ebe03cf3d0
* src/tests/safra.cc: Output error message for wrong ltl formula. * src/twaalgos/safra.cc: Default comparision of vector does not correspond to the desired comparision.
384 lines
12 KiB
C++
384 lines
12 KiB
C++
// -*- coding: utf-8 -*-
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// Copyright (C) 2015 Laboratoire de Recherche et
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// Développement de l'Epita.
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//
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// This file is part of Spot, a model checking library.
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//
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// Spot is free software; you can redistribute it and/or modify it
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// under the terms of the GNU General Public License as published by
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// the Free Software Foundation; either version 3 of the License, or
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// (at your option) any later version.
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//
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// Spot is distributed in the hope that it will be useful, but WITHOUT
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// ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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// or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public
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// License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with this program. If not, see <http://www.gnu.org/licenses/>.
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#include <deque>
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#include <utility>
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#include <unordered_map>
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#include "safra.hh"
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#include "twaalgos/degen.hh"
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namespace spot
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{
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namespace
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{
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// Returns true if lhs has a smaller nesting pattern than rhs
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// If lhs and rhs are the same, return false.
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bool nesting_cmp(const std::vector<node_helper::brace_t>& lhs,
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const std::vector<node_helper::brace_t>& rhs)
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{
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size_t m = std::min(lhs.size(), rhs.size());
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size_t i = 0;
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for (; i < m; ++i)
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{
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if (lhs[i] < rhs[i])
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return true;
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}
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return lhs.size() > rhs.size();
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}
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// Used to remove all acceptance whos value is above max_acc
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void remove_dead_acc(twa_graph_ptr& aut, unsigned max_acc)
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{
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assert(max_acc < 32);
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unsigned mask = (1 << max_acc) - 1;
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for (auto& t: aut->transitions())
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{
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t.acc &= mask;
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}
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}
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}
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auto
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safra_state::compute_succs(const const_twa_graph_ptr& aut,
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const std::vector<unsigned>& bddnums,
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std::unordered_map<bdd,
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std::pair<unsigned, unsigned>,
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bdd_hash>& deltas) const -> succs_t
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{
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succs_t res;
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// Given a bdd returns index of associated safra_state in res
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std::map<unsigned, unsigned> bdd2num;
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for (auto& node: nodes_)
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{
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for (auto& t: aut->out(node.first))
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{
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auto p = deltas[t.cond];
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for (unsigned j = p.first; j < p.second; ++j)
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{
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auto i = bdd2num.insert(std::make_pair(bddnums[j], res.size()));
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unsigned idx;
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if (!i.second)
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idx = i.first->second;
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else
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{
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// Each new node starts out with same number of nodes as src
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idx = res.size();
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res.emplace_back(safra_state(nb_braces_.size()),
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bddnums[j]);
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}
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safra_state& ss = res[idx].first;
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ss.update_succ(node.second, t.dst, t.acc);
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assert(ss.nb_braces_.size() == ss.is_green_.size());
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}
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}
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}
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for (auto& s: res)
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{
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safra_state& tmp = s.first;
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s.first.color_ = tmp.finalize_construction();
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}
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return res;
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}
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unsigned safra_state::finalize_construction()
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{
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unsigned red = -1U;
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unsigned green = -1U;
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std::vector<unsigned> rem_succ_of;
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assert(is_green_.size() == nb_braces_.size());
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for (unsigned i = 0; i < is_green_.size(); ++i)
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{
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if (nb_braces_[i] == 0)
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{
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// It is impossible to emit red == -1 as those transitions would
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// lead us in a sink states which are not created here.
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assert(i >= 1);
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red = std::min(red, 2 * i - 1);
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// Step A3: Brackets that do not contain any nodes emit red
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is_green_[i] = false;
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}
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else if (is_green_[i])
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{
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green = std::min(green, 2 * i);
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// Step A4 Emit green
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rem_succ_of.emplace_back(i);
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}
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}
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for (auto& n: nodes_)
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{
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// Step A4 Remove all brackets inside each green pair
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node_helper::truncate_braces(n.second, rem_succ_of, nb_braces_);
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}
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// Step A5 define the rem variable
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std::vector<unsigned> decr_by(nb_braces_.size());
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unsigned decr = 0;
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for (unsigned i = 0; i < nb_braces_.size(); ++i)
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{
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// Step A5 renumber braces
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nb_braces_[i - decr] = nb_braces_[i];
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if (nb_braces_[i] == 0)
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{
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++decr;
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}
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// Step A5, renumber braces
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decr_by[i] = decr;
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}
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nb_braces_.resize(nb_braces_.size() - decr);
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for (auto& n: nodes_)
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{
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node_helper::renumber(n.second, decr_by);
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}
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return std::min(red, green);
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}
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void node_helper::renumber(std::vector<brace_t>& braces,
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const std::vector<unsigned>& decr_by)
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{
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for (unsigned idx = 0; idx < braces.size(); ++idx)
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{
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braces[idx] -= decr_by[braces[idx]];
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}
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}
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void
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node_helper::truncate_braces(std::vector<brace_t>& braces,
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const std::vector<unsigned>& rem_succ_of,
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std::vector<size_t>& nb_braces)
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{
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for (unsigned idx = 0; idx < braces.size(); ++idx)
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{
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bool found = false;
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// find first brace that matches rem_succ_of
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for (auto s: rem_succ_of)
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{
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found |= braces[idx] == s;
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}
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if (found)
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{
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assert(idx < braces.size() - 1);
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// For each deleted brace, decrement elements of nb_braces
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// This corresponds to A4 step
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for (unsigned i = idx + 1; i < braces.size(); ++i)
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{
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--nb_braces[braces[i]];
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}
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braces.resize(idx + 1);
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break;
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}
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}
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}
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void safra_state::update_succ(const std::vector<node_helper::brace_t>& braces,
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unsigned dst, const acc_cond::mark_t acc)
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{
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std::vector<node_helper::brace_t> copy = braces;
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// TODO handle multiple accepting sets
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if (acc.count())
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{
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assert(acc.has(0) && acc.count() == 1 &&
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"Only one TBA are accepted at the moment");
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// Accepting transition generate new braces: step A1
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copy.emplace_back(nb_braces_.size());
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// nb_braces_ gets updated later so put 0 for now
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nb_braces_.emplace_back(0);
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// Newly created braces cannot emit green as they won't have
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// any braces inside them (by construction)
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is_green_.push_back(false);
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}
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auto i = nodes_.emplace(dst, copy);
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if (!i.second)
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{
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// Step A2: Only keep the smallest nesting pattern (i-e braces_) for
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// identical nodes. Nesting_cmp returnes true if copy is smaller
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if (nesting_cmp(copy, i.first->second))
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{
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// Remove brace count of replaced node
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for (auto b: i.first->second)
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--nb_braces_[b];
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i.first->second = std::move(copy);
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}
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else
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// Node already exists and has bigger nesting pattern value
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return;
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}
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// After inserting new node, update the brace count per node
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for (auto b: i.first->second)
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++nb_braces_[b];
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// Step A4: For a brace to emit green it must surround other braces.
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// Hence, the last brace cannot emit green as it is the most inside brace.
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is_green_[i.first->second.back()] = false;
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}
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// Called only to initialize first state
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safra_state::safra_state(unsigned val, bool init_state)
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{
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if (init_state)
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{
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unsigned state_num = val;
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// One brace set
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is_green_.push_back(true);
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// First brace has init_state hence one state inside the first braces.
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nb_braces_.push_back(1);
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std::vector<node_helper::brace_t> braces = { 0 };
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nodes_.emplace(state_num, std::move(braces));
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}
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else
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{
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unsigned nb_braces = val;
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// One brace set
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is_green_.assign(nb_braces, true);
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// First brace has init_state hence one state inside the first braces.
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nb_braces_.assign(nb_braces, 0);
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}
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}
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bool
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safra_state::operator<(const safra_state& other) const
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{
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return nodes_ < other.nodes_;
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}
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void safra_state::print_debug(unsigned state_id)
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{
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std::cerr << "State: " << state_id << "{ ";
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for (auto& n: nodes_)
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{
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std::cerr << n.first << " [";
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for (auto& b: n.second)
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{
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std::cerr << b << ' ';
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}
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std::cerr << "], ";
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}
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std::cerr << "}\n";
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}
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twa_graph_ptr
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tgba_determinisation(const const_twa_graph_ptr& a)
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{
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// Degeneralize
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const_twa_graph_ptr aut;
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if (a->acc().is_generalized_buchi())
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aut = spot::degeneralize_tba(a);
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else
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aut = a;
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bdd allap = bddtrue;
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{
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typedef std::set<bdd, bdd_less_than> sup_map;
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sup_map sup;
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// Record occurrences of all guards
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for (auto& t: aut->transitions())
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sup.emplace(t.cond);
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for (auto& i: sup)
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allap &= bdd_support(i);
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}
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// Preprocessing
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// Used to convert atomic bdd to id
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std::unordered_map<bdd, unsigned, bdd_hash> bdd2num;
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std::vector<bdd> num2bdd;
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// Nedded for compute succs
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// Used to convert large bdd to indexes
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std::unordered_map<bdd, std::pair<unsigned, unsigned>, bdd_hash> deltas;
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std::vector<unsigned> bddnums;
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for (auto& t: aut->transitions())
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{
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auto it = deltas.find(t.cond);
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if (it == deltas.end())
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{
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bdd all = t.cond;
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unsigned prev = bddnums.size();
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while (all != bddfalse)
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{
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bdd one = bdd_satoneset(all, allap, bddfalse);
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all -= one;
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auto p = bdd2num.emplace(one, num2bdd.size());
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if (p.second)
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num2bdd.push_back(one);
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bddnums.emplace_back(p.first->second);
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}
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deltas[t.cond] = std::make_pair(prev, bddnums.size());
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}
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}
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auto res = make_twa_graph(aut->get_dict());
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res->copy_ap_of(aut);
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res->prop_copy(aut,
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{ false, // state based
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true, // inherently_weak
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false, // deterministic
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true // stutter inv
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});
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// Given a safra_state get its associated state in output automata.
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// Required to create new transitions from 2 safra-state
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typedef std::map<safra_state, int> power_set;
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power_set seen;
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safra_state init(aut->get_init_state_number(), true);
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unsigned num = res->new_state();
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res->set_init_state(num);
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seen.insert(std::make_pair(init, num));
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std::deque<safra_state> todo;
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todo.push_back(init);
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unsigned sets = 0;
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while (!todo.empty())
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{
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using succs_t = safra_state::succs_t;
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safra_state curr = todo.front();
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unsigned src_num = seen.find(curr)->second;
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todo.pop_front();
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succs_t succs = curr.compute_succs(aut, bddnums, deltas);
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for (auto s: succs)
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{
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auto i = seen.find(s.first);
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unsigned dst_num;
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if (i != seen.end())
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{
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dst_num = i->second;
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}
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else
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{
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dst_num = res->new_state();
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// s.first.print_debug(dst_num);
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todo.push_back(s.first);
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seen.insert(std::make_pair(s.first, dst_num));
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}
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if (s.first.color_ != -1U)
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{
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res->new_transition(src_num, dst_num, num2bdd[s.second],
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{s.first.color_});
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// We only care about green acc
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if (s.first.color_ % 2 == 0)
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sets = std::max(s.first.color_ + 1, sets);
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}
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else
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res->new_transition(src_num, dst_num, num2bdd[s.second]);
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}
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}
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//
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remove_dead_acc(res, sets);
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res->set_acceptance(sets, acc_cond::acc_code::parity(false, false, sets));
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res->prop_deterministic(true);
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res->prop_state_based_acc(false);
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return res;
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}
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}
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