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https://github.com/Z3Prover/z3
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80 lines
3.3 KiB
C++
80 lines
3.3 KiB
C++
/*++
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Copyright (c) 2021 Microsoft Corporation
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Module Name:
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polysat boolean variables
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Author:
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Jakob Rath 2021-04-6
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--*/
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#pragma once
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#include "math/polysat/types.h"
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#include "util/sat_literal.h"
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namespace polysat {
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class clause;
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class bool_var_manager {
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svector<sat::bool_var> m_unused; // previously deleted variables that can be reused by new_var();
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svector<lbool> m_value; // current value (indexed by literal)
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unsigned_vector m_level; // level of assignment (indexed by variable)
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unsigned_vector m_deps; // dependencies of external asserts
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unsigned_vector m_activity; //
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ptr_vector<clause> m_reason; // propagation reason, NULL for decisions and external asserts (indexed by variable)
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// For enumerative backtracking we store the lemma we're handling with a certain decision
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ptr_vector<clause> m_lemma;
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var_queue m_free_vars; // free Boolean variables
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vector<ptr_vector<clause>> m_watch; // watch list for literals into clauses
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public:
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bool_var_manager(): m_free_vars(m_activity) {}
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// allocated size (not the number of active variables)
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unsigned size() const { return m_level.size(); }
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sat::bool_var new_var();
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void del_var(sat::bool_var var);
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bool is_assigned(sat::bool_var var) const { return value(var) != l_undef; }
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bool is_assigned(sat::literal lit) const { return value(lit) != l_undef; }
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bool is_decision(sat::bool_var var) const { return is_assigned(var) && !reason(var); }
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bool is_decision(sat::literal lit) const { return is_decision(lit.var()); }
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bool is_propagation(sat::bool_var var) const { return is_assigned(var) && reason(var); }
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lbool value(sat::bool_var var) const { return value(sat::literal(var)); }
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lbool value(sat::literal lit) const { return m_value[lit.index()]; }
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bool is_true(sat::literal lit) const { return value(lit) == l_true; }
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bool is_false(sat::literal lit) const { return value(lit) == l_false; }
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unsigned level(sat::bool_var var) const { SASSERT(is_assigned(var)); return m_level[var]; }
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unsigned level(sat::literal lit) const { return level(lit.var()); }
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clause* reason(sat::bool_var var) const { SASSERT(is_assigned(var)); return m_reason[var]; }
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clause* lemma(sat::bool_var var) const { SASSERT(is_decision(var)); return m_lemma[var]; }
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ptr_vector<clause>& watch(sat::literal lit) { return m_watch[lit.index()]; }
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unsigned_vector& activity() { return m_activity; }
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bool can_decide() const { return !m_free_vars.empty(); }
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sat::bool_var next_var() { return m_free_vars.next_var(); }
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// TODO connect activity updates with solver
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void inc_activity(sat::literal lit) { m_activity[lit.var()]++; }
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void dec_activity(sat::literal lit) { m_activity[lit.var()] /= 2; }
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/// Set the given literal to true
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void assign(sat::literal lit, unsigned lvl, clause* reason, clause* lemma, unsigned dep = null_dependency);
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void unassign(sat::literal lit);
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std::ostream& display(std::ostream& out) const;
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};
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inline std::ostream& operator<<(std::ostream& out, bool_var_manager const& m) { return m.display(out); }
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}
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