Source

z3 / src / muz_qe / pdr_sym_mux.h

/*++
Copyright (c) 2011 Microsoft Corporation

Module Name:

    sym_mux.h

Abstract:

    A symbol multiplexer that helps with having multiple versions of each of a set of symbols.

Author:

    Krystof Hoder (t-khoder) 2011-9-8.

Revision History:

--*/

#ifndef _SYM_MUX_H_
#define _SYM_MUX_H_

#include "ast.h"
#include "map.h"
#include "vector.h"

class model_core;

namespace pdr {
class sym_mux
{
public:
    typedef ptr_vector<app> app_vector;
    typedef ptr_vector<func_decl> decl_vector;
private:
    typedef obj_map<func_decl,unsigned> sym2u;
    typedef obj_map<func_decl, decl_vector> sym2dv;
    typedef obj_map<func_decl,func_decl *> sym2sym;
    typedef obj_map<func_decl, func_decl *> sym2pred;
    typedef hashtable<symbol, symbol_hash_proc, symbol_eq_proc> symbols;

    ast_manager &           m;
    mutable ast_ref_vector  m_ref_holder;
    mutable expr_mark       m_visited;

    mutable unsigned       m_next_sym_suffix_idx;
    mutable symbols        m_used_suffixes;
    /** Here we have default suffixes for each of the variants */
    mutable vector<std::string> m_suffixes;


    /**
       Primary symbol is the 0-th variant. This member maps from primary symbol
       to vector of all its variants (including the primary variant).
    */
    sym2dv m_prim2all;

    /**
       For each symbol contains its variant index
    */
    mutable sym2u m_sym2idx;
    /**
       For each symbol contains its primary variant
    */
    mutable sym2sym m_sym2prim;

    /**
       Maps prefixes passed to the create_tuple to 
       the primary symbol created from it.
    */
    sym2pred m_prefix2prim;

    /**
       Maps pripary symbols to prefixes that were used to create them.
    */
    sym2sym     m_prim2prefix;

    decl_vector m_prim_preds;

    obj_hashtable<func_decl> m_non_model_syms;

    struct formula_checker;
    struct conv_rewriter_cfg;
    struct shifting_rewriter_cfg;
    class decl_idx_comparator;
    class hmg_checker;
    class nonmodel_sym_checker;
    class index_renamer_cfg;
    class index_collector;
    class variable_collector;

    std::string get_suffix(unsigned i) const;
    void ensure_tuple_size(func_decl * prim, unsigned sz) const;

    expr_ref isolate_o_idx(expr* e, unsigned idx) const;
public:
    sym_mux(ast_manager & m, const vector<std::string> & suffixes);

    ast_manager & get_manager() const { return m; }

    bool is_muxed(func_decl * sym) const { return m_sym2idx.contains(sym); }

    bool try_get_index(func_decl * sym, unsigned & idx) const {
        return m_sym2idx.find(sym,idx);
    }

    bool has_index(func_decl * sym, unsigned idx) const {
        unsigned actual_idx;
        return try_get_index(sym, actual_idx) && idx==actual_idx;
    }

    /** Return primary symbol. sym must be muxed. */
    func_decl * get_primary(func_decl * sym) const {
        func_decl * prim;
        TRUSTME(m_sym2prim.find(sym, prim));
        return prim;
    }

    /**
    Return primary symbol created from prefix, or 0 if the prefix was never used.
    */
    func_decl * try_get_primary_by_prefix(func_decl* prefix) const {
        func_decl * res;
        if(!m_prefix2prim.find(prefix, res)) {
            return 0;
        }
        return res;
    }

    /**
    Return symbol created from prefix, or 0 if the prefix was never used.
    */
    func_decl * try_get_by_prefix(func_decl* prefix, unsigned idx) const {
        func_decl * prim = try_get_primary_by_prefix(prefix);
        if(!prim) {
            return 0;
        }
        return conv(prim, 0, idx);
    }

    /**
    Marks symbol as non-model which means it will not appear in models collected by 
    get_muxed_cube_from_model function.
    This is to take care of auxiliary symbols introduced by the disjunction relations
    to relativize lemmas coming from disjuncts.
    */
    void mark_as_non_model(func_decl * sym) {
        SASSERT(is_muxed(sym));
        m_non_model_syms.insert(get_primary(sym));
    }

    func_decl * get_or_create_symbol_by_prefix(func_decl* prefix, unsigned idx, 
        unsigned arity, sort * const * domain, sort * range);



    bool is_muxed_lit(expr * e, unsigned idx) const;

    bool is_non_model_sym(func_decl * s) const { 
        return is_muxed(s) && m_non_model_syms.contains(get_primary(s));
    }

    /**
    Create a multiplexed tuple of propositional constants.
    Symbols may be suplied in the tuple vector,
    those beyond the size of the array and those with corresponding positions 
    assigned to zero will be created using prefix.
    Tuple length must be at least one.
    */
    void create_tuple(func_decl* prefix, unsigned arity, sort * const * domain, sort * range, 
        unsigned tuple_length, decl_vector & tuple);

    /**
    Return true if the only multiplexed symbols which e contains are of index idx.
    */
    bool is_homogenous_formula(expr * e, unsigned idx) const;
    bool is_homogenous(const expr_ref_vector & vect, unsigned idx) const;

    /**
    Return true if all multiplexed symbols which e contains are of one index.
    */
    bool is_homogenous_formula(expr * e) const;

    /**
    Return true if expression e contains a muxed symbol of index idx.
    */
    bool contains(expr * e, unsigned idx) const;

    /**
        Collect indices used in expression.
    */
    void collect_indices(expr* e, unsigned_vector& indices) const;

    /**
        Collect used variables of each index.
    */
    void collect_variables(expr* e, vector<ptr_vector<app> >& vars) const;

    /**
    Convert symbol sym which has to be of src_idx variant into variant tgt_idx.
    */
    func_decl * conv(func_decl * sym, unsigned src_idx, unsigned tgt_idx) const;

    
    /**
    Convert src_idx symbols in formula f variant into tgt_idx.
    If homogenous is true, formula cannot contain symbols of other variants.
    */
    void conv_formula(expr * f, unsigned src_idx, unsigned tgt_idx, expr_ref & res, bool homogenous=true) const;
    void conv_formula_vector(const expr_ref_vector & vect, unsigned src_idx, unsigned tgt_idx, 
        expr_ref_vector & res) const;

    /**
    Shifts the muxed symbols in f by dist. Dist can be negative, but it should never shift 
    symbol index to a negative value.
    */
    void shift_formula(expr * f, int dist, expr_ref & res) const;

    /**
    Remove from vect literals (atoms or negations of atoms) of symbols
    that contain multiplexed symbols with indexes other than idx.

    Each of the literals can contain only symbols multiplexed with one index
    (this trivially holds if the literals are propositional).

    Order of elements in vect may be modified by this function
    */
    void filter_idx(expr_ref_vector & vect, unsigned idx) const;

    /**
        Partition literals into o_literals and others.
    */
    void partition_o_idx(expr_ref_vector const& lits, 
                         expr_ref_vector& o_lits,
                         expr_ref_vector& other, unsigned idx) const;

    bool has_nonmodel_symbol(expr * e) const;
    void filter_non_model_lits(expr_ref_vector & vect) const;

    func_decl * const * begin_prim_preds() const { return m_prim_preds.begin(); }
    func_decl * const * end_prim_preds() const { return m_prim_preds.end(); }

    void get_muxed_cube_from_model(const model_core & model, expr_ref_vector & res) const;

    std::string pp_model(const model_core & mdl) const;
};
}

#endif