smt_terms.h

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// Author: Diffblue Ltd.
 
#ifndef CPROVER_SOLVERS_SMT2_INCREMENTAL_SMT_TERMS_H
#define CPROVER_SOLVERS_SMT2_INCREMENTAL_SMT_TERMS_H
 
#include <util/irep.h>
 
#include <solvers/smt2_incremental/response_or_error.h>
 
#include "smt_index.h"
#include "smt_sorts.h"
 
#include <functional>
#include <utility>
 
class BigInt; // IWYU pragma: keep
using mp_integer = BigInt;
 
class smt_term_const_downcast_visitort;
class smt_termt : protected irept, private smt_sortt::storert<smt_termt>
{
public:
  // smt_termt does not support the notion of an empty / null state. Use
  // std::optional<smt_termt> instead if an empty term is required.
  smt_termt() = delete;
 
  using irept::pretty;
 
  bool operator==(const smt_termt &) const;
  bool operator!=(const smt_termt &) const;
 
  const smt_sortt &get_sort() const;
 
  void accept(smt_term_const_downcast_visitort &) const;
  void accept(smt_term_const_downcast_visitort &&) const;
 
  template <typename derivedt>
  class storert
  {
  protected:
    storert();
    static irept upcast(smt_termt term);
    static const smt_termt &downcast(const irept &);
  };
 
protected:
  smt_termt(irep_idt id, smt_sortt sort);
};
 
template <typename derivedt>
smt_termt::storert<derivedt>::storert()
{
  static_assert(
    std::is_base_of<irept, derivedt>::value &&
      std::is_base_of<storert<derivedt>, derivedt>::value,
    "Only irept based classes need to upcast smt_termt to store it.");
}
 
template <typename derivedt>
irept smt_termt::storert<derivedt>::upcast(smt_termt term)
{
  return static_cast<irept &&>(std::move(term));
}
 
template <typename derivedt>
const smt_termt &smt_termt::storert<derivedt>::downcast(const irept &irep)
{
  return static_cast<const smt_termt &>(irep);
}
 
class smt_bool_literal_termt : public smt_termt
{
public:
  explicit smt_bool_literal_termt(bool value);
  bool value() const;
};
 
class smt_identifier_termt : public smt_termt,
                             private smt_indext::storert<smt_identifier_termt>
{
public:
  smt_identifier_termt(
    irep_idt identifier,
    smt_sortt sort,
    std::vector<smt_indext> indices = {});
  irep_idt identifier() const;
  std::vector<std::reference_wrapper<const smt_indext>> indices() const;
};
 
class smt_bit_vector_constant_termt : public smt_termt
{
public:
  smt_bit_vector_constant_termt(const mp_integer &value, smt_bit_vector_sortt);
  smt_bit_vector_constant_termt(const mp_integer &value, std::size_t bit_width);
  mp_integer value() const;
 
  // This deliberately hides smt_termt::get_sort, because bit_vector terms
  // always have bit_vector sorts. The same sort data is returned for both
  // functions either way. Therefore this hiding is benign if the kind of sort
  // is not important and useful for avoiding casts if the term is a known
  // smt_bit_vector_constant_termt at compile time and the `bit_width()` is
  // needed.
  const smt_bit_vector_sortt &get_sort() const;
};
 
class smt_function_application_termt : public smt_termt
{
private:
  smt_function_application_termt(
    smt_identifier_termt function_identifier,
    std::vector<smt_termt> arguments);
 
  // This is used to detect if \p functiont has an `indicies` member function.
  // It will resolve to std::true_type if it does or std::false type otherwise.
  template <class functiont, class = void>
  struct has_indicest : std::false_type
  {
  };
 
  template <class functiont>
  struct has_indicest<
    functiont,
    std::void_t<decltype(std::declval<functiont>().indices())>> : std::true_type
  {
  };
 
  template <class functiont>
  static std::vector<smt_indext> indices(const functiont &function)
  {
    if constexpr(has_indicest<functiont>::value)
      return function.indices();
    else
      return {};
  }
 
public:
  const smt_identifier_termt &function_identifier() const;
  std::vector<std::reference_wrapper<const smt_termt>> arguments() const;
 
  template <typename functiont>
  class factoryt
  {
  private:
    functiont function;
 
  public:
    template <typename... function_type_argument_typest>
    explicit factoryt(function_type_argument_typest &&...arguments) noexcept
      : function{std::forward<function_type_argument_typest>(arguments)...}
    {
    }
 
    template <typename... argument_typest>
    smt_function_application_termt
    operator()(argument_typest &&...arguments) const
    {
      function.validate(arguments...);
      auto return_sort = function.return_sort(arguments...);
      return smt_function_application_termt{
        smt_identifier_termt{
          function.identifier(), std::move(return_sort), indices(function)},
        {std::forward<argument_typest>(arguments)...}};
    }
 
    template <typename... argument_typest>
    response_or_errort<smt_termt>
    validation(argument_typest &&...arguments) const
    {
      const auto validation_errors = function.validation_errors(arguments...);
      if(!validation_errors.empty())
        return response_or_errort<smt_termt>{validation_errors};
      auto return_sort = function.return_sort(arguments...);
      return response_or_errort<smt_termt>{smt_function_application_termt{
        smt_identifier_termt{
          function.identifier(), std::move(return_sort), indices(function)},
        {std::forward<argument_typest>(arguments)...}}};
    }
  };
};
 
class smt_forall_termt : public smt_termt
{
public:
  smt_forall_termt(
    std::vector<smt_identifier_termt> bound_variables,
    smt_termt predicate);
  std::vector<std::reference_wrapper<const smt_identifier_termt>>
  bound_variables() const;
  const smt_termt &predicate() const;
};
 
class smt_exists_termt : public smt_termt
{
public:
  smt_exists_termt(
    std::vector<smt_identifier_termt> bound_variables,
    smt_termt predicate);
  std::vector<std::reference_wrapper<const smt_identifier_termt>>
  bound_variables() const;
  const smt_termt &predicate() const;
};
 
class smt_term_const_downcast_visitort
{
public:
#define TERM_ID(the_id) virtual void visit(const smt_##the_id##_termt &) = 0;
#include "smt_terms.def"
#undef TERM_ID
};
 
#endif // CPROVER_SOLVERS_SMT2_INCREMENTAL_SMT_TERMS_H