73 lines
2.4 KiB
C++
73 lines
2.4 KiB
C++
/*
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Copyright (c) 2013 Microsoft Corporation. All rights reserved.
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Released under Apache 2.0 license as described in the file LICENSE.
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Author: Leonardo de Moura
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*/
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#pragma once
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#include <unordered_map>
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#include <utility>
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#include <functional>
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#include <vector>
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#include "util/name.h"
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#include "util/hash.h"
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#include "util/name_map.h"
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#include "util/optional.h"
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namespace lean {
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/**
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\brief Store the set of universe constraints.
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It is based on Floyd-Warshall all-pairs shortest path algorithm.
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*/
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class universe_constraints {
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typedef std::pair<name, int> edge;
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typedef std::vector<edge> edges;
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typedef name_map<edges> node_to_edges;
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typedef std::pair<name, name> name_pair;
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struct name_pair_hash_fn {
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unsigned operator()(name_pair const & p) const { return hash(p.first.hash(), p.second.hash()); }
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};
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typedef std::unordered_map<name_pair, int, name_pair_hash_fn, std::equal_to<name_pair>> distances;
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node_to_edges m_incoming_edges;
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node_to_edges m_outgoing_edges;
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distances m_distances;
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public:
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/**
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\brief Add a new variable.
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\pre The variables does not exist in this set of constraints.
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*/
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void add_var(name const & n);
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/**
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\brief Return true iff this set of constraints contains the variable n.
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That is, it was added using add_var.
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*/
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bool contains(name const & n) const;
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/** \brief Return true iff n1 >= n2 + k is implied by this set of constraints. */
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bool is_implied(name const & n1, name const & n2, int k) const;
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/** \brief Return true iff n1 < n2 + k is not implied by this set of constraints. */
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bool is_consistent(name const & n1, name const & n2, int k) const;
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/**
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\brief Return true iff the constraint n1 >= n2 + k produces an integer overflow when added
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to the set of constraints.
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*/
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bool overflows(name const & n1, name const & n2, int k) const;
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/**
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\brief Add new constraint n1 >= n2 + k.
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\pre is_consistent(n1, n2, k)
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\pre contains(n1)
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\pre contains(n2)
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*/
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void add_constraint(name const & n1, name const & n2, int k);
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/**
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\brief Return the "distance" between n1 and n2.
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That is, the best k s.t. n1 >= n2 + k is implied by this set of constraints
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but n1 >= n2 + k + i is not for any i > 0.
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If there is no such k, then return none.
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*/
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optional<int> get_distance(name const & n1, name const & n2) const;
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};
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}
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