/*++
Copyright (c) 2011 Microsoft Corporation

Module Name:

    model_implicant.h

Abstract:

    Facility to extract prime implicant from model.

Author:

    Krystof Hoder (t-khoder) 2011-8-19.

Revision History:

--*/

#ifndef MODEL_IMPLICANT_H_
#define MODEL_IMPLICANT_H_

#include "ast/ast.h"
#include "ast/ast_pp.h"
#include "util/obj_hashtable.h"
#include "util/ref_vector.h"
#include "util/trace.h"
#include "util/vector.h"
#include "ast/arith_decl_plugin.h"
#include "ast/array_decl_plugin.h"

class model;
class model_core;

class model_implicant {
    ast_manager&           m;
    arith_util             m_arith;
    array_util             m_array;
    obj_map<expr,rational> m_numbers;
    expr_ref_vector        m_refs;
    obj_map<expr, expr*>   m_values;
    model_ref              m_model;
    
    //00 -- non-visited
    //01 -- X
    //10 -- false
    //11 -- true
    expr_mark      m1;
    expr_mark      m2;
    expr_mark      m_visited;
    
    
    void reset();
    void setup_model(model_ref& model);
    void assign_value(expr* e, expr* v);
    void collect(ptr_vector<expr> const& formulas, ptr_vector<expr>& tocollect);
    void process_formula(app* e, ptr_vector<expr>& todo, ptr_vector<expr>& tocollect);
    expr_ref_vector prune_by_cone_of_influence(ptr_vector<expr> const & formulas);
    void eval_arith(app* e);
    void eval_basic(app* e);
    void eval_eq(app* e, expr* arg1, expr* arg2);
    void eval_array_eq(app* e, expr* arg1, expr* arg2);
    void inherit_value(expr* e, expr* v);
    
    inline bool is_unknown(expr* x)  { return !m1.is_marked(x) && !m2.is_marked(x); }
    inline void set_unknown(expr* x)  { m1.mark(x, false); m2.mark(x, false); }
    inline bool is_x(expr* x)  { return !m1.is_marked(x) && m2.is_marked(x); }
    inline bool is_false(expr* x)  { return m1.is_marked(x) && !m2.is_marked(x); }
    inline bool is_true(expr* x)  { return m1.is_marked(x) && m2.is_marked(x); }
    inline void set_x(expr* x) { SASSERT(is_unknown(x)); m2.mark(x); }
    inline void set_v(expr* x) { SASSERT(is_unknown(x)); m1.mark(x); }
    inline void set_false(expr* x) { SASSERT(is_unknown(x)); m1.mark(x); }
    inline void set_true(expr* x) { SASSERT(is_unknown(x)); m1.mark(x); m2.mark(x); }
    inline void set_bool(expr* x, bool v) { if (v) { set_true(x); } else { set_false(x); } }
    inline rational const& get_number(expr* x) const { return m_numbers.find(x); }
    inline void set_number(expr* x, rational const& v) { 
        set_v(x); TRACE("pdr_verbose", tout << mk_pp(x,m) << " " << v << "\n";); m_numbers.insert(x,v); 
    }
    inline expr* get_value(expr* x) { return m_values.find(x); }
    inline void set_value(expr* x, expr* v) { set_v(x); m_refs.push_back(v); m_values.insert(x, v); }
    
    bool check_model(ptr_vector<expr> const & formulas);
    
    bool extract_array_func_interp(expr* a, vector<expr_ref_vector>& stores, expr_ref& else_case);
    
    void eval_exprs(expr_ref_vector& es);
    
public:
    model_implicant(ast_manager& m) : 
        m(m), m_arith(m), m_array(m), m_refs(m) {}
    
    /**
       \brief extract equalities from model that suffice to satisfy formula.
       
       \pre model satisfies formulas
    */
    
       expr_ref_vector minimize_model(ptr_vector<expr> const & formulas, model_ref& mdl);
    
    /**
       \brief extract literals from model that satisfy formulas.
       
       \pre model satisfies formulas
    */
    expr_ref_vector minimize_literals(ptr_vector<expr> const & formulas, model_ref& mdl);
    
    /** 
        for_each_expr visitor.
    */
    void operator()(expr* e) {} 
    
    expr_ref eval(model_ref& mdl, expr* e);
    
    expr_ref eval(model_ref& mdl, func_decl* d);
};


#endif