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Add a constant_term() visitor to decide whether #e is accepted.

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* src/ltlvisit/Makefile.am: Add consterm.cc and consterm.hh.
* src/ltlvisit/consterm.hh, src/ltlvisit/consterm.cc: New files.
* src/ltltest/Makefile.am: Add consterm.cc and consterm.test.
* src/ltltest/consterm.cc, src/ltltest/consterm.test: New files.
This commit is contained in:
Alexandre Duret-Lutz 2010-01-11 16:01:38 +01:00
parent 2d1aa0a5a0
commit 97b7211bb7
6 changed files with 307 additions and 1 deletions
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150
src/ltlvisit/consterm.cc Normal file
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// Copyright (C) 2010 Laboratoire de Recherche et Développement de
// l'EPITA (LRDE).
//
// This file is part of Spot, a model checking library.
//
// Spot is free software; you can redistribute it and/or modify it
// under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 2 of the License, or
// (at your option) any later version.
//
// Spot is distributed in the hope that it will be useful, but WITHOUT
// ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
// or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public
// License for more details.
//
// You should have received a copy of the GNU General Public License
// along with Spot; see the file COPYING. If not, write to the Free
// Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
// 02111-1307, USA.
#include "ltlvisit/consterm.hh"
#include "ltlast/allnodes.hh"
#include "ltlast/visitor.hh"
namespace spot
{
namespace ltl
{
namespace
{
class consterm_visitor: public const_visitor
{
public:
consterm_visitor() {}
virtual ~consterm_visitor() {}
bool result() const { return result_; }
void
visit(const atomic_prop*)
{
result_ = false;
}
void
visit(const constant* c)
{
result_ = (c == constant::empty_word_instance());
}
void
visit(const binop* bo)
{
switch (bo->op())
{
case binop::Xor:
case binop::Implies:
case binop::Equiv:
assert(!"const_term not yet defined on Xor, Implies and Equiv");
break;
case binop::U:
case binop::W:
case binop::M:
case binop::R:
result_ = false;
break;
}
}
void
visit(const unop* uo)
{
switch (uo->op())
{
case unop::Not:
case unop::X:
case unop::F:
case unop::G:
case unop::Finish:
result_ = false;
break;
case unop::Star:
result_ = true;
break;
}
}
void
visit(const automatop*)
{
assert(!"automatop not supported for constant term");
result_ = false;
}
void
visit(const multop* mo)
{
if (mo->op() == multop::Concat)
{
result_ = false;
return;
}
unsigned max = mo->size();
// This sets the initial value of result_.
mo->nth(0)->accept(*this);
for (unsigned n = 1; n < max; ++n)
{
bool r = constant_term_as_bool(mo->nth(n));
switch (mo->op())
{
case multop::Or:
result_ |= r;
if (result_)
return;
break;
case multop::And:
result_ &= r;
if (!result_)
return;
break;
case multop::Concat:
assert(!"unreachable code");
break;
}
}
}
private:
bool result_;
};
}
bool constant_term_as_bool(const formula* f)
{
consterm_visitor v;
f->accept(v);
return v.result();
}
formula* constant_term(const formula* f)
{
return constant_term_as_bool(f) ?
constant::empty_word_instance() : constant::false_instance();
}
}
}