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/***********************************************************************************[SolverTypes.h]
MiniSat -- Copyright (c) 2003-2006, Niklas Een, Niklas Sorensson
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and
associated documentation files (the "Software"), to deal in the Software without restriction,
including without limitation the rights to use, copy, modify, merge, publish, distribute,
sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all copies or
substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT
NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT
OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
**************************************************************************************************/
#ifndef SolverTypes_h
#define SolverTypes_h
#include <cassert>
#include <stdint.h>
//=================================================================================================
// Variables, literals, lifted booleans, clauses:
// NOTE! Variables are just integers. No abstraction here. They should be chosen from 0..N,
// so that they can be used as array indices.
typedef int Var;
#define var_Undef (-1)
class Lit {
int x;
public:
Lit() : x(2*var_Undef) { } // (lit_Undef)
explicit Lit(Var var, bool sign = false) : x((var+var) + (int)sign) { }
// Don't use these for constructing/deconstructing literals. Use the normal constructors instead.
friend int toInt (Lit p); // Guarantees small, positive integers suitable for array indexing.
friend Lit toLit (int i); // Inverse of 'toInt()'
friend Lit operator ~(Lit p);
friend bool sign (Lit p);
friend int var (Lit p);
friend Lit unsign (Lit p);
friend Lit id (Lit p, bool sgn);
bool operator == (Lit p) const { return x == p.x; }
bool operator != (Lit p) const { return x != p.x; }
bool operator < (Lit p) const { return x < p.x; } // '<' guarantees that p, ~p are adjacent in the ordering.
};
inline int toInt (Lit p) { return p.x; }
inline Lit toLit (int i) { Lit p; p.x = i; return p; }
inline Lit operator ~(Lit p) { Lit q; q.x = p.x ^ 1; return q; }
inline bool sign (Lit p) { return p.x & 1; }
inline int var (Lit p) { return p.x >> 1; }
inline Lit unsign (Lit p) { Lit q; q.x = p.x & ~1; return q; }
inline Lit id (Lit p, bool sgn) { Lit q; q.x = p.x ^ (int)sgn; return q; }
const Lit lit_Undef(var_Undef, false); // }- Useful special constants.
const Lit lit_Error(var_Undef, true ); // }
//=================================================================================================
// Lifted booleans:
class lbool {
char value;
explicit lbool(int v) : value(v) { }
public:
lbool() : value(0) { }
lbool(bool x) : value((int)x*2-1) { }
int toInt(void) const { return value; }
bool operator == (lbool b) const { return value == b.value; }
bool operator != (lbool b) const { return value != b.value; }
lbool operator ^ (bool b) const { return b ? lbool(-value) : lbool(value); }
friend int toInt (lbool l);
friend lbool toLbool(int v);
};
inline int toInt (lbool l) { return l.toInt(); }
inline lbool toLbool(int v) { return lbool(v); }
const lbool l_True = toLbool( 1);
const lbool l_False = toLbool(-1);
const lbool l_Undef = toLbool( 0);
//=================================================================================================
// Clause -- a simple class for representing a clause:
class Clause;
template<class V>
Clause* Clause_new(const V& ps, bool learnt = false);
class Clause {
uint32_t size_etc;
union { float act; uint32_t abst; } extra;
Lit data[0];
public:
void calcAbstraction() {
uint32_t abstraction = 0;
for (int i = 0; i < size(); i++)
abstraction |= 1 << (var(data[i]) & 31);
extra.abst = abstraction; }
// NOTE: This constructor cannot be used directly (doesn't allocate enough memory).
template<class V>
Clause(const V& ps, bool learnt) {
size_etc = (ps.size() << 3) | (uint32_t)learnt;
for (int i = 0; i < ps.size(); i++) data[i] = ps[i];
if (learnt) extra.act = 0; else calcAbstraction(); }
// -- use this function instead:
template<class V>
friend Clause* Clause_new(const V& ps, bool learnt) {
assert(sizeof(Lit) == sizeof(uint32_t));
assert(sizeof(float) == sizeof(uint32_t));
void* mem = malloc(sizeof(Clause) + sizeof(uint32_t)*(ps.size()));
return new (mem) Clause(ps, learnt); }
int size () const { return size_etc >> 3; }
void shrink (int i) { assert(i <= size()); size_etc = (((size_etc >> 3) - i) << 3) | (size_etc & 7); }
void pop () { shrink(1); }
bool learnt () const { return size_etc & 1; }
uint32_t mark () const { return (size_etc >> 1) & 3; }
void mark (uint32_t m) { size_etc = (size_etc & ~6) | ((m & 3) << 1); }
const Lit& last () const { return data[size()-1]; }
// NOTE: somewhat unsafe to change the clause in-place! Must manually call 'calcAbstraction' afterwards for
// subsumption operations to behave correctly.
Lit& operator [] (int i) { return data[i]; }
Lit operator [] (int i) const { return data[i]; }
operator const Lit* (void) const { return data; }
float& activity () { return extra.act; }
uint32_t abstraction () const { return extra.abst; }
Lit subsumes (const Clause& other) const;
void strengthen (Lit p);
};
/*_________________________________________________________________________________________________
|
| subsumes : (other : const Clause&) -> Lit
|
| Description:
| Checks if clause subsumes 'other', and at the same time, if it can be used to simplify 'other'
| by subsumption resolution.
|
| Result:
| lit_Error - No subsumption or simplification
| lit_Undef - Clause subsumes 'other'
| p - The literal p can be deleted from 'other'
|________________________________________________________________________________________________@*/
inline Lit Clause::subsumes(const Clause& other) const
{
if (other.size() < size() || (extra.abst & ~other.extra.abst) != 0)
return lit_Error;
Lit ret = lit_Undef;
const Lit* c = (const Lit*)(*this);
const Lit* d = (const Lit*)other;
for (int i = 0; i < size(); i++) {
// search for c[i] or ~c[i]
for (int j = 0; j < other.size(); j++)
if (c[i] == d[j])
goto ok;
else if (ret == lit_Undef && c[i] == ~d[j]){
ret = c[i];
goto ok;
}
// did not find it
return lit_Error;
ok:;
}
return ret;
}
inline void Clause::strengthen(Lit p)
{
remove(*this, p);
calcAbstraction();
}
#endif
|
