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