absl/strings/strip.h

0001 //
0002 // Copyright 2017 The Abseil Authors.
0003 //
0004 // Licensed under the Apache License, Version 2.0 (the "License");
0005 // you may not use this file except in compliance with the License.
0006 // You may obtain a copy of the License at
0007 //
0008 //      https://www.apache.org/licenses/LICENSE-2.0
0009 //
0010 // Unless required by applicable law or agreed to in writing, software
0011 // distributed under the License is distributed on an "AS IS" BASIS,
0012 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
0013 // See the License for the specific language governing permissions and
0014 // limitations under the License.
0015 //
0016 // -----------------------------------------------------------------------------
0017 // File: strip.h
0018 // -----------------------------------------------------------------------------
0019 //
0020 // This file contains various functions for stripping substrings from a string.
0021 #ifndef ABSL_STRINGS_STRIP_H_
0022 #define ABSL_STRINGS_STRIP_H_
0023
0024 #include <cstddef>
0025 #include <string>
0026
0027 #include "absl/base/macros.h"
0028 #include "absl/base/nullability.h"
0029 #include "absl/strings/ascii.h"
0030 #include "absl/strings/match.h"
0031 #include "absl/strings/string_view.h"
0032
0033 namespace absl {
0034 ABSL_NAMESPACE_BEGIN
0035
0036 // ConsumePrefix()
0037 //
0038 // Strips the `expected` prefix, if found, from the start of `str`.
0039 // If the operation succeeded, `true` is returned.  If not, `false`
0040 // is returned and `str` is not modified.
0041 //
0042 // Example:
0043 //
0044 //   absl::string_view input("abc");
0045 //   EXPECT_TRUE(absl::ConsumePrefix(&input, "a"));
0046 //   EXPECT_EQ(input, "bc");
0047 inline bool ConsumePrefix(absl::Nonnull<absl::string_view*> str,
0048                           absl::string_view expected) {
0049   if (!absl::StartsWith(*str, expected)) return false;
0050   str->remove_prefix(expected.size());
0051   return true;
0052 }
0053 // ConsumeSuffix()
0054 //
0055 // Strips the `expected` suffix, if found, from the end of `str`.
0056 // If the operation succeeded, `true` is returned.  If not, `false`
0057 // is returned and `str` is not modified.
0058 //
0059 // Example:
0060 //
0061 //   absl::string_view input("abcdef");
0062 //   EXPECT_TRUE(absl::ConsumeSuffix(&input, "def"));
0063 //   EXPECT_EQ(input, "abc");
0064 inline bool ConsumeSuffix(absl::Nonnull<absl::string_view*> str,
0065                           absl::string_view expected) {
0066   if (!absl::EndsWith(*str, expected)) return false;
0067   str->remove_suffix(expected.size());
0068   return true;
0069 }
0070
0071 // StripPrefix()
0072 //
0073 // Returns a view into the input string `str` with the given `prefix` removed,
0074 // but leaving the original string intact. If the prefix does not match at the
0075 // start of the string, returns the original string instead.
0076 ABSL_MUST_USE_RESULT inline absl::string_view StripPrefix(
0077     absl::string_view str, absl::string_view prefix) {
0078   if (absl::StartsWith(str, prefix)) str.remove_prefix(prefix.size());
0079   return str;
0080 }
0081
0082 // StripSuffix()
0083 //
0084 // Returns a view into the input string `str` with the given `suffix` removed,
0085 // but leaving the original string intact. If the suffix does not match at the
0086 // end of the string, returns the original string instead.
0087 ABSL_MUST_USE_RESULT inline absl::string_view StripSuffix(
0088     absl::string_view str, absl::string_view suffix) {
0089   if (absl::EndsWith(str, suffix)) str.remove_suffix(suffix.size());
0090   return str;
0091 }
0092
0093 ABSL_NAMESPACE_END
0094 }  // namespace absl
0095
0096 #endif  // ABSL_STRINGS_STRIP_H_