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| 1 /* | 1 /* |
| 2 * Copyright 2016 The WebRTC Project Authors. All rights reserved. | 2 * Copyright 2016 The WebRTC Project Authors. All rights reserved. |
| 3 * | 3 * |
| 4 * Use of this source code is governed by a BSD-style license | 4 * Use of this source code is governed by a BSD-style license |
| 5 * that can be found in the LICENSE file in the root of the source | 5 * that can be found in the LICENSE file in the root of the source |
| 6 * tree. An additional intellectual property rights grant can be found | 6 * tree. An additional intellectual property rights grant can be found |
| 7 * in the file PATENTS. All contributing project authors may | 7 * in the file PATENTS. All contributing project authors may |
| 8 * be found in the AUTHORS file in the root of the source tree. | 8 * be found in the AUTHORS file in the root of the source tree. |
| 9 */ | 9 */ |
| 10 | 10 |
| (...skipping 13 matching lines...) Expand all Loading... |
| 24 // arguments were first converted to infinite-range signed integers, and then | 24 // arguments were first converted to infinite-range signed integers, and then |
| 25 // compared, although of course nothing expensive like that actually takes | 25 // compared, although of course nothing expensive like that actually takes |
| 26 // place. In practice, for signed/signed and unsigned/unsigned comparisons and | 26 // place. In practice, for signed/signed and unsigned/unsigned comparisons and |
| 27 // some mixed-signed comparisons with a compile-time constant, the overhead is | 27 // some mixed-signed comparisons with a compile-time constant, the overhead is |
| 28 // zero; in the remaining cases, it is just a few machine instructions (no | 28 // zero; in the remaining cases, it is just a few machine instructions (no |
| 29 // branches). | 29 // branches). |
| 30 | 30 |
| 31 #ifndef WEBRTC_BASE_SAFE_COMPARE_H_ | 31 #ifndef WEBRTC_BASE_SAFE_COMPARE_H_ |
| 32 #define WEBRTC_BASE_SAFE_COMPARE_H_ | 32 #define WEBRTC_BASE_SAFE_COMPARE_H_ |
| 33 | 33 |
| 34 #include <stddef.h> | |
| 35 #include <stdint.h> | |
| 36 | 34 |
| 37 #include <type_traits> | 35 // This header is deprecated and is just left here temporarily during |
| 38 #include <utility> | 36 // refactoring. See https://bugs.webrtc.org/7634 for more details. |
| 39 | 37 #include "webrtc/rtc_base/safe_compare.h" |
| 40 #include "webrtc/base/type_traits.h" | |
| 41 | |
| 42 namespace rtc { | |
| 43 | |
| 44 namespace safe_cmp_impl { | |
| 45 | |
| 46 template <size_t N> | |
| 47 struct LargerIntImpl : std::false_type {}; | |
| 48 template <> | |
| 49 struct LargerIntImpl<sizeof(int8_t)> : std::true_type { | |
| 50 using type = int16_t; | |
| 51 }; | |
| 52 template <> | |
| 53 struct LargerIntImpl<sizeof(int16_t)> : std::true_type { | |
| 54 using type = int32_t; | |
| 55 }; | |
| 56 template <> | |
| 57 struct LargerIntImpl<sizeof(int32_t)> : std::true_type { | |
| 58 using type = int64_t; | |
| 59 }; | |
| 60 | |
| 61 // LargerInt<T1, T2>::value is true iff there's a signed type that's larger | |
| 62 // than T1 (and no larger than the larger of T2 and int*, for performance | |
| 63 // reasons); and if there is such a type, LargerInt<T1, T2>::type is an alias | |
| 64 // for it. | |
| 65 template <typename T1, typename T2> | |
| 66 struct LargerInt | |
| 67 : LargerIntImpl<sizeof(T1) < sizeof(T2) || sizeof(T1) < sizeof(int*) | |
| 68 ? sizeof(T1) | |
| 69 : 0> {}; | |
| 70 | |
| 71 template <typename T> | |
| 72 constexpr typename std::make_unsigned<T>::type MakeUnsigned(T a) { | |
| 73 return static_cast<typename std::make_unsigned<T>::type>(a); | |
| 74 } | |
| 75 | |
| 76 // Overload for when both T1 and T2 have the same signedness. | |
| 77 template <typename Op, | |
| 78 typename T1, | |
| 79 typename T2, | |
| 80 typename std::enable_if<std::is_signed<T1>::value == | |
| 81 std::is_signed<T2>::value>::type* = nullptr> | |
| 82 constexpr bool Cmp(T1 a, T2 b) { | |
| 83 return Op::Op(a, b); | |
| 84 } | |
| 85 | |
| 86 // Overload for signed - unsigned comparison that can be promoted to a bigger | |
| 87 // signed type. | |
| 88 template <typename Op, | |
| 89 typename T1, | |
| 90 typename T2, | |
| 91 typename std::enable_if<std::is_signed<T1>::value && | |
| 92 std::is_unsigned<T2>::value && | |
| 93 LargerInt<T2, T1>::value>::type* = nullptr> | |
| 94 constexpr bool Cmp(T1 a, T2 b) { | |
| 95 return Op::Op(a, static_cast<typename LargerInt<T2, T1>::type>(b)); | |
| 96 } | |
| 97 | |
| 98 // Overload for unsigned - signed comparison that can be promoted to a bigger | |
| 99 // signed type. | |
| 100 template <typename Op, | |
| 101 typename T1, | |
| 102 typename T2, | |
| 103 typename std::enable_if<std::is_unsigned<T1>::value && | |
| 104 std::is_signed<T2>::value && | |
| 105 LargerInt<T1, T2>::value>::type* = nullptr> | |
| 106 constexpr bool Cmp(T1 a, T2 b) { | |
| 107 return Op::Op(static_cast<typename LargerInt<T1, T2>::type>(a), b); | |
| 108 } | |
| 109 | |
| 110 // Overload for signed - unsigned comparison that can't be promoted to a bigger | |
| 111 // signed type. | |
| 112 template <typename Op, | |
| 113 typename T1, | |
| 114 typename T2, | |
| 115 typename std::enable_if<std::is_signed<T1>::value && | |
| 116 std::is_unsigned<T2>::value && | |
| 117 !LargerInt<T2, T1>::value>::type* = nullptr> | |
| 118 constexpr bool Cmp(T1 a, T2 b) { | |
| 119 return a < 0 ? Op::Op(-1, 0) : Op::Op(safe_cmp_impl::MakeUnsigned(a), b); | |
| 120 } | |
| 121 | |
| 122 // Overload for unsigned - signed comparison that can't be promoted to a bigger | |
| 123 // signed type. | |
| 124 template <typename Op, | |
| 125 typename T1, | |
| 126 typename T2, | |
| 127 typename std::enable_if<std::is_unsigned<T1>::value && | |
| 128 std::is_signed<T2>::value && | |
| 129 !LargerInt<T1, T2>::value>::type* = nullptr> | |
| 130 constexpr bool Cmp(T1 a, T2 b) { | |
| 131 return b < 0 ? Op::Op(0, -1) : Op::Op(a, safe_cmp_impl::MakeUnsigned(b)); | |
| 132 } | |
| 133 | |
| 134 #define RTC_SAFECMP_MAKE_OP(name, op) \ | |
| 135 struct name { \ | |
| 136 template <typename T1, typename T2> \ | |
| 137 static constexpr bool Op(T1 a, T2 b) { \ | |
| 138 return a op b; \ | |
| 139 } \ | |
| 140 }; | |
| 141 RTC_SAFECMP_MAKE_OP(EqOp, ==) | |
| 142 RTC_SAFECMP_MAKE_OP(NeOp, !=) | |
| 143 RTC_SAFECMP_MAKE_OP(LtOp, <) | |
| 144 RTC_SAFECMP_MAKE_OP(LeOp, <=) | |
| 145 RTC_SAFECMP_MAKE_OP(GtOp, >) | |
| 146 RTC_SAFECMP_MAKE_OP(GeOp, >=) | |
| 147 #undef RTC_SAFECMP_MAKE_OP | |
| 148 | |
| 149 } // namespace safe_cmp_impl | |
| 150 | |
| 151 #define RTC_SAFECMP_MAKE_FUN(name) \ | |
| 152 template <typename T1, typename T2> \ | |
| 153 constexpr \ | |
| 154 typename std::enable_if<IsIntlike<T1>::value && IsIntlike<T2>::value, \ | |
| 155 bool>::type Safe##name(T1 a, T2 b) { \ | |
| 156 /* Unary plus here turns enums into real integral types. */ \ | |
| 157 return safe_cmp_impl::Cmp<safe_cmp_impl::name##Op>(+a, +b); \ | |
| 158 } \ | |
| 159 template <typename T1, typename T2> \ | |
| 160 constexpr \ | |
| 161 typename std::enable_if<!IsIntlike<T1>::value || !IsIntlike<T2>::value, \ | |
| 162 bool>::type Safe##name(const T1& a, \ | |
| 163 const T2& b) { \ | |
| 164 return safe_cmp_impl::name##Op::Op(a, b); \ | |
| 165 } | |
| 166 RTC_SAFECMP_MAKE_FUN(Eq) | |
| 167 RTC_SAFECMP_MAKE_FUN(Ne) | |
| 168 RTC_SAFECMP_MAKE_FUN(Lt) | |
| 169 RTC_SAFECMP_MAKE_FUN(Le) | |
| 170 RTC_SAFECMP_MAKE_FUN(Gt) | |
| 171 RTC_SAFECMP_MAKE_FUN(Ge) | |
| 172 #undef RTC_SAFECMP_MAKE_FUN | |
| 173 | |
| 174 } // namespace rtc | |
| 175 | 38 |
| 176 #endif // WEBRTC_BASE_SAFE_COMPARE_H_ | 39 #endif // WEBRTC_BASE_SAFE_COMPARE_H_ |
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