theory_atom.hh

#pragma once
 
#include <clingo/ground/matcher.hh>
#include <clingo/ground/statement.hh>
#include <clingo/ground/term.hh>
#include <clingo/ground/theory_term.hh>
 
#include <clingo/util/macro.hh>
#include <clingo/util/small_vector.hh>
 
#include <memory_resource>
 
namespace CppClingo::Ground {
 
// Outline:
// - rules:
//      H :- L, B.
//   accu :- A, E.
//   - literal L simply matches everything
//   - atom A matches the theory atoms output while grounding
//   - statements elem gather the ground elements of theory atoms
//     whose grounding is delayed until output
// - propagate
//   - no propagation is necessary because theory atoms always match
// - output
//   - as with other aggregates, output is delayed until the end of a component
//   - unlike other aggregates, elements are grounded during output
// - classes
//   - AtomTheory       (ground representation for theory atoms)
//   - BaseTheory       (a base for theory atoms)
//   - StateTheoryAtom  (gathers state for grounding/output)
//   - MatchTheory      (match object for theory atoms)
//   - LitMatchTheory   (binder to ground theory elements)
//   - StmTheoryElement (statement to accumulate elements)
//   - LitTheoryAtom    (atom to capture theory atoms in bodies)
//   - StmTheoryAtom    (statement to capture theory atoms in heads)
 
 
using TheoryRGuard = std::optional<std::pair<String, UTheoryTerm>>;
 
class AtomTheory {
  public:
    AtomTheory(Symbol name, std::optional<size_t> rhs) : name_{name}, rhs_{rhs ? *rhs : invalid_offset} {}
 
    void add_elem(size_t idx);
    [[nodiscard]] auto elems() const -> std::span<size_t const>;
 
    [[nodiscard]] auto uid() const -> std::optional<size_t>;
    void uid(size_t uid);
 
    [[nodiscard]] auto name() const -> Symbol { return name_; }
 
    [[nodiscard]] auto rhs() const -> std::optional<size_t> {
        if (rhs_ != invalid_offset) {
            return rhs_;
        }
        return std::nullopt;
    }
 
  private:
    Util::small_vector<size_t> elems_;
    Symbol name_;
    size_t uid_ = invalid_offset;
    size_t rhs_;
};
 
class BaseTheory : public BaseImpl<Symbol const *, BaseTheory> {
  public:
    using BaseImpl::contains;
    using AtomMap = Util::ordered_map<Symbol const *, AtomTheory, Util::array_hash, Util::array_equal_to>;
 
    BaseTheory(size_t size) : atoms_{0, size, size} {}
 
    auto add(Symbol const *sym, Symbol name, std::optional<size_t> rhs) -> std::pair<AtomMap::iterator, bool>;
 
    [[nodiscard]] auto size() const -> size_t;
 
    [[nodiscard]] auto index(Symbol const *sym) const -> size_t;
    [[nodiscard]] auto nth(size_t i) const -> AtomMap::const_iterator;
    [[nodiscard]] auto nth(size_t i) -> AtomMap::iterator;
 
    [[nodiscard]] auto atoms() -> AtomMap &;
 
  private:
    AtomMap atoms_;
};
 
class StateTheory : public Ground::State {
  public:
    class ElementKey {
      private:
        struct priv_tag {};
 
      public:
        ElementKey(priv_tag tag, EvalContext const &ctx, OutputTheory &out, size_t atom_idx,
                   UTheoryTermVec const &terms);
        ElementKey(ElementKey const &other) = delete;
        static void construct(std::pmr::monotonic_buffer_resource &mbr, EvalContext const &ctx, OutputTheory &out,
                              size_t atom_idx, UTheoryTermVec const &terms, ElementKey *&target);
 
        [[nodiscard]] auto terms() const -> UTheoryTermVec const &;
        [[nodiscard]] auto size() const -> size_t;
        [[nodiscard]] auto span() const -> std::span<size_t const>;
        [[nodiscard]] auto hash() const -> size_t;
        friend auto operator==(ElementKey const &a, ElementKey const &b) -> bool;
 
      private:
        size_t n_;
        size_t atom_idx_;
        // NOLINTBEGIN
        CLINGO_IGNORE_ZERO_SIZED_ARRAY_B
        size_t syms_[0];
        CLINGO_IGNORE_ZERO_SIZED_ARRAY_E
        // NOLINTEND
    };
 
    using AtomMap = BaseTheory::AtomMap;
    using ElementMap = Util::ordered_map<ElementKey *, Util::small_vector<size_t>>;
 
    StateTheory(std::pmr::monotonic_buffer_resource &mbr, VariableVec global, UTerm name, TheoryRGuard guard,
                OutputTheory::AtomType type)
        : base_{global.size()}, mbr_{&mbr}, global_{std::move(global)}, name_{std::move(name)},
          guard_{std::move(guard)}, type_{type} {}
 
    auto find_atom(Assignment &ass) -> AtomMap::iterator;
    auto insert_atom(Symbol name, std::optional<size_t> rhs, Assignment &ass) -> std::pair<AtomMap::iterator, bool>;
    void insert_elem(EvalContext const &ctx, AtomMap::iterator it, UTheoryTermVec const &tuple, ElementKey *&elem_key,
                     auto const &get_cond);
    void print(std::ostream &out);
    void output(Logger &log, SymbolStore &store, OutputStm &out) override;
    [[nodiscard]] auto global() const -> VariableVec const &;
    [[nodiscard]] auto name() const -> UTerm const &;
    [[nodiscard]] auto guard() const -> TheoryRGuard const &;
    [[nodiscard]] auto base() -> BaseTheory &;
    void elems(UStmVec elems);
 
  private:
    BaseTheory base_;
    ElementMap tuples_;
    std::pmr::monotonic_buffer_resource *mbr_;
    VariableVec global_;
    UTerm name_;
    TheoryRGuard guard_;
    UStmVec elems_;
    Symbol *atom_key_ = nullptr;
    OutputTheory::AtomType type_;
};
 
class MatchTheory {
  public:
    using Key = Symbol const *;
 
    MatchTheory(StateTheory &state) : state_{&state} { eval_.reserve(state_->global().size()); }
 
    [[nodiscard]] auto vars() const -> VariableSet;
 
    [[nodiscard]] auto signature(VariableSet const &bound, VariableSet const &bind) const -> VariableVec;
 
    [[nodiscard]] auto match(EvalContext const &ctx, Symbol const *sym) const -> bool;
 
    [[nodiscard]] auto eval(EvalContext const &ctx) const -> std::optional<Symbol const *>;
 
    friend auto operator<<(std::ostream &out, MatchTheory const &m) -> std::ostream &;
 
    [[nodiscard]] auto state() const -> StateTheory &;
 
  private:
    std::vector<Symbol> mutable eval_;
    StateTheory *state_;
};
 
class LitMatchTheory : public Lit, private MatchTheory {
  public:
    LitMatchTheory(StateTheory &state) : MatchTheory{state} {}
 
  private:
    void do_vars(VariableSet &vars, VarSelectMode mode) const override;
    [[nodiscard]] auto do_domain() const -> bool override;
    [[nodiscard]] auto do_single_pass() const -> bool override;
    [[nodiscard]] auto do_matcher(std::pmr::monotonic_buffer_resource &mbr, MatcherType type,
                                  std::vector<bool> const &bound)
        -> std::pair<UMatcher, std::optional<size_t>> override;
    [[nodiscard]] auto do_score(std::vector<bool> const &bound) const -> double override;
    void do_print(std::ostream &out) const override;
    auto do_output(EvalContext const &ctx, OutputLit &out) const -> bool override;
    [[nodiscard]] auto do_copy() const -> ULit override;
    [[nodiscard]] auto do_hash() const -> size_t override;
    [[nodiscard]] auto do_equal_to(Lit const &other) const -> bool override;
    [[nodiscard]] auto do_compare_to(Lit const &other) const -> std::weak_ordering override;
 
    size_t offset_ = invalid_offset;
};
 
class StmTheoryElement : public Stm {
  public:
    StmTheoryElement(StateTheory &state, UTheoryTermVec tuple, ULitVec body)
        : state_{&state}, tuple_{std::move(tuple)}, body_{std::move(body)} {}
 
  private:
    [[nodiscard]] auto do_body() const -> ULitVec const & override;
    [[nodiscard]] auto do_important() const -> VariableSet override;
    void do_init([[maybe_unused]] size_t gen) override;
    [[nodiscard]] auto do_report(EvalContext const &ctx) -> bool override;
    void do_propagate(SymbolStore &store, OutputStm &out, Queue &queue) override;
    [[nodiscard]] auto do_priority() const -> size_t override;
    void do_print_head(std::ostream &out) const override;
    void do_print(std::ostream &out) const override;
 
    StateTheory *state_;
    StateTheory::ElementKey *elem_key_ = nullptr;
    UTheoryTermVec tuple_;
    ULitVec body_;
};
 
class LitBdTheory : public Lit {
  public:
    LitBdTheory(StateTheory &state, Sign sign) : state_{&state}, sign_{sign} {}
 
  private:
    void do_vars(VariableSet &vars, VarSelectMode mode) const override;
    [[nodiscard]] auto do_domain() const -> bool override;
    [[nodiscard]] auto do_single_pass() const -> bool override;
    [[nodiscard]] auto do_matcher(std::pmr::monotonic_buffer_resource &mbr, MatcherType type,
                                  std::vector<bool> const &bound)
        -> std::pair<UMatcher, std::optional<size_t>> override;
    [[nodiscard]] auto do_score(std::vector<bool> const &bound) const -> double override;
    void do_print(std::ostream &out) const override;
    auto do_output(EvalContext const &ctx, OutputLit &out) const -> bool override;
    [[nodiscard]] auto do_copy() const -> ULit override;
    [[nodiscard]] auto do_hash() const -> size_t override;
    [[nodiscard]] auto do_equal_to(Lit const &other) const -> bool override;
    [[nodiscard]] auto do_compare_to(Lit const &other) const -> std::weak_ordering override;
 
    StateTheory *state_;
    Symbol name_;
    Sign sign_;
};
 
class StmHdTheory : public Stm {
  public:
    StmHdTheory(StateTheory &state, ULitVec body) : state_{&state}, body_{std::move(body)} {}
 
  private:
    [[nodiscard]] auto do_body() const -> ULitVec const & override;
    [[nodiscard]] auto do_important() const -> VariableSet override;
    void do_init([[maybe_unused]] size_t gen) override;
    [[nodiscard]] auto do_report(EvalContext const &ctx) -> bool override;
    void do_propagate(SymbolStore &store, OutputStm &out, Queue &queue) override;
    [[nodiscard]] auto do_priority() const -> size_t override;
    void do_print_head(std::ostream &out) const override;
    void do_print(std::ostream &out) const override;
 
    StateTheory *state_;
    ULitVec body_;
};
 
 
} // namespace CppClingo::Ground