1 // Copyright 2017 The Abseil Authors.
2 //
3 // Licensed under the Apache License, Version 2.0 (the "License");
4 // you may not use this file except in compliance with the License.
5 // You may obtain a copy of the License at
6 //
7 // https://www.apache.org/licenses/LICENSE-2.0
8 //
9 // Unless required by applicable law or agreed to in writing, software
10 // distributed under the License is distributed on an "AS IS" BASIS,
11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12 // See the License for the specific language governing permissions and
13 // limitations under the License.
14
15 #include "absl/strings/str_replace.h"
16
17 #include "absl/strings/str_cat.h"
18
19 namespace absl {
20 ABSL_NAMESPACE_BEGIN
21 namespace strings_internal {
22
23 using FixedMapping =
24 std::initializer_list<std::pair<absl::string_view, absl::string_view>>;
25
26 // Applies the ViableSubstitutions in subs_ptr to the absl::string_view s, and
27 // stores the result in *result_ptr. Returns the number of substitutions that
28 // occurred.
ApplySubstitutions(absl::string_view s,std::vector<strings_internal::ViableSubstitution> * subs_ptr,std::string * result_ptr)29 int ApplySubstitutions(
30 absl::string_view s,
31 std::vector<strings_internal::ViableSubstitution>* subs_ptr,
32 std::string* result_ptr) {
33 auto& subs = *subs_ptr;
34 int substitutions = 0;
35 size_t pos = 0;
36 while (!subs.empty()) {
37 auto& sub = subs.back();
38 if (sub.offset >= pos) {
39 if (pos <= s.size()) {
40 StrAppend(result_ptr, s.substr(pos, sub.offset - pos), sub.replacement);
41 }
42 pos = sub.offset + sub.old.size();
43 substitutions += 1;
44 }
45 sub.offset = s.find(sub.old, pos);
46 if (sub.offset == s.npos) {
47 subs.pop_back();
48 } else {
49 // Insertion sort to ensure the last ViableSubstitution continues to be
50 // before all the others.
51 size_t index = subs.size();
52 while (--index && subs[index - 1].OccursBefore(subs[index])) {
53 std::swap(subs[index], subs[index - 1]);
54 }
55 }
56 }
57 result_ptr->append(s.data() + pos, s.size() - pos);
58 return substitutions;
59 }
60
61 } // namespace strings_internal
62
63 // We can implement this in terms of the generic StrReplaceAll, but
64 // we must specify the template overload because C++ cannot deduce the type
65 // of an initializer_list parameter to a function, and also if we don't specify
66 // the type, we just call ourselves.
67 //
68 // Note that we implement them here, rather than in the header, so that they
69 // aren't inlined.
70
StrReplaceAll(absl::string_view s,strings_internal::FixedMapping replacements)71 std::string StrReplaceAll(absl::string_view s,
72 strings_internal::FixedMapping replacements) {
73 return StrReplaceAll<strings_internal::FixedMapping>(s, replacements);
74 }
75
StrReplaceAll(strings_internal::FixedMapping replacements,std::string * target)76 int StrReplaceAll(strings_internal::FixedMapping replacements,
77 std::string* target) {
78 return StrReplaceAll<strings_internal::FixedMapping>(replacements, target);
79 }
80
81 ABSL_NAMESPACE_END
82 } // namespace absl
83