/*++
Copyright (c) 2011 Microsoft Corporation

Module Name:

    sat_justification.h

Abstract:

    Justifications for SAT assignments

Author:

    Leonardo de Moura (leonardo) 2011-05-21.

Revision History:

--*/
#ifndef _SAT_JUSTIFICATIONS_H_
#define _SAT_JUSTIFICATIONS_H_

namespace sat {
    
    class justification {
    public:
        enum kind { NONE, BINARY, TERNARY, CLAUSE, EXT_JUSTIFICATION };
    private:
        unsigned m_val1;
        unsigned m_val2; 
        justification(ext_justification_idx idx, kind k):m_val1(idx), m_val2(k) {}
    public:
        justification():m_val1(0), m_val2(NONE) {}
        justification(literal l):m_val1(l.to_uint()), m_val2(BINARY) {}
        justification(literal l1, literal l2):m_val1(l1.to_uint()), m_val2(TERNARY + (l2.to_uint() << 3)) {}
        justification(clause_offset cls_off):m_val1(cls_off), m_val2(CLAUSE) {}
        justification mk_ext_justification(ext_justification_idx idx) { return justification(idx, EXT_JUSTIFICATION); }
        
        kind get_kind() const { return static_cast<kind>(m_val2 & 7); }
        
        bool is_none() const { return m_val2 == NONE; }
        
        bool is_binary_clause() const { return m_val2 == BINARY; }
        literal get_literal() const { SASSERT(is_binary_clause()); return to_literal(m_val1); }

        bool is_ternary_clause() const { return get_kind() == TERNARY; }
        literal get_literal1() const { SASSERT(is_ternary_clause()); return to_literal(m_val1); }
        literal get_literal2() const { SASSERT(is_ternary_clause()); return to_literal(m_val2 >> 3); }

        bool is_clause() const { return m_val2 == CLAUSE; }
        clause_offset get_clause_offset() const { return m_val1; }
        
        bool is_ext_justification() const { return m_val2 == EXT_JUSTIFICATION; }
        ext_justification_idx get_ext_justification_idx() const { return m_val1; }
    };
};

#endif