1 | // |
2 | // Copyright 2017 The Abseil Authors. |
3 | // |
4 | // Licensed under the Apache License, Version 2.0 (the "License"); |
5 | // you may not use this file except in compliance with the License. |
6 | // You may obtain a copy of the License at |
7 | // |
8 | // https://www.apache.org/licenses/LICENSE-2.0 |
9 | // |
10 | // Unless required by applicable law or agreed to in writing, software |
11 | // distributed under the License is distributed on an "AS IS" BASIS, |
12 | // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
13 | // See the License for the specific language governing permissions and |
14 | // limitations under the License. |
15 | // |
16 | // ----------------------------------------------------------------------------- |
17 | // File: macros.h |
18 | // ----------------------------------------------------------------------------- |
19 | // |
20 | // This header file defines the set of language macros used within Abseil code. |
21 | // For the set of macros used to determine supported compilers and platforms, |
22 | // see absl/base/config.h instead. |
23 | // |
24 | // This code is compiled directly on many platforms, including client |
25 | // platforms like Windows, Mac, and embedded systems. Before making |
26 | // any changes here, make sure that you're not breaking any platforms. |
27 | |
28 | #ifndef ABSL_BASE_MACROS_H_ |
29 | #define ABSL_BASE_MACROS_H_ |
30 | |
31 | #include <cassert> |
32 | #include <cstddef> |
33 | |
34 | #include "absl/base/attributes.h" |
35 | #include "absl/base/config.h" |
36 | #include "absl/base/optimization.h" |
37 | #include "absl/base/port.h" |
38 | |
39 | // ABSL_ARRAYSIZE() |
40 | // |
41 | // Returns the number of elements in an array as a compile-time constant, which |
42 | // can be used in defining new arrays. If you use this macro on a pointer by |
43 | // mistake, you will get a compile-time error. |
44 | #define ABSL_ARRAYSIZE(array) \ |
45 | (sizeof(::absl::macros_internal::ArraySizeHelper(array))) |
46 | |
47 | namespace absl { |
48 | ABSL_NAMESPACE_BEGIN |
49 | namespace macros_internal { |
50 | // Note: this internal template function declaration is used by ABSL_ARRAYSIZE. |
51 | // The function doesn't need a definition, as we only use its type. |
52 | template <typename T, size_t N> |
53 | auto ArraySizeHelper(const T (&array)[N]) -> char (&)[N]; |
54 | } // namespace macros_internal |
55 | ABSL_NAMESPACE_END |
56 | } // namespace absl |
57 | |
58 | // ABSL_BAD_CALL_IF() |
59 | // |
60 | // Used on a function overload to trap bad calls: any call that matches the |
61 | // overload will cause a compile-time error. This macro uses a clang-specific |
62 | // "enable_if" attribute, as described at |
63 | // https://clang.llvm.org/docs/AttributeReference.html#enable-if |
64 | // |
65 | // Overloads which use this macro should be bracketed by |
66 | // `#ifdef ABSL_BAD_CALL_IF`. |
67 | // |
68 | // Example: |
69 | // |
70 | // int isdigit(int c); |
71 | // #ifdef ABSL_BAD_CALL_IF |
72 | // int isdigit(int c) |
73 | // ABSL_BAD_CALL_IF(c <= -1 || c > 255, |
74 | // "'c' must have the value of an unsigned char or EOF"); |
75 | // #endif // ABSL_BAD_CALL_IF |
76 | #if ABSL_HAVE_ATTRIBUTE(enable_if) |
77 | #define ABSL_BAD_CALL_IF(expr, msg) \ |
78 | __attribute__((enable_if(expr, "Bad call trap"), unavailable(msg))) |
79 | #endif |
80 | |
81 | // ABSL_ASSERT() |
82 | // |
83 | // In C++11, `assert` can't be used portably within constexpr functions. |
84 | // ABSL_ASSERT functions as a runtime assert but works in C++11 constexpr |
85 | // functions. Example: |
86 | // |
87 | // constexpr double Divide(double a, double b) { |
88 | // return ABSL_ASSERT(b != 0), a / b; |
89 | // } |
90 | // |
91 | // This macro is inspired by |
92 | // https://akrzemi1.wordpress.com/2017/05/18/asserts-in-constexpr-functions/ |
93 | #if defined(NDEBUG) |
94 | #define ABSL_ASSERT(expr) \ |
95 | (false ? static_cast<void>(expr) : static_cast<void>(0)) |
96 | #else |
97 | #define ABSL_ASSERT(expr) \ |
98 | (ABSL_PREDICT_TRUE((expr)) ? static_cast<void>(0) \ |
99 | : [] { assert(false && #expr); }()) // NOLINT |
100 | #endif |
101 | |
102 | // `ABSL_INTERNAL_HARDENING_ABORT()` controls how `ABSL_HARDENING_ASSERT()` |
103 | // aborts the program in release mode (when NDEBUG is defined). The |
104 | // implementation should abort the program as quickly as possible and ideally it |
105 | // should not be possible to ignore the abort request. |
106 | #define ABSL_INTERNAL_HARDENING_ABORT() \ |
107 | do { \ |
108 | ABSL_INTERNAL_IMMEDIATE_ABORT_IMPL(); \ |
109 | ABSL_INTERNAL_UNREACHABLE_IMPL(); \ |
110 | } while (false) |
111 | |
112 | // ABSL_HARDENING_ASSERT() |
113 | // |
114 | // `ABSL_HARDENING_ASSERT()` is like `ABSL_ASSERT()`, but used to implement |
115 | // runtime assertions that should be enabled in hardened builds even when |
116 | // `NDEBUG` is defined. |
117 | // |
118 | // When `NDEBUG` is not defined, `ABSL_HARDENING_ASSERT()` is identical to |
119 | // `ABSL_ASSERT()`. |
120 | // |
121 | // See `ABSL_OPTION_HARDENED` in `absl/base/options.h` for more information on |
122 | // hardened mode. |
123 | #if ABSL_OPTION_HARDENED == 1 && defined(NDEBUG) |
124 | #define ABSL_HARDENING_ASSERT(expr) \ |
125 | (ABSL_PREDICT_TRUE((expr)) ? static_cast<void>(0) \ |
126 | : [] { ABSL_INTERNAL_HARDENING_ABORT(); }()) |
127 | #else |
128 | #define ABSL_HARDENING_ASSERT(expr) ABSL_ASSERT(expr) |
129 | #endif |
130 | |
131 | #ifdef ABSL_HAVE_EXCEPTIONS |
132 | #define ABSL_INTERNAL_TRY try |
133 | #define ABSL_INTERNAL_CATCH_ANY catch (...) |
134 | #define ABSL_INTERNAL_RETHROW do { throw; } while (false) |
135 | #else // ABSL_HAVE_EXCEPTIONS |
136 | #define ABSL_INTERNAL_TRY if (true) |
137 | #define ABSL_INTERNAL_CATCH_ANY else if (false) |
138 | #define ABSL_INTERNAL_RETHROW do {} while (false) |
139 | #endif // ABSL_HAVE_EXCEPTIONS |
140 | |
141 | #endif // ABSL_BASE_MACROS_H_ |
142 | |