648db22b |
1 | /* |
2 | * Copyright (c) Meta Platforms, Inc. and affiliates. |
3 | * All rights reserved. |
4 | * |
5 | * This source code is licensed under both the BSD-style license (found in the |
6 | * LICENSE file in the root directory of this source tree) and the GPLv2 (found |
7 | * in the COPYING file in the root directory of this source tree). |
8 | */ |
9 | |
10 | /** |
11 | * A subset of `folly/Range.h`. |
12 | * All code copied verbatim modulo formatting |
13 | */ |
14 | #pragma once |
15 | |
16 | #include "utils/Likely.h" |
17 | #include "utils/Portability.h" |
18 | |
19 | #include <algorithm> |
20 | #include <cstddef> |
21 | #include <cstring> |
22 | #include <stdexcept> |
23 | #include <string> |
24 | #include <type_traits> |
25 | |
26 | namespace pzstd { |
27 | |
28 | namespace detail { |
29 | /* |
30 | *Use IsCharPointer<T>::type to enable const char* or char*. |
31 | *Use IsCharPointer<T>::const_type to enable only const char*. |
32 | */ |
33 | template <class T> |
34 | struct IsCharPointer {}; |
35 | |
36 | template <> |
37 | struct IsCharPointer<char*> { |
38 | typedef int type; |
39 | }; |
40 | |
41 | template <> |
42 | struct IsCharPointer<const char*> { |
43 | typedef int const_type; |
44 | typedef int type; |
45 | }; |
46 | |
47 | } // namespace detail |
48 | |
49 | template <typename Iter> |
50 | class Range { |
51 | Iter b_; |
52 | Iter e_; |
53 | |
54 | public: |
55 | using size_type = std::size_t; |
56 | using iterator = Iter; |
57 | using const_iterator = Iter; |
58 | using value_type = typename std::remove_reference< |
59 | typename std::iterator_traits<Iter>::reference>::type; |
60 | using reference = typename std::iterator_traits<Iter>::reference; |
61 | |
62 | constexpr Range() : b_(), e_() {} |
63 | constexpr Range(Iter begin, Iter end) : b_(begin), e_(end) {} |
64 | |
65 | constexpr Range(Iter begin, size_type size) : b_(begin), e_(begin + size) {} |
66 | |
67 | template <class T = Iter, typename detail::IsCharPointer<T>::type = 0> |
68 | /* implicit */ Range(Iter str) : b_(str), e_(str + std::strlen(str)) {} |
69 | |
70 | template <class T = Iter, typename detail::IsCharPointer<T>::const_type = 0> |
71 | /* implicit */ Range(const std::string& str) |
72 | : b_(str.data()), e_(b_ + str.size()) {} |
73 | |
74 | // Allow implicit conversion from Range<From> to Range<To> if From is |
75 | // implicitly convertible to To. |
76 | template < |
77 | class OtherIter, |
78 | typename std::enable_if< |
79 | (!std::is_same<Iter, OtherIter>::value && |
80 | std::is_convertible<OtherIter, Iter>::value), |
81 | int>::type = 0> |
82 | constexpr /* implicit */ Range(const Range<OtherIter>& other) |
83 | : b_(other.begin()), e_(other.end()) {} |
84 | |
85 | Range(const Range&) = default; |
86 | Range(Range&&) = default; |
87 | |
88 | Range& operator=(const Range&) = default; |
89 | Range& operator=(Range&&) = default; |
90 | |
91 | constexpr size_type size() const { |
92 | return e_ - b_; |
93 | } |
94 | bool empty() const { |
95 | return b_ == e_; |
96 | } |
97 | Iter data() const { |
98 | return b_; |
99 | } |
100 | Iter begin() const { |
101 | return b_; |
102 | } |
103 | Iter end() const { |
104 | return e_; |
105 | } |
106 | |
107 | void advance(size_type n) { |
108 | if (UNLIKELY(n > size())) { |
109 | throw std::out_of_range("index out of range"); |
110 | } |
111 | b_ += n; |
112 | } |
113 | |
114 | void subtract(size_type n) { |
115 | if (UNLIKELY(n > size())) { |
116 | throw std::out_of_range("index out of range"); |
117 | } |
118 | e_ -= n; |
119 | } |
120 | |
121 | Range subpiece(size_type first, size_type length = std::string::npos) const { |
122 | if (UNLIKELY(first > size())) { |
123 | throw std::out_of_range("index out of range"); |
124 | } |
125 | |
126 | return Range(b_ + first, std::min(length, size() - first)); |
127 | } |
128 | }; |
129 | |
130 | using ByteRange = Range<const unsigned char*>; |
131 | using MutableByteRange = Range<unsigned char*>; |
132 | using StringPiece = Range<const char*>; |
133 | } |