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z3/src/util/lp/factorization.h
Lev 267457aaf4 fix a bug in factorization
Signed-off-by: Lev <levnach@hotmail.com>
2020-01-28 10:04:21 -08:00

125 lines
3.3 KiB
C++

/*++
Copyright (c) 2017 Microsoft Corporation
Module Name:
<name>
Abstract:
<abstract>
Author:
Nikolaj Bjorner (nbjorner)
Lev Nachmanson (levnach)
Revision History:
--*/
#pragma once
#include "util/rational.h"
#include "util/lp/monomial.h"
namespace nla {
struct factorization_factory;
typedef unsigned lpvar;
enum class factor_type { VAR, RM }; // RM stands for rooted monomial
class factor {
unsigned m_index;
factor_type m_type;
public:
factor() {}
factor(unsigned j) : factor(j, factor_type::VAR) {}
factor(unsigned i, factor_type t) : m_index(i), m_type(t) {}
unsigned index() const {return m_index;}
unsigned& index() {return m_index;}
factor_type type() const {return m_type;}
factor_type& type() {return m_type;}
bool is_var() const { return m_type == factor_type::VAR; }
};
inline bool operator==(const factor& a, const factor& b) {
return a.index() == b.index() && a.type() == b.type();
}
inline bool operator!=(const factor& a, const factor& b) {
return ! (a == b);
}
class factorization {
vector<factor> m_vars;
public:
bool is_empty() const { return m_vars.empty(); }
const vector<factor> & vars() const { return m_vars; }
factor operator[](unsigned k) const { return m_vars[k]; }
size_t size() const { return m_vars.size(); }
const factor* begin() const { return m_vars.begin(); }
const factor* end() const { return m_vars.end(); }
void push_back(factor v) {m_vars.push_back(v);}
};
struct const_iterator_mon {
// fields
svector<bool> m_mask;
const factorization_factory * m_ff;
bool m_full_factorization_returned;
//typedefs
typedef const_iterator_mon self_type;
typedef factorization value_type;
typedef const factorization reference;
typedef int difference_type;
typedef std::forward_iterator_tag iterator_category;
void init_vars_by_the_mask(unsigned_vector & k_vars, unsigned_vector & j_vars) const;
bool get_factors(factor& k, factor& j, rational& sign) const;
reference operator*() const;
void advance_mask();
self_type operator++();
self_type operator++(int);
const_iterator_mon(const svector<bool>& mask, const factorization_factory *f);
bool operator==(const self_type &other) const;
bool operator!=(const self_type &other) const;
factorization create_binary_factorization(factor j, factor k) const;
factorization create_full_factorization() const;
};
struct factorization_factory {
const svector<lpvar>& m_vars;
// returns true if found
virtual bool find_rm_monomial_of_vars(const svector<lpvar>& vars, unsigned& i) const = 0;
factorization_factory(const svector<lpvar>& vars) :
m_vars(vars) {
}
const_iterator_mon begin() const {
// we keep the last element always in the first factor to avoid
// repeating a pair twice
svector<bool> mask(m_vars.size() - 1, false);
return const_iterator_mon(mask, this);
}
const_iterator_mon end() const {
svector<bool> mask(m_vars.size() - 1, true);
auto it = const_iterator_mon(mask, this);
it.m_full_factorization_returned = true;
return it;
}
};
}