1 /*
2 * Copyright 2013 Google Inc.
3 *
4 * Use of this source code is governed by a BSD-style license that can be
5 * found in the LICENSE file.
6 *
7 *
8 * This header provides some std:: features early in the skstd namespace
9 * and several Skia-specific additions in the sknonstd namespace.
10 */
11
12 #ifndef SkTLogic_DEFINED
13 #define SkTLogic_DEFINED
14
15 #include <iterator>
16 #include <type_traits>
17 #include "include/private/base/SkTo.h"
18
19 // The sknonstd namespace contains things we would like to be proposed and feel std-ish.
20 namespace sknonstd {
21
22 // The name 'copy' here is fraught with peril. In this case it means 'append', not 'overwrite'.
23 // Alternate proposed names are 'propagate', 'augment', or 'append' (and 'add', but already taken).
24 // std::experimental::propagate_const already exists for other purposes in TSv2.
25 // These also follow the <dest, source> pattern used by boost.
26 template <typename D, typename S> struct copy_const {
27 using type = std::conditional_t<std::is_const<S>::value, std::add_const_t<D>, D>;
28 };
29 template <typename D, typename S> using copy_const_t = typename copy_const<D, S>::type;
30
31 template <typename D, typename S> struct copy_volatile {
32 using type = std::conditional_t<std::is_volatile<S>::value, std::add_volatile_t<D>, D>;
33 };
34 template <typename D, typename S> using copy_volatile_t = typename copy_volatile<D, S>::type;
35
36 template <typename D, typename S> struct copy_cv {
37 using type = copy_volatile_t<copy_const_t<D, S>, S>;
38 };
39 template <typename D, typename S> using copy_cv_t = typename copy_cv<D, S>::type;
40
41 // The name 'same' here means 'overwrite'.
42 // Alternate proposed names are 'replace', 'transfer', or 'qualify_from'.
43 // same_xxx<D, S> can be written as copy_xxx<remove_xxx_t<D>, S>
44 template <typename D, typename S> using same_const = copy_const<std::remove_const_t<D>, S>;
45 template <typename D, typename S> using same_const_t = typename same_const<D, S>::type;
46 template <typename D, typename S> using same_volatile =copy_volatile<std::remove_volatile_t<D>,S>;
47 template <typename D, typename S> using same_volatile_t = typename same_volatile<D, S>::type;
48 template <typename D, typename S> using same_cv = copy_cv<std::remove_cv_t<D>, S>;
49 template <typename D, typename S> using same_cv_t = typename same_cv<D, S>::type;
50
51 } // namespace sknonstd
52
53 template <typename Container>
SkCount(const Container & c)54 constexpr int SkCount(const Container& c) { return SkTo<int>(std::size(c)); }
55
56 #endif
57