.
6 
7 \*******************************************************************/
8 
9 #include "string_constraint.h"
10 
11 #include <solvers/sat/satcheck.h>
12 #include <util/symbol_table.h>
13 
18 static bool cannot_be_neg(const exprt &expr)
19 {
20  // this is an internal check, no need for user visibility
22  satcheck_no_simplifiert sat_check(null_message_handler);
23  symbol_tablet symbol_table;
24  namespacet ns(symbol_table);
25  boolbvt solver{ns, sat_check, null_message_handler};
26  const exprt zero = from_integer(0, expr.type());
27  const binary_relation_exprt non_neg(expr, ID_lt, zero);
28  solver << non_neg;
30 }
31 
33  const symbol_exprt &_univ_var,
34  const exprt &lower_bound,
35  const exprt &upper_bound,
36  const exprt &body)
37  : univ_var(_univ_var),
38  lower_bound(lower_bound),
39  upper_bound(upper_bound),
40  body(body)
41 {
42  INVARIANT(
44  "String constraints must have non-negative lower bound.\n" +
46  INVARIANT(
48  "String constraints must have non-negative upper bound.\n" +
50 }
51 
56 {
57  std::ostringstream out;
58  out << "forall x in [" << format(expr.univ_lower_bound) << ", "
59  << format(expr.univ_upper_bound) << "). " << format(expr.premise)
60  << " => ("
61  << "exists y in [" << format(expr.exists_lower_bound) << ", "
62  << format(expr.exists_upper_bound) << "). " << format(expr.s0)
63  << "[x+y] != " << format(expr.s1) << "[y])";
64  return out.str();
65 }
66 
67 void replace(
68  const union_find_replacet &replace_map,
70 {
71  replace_map.replace_expr(constraint.univ_lower_bound);
72  replace_map.replace_expr(constraint.univ_upper_bound);
73  replace_map.replace_expr(constraint.premise);
74  replace_map.replace_expr(constraint.exists_lower_bound);
75  replace_map.replace_expr(constraint.exists_upper_bound);
76  replace_map.replace_expr(constraint.s0);
77  replace_map.replace_expr(constraint.s1);
78 }
79 
83 {
84  return left.univ_upper_bound == right.univ_upper_bound &&
85  left.univ_lower_bound == right.univ_lower_bound &&
86  left.exists_lower_bound == right.exists_lower_bound &&
87  left.exists_upper_bound == right.exists_upper_bound &&
88  left.premise == right.premise && left.s0 == right.s0 &&
89  left.s1 == right.s1;
90 }
format
static format_containert< T > format(const T &o)
Definition: format.h:35
symbol_tablet
The symbol table.
Definition: symbol_table.h:19
string_constraintt::string_constraintt
string_constraintt()=delete
string_not_contains_constraintt::univ_upper_bound
exprt univ_upper_bound
Definition: string_constraint.h:129
irept::pretty
std::string pretty(unsigned indent=0, unsigned max_indent=0) const
Definition: irep.cpp:488
decision_proceduret::resultt::D_UNSATISFIABLE
replace
void replace(const union_find_replacet &replace_map, string_not_contains_constraintt &constraint)
Definition: string_constraint.cpp:67
union_find_replacet::replace_expr
bool replace_expr(exprt &expr) const
Replace subexpressions of expr by the representative element of the set they belong to.
Definition: union_find_replace.cpp:28
exprt
Base class for all expressions.
Definition: expr.h:52
to_string
std::string to_string(const string_not_contains_constraintt &expr)
Used for debug printing.
Definition: string_constraint.cpp:55
string_not_contains_constraintt::exists_upper_bound
exprt exists_upper_bound
Definition: string_constraint.h:132
symbol_exprt
Expression to hold a symbol (variable)
Definition: std_expr.h:81
string_not_contains_constraintt::premise
exprt premise
Definition: string_constraint.h:130
string_constraintt::upper_bound
exprt upper_bound
Definition: string_constraint.h:66
string_constraintt::lower_bound
exprt lower_bound
Definition: string_constraint.h:65
namespacet
A namespacet is essentially one or two symbol tables bound together, to allow for symbol lookups in t...
Definition: namespace.h:91
exprt::type
typet & type()
Return the type of the expression.
Definition: expr.h:81
string_not_contains_constraintt::exists_lower_bound
exprt exists_lower_bound
Definition: string_constraint.h:131
string_not_contains_constraintt::univ_lower_bound
exprt univ_lower_bound
Definition: string_constraint.h:128
null_message_handlert
Definition: message.h:76
satcheck.h
string_constraint.h
union_find_replacet
Similar interface to union-find for expressions, with a function for replacing sub-expressions by the...
Definition: union_find_replace.h:16
from_integer
constant_exprt from_integer(const mp_integer &int_value, const typet &type)
Definition: arith_tools.cpp:99
solver
int solver(std::istream &in)
Definition: smt2_solver.cpp:364
binary_relation_exprt
A base class for relations, i.e., binary predicates whose two operands have the same type.
Definition: std_expr.h:724
string_not_contains_constraintt::s0
array_string_exprt s0
Definition: string_constraint.h:133
cannot_be_neg
static bool cannot_be_neg(const exprt &expr)
Runs a solver instance to verify whether an expression can only be non-negative.
Definition: string_constraint.cpp:18
boolbvt
Definition: boolbv.h:34
string_not_contains_constraintt
Constraints to encode non containement of strings.
Definition: string_constraint.h:126
operator==
bool operator==(const string_not_contains_constraintt &left, const string_not_contains_constraintt &right)
Definition: string_constraint.cpp:80
symbol_table.h
Author: Diffblue Ltd.
string_not_contains_constraintt::s1
array_string_exprt s1
Definition: string_constraint.h:134
null_message_handler
null_message_handlert null_message_handler
Definition: message.cpp:14
validation_modet::INVARIANT