Theory of Sequences

examples/api/cpp/sequences.cpp

 1 /******************************************************************************
 2  * Top contributors (to current version):
 3  *   Andres Noetzli, Mathias Preiner, Aina Niemetz
 4  *
 5  * This file is part of the cvc5 project.
 6  *
 7  * Copyright (c) 2009-2022 by the authors listed in the file AUTHORS
 8  * in the top-level source directory and their institutional affiliations.
 9  * All rights reserved.  See the file COPYING in the top-level source
10  * directory for licensing information.
11  * ****************************************************************************
12  *
13  * A simple demonstration of reasoning about sequences with cvc5 via C++ API.
14  */
15 
16 #include <cvc5/cvc5.h>
17 
18 #include <iostream>
19 
20 using namespace cvc5;
21 
22 int main()
23 {
24   Solver slv;
25 
26   // Set the logic
27   slv.setLogic("QF_SLIA");
28   // Produce models
29   slv.setOption("produce-models", "true");
30   // The option strings-exp is needed
31   slv.setOption("strings-exp", "true");
32   // Set output language to SMTLIB2
33   slv.setOption("output-language", "smt2");
34 
35   // Sequence sort
36   Sort intSeq = slv.mkSequenceSort(slv.getIntegerSort());
37 
38   // Sequence variables
39   Term x = slv.mkConst(intSeq, "x");
40   Term y = slv.mkConst(intSeq, "y");
41 
42   // Empty sequence
43   Term empty = slv.mkEmptySequence(slv.getIntegerSort());
44   // Sequence concatenation: x.y.empty
45   Term concat = slv.mkTerm(SEQ_CONCAT, {x, y, empty});
46   // Sequence length: |x.y.empty|
47   Term concat_len = slv.mkTerm(SEQ_LENGTH, {concat});
48   // |x.y.empty| > 1
49   Term formula1 = slv.mkTerm(GT, {concat_len, slv.mkInteger(1)});
50   // Sequence unit: seq(1)
51   Term unit = slv.mkTerm(SEQ_UNIT, {slv.mkInteger(1)});
52   // x = seq(1)
53   Term formula2 = slv.mkTerm(EQUAL, {x, unit});
54 
55   // Make a query
56   Term q = slv.mkTerm(AND, {formula1, formula2});
57 
58   // check sat
59   Result result = slv.checkSatAssuming(q);
60   std::cout << "cvc5 reports: " << q << " is " << result << "." << std::endl;
61 
62   if (result.isSat())
63   {
64     std::cout << "  x = " << slv.getValue(x) << std::endl;
65     std::cout << "  y = " << slv.getValue(y) << std::endl;
66   }
67 }