412 lines
17 KiB
C++
412 lines
17 KiB
C++
/*
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* Copyright © 2018 Google, Inc.
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*
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* This is part of HarfBuzz, a text shaping library.
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*
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* Permission is hereby granted, without written agreement and without
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* license or royalty fees, to use, copy, modify, and distribute this
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* software and its documentation for any purpose, provided that the
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* above copyright notice and the following two paragraphs appear in
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* all copies of this software.
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*
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* IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
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* DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
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* ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
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* IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
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* DAMAGE.
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*
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* THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
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* BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
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* FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS
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* ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
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* PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
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*
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* Google Author(s): Behdad Esfahbod
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*/
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#ifndef HB_META_HH
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#define HB_META_HH
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#include "hb.hh"
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/*
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* C++ template meta-programming & fundamentals used with them.
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*/
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/* Void! For when we need a expression-type of void. */
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struct hb_empty_t {};
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/* https://en.cppreference.com/w/cpp/types/void_t */
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template<typename... Ts> struct _hb_void_t { typedef void type; };
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template<typename... Ts> using hb_void_t = typename _hb_void_t<Ts...>::type;
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template<typename Head, typename... Ts> struct _hb_head_t { typedef Head type; };
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template<typename... Ts> using hb_head_t = typename _hb_head_t<Ts...>::type;
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template <typename T, T v> struct hb_integral_constant { static constexpr T value = v; };
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template <bool b> using hb_bool_constant = hb_integral_constant<bool, b>;
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using hb_true_type = hb_bool_constant<true>;
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using hb_false_type = hb_bool_constant<false>;
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/* Basic type SFINAE. */
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template <bool B, typename T = void> struct hb_enable_if {};
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template <typename T> struct hb_enable_if<true, T> { typedef T type; };
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#define hb_enable_if(Cond) typename hb_enable_if<(Cond)>::type* = nullptr
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/* Concepts/Requires alias: */
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#define hb_requires(Cond) hb_enable_if((Cond))
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template <typename T, typename T2> struct hb_is_same : hb_false_type {};
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template <typename T> struct hb_is_same<T, T> : hb_true_type {};
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#define hb_is_same(T, T2) hb_is_same<T, T2>::value
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/* Function overloading SFINAE and priority. */
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#define HB_RETURN(Ret, E) -> hb_head_t<Ret, decltype ((E))> { return (E); }
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#define HB_AUTO_RETURN(E) -> decltype ((E)) { return (E); }
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#define HB_VOID_RETURN(E) -> hb_void_t<decltype ((E))> { (E); }
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template <unsigned Pri> struct hb_priority : hb_priority<Pri - 1> {};
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template <> struct hb_priority<0> {};
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#define hb_prioritize hb_priority<16> ()
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#define HB_FUNCOBJ(x) static_const x HB_UNUSED
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template <typename T> struct hb_type_identity_t { typedef T type; };
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template <typename T> using hb_type_identity = typename hb_type_identity_t<T>::type;
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struct
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{
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template <typename T> constexpr T*
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operator () (T& arg) const
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{
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#pragma GCC diagnostic push
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#pragma GCC diagnostic ignored "-Wcast-align"
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/* https://en.cppreference.com/w/cpp/memory/addressof */
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return reinterpret_cast<T*> (
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&const_cast<char&> (
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reinterpret_cast<const volatile char&> (arg)));
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#pragma GCC diagnostic pop
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}
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}
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HB_FUNCOBJ (hb_addressof);
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template <typename T> static inline T hb_declval ();
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#define hb_declval(T) (hb_declval<T> ())
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template <typename T> struct hb_match_const : hb_type_identity_t<T>, hb_bool_constant<false>{};
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template <typename T> struct hb_match_const<const T> : hb_type_identity_t<T>, hb_bool_constant<true> {};
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template <typename T> using hb_remove_const = typename hb_match_const<T>::type;
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template <typename T> using hb_add_const = const T;
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#define hb_is_const(T) hb_match_const<T>::value
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template <typename T> struct hb_match_reference : hb_type_identity_t<T>, hb_bool_constant<false>{};
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template <typename T> struct hb_match_reference<T &> : hb_type_identity_t<T>, hb_bool_constant<true> {};
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template <typename T> struct hb_match_reference<T &&> : hb_type_identity_t<T>, hb_bool_constant<true> {};
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template <typename T> using hb_remove_reference = typename hb_match_reference<T>::type;
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template <typename T> auto _hb_try_add_lvalue_reference (hb_priority<1>) -> hb_type_identity<T&>;
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template <typename T> auto _hb_try_add_lvalue_reference (hb_priority<0>) -> hb_type_identity<T>;
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template <typename T> using hb_add_lvalue_reference = decltype (_hb_try_add_lvalue_reference<T> (hb_prioritize));
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template <typename T> auto _hb_try_add_rvalue_reference (hb_priority<1>) -> hb_type_identity<T&&>;
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template <typename T> auto _hb_try_add_rvalue_reference (hb_priority<0>) -> hb_type_identity<T>;
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template <typename T> using hb_add_rvalue_reference = decltype (_hb_try_add_rvalue_reference<T> (hb_prioritize));
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#define hb_is_reference(T) hb_match_reference<T>::value
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template <typename T> struct hb_match_pointer : hb_type_identity_t<T>, hb_bool_constant<false>{};
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template <typename T> struct hb_match_pointer<T *> : hb_type_identity_t<T>, hb_bool_constant<true> {};
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template <typename T> using hb_remove_pointer = typename hb_match_pointer<T>::type;
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template <typename T> auto _hb_try_add_pointer (hb_priority<1>) -> hb_type_identity<hb_remove_reference<T>*>;
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template <typename T> auto _hb_try_add_pointer (hb_priority<1>) -> hb_type_identity<T>;
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template <typename T> using hb_add_pointer = decltype (_hb_try_add_pointer<T> (hb_prioritize));
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#define hb_is_pointer(T) hb_match_pointer<T>::value
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/* TODO Add feature-parity to std::decay. */
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template <typename T> using hb_decay = hb_remove_const<hb_remove_reference<T>>;
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template<bool B, class T, class F>
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struct _hb_conditional { typedef T type; };
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template<class T, class F>
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struct _hb_conditional<false, T, F> { typedef F type; };
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template<bool B, class T, class F>
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using hb_conditional = typename _hb_conditional<B, T, F>::type;
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template <typename From, typename To>
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struct hb_is_convertible
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{
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private:
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static constexpr bool from_void = hb_is_same (void, hb_decay<From>);
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static constexpr bool to_void = hb_is_same (void, hb_decay<To> );
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static constexpr bool either_void = from_void || to_void;
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static constexpr bool both_void = from_void && to_void;
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static hb_true_type impl2 (hb_conditional<to_void, int, To>);
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template <typename T>
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static auto impl (hb_priority<1>) -> decltype (impl2 (hb_declval (T)));
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template <typename T>
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static hb_false_type impl (hb_priority<0>);
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public:
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static constexpr bool value = both_void ||
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(!either_void &&
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decltype (impl<hb_conditional<from_void, int, From>> (hb_prioritize))::value);
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};
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#define hb_is_convertible(From,To) hb_is_convertible<From, To>::value
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template <typename Base, typename Derived>
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using hb_is_base_of = hb_is_convertible<hb_decay<Derived> *, hb_decay<Base> *>;
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#define hb_is_base_of(Base,Derived) hb_is_base_of<Base, Derived>::value
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template <typename From, typename To>
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using hb_is_cr_convertible = hb_bool_constant<
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hb_is_same (hb_decay<From>, hb_decay<To>) &&
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(!hb_is_const (From) || hb_is_const (To)) &&
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(!hb_is_reference (To) || hb_is_const (To) || hb_is_reference (To))
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>;
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#define hb_is_cr_convertible(From,To) hb_is_cr_convertible<From, To>::value
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/* std::move and std::forward */
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template <typename T>
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static constexpr hb_remove_reference<T>&& hb_move (T&& t) { return (hb_remove_reference<T>&&) (t); }
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template <typename T>
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static constexpr T&& hb_forward (hb_remove_reference<T>& t) { return (T&&) t; }
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template <typename T>
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static constexpr T&& hb_forward (hb_remove_reference<T>&& t) { return (T&&) t; }
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struct
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{
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template <typename T> constexpr auto
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operator () (T&& v) const HB_AUTO_RETURN (hb_forward<T> (v))
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template <typename T> constexpr auto
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operator () (T *v) const HB_AUTO_RETURN (*v)
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}
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HB_FUNCOBJ (hb_deref);
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struct
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{
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template <typename T> constexpr auto
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operator () (T&& v) const HB_AUTO_RETURN (hb_forward<T> (v))
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template <typename T> constexpr auto
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operator () (T& v) const HB_AUTO_RETURN (hb_addressof (v))
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}
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HB_FUNCOBJ (hb_ref);
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template <typename T>
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struct hb_reference_wrapper
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{
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hb_reference_wrapper (T v) : v (v) {}
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bool operator == (const hb_reference_wrapper& o) const { return v == o.v; }
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bool operator != (const hb_reference_wrapper& o) const { return v != o.v; }
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operator T () const { return v; }
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T get () const { return v; }
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T v;
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};
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template <typename T>
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struct hb_reference_wrapper<T&>
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{
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hb_reference_wrapper (T& v) : v (hb_addressof (v)) {}
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bool operator == (const hb_reference_wrapper& o) const { return v == o.v; }
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bool operator != (const hb_reference_wrapper& o) const { return v != o.v; }
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operator T& () const { return *v; }
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T& get () const { return *v; }
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T* v;
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};
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template <typename T>
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using hb_is_integral = hb_bool_constant<
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hb_is_same (hb_decay<T>, char) ||
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hb_is_same (hb_decay<T>, signed char) ||
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hb_is_same (hb_decay<T>, unsigned char) ||
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hb_is_same (hb_decay<T>, signed int) ||
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hb_is_same (hb_decay<T>, unsigned int) ||
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hb_is_same (hb_decay<T>, signed short) ||
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hb_is_same (hb_decay<T>, unsigned short) ||
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hb_is_same (hb_decay<T>, signed long) ||
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hb_is_same (hb_decay<T>, unsigned long) ||
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hb_is_same (hb_decay<T>, signed long long) ||
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hb_is_same (hb_decay<T>, unsigned long long) ||
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false
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>;
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#define hb_is_integral(T) hb_is_integral<T>::value
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template <typename T>
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using hb_is_floating_point = hb_bool_constant<
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hb_is_same (hb_decay<T>, float) ||
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hb_is_same (hb_decay<T>, double) ||
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hb_is_same (hb_decay<T>, long double) ||
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false
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>;
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#define hb_is_floating_point(T) hb_is_floating_point<T>::value
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template <typename T>
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using hb_is_arithmetic = hb_bool_constant<
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hb_is_integral (T) ||
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hb_is_floating_point (T) ||
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false
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>;
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#define hb_is_arithmetic(T) hb_is_arithmetic<T>::value
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template <typename T>
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using hb_is_signed = hb_conditional<hb_is_arithmetic (T),
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hb_bool_constant<(T) -1 < (T) 0>,
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hb_false_type>;
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#define hb_is_signed(T) hb_is_signed<T>::value
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template <typename T>
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using hb_is_unsigned = hb_conditional<hb_is_arithmetic (T),
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hb_bool_constant<(T) 0 < (T) -1>,
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hb_false_type>;
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#define hb_is_unsigned(T) hb_is_unsigned<T>::value
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template <typename T> struct hb_int_min;
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template <> struct hb_int_min<char> : hb_integral_constant<char, CHAR_MIN> {};
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template <> struct hb_int_min<signed char> : hb_integral_constant<signed char, SCHAR_MIN> {};
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template <> struct hb_int_min<unsigned char> : hb_integral_constant<unsigned char, 0> {};
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template <> struct hb_int_min<signed short> : hb_integral_constant<signed short, SHRT_MIN> {};
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template <> struct hb_int_min<unsigned short> : hb_integral_constant<unsigned short, 0> {};
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template <> struct hb_int_min<signed int> : hb_integral_constant<signed int, INT_MIN> {};
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template <> struct hb_int_min<unsigned int> : hb_integral_constant<unsigned int, 0> {};
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template <> struct hb_int_min<signed long> : hb_integral_constant<signed long, LONG_MIN> {};
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template <> struct hb_int_min<unsigned long> : hb_integral_constant<unsigned long, 0> {};
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template <> struct hb_int_min<signed long long> : hb_integral_constant<signed long long, LLONG_MIN> {};
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template <> struct hb_int_min<unsigned long long> : hb_integral_constant<unsigned long long, 0> {};
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#define hb_int_min(T) hb_int_min<T>::value
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template <typename T> struct hb_int_max;
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template <> struct hb_int_max<char> : hb_integral_constant<char, CHAR_MAX> {};
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template <> struct hb_int_max<signed char> : hb_integral_constant<signed char, SCHAR_MAX> {};
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template <> struct hb_int_max<unsigned char> : hb_integral_constant<unsigned char, UCHAR_MAX> {};
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template <> struct hb_int_max<signed short> : hb_integral_constant<signed short, SHRT_MAX> {};
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template <> struct hb_int_max<unsigned short> : hb_integral_constant<unsigned short, USHRT_MAX> {};
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template <> struct hb_int_max<signed int> : hb_integral_constant<signed int, INT_MAX> {};
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template <> struct hb_int_max<unsigned int> : hb_integral_constant<unsigned int, UINT_MAX> {};
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template <> struct hb_int_max<signed long> : hb_integral_constant<signed long, LONG_MAX> {};
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template <> struct hb_int_max<unsigned long> : hb_integral_constant<unsigned long, ULONG_MAX> {};
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template <> struct hb_int_max<signed long long> : hb_integral_constant<signed long long, LLONG_MAX> {};
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template <> struct hb_int_max<unsigned long long> : hb_integral_constant<unsigned long long, ULLONG_MAX> {};
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#define hb_int_max(T) hb_int_max<T>::value
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template <typename T, typename>
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struct _hb_is_destructible : hb_false_type {};
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template <typename T>
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struct _hb_is_destructible<T, hb_void_t<decltype (hb_declval (T).~T ())>> : hb_true_type {};
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template <typename T>
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using hb_is_destructible = _hb_is_destructible<T, void>;
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#define hb_is_destructible(T) hb_is_destructible<T>::value
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template <typename T, typename, typename ...Ts>
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struct _hb_is_constructible : hb_false_type {};
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template <typename T, typename ...Ts>
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struct _hb_is_constructible<T, hb_void_t<decltype (T (hb_declval (Ts)...))>, Ts...> : hb_true_type {};
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template <typename T, typename ...Ts>
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using hb_is_constructible = _hb_is_constructible<T, void, Ts...>;
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#define hb_is_constructible(...) hb_is_constructible<__VA_ARGS__>::value
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template <typename T>
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using hb_is_default_constructible = hb_is_constructible<T>;
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#define hb_is_default_constructible(T) hb_is_default_constructible<T>::value
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template <typename T>
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using hb_is_copy_constructible = hb_is_constructible<T, hb_add_lvalue_reference<hb_add_const<T>>>;
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#define hb_is_copy_constructible(T) hb_is_copy_constructible<T>::value
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template <typename T>
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using hb_is_move_constructible = hb_is_constructible<T, hb_add_rvalue_reference<hb_add_const<T>>>;
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#define hb_is_move_constructible(T) hb_is_move_constructible<T>::value
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template <typename T, typename U, typename>
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struct _hb_is_assignable : hb_false_type {};
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template <typename T, typename U>
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struct _hb_is_assignable<T, U, hb_void_t<decltype (hb_declval (T) = hb_declval (U))>> : hb_true_type {};
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template <typename T, typename U>
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using hb_is_assignable = _hb_is_assignable<T, U, void>;
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#define hb_is_assignable(T,U) hb_is_assignable<T, U>::value
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template <typename T>
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using hb_is_copy_assignable = hb_is_assignable<hb_add_lvalue_reference<T>,
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hb_add_lvalue_reference<hb_add_const<T>>>;
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#define hb_is_copy_assignable(T) hb_is_copy_assignable<T>::value
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template <typename T>
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using hb_is_move_assignable = hb_is_assignable<hb_add_lvalue_reference<T>,
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hb_add_rvalue_reference<T>>;
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#define hb_is_move_assignable(T) hb_is_move_assignable<T>::value
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/* Trivial versions. */
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template <typename T> union hb_trivial { T value; };
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/* Don't know how to do the following. */
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template <typename T>
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using hb_is_trivially_destructible= hb_is_destructible<hb_trivial<T>>;
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#define hb_is_trivially_destructible(T) hb_is_trivially_destructible<T>::value
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/* Don't know how to do the following. */
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//template <typename T, typename ...Ts>
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//using hb_is_trivially_constructible= hb_is_constructible<hb_trivial<T>, hb_trivial<Ts>...>;
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//#define hb_is_trivially_constructible(...) hb_is_trivially_constructible<__VA_ARGS__>::value
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template <typename T>
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using hb_is_trivially_default_constructible= hb_is_default_constructible<hb_trivial<T>>;
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#define hb_is_trivially_default_constructible(T) hb_is_trivially_default_constructible<T>::value
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template <typename T>
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using hb_is_trivially_copy_constructible= hb_is_copy_constructible<hb_trivial<T>>;
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#define hb_is_trivially_copy_constructible(T) hb_is_trivially_copy_constructible<T>::value
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template <typename T>
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using hb_is_trivially_move_constructible= hb_is_move_constructible<hb_trivial<T>>;
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#define hb_is_trivially_move_constructible(T) hb_is_trivially_move_constructible<T>::value
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/* Don't know how to do the following. */
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//template <typename T, typename U>
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//using hb_is_trivially_assignable= hb_is_assignable<hb_trivial<T>, hb_trivial<U>>;
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//#define hb_is_trivially_assignable(T,U) hb_is_trivially_assignable<T, U>::value
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template <typename T>
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using hb_is_trivially_copy_assignable= hb_is_copy_assignable<hb_trivial<T>>;
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#define hb_is_trivially_copy_assignable(T) hb_is_trivially_copy_assignable<T>::value
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template <typename T>
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using hb_is_trivially_move_assignable= hb_is_move_assignable<hb_trivial<T>>;
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#define hb_is_trivially_move_assignable(T) hb_is_trivially_move_assignable<T>::value
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template <typename T>
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using hb_is_trivially_copyable= hb_bool_constant<
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hb_is_trivially_destructible (T) &&
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(!hb_is_move_assignable (T) || hb_is_trivially_move_assignable (T)) &&
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(!hb_is_move_constructible (T) || hb_is_trivially_move_constructible (T)) &&
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(!hb_is_copy_assignable (T) || hb_is_trivially_copy_assignable (T)) &&
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(!hb_is_copy_constructible (T) || hb_is_trivially_copy_constructible (T)) &&
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true
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>;
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#define hb_is_trivially_copyable(T) hb_is_trivially_copyable<T>::value
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template <typename T>
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using hb_is_trivial= hb_bool_constant<
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hb_is_trivially_copyable (T) &&
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hb_is_trivially_default_constructible (T)
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>;
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#define hb_is_trivial(T) hb_is_trivial<T>::value
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/* hb_unwrap_type (T)
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* If T has no T::type, returns T. Otherwise calls itself on T::type recursively.
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*/
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template <typename T, typename>
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struct _hb_unwrap_type : hb_type_identity_t<T> {};
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template <typename T>
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struct _hb_unwrap_type<T, hb_void_t<typename T::type>> : _hb_unwrap_type<typename T::type, void> {};
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template <typename T>
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using hb_unwrap_type = _hb_unwrap_type<T, void>;
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#define hb_unwrap_type(T) typename hb_unwrap_type<T>::type
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#endif /* HB_META_HH */
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