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
|
/*
* Copyright 2017 The WebRTC Project Authors. All rights reserved.
*
* Use of this source code is governed by a BSD-style license
* that can be found in the LICENSE file in the root of the source
* tree. An additional intellectual property rights grant can be found
* in the file PATENTS. All contributing project authors may
* be found in the AUTHORS file in the root of the source tree.
*/
#ifndef RTC_BASE_STRING_TO_NUMBER_H_
#define RTC_BASE_STRING_TO_NUMBER_H_
#include <limits>
#include <string>
#include <type_traits>
#include "absl/strings/string_view.h"
#include "absl/types/optional.h"
namespace rtc {
// This file declares a family of functions to parse integers from strings.
// The standard C library functions either fail to indicate errors (atoi, etc.)
// or are a hassle to work with (strtol, sscanf, etc.). The standard C++ library
// functions (std::stoi, etc.) indicate errors by throwing exceptions, which
// are disabled in WebRTC.
//
// Integers are parsed using:
// absl::optional<int-type> StringToNumber(absl::string_view str,
// int base = 10);
//
// These functions parse a value from the beginning of a string into one of the
// fundamental integer types, or returns an empty Optional if parsing
// failed. Values outside of the range supported by the type will be
// rejected. The strings must begin with a digit or a minus sign. No leading
// space nor trailing contents are allowed.
// By setting base to 0, one of octal, decimal or hexadecimal will be
// detected from the string's prefix (0, nothing or 0x, respectively).
// If non-zero, base can be set to a value between 2 and 36 inclusively.
namespace string_to_number_internal {
// These must be (unsigned) long long, to match the signature of strto(u)ll.
using unsigned_type = unsigned long long; // NOLINT(runtime/int)
using signed_type = long long; // NOLINT(runtime/int)
absl::optional<signed_type> ParseSigned(absl::string_view str, int base);
absl::optional<unsigned_type> ParseUnsigned(absl::string_view str, int base);
template <typename T>
absl::optional<T> ParseFloatingPoint(absl::string_view str);
} // namespace string_to_number_internal
template <typename T>
typename std::enable_if<std::is_integral<T>::value && std::is_signed<T>::value,
absl::optional<T>>::type
StringToNumber(absl::string_view str, int base = 10) {
using string_to_number_internal::signed_type;
static_assert(
std::numeric_limits<T>::max() <=
std::numeric_limits<signed_type>::max() &&
std::numeric_limits<T>::lowest() >=
std::numeric_limits<signed_type>::lowest(),
"StringToNumber only supports signed integers as large as long long int");
absl::optional<signed_type> value =
string_to_number_internal::ParseSigned(str, base);
if (value && *value >= std::numeric_limits<T>::lowest() &&
*value <= std::numeric_limits<T>::max()) {
return static_cast<T>(*value);
}
return absl::nullopt;
}
template <typename T>
typename std::enable_if<std::is_integral<T>::value &&
std::is_unsigned<T>::value,
absl::optional<T>>::type
StringToNumber(absl::string_view str, int base = 10) {
using string_to_number_internal::unsigned_type;
static_assert(std::numeric_limits<T>::max() <=
std::numeric_limits<unsigned_type>::max(),
"StringToNumber only supports unsigned integers as large as "
"unsigned long long int");
absl::optional<unsigned_type> value =
string_to_number_internal::ParseUnsigned(str, base);
if (value && *value <= std::numeric_limits<T>::max()) {
return static_cast<T>(*value);
}
return absl::nullopt;
}
template <typename T>
typename std::enable_if<std::is_floating_point<T>::value,
absl::optional<T>>::type
StringToNumber(absl::string_view str, int base = 10) {
static_assert(
std::numeric_limits<T>::max() <= std::numeric_limits<long double>::max(),
"StringToNumber only supports floating-point numbers as large "
"as long double");
return string_to_number_internal::ParseFloatingPoint<T>(str);
}
} // namespace rtc
#endif // RTC_BASE_STRING_TO_NUMBER_H_
|
