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Diffstat (limited to 'minisat/solver/SolverTypes.H')
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diff --git a/minisat/solver/SolverTypes.H b/minisat/solver/SolverTypes.H new file mode 100644 index 0000000..f590f8e --- /dev/null +++ b/minisat/solver/SolverTypes.H @@ -0,0 +1,201 @@ +/***********************************************************************************[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 |