181 lines
7.6 KiB
C++
181 lines
7.6 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_void_t { typedef void value; };
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/* Void meta-function ala std::void_t
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* https://en.cppreference.com/w/cpp/types/void_t */
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template<typename... Ts> struct _hb_void_tt { typedef void type; };
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template<typename... Ts> using hb_void_tt = typename _hb_void_tt<Ts...>::type;
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template<typename Head, typename... Ts> struct _hb_head_tt { typedef Head type; };
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template<typename... Ts> using hb_head_tt = typename _hb_head_tt<Ts...>::type;
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/* Bool! For when we need to evaluate type-dependent expressions
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* in a template argument. */
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template <bool b> struct hb_bool_tt { enum { value = b }; };
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typedef hb_bool_tt<true> hb_true_t;
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typedef hb_bool_tt<false> hb_false_t;
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/* Function overloading SFINAE and priority. */
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#define HB_RETURN(Ret, E) -> hb_head_tt<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_tt<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_match_identity { typedef T type; };
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template <typename T> using hb_type_identity = typename hb_match_identity<T>::type;
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struct
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{
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template <typename T>
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T* operator () (const 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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} 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 { typedef T type; enum { value = false }; };
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template <typename T> struct hb_match_const<const T> { typedef T type; enum { value = true }; };
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template <typename T> using hb_remove_const = typename hb_match_const<T>::type;
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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 { typedef T type; enum { value = false }; };
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template <typename T> struct hb_match_reference<T &> { typedef T type; enum { value = true }; };
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template <typename T> using hb_remove_reference = typename hb_match_reference<T>::type;
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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 { typedef T type; enum { value = false }; };
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template <typename T> struct hb_match_pointer<T *> { typedef T type; enum { value = true }; };
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template <typename T> using hb_remove_pointer = typename hb_match_pointer<T>::type;
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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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#define hb_is_cr_convertible_to(A, B) ( \
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hb_is_same (hb_decay<A>, hb_decay<B>) && \
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hb_is_const (A) <= hb_is_const (B) && \
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hb_is_reference (A) >= hb_is_reference (B))
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/* std::move and std::forward */
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template <typename T>
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static 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 T&& hb_forward (hb_remove_reference<T>& t) { return (T&&) t; }
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template <typename T>
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static 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> auto
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operator () (T&& v) const HB_AUTO_RETURN (hb_forward<T> (v))
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template <typename T> auto
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operator () (T *v) const HB_AUTO_RETURN (*v)
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} HB_FUNCOBJ (hb_deref_pointer);
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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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template <typename T, typename T2> struct hb_is_same : hb_false_t {};
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template <typename T> struct hb_is_same<T, T> : hb_true_t {};
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#define hb_is_same(T, T2) hb_is_same<T, T2>::value
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template <typename T> struct hb_is_signed;
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template <> struct hb_is_signed<char> { enum { value = CHAR_MIN < 0 }; };
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template <> struct hb_is_signed<signed char> { enum { value = true }; };
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template <> struct hb_is_signed<unsigned char> { enum { value = false }; };
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template <> struct hb_is_signed<signed short> { enum { value = true }; };
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template <> struct hb_is_signed<unsigned short> { enum { value = false }; };
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template <> struct hb_is_signed<signed int> { enum { value = true }; };
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template <> struct hb_is_signed<unsigned int> { enum { value = false }; };
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template <> struct hb_is_signed<signed long> { enum { value = true }; };
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template <> struct hb_is_signed<unsigned long> { enum { value = false }; };
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template <> struct hb_is_signed<signed long long> { enum { value = true }; };
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template <> struct hb_is_signed<unsigned long long> { enum { value = false }; };
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#define hb_is_signed(T) hb_is_signed<T>::value
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template <typename T> struct hb_int_min { static constexpr T value = 0; };
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template <> struct hb_int_min<char> { static constexpr char value = CHAR_MIN; };
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template <> struct hb_int_min<int> { static constexpr int value = INT_MIN; };
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template <> struct hb_int_min<long> { static constexpr long value = LONG_MIN; };
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#define hb_int_min(T) hb_int_min<T>::value
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template <bool is_signed> struct hb_signedness_int;
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template <> struct hb_signedness_int<false> { typedef unsigned int value; };
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template <> struct hb_signedness_int<true> { typedef signed int value; };
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#define hb_signedness_int(T) hb_signedness_int<T>::value
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template <typename T> struct hb_is_integer { enum { value = false }; };
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template <> struct hb_is_integer<char> { enum { value = true }; };
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template <> struct hb_is_integer<signed char> { enum { value = true }; };
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template <> struct hb_is_integer<unsigned char> { enum { value = true }; };
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template <> struct hb_is_integer<signed short> { enum { value = true }; };
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template <> struct hb_is_integer<unsigned short> { enum { value = true }; };
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template <> struct hb_is_integer<signed int> { enum { value = true }; };
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template <> struct hb_is_integer<unsigned int> { enum { value = true }; };
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template <> struct hb_is_integer<signed long> { enum { value = true }; };
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template <> struct hb_is_integer<unsigned long> { enum { value = true }; };
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template <> struct hb_is_integer<signed long long> { enum { value = true }; };
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template <> struct hb_is_integer<unsigned long long> { enum { value = true }; };
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#define hb_is_integer(T) hb_is_integer<T>::value
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#endif /* HB_META_HH */
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