z3/src/sat/smt/q_clause.h

/*++
Copyright (c) 2020 Microsoft Corporation

Module Name:

    q_clause.h

Abstract:

    Literals, clauses, justifications for quantifier instantiation

Author:

    Nikolaj Bjorner (nbjorner) 2021-01-24

--*/
#pragma once

#include "util/dlist.h"
#include "ast/ast.h"
#include "ast/quantifier_stat.h"
#include "ast/euf/euf_enode.h"
#include "sat/smt/euf_solver.h"


namespace q {

    struct lit {
        expr_ref lhs;
        expr_ref rhs;
        bool     sign;
        lit(expr_ref const& lhs, expr_ref const& rhs, bool sign):
            lhs(lhs), rhs(rhs), sign(sign) {
            SASSERT(!rhs.m().is_false(rhs) || !sign);
        }
        std::ostream& display(std::ostream& out) const;
    };

    struct binding;

    struct clause {
        unsigned            m_index;
        vector<lit>         m_lits;
        quantifier_ref      m_q;
        unsigned            m_watch = 0;
        sat::literal        m_literal = sat::null_literal;
        q::quantifier_stat* m_stat = nullptr;
        binding* m_bindings = nullptr;


        clause(ast_manager& m, unsigned idx) : m_index(idx), m_q(m) {}

        std::ostream& display(euf::solver& ctx, std::ostream& out) const;
        lit const& operator[](unsigned i) const { return m_lits[i]; }
        lit& operator[](unsigned i) { return m_lits[i]; }
        unsigned size() const { return m_lits.size(); }
        unsigned num_decls() const { return m_q->get_num_decls(); }
        unsigned index() const { return m_index; }
        quantifier* q() const { return m_q; }
    };


    struct binding : public dll_base<binding> {
        clause*            c;
        app*               m_pattern;
        unsigned           m_max_generation;
        unsigned           m_min_top_generation;
        unsigned           m_max_top_generation;
        euf::enode*        m_nodes[0];

        binding(clause& c, app* pat, unsigned max_generation, unsigned min_top, unsigned max_top):
            c(&c),
            m_pattern(pat),
            m_max_generation(max_generation),
            m_min_top_generation(min_top),
            m_max_top_generation(max_top) {}

        euf::enode* const* nodes() { return m_nodes; }

        euf::enode* operator[](unsigned i) const { return m_nodes[i]; }

        std::ostream& display(euf::solver& ctx, std::ostream& out) const;

        unsigned size() const { return c->num_decls(); }
        
        quantifier* q() const { return c->m_q; }

        bool eq(binding const& other) const {
            if (q() != other.q())
                return false;
            for (unsigned i = size(); i-- > 0; )
                if ((*this)[i] != other[i])
                    return false;
            return true;
        }
    };

    struct binding_khasher {
        unsigned operator()(binding const* f) const { return f->q()->get_id(); }
    };

    struct binding_chasher {
        unsigned operator()(binding const* f, unsigned idx) const { return f->m_nodes[idx]->hash(); }
    };

    struct binding_hash_proc {
        unsigned operator()(binding const* f) const {
            return get_composite_hash<binding*, binding_khasher, binding_chasher>(const_cast<binding*>(f), f->size());
        }
    };

    struct binding_eq_proc {
        bool operator()(binding const* a, binding const* b) const { return a->eq(*b); }
    };

    typedef ptr_hashtable<binding, binding_hash_proc, binding_eq_proc> bindings;

    inline std::ostream& operator<<(std::ostream& out, binding const& f) {
        out << "[fp " << f.q()->get_id() << ":";
        for (unsigned i = 0; i < f.size(); ++i)
            out << " " << f[i]->get_expr_id();
        return out << "]";
    }

    struct justification {
        expr* m_lhs, * m_rhs;
        bool      m_sign;
        unsigned  m_generation;
        unsigned  m_num_ex;
        size_t** m_explain;
        clause& m_clause;
        euf::enode* const* m_binding;
        justification(lit const& l, clause& c, euf::enode* const* b, unsigned generation, unsigned n, size_t** ev) :
            m_lhs(l.lhs), m_rhs(l.rhs), m_sign(l.sign), m_generation(generation), m_num_ex(n), m_explain(ev), m_clause(c), m_binding(b) {}
        sat::ext_constraint_idx to_index() const {
            return sat::constraint_base::mem2base(this);
        }
        static justification& from_index(size_t idx) {
            return *reinterpret_cast<justification*>(sat::constraint_base::from_index(idx)->mem());
        }
        static size_t get_obj_size() { return sat::constraint_base::obj_size(sizeof(justification)); }
    };

}