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/********************* */
/*! \file Strings.java
** \verbatim
** Original author: Tianyi Liang
** Major contributors: none
** Minor contributors (to current version): none
** This file is part of the CVC4 project.
** Copyright (c) 2009-2014 New York University and The University of Iowa
** See the file COPYING in the top-level source directory for licensing
** information.\endverbatim
**
** \brief Reasoning about strings with CVC4 via Java API.
**
** A simple demonstration of reasoning about strings with CVC4 via Jave API.
**/
import edu.nyu.acsys.CVC4.*;
public class Strings {
public static void main(String[] args) {
System.loadLibrary("cvc4jni");
ExprManager em = new ExprManager();
SmtEngine smt = new SmtEngine(em);
// Set the logic
smt.setLogic("S");
// Produce models
smt.setOption("produce-models", new SExpr(true));
// The option strings-exp is needed
smt.setOption("strings-exp", new SExpr(true));
// output-language
smt.setOption("output-language", new SExpr("smt2"));
// String type
Type string = em.stringType();
// String constants
Expr ab = em.mkConst(new CVC4String("ab"));
Expr abc = em.mkConst(new CVC4String("abc"));
// Variables
Expr x = em.mkVar("x", string);
Expr y = em.mkVar("y", string);
Expr z = em.mkVar("z", string);
// String concatenation: x.ab.y
Expr lhs = em.mkExpr(Kind.STRING_CONCAT, x, ab, y);
// String concatenation: abc.z
Expr rhs = em.mkExpr(Kind.STRING_CONCAT, abc, z);;
// x.ab.y = abc.z
Expr formula1 = em.mkExpr(Kind.EQUAL, lhs, rhs);
// Length of y: |y|
Expr leny = em.mkExpr(Kind.STRING_LENGTH, y);
// |y| >= 0
Expr formula2 = em.mkExpr(Kind.GEQ, leny, em.mkConst(new Rational(0)));
// Regular expression: (ab[c-e]*f)|g|h
Expr r = em.mkExpr(Kind.REGEXP_UNION,
em.mkExpr(Kind.REGEXP_CONCAT,
em.mkExpr(Kind.STRING_TO_REGEXP, em.mkConst(new CVC4String("ab"))),
em.mkExpr(Kind.REGEXP_STAR,
em.mkExpr(Kind.REGEXP_RANGE, em.mkConst(new CVC4String("c")), em.mkConst(new CVC4String("e")))),
em.mkExpr(Kind.STRING_TO_REGEXP, em.mkConst(new CVC4String("f")))),
em.mkExpr(Kind.STRING_TO_REGEXP, em.mkConst(new CVC4String("g"))),
em.mkExpr(Kind.STRING_TO_REGEXP, em.mkConst(new CVC4String("h"))));
// String variables
Expr s1 = em.mkVar("s1", string);
Expr s2 = em.mkVar("s2", string);
// String concatenation: s1.s2
Expr s = em.mkExpr(Kind.STRING_CONCAT, s1, s2);
// s1.s2 in (ab[c-e]*f)|g|h
Expr formula3 = em.mkExpr(Kind.STRING_IN_REGEXP, s, r);
// Make a query
Expr q = em.mkExpr(Kind.AND,
formula1,
formula2,
formula3);
// check sat
Result result = smt.checkSat(q);
System.out.println("CVC4 reports: " + q + " is " + result + ".");
System.out.println(" x = " + smt.getValue(x));
System.out.println(" s1.s2 = " + smt.getValue(s));
}
}
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