/* * Copyright © 2018 Google, Inc. * * This is part of HarfBuzz, a text shaping library. * * Permission is hereby granted, without written agreement and without * license or royalty fees, to use, copy, modify, and distribute this * software and its documentation for any purpose, provided that the * above copyright notice and the following two paragraphs appear in * all copies of this software. * * IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN * IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH * DAMAGE. * * THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING, * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND * FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS * ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS. * * Google Author(s): Behdad Esfahbod */ #ifndef HB_META_HH #define HB_META_HH #include "hb.hh" #include <memory> #include <type_traits> #include <utility> /* * C++ template meta-programming & fundamentals used with them. */ /* Void! For when we need a expression-type of void. */ struct hb_empty_t {}; /* https://en.cppreference.com/w/cpp/types/void_t */ template<typename... Ts> struct _hb_void_t { typedef void type; }; template<typename... Ts> using hb_void_t = typename _hb_void_t<Ts...>::type; template<typename Head, typename... Ts> struct _hb_head_t { typedef Head type; }; template<typename... Ts> using hb_head_t = typename _hb_head_t<Ts...>::type; template <typename T, T v> struct hb_integral_constant { static constexpr T value = v; }; template <bool b> using hb_bool_constant = hb_integral_constant<bool, b>; using hb_true_type = hb_bool_constant<true>; using hb_false_type = hb_bool_constant<false>; /* Static-assert as expression. */ template <bool cond> struct static_assert_expr; template <> struct static_assert_expr<true> : hb_false_type {}; #define static_assert_expr(C) static_assert_expr<C>::value /* Basic type SFINAE. */ template <bool B, typename T = void> struct hb_enable_if {}; template <typename T> struct hb_enable_if<true, T> { typedef T type; }; #define hb_enable_if(Cond) typename hb_enable_if<(Cond)>::type* = nullptr /* Concepts/Requires alias: */ #define hb_requires(Cond) hb_enable_if((Cond)) template <typename T, typename T2> struct hb_is_same : hb_false_type {}; template <typename T> struct hb_is_same<T, T> : hb_true_type {}; #define hb_is_same(T, T2) hb_is_same<T, T2>::value /* Function overloading SFINAE and priority. */ #define HB_RETURN(Ret, E) -> hb_head_t<Ret, decltype ((E))> { return (E); } #define HB_AUTO_RETURN(E) -> decltype ((E)) { return (E); } #define HB_VOID_RETURN(E) -> hb_void_t<decltype ((E))> { (E); } template <unsigned Pri> struct hb_priority : hb_priority<Pri - 1> {}; template <> struct hb_priority<0> {}; #define hb_prioritize hb_priority<16> () #define HB_FUNCOBJ(x) static_const x HB_UNUSED template <typename T> struct hb_type_identity_t { typedef T type; }; template <typename T> using hb_type_identity = typename hb_type_identity_t<T>::type; template <typename T> static inline T hb_declval (); #define hb_declval(T) (hb_declval<T> ()) template <typename T> struct hb_match_const : hb_type_identity_t<T>, hb_false_type {}; template <typename T> struct hb_match_const<const T> : hb_type_identity_t<T>, hb_true_type {}; template <typename T> using hb_remove_const = typename hb_match_const<T>::type; template <typename T> struct hb_match_reference : hb_type_identity_t<T>, hb_false_type {}; template <typename T> struct hb_match_reference<T &> : hb_type_identity_t<T>, hb_true_type {}; template <typename T> struct hb_match_reference<T &&> : hb_type_identity_t<T>, hb_true_type {}; template <typename T> using hb_remove_reference = typename hb_match_reference<T>::type; template <typename T> auto _hb_try_add_lvalue_reference (hb_priority<1>) -> hb_type_identity<T&>; template <typename T> auto _hb_try_add_lvalue_reference (hb_priority<0>) -> hb_type_identity<T>; template <typename T> using hb_add_lvalue_reference = decltype (_hb_try_add_lvalue_reference<T> (hb_prioritize)); template <typename T> auto _hb_try_add_rvalue_reference (hb_priority<1>) -> hb_type_identity<T&&>; template <typename T> auto _hb_try_add_rvalue_reference (hb_priority<0>) -> hb_type_identity<T>; template <typename T> using hb_add_rvalue_reference = decltype (_hb_try_add_rvalue_reference<T> (hb_prioritize)); template <typename T> struct hb_match_pointer : hb_type_identity_t<T>, hb_false_type {}; template <typename T> struct hb_match_pointer<T *> : hb_type_identity_t<T>, hb_true_type {}; template <typename T> using hb_remove_pointer = typename hb_match_pointer<T>::type; template <typename T> auto _hb_try_add_pointer (hb_priority<1>) -> hb_type_identity<hb_remove_reference<T>*>; template <typename T> auto _hb_try_add_pointer (hb_priority<1>) -> hb_type_identity<T>; template <typename T> using hb_add_pointer = decltype (_hb_try_add_pointer<T> (hb_prioritize)); /* TODO Add feature-parity to std::decay. */ template <typename T> using hb_decay = hb_remove_const<hb_remove_reference<T>>; #define hb_is_convertible(From,To) std::is_convertible<From, To>::value template <typename From, typename To> using hb_is_cr_convertible = hb_bool_constant< hb_is_same (hb_decay<From>, hb_decay<To>) && (!std::is_const<From>::value || std::is_const<To>::value) && (!std::is_reference<To>::value || std::is_const<To>::value || std::is_reference<To>::value) >; #define hb_is_cr_convertible(From,To) hb_is_cr_convertible<From, To>::value struct { template <typename T> constexpr auto operator () (T&& v) const HB_AUTO_RETURN (std::forward<T> (v)) template <typename T> constexpr auto operator () (T *v) const HB_AUTO_RETURN (*v) } HB_FUNCOBJ (hb_deref); template <typename T> struct hb_reference_wrapper { hb_reference_wrapper (T v) : v (v) {} bool operator == (const hb_reference_wrapper& o) const { return v == o.v; } bool operator != (const hb_reference_wrapper& o) const { return v != o.v; } operator T () const { return v; } T get () const { return v; } T v; }; template <typename T> struct hb_reference_wrapper<T&> { hb_reference_wrapper (T& v) : v (std::addressof (v)) {} bool operator == (const hb_reference_wrapper& o) const { return v == o.v; } bool operator != (const hb_reference_wrapper& o) const { return v != o.v; } operator T& () const { return *v; } T& get () const { return *v; } T* v; }; /* Type traits */ template <typename T> struct hb_int_min; template <> struct hb_int_min<char> : hb_integral_constant<char, CHAR_MIN> {}; template <> struct hb_int_min<signed char> : hb_integral_constant<signed char, SCHAR_MIN> {}; template <> struct hb_int_min<unsigned char> : hb_integral_constant<unsigned char, 0> {}; template <> struct hb_int_min<signed short> : hb_integral_constant<signed short, SHRT_MIN> {}; template <> struct hb_int_min<unsigned short> : hb_integral_constant<unsigned short, 0> {}; template <> struct hb_int_min<signed int> : hb_integral_constant<signed int, INT_MIN> {}; template <> struct hb_int_min<unsigned int> : hb_integral_constant<unsigned int, 0> {}; template <> struct hb_int_min<signed long> : hb_integral_constant<signed long, LONG_MIN> {}; template <> struct hb_int_min<unsigned long> : hb_integral_constant<unsigned long, 0> {}; template <> struct hb_int_min<signed long long> : hb_integral_constant<signed long long, LLONG_MIN> {}; template <> struct hb_int_min<unsigned long long> : hb_integral_constant<unsigned long long, 0> {}; template <typename T> struct hb_int_min<T *> : hb_integral_constant<T *, nullptr> {}; #define hb_int_min(T) hb_int_min<T>::value template <typename T> struct hb_int_max; template <> struct hb_int_max<char> : hb_integral_constant<char, CHAR_MAX> {}; template <> struct hb_int_max<signed char> : hb_integral_constant<signed char, SCHAR_MAX> {}; template <> struct hb_int_max<unsigned char> : hb_integral_constant<unsigned char, UCHAR_MAX> {}; template <> struct hb_int_max<signed short> : hb_integral_constant<signed short, SHRT_MAX> {}; template <> struct hb_int_max<unsigned short> : hb_integral_constant<unsigned short, USHRT_MAX> {}; template <> struct hb_int_max<signed int> : hb_integral_constant<signed int, INT_MAX> {}; template <> struct hb_int_max<unsigned int> : hb_integral_constant<unsigned int, UINT_MAX> {}; template <> struct hb_int_max<signed long> : hb_integral_constant<signed long, LONG_MAX> {}; template <> struct hb_int_max<unsigned long> : hb_integral_constant<unsigned long, ULONG_MAX> {}; template <> struct hb_int_max<signed long long> : hb_integral_constant<signed long long, LLONG_MAX> {}; template <> struct hb_int_max<unsigned long long> : hb_integral_constant<unsigned long long, ULLONG_MAX> {}; #define hb_int_max(T) hb_int_max<T>::value #if defined(__GNUC__) && __GNUC__ < 5 && !defined(__clang__) #define hb_is_trivially_copyable(T) __has_trivial_copy(T) #define hb_is_trivially_copy_assignable(T) __has_trivial_assign(T) #define hb_is_trivially_constructible(T) __has_trivial_constructor(T) #define hb_is_trivially_copy_constructible(T) __has_trivial_copy_constructor(T) #define hb_is_trivially_destructible(T) __has_trivial_destructor(T) #else #define hb_is_trivially_copyable(T) std::is_trivially_copyable<T>::value #define hb_is_trivially_copy_assignable(T) std::is_trivially_copy_assignable<T>::value #define hb_is_trivially_constructible(T) std::is_trivially_constructible<T>::value #define hb_is_trivially_copy_constructible(T) std::is_trivially_copy_constructible<T>::value #define hb_is_trivially_destructible(T) std::is_trivially_destructible<T>::value #endif /* Class traits. */ #define HB_DELETE_COPY_ASSIGN(TypeName) \ TypeName(const TypeName&) = delete; \ void operator=(const TypeName&) = delete #define HB_DELETE_CREATE_COPY_ASSIGN(TypeName) \ TypeName() = delete; \ TypeName(const TypeName&) = delete; \ void operator=(const TypeName&) = delete /* hb_unwrap_type (T) * If T has no T::type, returns T. Otherwise calls itself on T::type recursively. */ template <typename T, typename> struct _hb_unwrap_type : hb_type_identity_t<T> {}; template <typename T> struct _hb_unwrap_type<T, hb_void_t<typename T::type>> : _hb_unwrap_type<typename T::type, void> {}; template <typename T> using hb_unwrap_type = _hb_unwrap_type<T, void>; #define hb_unwrap_type(T) typename hb_unwrap_type<T>::type #endif /* HB_META_HH */