1///////////////////////////////////////////////////////////////////////////////
2//
3// Copyright (c) 2015 Microsoft Corporation. All rights reserved.
4//
5// This code is licensed under the MIT License (MIT).
6//
7// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
8// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
9// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
10// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
11// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
12// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
13// THE SOFTWARE.
14//
15///////////////////////////////////////////////////////////////////////////////
16
17#pragma once
18
19#ifndef GSL_CONTRACTS_H
20#define GSL_CONTRACTS_H
21
22#include <exception>
23#include <stdexcept>
24
25//
26// There are three configuration options for this GSL implementation's behavior
27// when pre/post conditions on the GSL types are violated:
28//
29// 1. GSL_TERMINATE_ON_CONTRACT_VIOLATION: std::terminate will be called (default)
30// 2. GSL_THROW_ON_CONTRACT_VIOLATION: a gsl::fail_fast exception will be thrown
31// 3. GSL_UNENFORCED_ON_CONTRACT_VIOLATION: nothing happens
32//
33#if !(defined(GSL_THROW_ON_CONTRACT_VIOLATION) || defined(GSL_TERMINATE_ON_CONTRACT_VIOLATION) ||  \
34      defined(GSL_UNENFORCED_ON_CONTRACT_VIOLATION))
35#define GSL_TERMINATE_ON_CONTRACT_VIOLATION
36#endif
37
38#define GSL_STRINGIFY_DETAIL(x) #x
39#define GSL_STRINGIFY(x) GSL_STRINGIFY_DETAIL(x)
40
41#if defined(__clang__) || defined(__GNUC__)
42#define GSL_LIKELY(x) __builtin_expect(!!(x), 1)
43#define GSL_UNLIKELY(x) __builtin_expect(!!(x), 0)
44#else
45#define GSL_LIKELY(x) (!!(x))
46#define GSL_UNLIKELY(x) (!!(x))
47#endif
48
49//
50// GSL_ASSUME(cond)
51//
52// Tell the optimizer that the predicate cond must hold. It is unspecified
53// whether or not cond is actually evaluated.
54//
55#ifdef _MSC_VER
56#define GSL_ASSUME(cond) __assume(cond)
57#elif defined(__clang__)
58#define GSL_ASSUME(cond) __builtin_assume(cond)
59#elif defined(__GNUC__)
60#define GSL_ASSUME(cond) ((cond) ? static_cast<void>(0) : __builtin_unreachable())
61#else
62#define GSL_ASSUME(cond) static_cast<void>(!!(cond))
63#endif
64
65//
66// GSL.assert: assertions
67//
68
69namespace gsl
70{
71struct fail_fast : public std::logic_error
72{
73    explicit fail_fast(char const* const message) : std::logic_error(message) {}
74};
75}
76
77#if defined(GSL_THROW_ON_CONTRACT_VIOLATION)
78
79#define GSL_CONTRACT_CHECK(type, cond)                                                             \
80    (GSL_LIKELY(cond) ? static_cast<void>(0)                                                       \
81                      : throw gsl::fail_fast("GSL: " type " failure at " __FILE__                  \
82                                             ": " GSL_STRINGIFY(__LINE__)))
83
84#elif defined(GSL_TERMINATE_ON_CONTRACT_VIOLATION)
85
86#define GSL_CONTRACT_CHECK(type, cond) (GSL_LIKELY(cond) ? static_cast<void>(0) : std::terminate())
87
88#elif defined(GSL_UNENFORCED_ON_CONTRACT_VIOLATION)
89
90#define GSL_CONTRACT_CHECK(type, cond) GSL_ASSUME(cond)
91
92#endif
93
94#define Expects(cond) GSL_CONTRACT_CHECK("Precondition", cond)
95#define Ensures(cond) GSL_CONTRACT_CHECK("Postcondition", cond)
96
97#endif // GSL_CONTRACTS_H
98