text: /*
      pybind11/attr.h: Infrastructure for processing custom
      type and function attributes
  
      Copyright (c) 2016 Wenzel Jakob <wenzel.jakob@epfl.ch>
  
      All rights reserved. Use of this source code is governed by a
      BSD-style license that can be found in the LICENSE file.
  */
  
  #pragma once
  
  #include "cast.h"
  
  NAMESPACE_BEGIN(pybind11)
  
  /// \addtogroup annotations
  /// @{
  
  /// Annotation for methods
  struct is_method { handle class_; is_method(const handle &c) : class_(c) { } };
  
  /// Annotation for operators
  struct is_operator { };
  
  /// Annotation for parent scope
  struct scope { handle value; scope(const handle &s) : value(s) { } };
  
  /// Annotation for documentation
  struct doc { const char *value; doc(const char *value) : value(value) { } };
  
  /// Annotation for function names
  struct name { const char *value; name(const char *value) : value(value) { } };
  
  /// Annotation indicating that a function is an overload associated with a given "sibling"
  struct sibling { handle value; sibling(const handle &value) : value(value.ptr()) { } };
  
  /// Annotation indicating that a class derives from another given type
  template <typename T> struct base {
      PYBIND11_DEPRECATED("base<T>() was deprecated in favor of specifying 'T' as a template argument to class_")
      base() { }
  };
  
  /// Keep patient alive while nurse lives
  template <size_t Nurse, size_t Patient> struct keep_alive { };
  
  /// Annotation indicating that a class is involved in a multiple inheritance relationship
  struct multiple_inheritance { };
  
  /// Annotation which enables dynamic attributes, i.e. adds `__dict__` to a class
  struct dynamic_attr { };
  
  /// Annotation which enables the buffer protocol for a type
  struct buffer_protocol { };
  
  /// Annotation which requests that a special metaclass is created for a type
  struct metaclass {
      handle value;
  
      PYBIND11_DEPRECATED("py::metaclass() is no longer required. It's turned on by default now.")
      metaclass() {}
  
      /// Override pybind11's default metaclass
      explicit metaclass(handle value) : value(value) { }
  };
  
  /// Annotation that marks a class as local to the module:
  struct module_local { const bool value; constexpr module_local(bool v = true) : value(v) { } };
  
  /// Annotation to mark enums as an arithmetic type
  struct arithmetic { };
  
  /** \rst
      A call policy which places one or more guard variables (``Ts...``) around the function call.
  
      For example, this definition:
  
      .. code-block:: cpp
  
          m.def("foo", foo, py::call_guard<T>());
  
      is equivalent to the following pseudocode:
  
      .. code-block:: cpp
  
          m.def("foo", [](args...) {
              T scope_guard;
              return foo(args...); // forwarded arguments
          });
   \endrst */
  template <typename... Ts> struct call_guard;
  
  template <> struct call_guard<> { using type = detail::void_type; };
  
  template <typename T>
  struct call_guard<T> {
      static_assert(std::is_default_constructible<T>::value,
                    "The guard type must be default constructible");
  
      using type = T;
  };
  
  template <typename T, typename... Ts>
  struct call_guard<T, Ts...> {
      struct type {
          T guard{}; // Compose multiple guard types with left-to-right default-constructor order
          typename call_guard<Ts...>::type next{};
      };
  };
  
  /// @} annotations
  
  NAMESPACE_BEGIN(detail)
  /* Forward declarations */
  enum op_id : int;
  enum op_type : int;
  struct undefined_t;
  template <op_id id, op_type ot, typename L = undefined_t, typename R = undefined_t> struct op_;
  template <typename... Args> struct init;
  template <typename... Args> struct init_alias;
  inline void keep_alive_impl(size_t Nurse, size_t Patient, function_call &call, handle ret);
  
  /// Internal data structure which holds metadata about a keyword argument
  struct argument_record {
      const char *name;  ///< Argument name
      const char *descr; ///< Human-readable version of the argument value
      handle value;      ///< Associated Python object
      bool convert : 1;  ///< True if the argument is allowed to convert when loading
      bool none : 1;     ///< True if None is allowed when loading
  
      argument_record(const char *name, const char *descr, handle value, bool convert, bool none)
          : name(name), descr(descr), value(value), convert(convert), none(none) { }
  };
  
  /// Internal data structure which holds metadata about a bound function (signature, overloads, etc.)
  struct function_record {
      function_record()
          : is_constructor(false), is_stateless(false), is_operator(false),
            has_args(false), has_kwargs(false), is_method(false) { }
  
      /// Function name
      char *name = nullptr; /* why no C++ strings? They generate heavier code.. */
  
      // User-specified documentation string
      char *doc = nullptr;
  
      /// Human-readable version of the function signature
      char *signature = nullptr;
  
      /// List of registered keyword arguments
      std::vector<argument_record> args;
  
      /// Pointer to lambda function which converts arguments and performs the actual call
      handle (*impl) (function_call &) = nullptr;
  
      /// Storage for the wrapped function pointer and captured data, if any
      void *data[3] = { };
  
      /// Pointer to custom destructor for 'data' (if needed)
      void (*free_data) (function_record *ptr) = nullptr;
  
      /// Return value policy associated with this function
      return_value_policy policy = return_value_policy::automatic;
  
      /// True if name == '__init__'
      bool is_constructor : 1;
  
      /// True if this is a stateless function pointer
      bool is_stateless : 1;
  
      /// True if this is an operator (__add__), etc.
      bool is_operator : 1;
  
      /// True if the function has a '*args' argument
      bool has_args : 1;
  
      /// True if the function has a '**kwargs' argument
      bool has_kwargs : 1;
  
      /// True if this is a method
      bool is_method : 1;
  
      /// Number of arguments (including py::args and/or py::kwargs, if present)
      std::uint16_t nargs;
  
      /// Python method object
      PyMethodDef *def = nullptr;
  
      /// Python handle to the parent scope (a class or a module)
      handle scope;
  
      /// Python handle to the sibling function representing an overload chain
      handle sibling;
  
      /// Pointer to next overload
      function_record *next = nullptr;
  };
  
  /// Special data structure which (temporarily) holds metadata about a bound class
  struct type_record {
      PYBIND11_NOINLINE type_record()
          : multiple_inheritance(false), dynamic_attr(false), buffer_protocol(false), module_local(false) { }
  
      /// Handle to the parent scope
      handle scope;
  
      /// Name of the class
      const char *name = nullptr;
  
      // Pointer to RTTI type_info data structure
      const std::type_info *type = nullptr;
  
      /// How large is the underlying C++ type?
      size_t type_size = 0;
  
      /// How large is the type's holder?
      size_t holder_size = 0;
  
      /// The global operator new can be overridden with a class-specific variant
      void *(*operator_new)(size_t) = ::operator new;
  
      /// Function pointer to class_<..>::init_instance
      void (*init_instance)(instance *, const void *) = nullptr;
  
      /// Function pointer to class_<..>::dealloc
      void (*dealloc)(const detail::value_and_holder &) = nullptr;
  
      /// List of base classes of the newly created type
      list bases;
  
      /// Optional docstring
      const char *doc = nullptr;
  
      /// Custom metaclass (optional)
      handle metaclass;
  
      /// Multiple inheritance marker
      bool multiple_inheritance : 1;
  
      /// Does the class manage a __dict__?
      bool dynamic_attr : 1;
  
      /// Does the class implement the buffer protocol?
      bool buffer_protocol : 1;
  
      /// Is the default (unique_ptr) holder type used?
      bool default_holder : 1;
  
      /// Is the class definition local to the module shared object?
      bool module_local : 1;
  
      PYBIND11_NOINLINE void add_base(const std::type_info &base, void *(*caster)(void *)) {
          auto base_info = detail::get_type_info(base, false);
          if (!base_info) {
              std::string tname(base.name());
              detail::clean_type_id(tname);
              pybind11_fail("generic_type: type \"" + std::string(name) +
                            "\" referenced unknown base type \"" + tname + "\"");
          }
  
          if (default_holder != base_info->default_holder) {
              std::string tname(base.name());
              detail::clean_type_id(tname);
              pybind11_fail("generic_type: type \"" + std::string(name) + "\" " +
                      (default_holder ? "does not have" : "has") +
                      " a non-default holder type while its base \"" + tname + "\" " +
                      (base_info->default_holder ? "does not" : "does"));
          }
  
          bases.append((PyObject *) base_info->type);
  
          if (base_info->type->tp_dictoffset != 0)
              dynamic_attr = true;
  
          if (caster)
              base_info->implicit_casts.emplace_back(type, caster);
      }
  };
  
  inline function_call::function_call(function_record &f, handle p) :
          func(f), parent(p) {
      args.reserve(f.nargs);
      args_convert.reserve(f.nargs);
  }
  
  /**
   * Partial template specializations to process custom attributes provided to
   * cpp_function_ and class_. These are either used to initialize the respective
   * fields in the type_record and function_record data structures or executed at
   * runtime to deal with custom call policies (e.g. keep_alive).
   */
  template <typename T, typename SFINAE = void> struct process_attribute;
  
  template <typename T> struct process_attribute_default {
      /// Default implementation: do nothing
      static void init(const T &, function_record *) { }
      static void init(const T &, type_record *) { }
      static void precall(function_call &) { }
      static void postcall(function_call &, handle) { }
  };
  
  /// Process an attribute specifying the function's name
  template <> struct process_attribute<name> : process_attribute_default<name> {
      static void init(const name &n, function_record *r) { r->name = const_cast<char *>(n.value); }
  };
  
  /// Process an attribute specifying the function's docstring
  template <> struct process_attribute<doc> : process_attribute_default<doc> {
      static void init(const doc &n, function_record *r) { r->doc = const_cast<char *>(n.value); }
  };
  
  /// Process an attribute specifying the function's docstring (provided as a C-style string)
  template <> struct process_attribute<const char *> : process_attribute_default<const char *> {
      static void init(const char *d, function_record *r) { r->doc = const_cast<char *>(d); }
      static void init(const char *d, type_record *r) { r->doc = const_cast<char *>(d); }
  };
  template <> struct process_attribute<char *> : process_attribute<const char *> { };
  
  /// Process an attribute indicating the function's return value policy
  template <> struct process_attribute<return_value_policy> : process_attribute_default<return_value_policy> {
      static void init(const return_value_policy &p, function_record *r) { r->policy = p; }
  };
  
  /// Process an attribute which indicates that this is an overloaded function associated with a given sibling
  template <> struct process_attribute<sibling> : process_attribute_default<sibling> {
      static void init(const sibling &s, function_record *r) { r->sibling = s.value; }
  };
  
  /// Process an attribute which indicates that this function is a method
  template <> struct process_attribute<is_method> : process_attribute_default<is_method> {
      static void init(const is_method &s, function_record *r) { r->is_method = true; r->scope = s.class_; }
  };
  
  /// Process an attribute which indicates the parent scope of a method
  template <> struct process_attribute<scope> : process_attribute_default<scope> {
      static void init(const scope &s, function_record *r) { r->scope = s.value; }
  };
  
  /// Process an attribute which indicates that this function is an operator
  template <> struct process_attribute<is_operator> : process_attribute_default<is_operator> {
      static void init(const is_operator &, function_record *r) { r->is_operator = true; }
  };
  
  /// Process a keyword argument attribute (*without* a default value)
  template <> struct process_attribute<arg> : process_attribute_default<arg> {
      static void init(const arg &a, function_record *r) {
          if (r->is_method && r->args.empty())
              r->args.emplace_back("self", nullptr, handle(), true /*convert*/, false /*none not allowed*/);
          r->args.emplace_back(a.name, nullptr, handle(), !a.flag_noconvert, a.flag_none);
      }
  };
  
  /// Process a keyword argument attribute (*with* a default value)
  template <> struct process_attribute<arg_v> : process_attribute_default<arg_v> {
      static void init(const arg_v &a, function_record *r) {
          if (r->is_method && r->args.empty())
              r->args.emplace_back("self", nullptr /*descr*/, handle() /*parent*/, true /*convert*/, false /*none not allowed*/);
  
          if (!a.value) {
  #if !defined(NDEBUG)
              std::string descr("'");
              if (a.name) descr += std::string(a.name) + ": ";
              descr += a.type + "'";
              if (r->is_method) {
                  if (r->name)
                      descr += " in method '" + (std::string) str(r->scope) + "." + (std::string) r->name + "'";
                  else
                      descr += " in method of '" + (std::string) str(r->scope) + "'";
              } else if (r->name) {
                  descr += " in function '" + (std::string) r->name + "'";
              }
              pybind11_fail("arg(): could not convert default argument "
                            + descr + " into a Python object (type not registered yet?)");
  #else
              pybind11_fail("arg(): could not convert default argument "
                            "into a Python object (type not registered yet?). "
                            "Compile in debug mode for more information.");
  #endif
          }
          r->args.emplace_back(a.name, a.descr, a.value.inc_ref(), !a.flag_noconvert, a.flag_none);
      }
  };
  
  /// Process a parent class attribute.  Single inheritance only (class_ itself already guarantees that)
  template <typename T>
  struct process_attribute<T, enable_if_t<is_pyobject<T>::value>> : process_attribute_default<handle> {
      static void init(const handle &h, type_record *r) { r->bases.append(h); }
  };
  
  /// Process a parent class attribute (deprecated, does not support multiple inheritance)
  template <typename T>
  struct process_attribute<base<T>> : process_attribute_default<base<T>> {
      static void init(const base<T> &, type_record *r) { r->add_base(typeid(T), nullptr); }
  };
  
  /// Process a multiple inheritance attribute
  template <>
  struct process_attribute<multiple_inheritance> : process_attribute_default<multiple_inheritance> {
      static void init(const multiple_inheritance &, type_record *r) { r->multiple_inheritance = true; }
  };
  
  template <>
  struct process_attribute<dynamic_attr> : process_attribute_default<dynamic_attr> {
      static void init(const dynamic_attr &, type_record *r) { r->dynamic_attr = true; }
  };
  
  template <>
  struct process_attribute<buffer_protocol> : process_attribute_default<buffer_protocol> {
      static void init(const buffer_protocol &, type_record *r) { r->buffer_protocol = true; }
  };
  
  template <>
  struct process_attribute<metaclass> : process_attribute_default<metaclass> {
      static void init(const metaclass &m, type_record *r) { r->metaclass = m.value; }
  };
  
  template <>
  struct process_attribute<module_local> : process_attribute_default<module_local> {
      static void init(const module_local &l, type_record *r) { r->module_local = l.value; }
  };
  
  /// Process an 'arithmetic' attribute for enums (does nothing here)
  template <>
  struct process_attribute<arithmetic> : process_attribute_default<arithmetic> {};
  
  template <typename... Ts>
  struct process_attribute<call_guard<Ts...>> : process_attribute_default<call_guard<Ts...>> { };
  
  /**
   * Process a keep_alive call policy -- invokes keep_alive_impl during the
   * pre-call handler if both Nurse, Patient != 0 and use the post-call handler
   * otherwise
   */
  template <size_t Nurse, size_t Patient> struct process_attribute<keep_alive<Nurse, Patient>> : public process_attribute_default<keep_alive<Nurse, Patient>> {
      template <size_t N = Nurse, size_t P = Patient, enable_if_t<N != 0 && P != 0, int> = 0>
      static void precall(function_call &call) { keep_alive_impl(Nurse, Patient, call, handle()); }
      template <size_t N = Nurse, size_t P = Patient, enable_if_t<N != 0 && P != 0, int> = 0>
      static void postcall(function_call &, handle) { }
      template <size_t N = Nurse, size_t P = Patient, enable_if_t<N == 0 || P == 0, int> = 0>
      static void precall(function_call &) { }
      template <size_t N = Nurse, size_t P = Patient, enable_if_t<N == 0 || P == 0, int> = 0>
      static void postcall(function_call &call, handle ret) { keep_alive_impl(Nurse, Patient, call, ret); }
  };
  
  /// Recursively iterate over variadic template arguments
  template <typename... Args> struct process_attributes {
      static void init(const Args&... args, function_record *r) {
          int unused[] = { 0, (process_attribute<typename std::decay<Args>::type>::init(args, r), 0) ... };
          ignore_unused(unused);
      }
      static void init(const Args&... args, type_record *r) {
          int unused[] = { 0, (process_attribute<typename std::decay<Args>::type>::init(args, r), 0) ... };
          ignore_unused(unused);
      }
      static void precall(function_call &call) {
          int unused[] = { 0, (process_attribute<typename std::decay<Args>::type>::precall(call), 0) ... };
          ignore_unused(unused);
      }
      static void postcall(function_call &call, handle fn_ret) {
          int unused[] = { 0, (process_attribute<typename std::decay<Args>::type>::postcall(call, fn_ret), 0) ... };
          ignore_unused(unused);
      }
  };
  
  template <typename T>
  using is_call_guard = is_instantiation<call_guard, T>;
  
  /// Extract the ``type`` from the first `call_guard` in `Extras...` (or `void_type` if none found)
  template <typename... Extra>
  using extract_guard_t = typename exactly_one_t<is_call_guard, call_guard<>, Extra...>::type;
  
  /// Check the number of named arguments at compile time
  template <typename... Extra,
            size_t named = constexpr_sum(std::is_base_of<arg, Extra>::value...),
            size_t self  = constexpr_sum(std::is_same<is_method, Extra>::value...)>
  constexpr bool expected_num_args(size_t nargs, bool has_args, bool has_kwargs) {
      return named == 0 || (self + named + has_args + has_kwargs) == nargs;
  }
  
  NAMESPACE_END(detail)
  NAMESPACE_END(pybind11)
  