#!/usr/bin/env python

#####################
#! \file strings.py
## \verbatim
## Top contributors (to current version):
##   Makai Mann
## This file is part of the CVC4 project.
## Copyright (c) 2009-2018 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 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("S")
    # 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.mkReal(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))