228 lines
10 KiB
C++
228 lines
10 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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#include <memory>
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#include <type_traits>
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#include <utility>
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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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/* Static-assert as expression. */
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template <bool cond> struct static_assert_expr;
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template <> struct static_assert_expr<true> : hb_false_type {};
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#define static_assert_expr(C) static_assert_expr<C>::value
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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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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_false_type {};
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template <typename T> struct hb_match_const<const T> : hb_type_identity_t<T>, hb_true_type {};
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template <typename T> using hb_remove_const = typename hb_match_const<T>::type;
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template <typename T> struct hb_match_reference : hb_type_identity_t<T>, hb_false_type {};
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template <typename T> struct hb_match_reference<T &> : hb_type_identity_t<T>, hb_true_type {};
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template <typename T> struct hb_match_reference<T &&> : hb_type_identity_t<T>, hb_true_type {};
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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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template <typename T> struct hb_match_pointer : hb_type_identity_t<T>, hb_false_type {};
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template <typename T> struct hb_match_pointer<T *> : hb_type_identity_t<T>, hb_true_type {};
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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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/* 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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#define hb_is_convertible(From,To) std::is_convertible<From, To>::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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(!std::is_const<From>::value || std::is_const<To>::value) &&
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(!std::is_reference<To>::value || std::is_const<To>::value || std::is_reference<To>::value)
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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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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 (std::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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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 (std::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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/* Type traits */
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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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template <typename T> struct hb_int_min<T *> : hb_integral_constant<T *, nullptr> {};
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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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#if defined(__GNUC__) && __GNUC__ < 5 && !defined(__clang__)
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#define hb_is_trivially_copyable(T) __has_trivial_copy(T)
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#define hb_is_trivially_copy_assignable(T) __has_trivial_assign(T)
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#define hb_is_trivially_constructible(T) __has_trivial_constructor(T)
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#define hb_is_trivially_copy_constructible(T) __has_trivial_copy_constructor(T)
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#define hb_is_trivially_destructible(T) __has_trivial_destructor(T)
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#else
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#define hb_is_trivially_copyable(T) std::is_trivially_copyable<T>::value
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#define hb_is_trivially_copy_assignable(T) std::is_trivially_copy_assignable<T>::value
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#define hb_is_trivially_constructible(T) std::is_trivially_constructible<T>::value
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#define hb_is_trivially_copy_constructible(T) std::is_trivially_copy_constructible<T>::value
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#define hb_is_trivially_destructible(T) std::is_trivially_destructible<T>::value
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#endif
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/* Class traits. */
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#define HB_DELETE_COPY_ASSIGN(TypeName) \
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TypeName(const TypeName&) = delete; \
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void operator=(const TypeName&) = delete
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#define HB_DELETE_CREATE_COPY_ASSIGN(TypeName) \
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TypeName() = delete; \
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TypeName(const TypeName&) = delete; \
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void operator=(const TypeName&) = delete
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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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