1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
|
/*
* Copyright 2013 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#ifndef SkTFitsIn_DEFINED
#define SkTFitsIn_DEFINED
#include "../private/SkTLogic.h"
#include <limits>
#include <type_traits>
namespace sktfitsin {
namespace Private {
/** SkTMux::type = (a && b) ? Both : (a) ? A : (b) ? B : Neither; */
template <bool a, bool b, typename Both, typename A, typename B, typename Neither>
struct SkTMux {
using type = skstd::conditional_t<a, skstd::conditional_t<b, Both, A>,
skstd::conditional_t<b, B, Neither>>;
};
/** SkTHasMoreDigits = (digits(A) >= digits(B)) ? true_type : false_type. */
template <typename A, typename B> struct SkTHasMoreDigits
: skstd::bool_constant<std::numeric_limits<A>::digits >= std::numeric_limits<B>::digits>
{ };
/** A high or low side predicate which is used when it is statically known
* that source values are in the range of the Destination.
*/
template <typename S> struct SkTOutOfRange_False {
using can_be_true = std::false_type;
using source_type = S;
static bool apply(S) {
return false;
}
};
/** A low side predicate which tests if the source value < Min(D).
* Assumes that Min(S) <= Min(D).
*/
template <typename D, typename S> struct SkTOutOfRange_LT_MinD {
using can_be_true = std::true_type;
using source_type = S;
static bool apply(S s) {
using precondition = SkTHasMoreDigits<S, D>;
static_assert(precondition::value, "minS > minD");
return s < static_cast<S>((std::numeric_limits<D>::min)());
}
};
/** A low side predicate which tests if the source value is less than 0. */
template <typename D, typename S> struct SkTOutOfRange_LT_Zero {
using can_be_true = std::true_type;
using source_type = S;
static bool apply(S s) {
return s < static_cast<S>(0);
}
};
/** A high side predicate which tests if the source value > Max(D).
* Assumes that Max(S) >= Max(D).
*/
template <typename D, typename S> struct SkTOutOfRange_GT_MaxD {
using can_be_true = std::true_type;
using source_type = S;
static bool apply(S s) {
using precondition = SkTHasMoreDigits<S, D>;
static_assert(precondition::value, "maxS < maxD");
return s > static_cast<S>((std::numeric_limits<D>::max)());
}
};
/** Composes two SkTOutOfRange predicates.
* First checks OutOfRange_Low then, if in range, OutOfRange_High.
*/
template <typename OutOfRange_Low, typename OutOfRange_High> struct SkTOutOfRange_Either {
using can_be_true = std::true_type;
using source_type = typename OutOfRange_Low::source_type;
static bool apply(source_type s) {
bool outOfRange = OutOfRange_Low::apply(s);
if (!outOfRange) {
outOfRange = OutOfRange_High::apply(s);
}
return outOfRange;
}
};
/** SkTCombineOutOfRange::type is an SkTOutOfRange_XXX type which is the
* optimal combination of OutOfRange_Low and OutOfRange_High.
*/
template <typename OutOfRange_Low, typename OutOfRange_High> struct SkTCombineOutOfRange {
using Both = SkTOutOfRange_Either<OutOfRange_Low, OutOfRange_High>;
using Neither = SkTOutOfRange_False<typename OutOfRange_Low::source_type>;
using apply_low = typename OutOfRange_Low::can_be_true;
using apply_high = typename OutOfRange_High::can_be_true;
using type = typename SkTMux<apply_low::value, apply_high::value,
Both, OutOfRange_Low, OutOfRange_High, Neither>::type;
};
template <typename D, typename S, typename OutOfRange_Low, typename OutOfRange_High>
struct SkTRangeChecker {
/** This is the method which is called at runtime to do the range check. */
static bool OutOfRange(S s) {
using Combined = typename SkTCombineOutOfRange<OutOfRange_Low, OutOfRange_High>::type;
return Combined::apply(s);
}
};
/** SkTFitsIn_Unsigned2Unsiged::type is an SkTRangeChecker with an OutOfRange(S s) method
* the implementation of which is tailored for the source and destination types.
* Assumes that S and D are unsigned integer types.
*/
template <typename D, typename S> struct SkTFitsIn_Unsigned2Unsiged {
using OutOfRange_Low = SkTOutOfRange_False<S>;
using OutOfRange_High = SkTOutOfRange_GT_MaxD<D, S>;
using HighSideOnlyCheck = SkTRangeChecker<D, S, OutOfRange_Low, OutOfRange_High>;
using NoCheck = SkTRangeChecker<D, S, SkTOutOfRange_False<S>, SkTOutOfRange_False<S>>;
// If std::numeric_limits<D>::digits >= std::numeric_limits<S>::digits, nothing to check.
// This also protects the precondition of SkTOutOfRange_GT_MaxD.
using sourceFitsInDesitination = SkTHasMoreDigits<D, S>;
using type = skstd::conditional_t<sourceFitsInDesitination::value, NoCheck, HighSideOnlyCheck>;
};
/** SkTFitsIn_Signed2Signed::type is an SkTRangeChecker with an OutOfRange(S s) method
* the implementation of which is tailored for the source and destination types.
* Assumes that S and D are signed integer types.
*/
template <typename D, typename S> struct SkTFitsIn_Signed2Signed {
using OutOfRange_Low = SkTOutOfRange_LT_MinD<D, S>;
using OutOfRange_High = SkTOutOfRange_GT_MaxD<D, S>;
using FullCheck = SkTRangeChecker<D, S, OutOfRange_Low, OutOfRange_High>;
using NoCheck = SkTRangeChecker<D, S, SkTOutOfRange_False<S>, SkTOutOfRange_False<S>>;
// If std::numeric_limits<D>::digits >= std::numeric_limits<S>::digits, nothing to check.
// This also protects the precondition of SkTOutOfRange_LT_MinD and SkTOutOfRange_GT_MaxD.
using sourceFitsInDesitination = SkTHasMoreDigits<D, S>;
using type = skstd::conditional_t<sourceFitsInDesitination::value, NoCheck, FullCheck>;
};
/** SkTFitsIn_Signed2Unsigned::type is an SkTRangeChecker with an OutOfRange(S s) method
* the implementation of which is tailored for the source and destination types.
* Assumes that S is a signed integer type and D is an unsigned integer type.
*/
template <typename D, typename S> struct SkTFitsIn_Signed2Unsigned {
using OutOfRange_Low = SkTOutOfRange_LT_Zero<D, S>;
using OutOfRange_High = SkTOutOfRange_GT_MaxD<D, S>;
using FullCheck = SkTRangeChecker<D, S, OutOfRange_Low, OutOfRange_High>;
using LowSideOnlyCheck = SkTRangeChecker<D, S, OutOfRange_Low, SkTOutOfRange_False<S>>;
// If std::numeric_limits<D>::max() >= std::numeric_limits<S>::max(),
// no need to check the high side. (Until C++11, assume more digits means greater max.)
// This also protects the precondition of SkTOutOfRange_GT_MaxD.
using sourceCannotExceedDest = SkTHasMoreDigits<D, S>;
using type = skstd::conditional_t<sourceCannotExceedDest::value, LowSideOnlyCheck, FullCheck>;
};
/** SkTFitsIn_Unsigned2Signed::type is an SkTRangeChecker with an OutOfRange(S s) method
* the implementation of which is tailored for the source and destination types.
* Assumes that S is an usigned integer type and D is a signed integer type.
*/
template <typename D, typename S> struct SkTFitsIn_Unsigned2Signed {
using OutOfRange_Low = SkTOutOfRange_False<S>;
using OutOfRange_High = SkTOutOfRange_GT_MaxD<D, S>;
using HighSideOnlyCheck = SkTRangeChecker<D, S, OutOfRange_Low, OutOfRange_High>;
using NoCheck = SkTRangeChecker<D, S, SkTOutOfRange_False<S>, SkTOutOfRange_False<S>>;
// If std::numeric_limits<D>::max() >= std::numeric_limits<S>::max(), nothing to check.
// (Until C++11, assume more digits means greater max.)
// This also protects the precondition of SkTOutOfRange_GT_MaxD.
using sourceCannotExceedDest = SkTHasMoreDigits<D, S>;
using type = skstd::conditional_t<sourceCannotExceedDest::value, NoCheck, HighSideOnlyCheck>;
};
/** SkTFitsIn::type is an SkTRangeChecker with an OutOfRange(S s) method
* the implementation of which is tailored for the source and destination types.
* Assumes that S and D are integer types.
*/
template <typename D, typename S> struct SkTFitsIn {
// One of the following will be the 'selector' type.
using S2S = SkTFitsIn_Signed2Signed<D, S>;
using S2U = SkTFitsIn_Signed2Unsigned<D, S>;
using U2S = SkTFitsIn_Unsigned2Signed<D, S>;
using U2U = SkTFitsIn_Unsigned2Unsiged<D, S>;
using S_is_signed = skstd::bool_constant<std::numeric_limits<S>::is_signed>;
using D_is_signed = skstd::bool_constant<std::numeric_limits<D>::is_signed>;
using selector = typename SkTMux<S_is_signed::value, D_is_signed::value,
S2S, S2U, U2S, U2U>::type;
// This type is an SkTRangeChecker.
using type = typename selector::type;
};
template <typename T, bool = std::is_enum<T>::value> struct underlying_type {
using type = skstd::underlying_type_t<T>;
};
template <typename T> struct underlying_type<T, false> {
using type = T;
};
} // namespace Private
} // namespace sktfitsin
/** Returns true if the integer source value 's' will fit in the integer destination type 'D'. */
template <typename D, typename S> inline bool SkTFitsIn(S s) {
static_assert(std::is_integral<S>::value || std::is_enum<S>::value, "S must be integral.");
static_assert(std::is_integral<D>::value || std::is_enum<D>::value, "D must be integral.");
using RealS = typename sktfitsin::Private::underlying_type<S>::type;
using RealD = typename sktfitsin::Private::underlying_type<D>::type;
return !sktfitsin::Private::SkTFitsIn<RealD, RealS>::type::OutOfRange(s);
}
#endif
|
