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#!/usr/bin/env python
#####################
## strings.py
## Top contributors (to current version):
## Makai Mann, Andres Noetzli
## This file is part of the CVC4 project.
## Copyright (c) 2009-2020 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.
##
## A simple demonstration of the solving capabilities of the CVC4
## strings solver through the Python API. This is a direct translation
## of strings-new.cpp.
##
import pycvc4
from pycvc4 import kinds
if __name__ == "__main__":
slv = pycvc4.Solver()
# Set the logic
slv.setLogic("QF_SLIA")
# Produce models
slv.setOption("produce-models", "true")
# The option strings-exp is needed
slv.setOption("strings-exp", "true")
# Set output language to SMTLIB2
slv.setOption("output-language", "smt2")
# String type
string = slv.getStringSort()
# std::string
str_ab = "ab"
# String constants
ab = slv.mkString(str_ab)
abc = slv.mkString("abc")
# String variables
x = slv.mkConst(string, "x")
y = slv.mkConst(string, "y")
z = slv.mkConst(string, "z")
# String concatenation: x.ab.y
lhs = slv.mkTerm(kinds.StringConcat, x, ab, y)
# String concatenation: abc.z
rhs = slv.mkTerm(kinds.StringConcat, abc, z)
# x.ab.y = abc.z
formula1 = slv.mkTerm(kinds.Equal, lhs, rhs)
# Length of y: |y|
leny = slv.mkTerm(kinds.StringLength, y)
# |y| >= 0
formula2 = slv.mkTerm(kinds.Geq, leny, slv.mkInteger(0))
# Regular expression: (ab[c-e]*f)|g|h
r = slv.mkTerm(kinds.RegexpUnion,
slv.mkTerm(kinds.RegexpConcat,
slv.mkTerm(kinds.StringToRegexp, slv.mkString("ab")),
slv.mkTerm(kinds.RegexpStar,
slv.mkTerm(kinds.RegexpRange, slv.mkString("c"), slv.mkString("e"))),
slv.mkTerm(kinds.StringToRegexp, slv.mkString("f"))),
slv.mkTerm(kinds.StringToRegexp, slv.mkString("g")),
slv.mkTerm(kinds.StringToRegexp, slv.mkString("h")))
# String variables
s1 = slv.mkConst(string, "s1")
s2 = slv.mkConst(string, "s2")
# String concatenation: s1.s2
s = slv.mkTerm(kinds.StringConcat, s1, s2)
# s1.s2 in (ab[c-e]*f)|g|h
formula3 = slv.mkTerm(kinds.StringInRegexp, s, r)
# Make a query
q = slv.mkTerm(kinds.And,
formula1,
formula2,
formula3)
# check sat
result = slv.checkSatAssuming(q)
print("CVC4 reports:", q, "is", result)
if result:
print("x = ", slv.getValue(x))
print(" s1.s2 =", slv.getValue(s))
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