1 /*
2 * Copyright 2018 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 #ifndef SkSpan_DEFINED
9 #define SkSpan_DEFINED
10
11 #include <cstddef>
12 #include <string>
13 #include <vector>
14
15 #include "include/private/SkTo.h"
16
17 template <typename T>
18 class SkSpan {
19 public:
SkSpan()20 constexpr SkSpan() : fPtr{nullptr}, fSize{0} {}
SkSpan(T * ptr,size_t size)21 constexpr SkSpan(T* ptr, size_t size) : fPtr{ptr}, fSize{size} {}
22 template <typename U, typename = typename std::enable_if<std::is_same<const U, T>::value>::type>
SkSpan(const SkSpan<U> & that)23 constexpr SkSpan(const SkSpan<U>& that) : fPtr(that.data()), fSize{that.size()} {}
24 constexpr SkSpan(const SkSpan& o) = default;
25 constexpr SkSpan& operator=(const SkSpan& that) {
26 fPtr = that.fPtr;
27 fSize = that.fSize;
28 return *this;
29 }
30 constexpr T& operator [] (size_t i) const { return fPtr[i]; }
front()31 constexpr T& front() const { return fPtr[0]; }
back()32 constexpr T& back() const { return fPtr[fSize - 1]; }
begin()33 constexpr T* begin() const { return fPtr; }
end()34 constexpr T* end() const { return fPtr + fSize; }
cbegin()35 constexpr const T* cbegin() const { return fPtr; }
cend()36 constexpr const T* cend() const { return fPtr + fSize; }
data()37 constexpr T* data() const { return fPtr; }
size()38 constexpr size_t size() const { return fSize; }
empty()39 constexpr bool empty() const { return fSize == 0; }
size_bytes()40 constexpr size_t size_bytes() const { return fSize * sizeof(T); }
first(size_t prefixLen)41 constexpr SkSpan<T> first(size_t prefixLen) { return SkSpan<T>{fPtr, prefixLen}; }
42
43 private:
44 T* fPtr;
45 size_t fSize;
46 };
47
48 template <typename T, typename S>
SkMakeSpan(T * p,S s)49 inline constexpr SkSpan<T> SkMakeSpan(T* p, S s) { return SkSpan<T>{p, SkTo<size_t>(s)}; }
50
51 template <size_t N, typename T>
SkMakeSpan(T (& a)[N])52 inline constexpr SkSpan<T> SkMakeSpan(T(&a)[N]) { return SkSpan<T>{a, N}; }
53
54 template <typename Container>
55 inline auto SkMakeSpan(Container& c)
56 -> SkSpan<typename std::remove_reference<decltype(*(c.data()))>::type> {
57 return {c.data(), c.size()};
58 }
59 #endif // SkSpan_DEFINED
60