harfbuzz/src/hb-meta.hh

109 lines
4.1 KiB
C++

/*
* 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"
/*
* C++ template meta-programming & fundamentals used with them.
*/
template <typename T> static inline T*
hb_addressof (const T& arg)
{
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wcast-align"
/* https://en.cppreference.com/w/cpp/memory/addressof */
return reinterpret_cast<T*>(
&const_cast<char&>(
reinterpret_cast<const volatile char&>(arg)));
#pragma GCC diagnostic pop
}
template <typename T> static inline T hb_declval ();
#define hb_declval(T) (hb_declval<T> ())
template <typename T> struct hb_match_const { typedef T type; enum { value = false }; };
template <typename T> struct hb_match_const<const T> { typedef T type; enum { value = true }; };
#define hb_remove_const(T) typename hb_match_const<T>::type
#define hb_is_const(T) hb_match_const<T>::value
template <typename T> struct hb_match_reference { typedef T type; enum { value = false }; };
template <typename T> struct hb_match_reference<T &> { typedef T type; enum { value = true }; };
#define hb_remove_reference(T) typename hb_match_reference<T>::type
#define hb_is_reference(T) hb_match_reference<T>::value
template <typename T> struct hb_match_pointer { typedef T type; enum { value = false }; };
template <typename T> struct hb_match_pointer<T *> { typedef T type; enum { value = true }; };
#define hb_remove_pointer(T) typename hb_match_pointer<T>::type
#define hb_is_pointer(T) hb_match_pointer<T>::value
/* Void! For when we need a expression-type of void. */
struct hb_void_t { typedef void value; };
/* Bool! For when we need to evaluate type-dependent expressions
* in a template argument. */
template <bool b> struct hb_bool_tt { enum { value = b }; };
typedef hb_bool_tt<true> hb_true_t;
typedef hb_bool_tt<false> hb_false_t;
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
/*
* Meta-functions.
*/
template <typename T> struct hb_is_signed;
/* https://github.com/harfbuzz/harfbuzz/issues/1535 */
template <> struct hb_is_signed<int8_t> { enum { value = true }; };
template <> struct hb_is_signed<int16_t> { enum { value = true }; };
template <> struct hb_is_signed<int32_t> { enum { value = true }; };
template <> struct hb_is_signed<int64_t> { enum { value = true }; };
template <> struct hb_is_signed<uint8_t> { enum { value = false }; };
template <> struct hb_is_signed<uint16_t> { enum { value = false }; };
template <> struct hb_is_signed<uint32_t> { enum { value = false }; };
template <> struct hb_is_signed<uint64_t> { enum { value = false }; };
#define hb_is_signed(T) hb_is_signed<T>::value
template <bool is_signed> struct hb_signedness_int;
template <> struct hb_signedness_int<false> { typedef unsigned int value; };
template <> struct hb_signedness_int<true> { typedef signed int value; };
#define hb_signedness_int(T) hb_signedness_int<T>::value
#endif /* HB_META_HH */