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: strip.h
18 // -----------------------------------------------------------------------------
19 //
20 // This file contains various functions for stripping substrings from a string.
21 #ifndef ABSL_STRINGS_STRIP_H_
22 #define ABSL_STRINGS_STRIP_H_
23
24 #include <cstddef>
25 #include <string>
26
27 #include "absl/base/attributes.h"
28 #include "absl/base/macros.h"
29 #include "absl/base/nullability.h"
30 #include "absl/strings/ascii.h"
31 #include "absl/strings/match.h"
32 #include "absl/strings/string_view.h"
33
34 namespace absl {
35 ABSL_NAMESPACE_BEGIN
36
37 // ConsumePrefix()
38 //
39 // Strips the `expected` prefix, if found, from the start of `str`.
40 // If the operation succeeded, `true` is returned. If not, `false`
41 // is returned and `str` is not modified.
42 //
43 // Example:
44 //
45 // absl::string_view input("abc");
46 // EXPECT_TRUE(absl::ConsumePrefix(&input, "a"));
47 // EXPECT_EQ(input, "bc");
ConsumePrefix(absl::Nonnull<absl::string_view * > str,absl::string_view expected)48 inline constexpr bool ConsumePrefix(absl::Nonnull<absl::string_view*> str,
49 absl::string_view expected) {
50 if (!absl::StartsWith(*str, expected)) return false;
51 str->remove_prefix(expected.size());
52 return true;
53 }
54 // ConsumeSuffix()
55 //
56 // Strips the `expected` suffix, if found, from the end of `str`.
57 // If the operation succeeded, `true` is returned. If not, `false`
58 // is returned and `str` is not modified.
59 //
60 // Example:
61 //
62 // absl::string_view input("abcdef");
63 // EXPECT_TRUE(absl::ConsumeSuffix(&input, "def"));
64 // EXPECT_EQ(input, "abc");
ConsumeSuffix(absl::Nonnull<absl::string_view * > str,absl::string_view expected)65 inline constexpr bool ConsumeSuffix(absl::Nonnull<absl::string_view*> str,
66 absl::string_view expected) {
67 if (!absl::EndsWith(*str, expected)) return false;
68 str->remove_suffix(expected.size());
69 return true;
70 }
71
72 // StripPrefix()
73 //
74 // Returns a view into the input string `str` with the given `prefix` removed,
75 // but leaving the original string intact. If the prefix does not match at the
76 // start of the string, returns the original string instead.
StripPrefix(absl::string_view str ABSL_ATTRIBUTE_LIFETIME_BOUND,absl::string_view prefix)77 [[nodiscard]] inline constexpr absl::string_view StripPrefix(
78 absl::string_view str ABSL_ATTRIBUTE_LIFETIME_BOUND,
79 absl::string_view prefix) {
80 if (absl::StartsWith(str, prefix)) str.remove_prefix(prefix.size());
81 return str;
82 }
83
84 // StripSuffix()
85 //
86 // Returns a view into the input string `str` with the given `suffix` removed,
87 // but leaving the original string intact. If the suffix does not match at the
88 // end of the string, returns the original string instead.
StripSuffix(absl::string_view str ABSL_ATTRIBUTE_LIFETIME_BOUND,absl::string_view suffix)89 [[nodiscard]] inline constexpr absl::string_view StripSuffix(
90 absl::string_view str ABSL_ATTRIBUTE_LIFETIME_BOUND,
91 absl::string_view suffix) {
92 if (absl::EndsWith(str, suffix)) str.remove_suffix(suffix.size());
93 return str;
94 }
95
96 ABSL_NAMESPACE_END
97 } // namespace absl
98
99 #endif // ABSL_STRINGS_STRIP_H_
100