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_split.h"
16
17#include <algorithm>
18#include <cassert>
19#include <cstdint>
20#include <cstdlib>
21#include <cstring>
22#include <iterator>
23#include <limits>
24#include <memory>
25
26#include "absl/base/internal/raw_logging.h"
27#include "absl/strings/ascii.h"
28
29namespace absl {
30
31namespace {
32
33// This GenericFind() template function encapsulates the finding algorithm
34// shared between the ByString and ByAnyChar delimiters. The FindPolicy
35// template parameter allows each delimiter to customize the actual find
36// function to use and the length of the found delimiter. For example, the
37// Literal delimiter will ultimately use absl::string_view::find(), and the
38// AnyOf delimiter will use absl::string_view::find_first_of().
39template <typename FindPolicy>
40absl::string_view GenericFind(absl::string_view text,
41 absl::string_view delimiter, size_t pos,
42 FindPolicy find_policy) {
43 if (delimiter.empty() && text.length() > 0) {
44 // Special case for empty std::string delimiters: always return a zero-length
45 // absl::string_view referring to the item at position 1 past pos.
46 return absl::string_view(text.data() + pos + 1, 0);
47 }
48 size_t found_pos = absl::string_view::npos;
49 absl::string_view found(text.data() + text.size(),
50 0); // By default, not found
51 found_pos = find_policy.Find(text, delimiter, pos);
52 if (found_pos != absl::string_view::npos) {
53 found = absl::string_view(text.data() + found_pos,
54 find_policy.Length(delimiter));
55 }
56 return found;
57}
58
59// Finds using absl::string_view::find(), therefore the length of the found
60// delimiter is delimiter.length().
61struct LiteralPolicy {
62 size_t Find(absl::string_view text, absl::string_view delimiter, size_t pos) {
63 return text.find(delimiter, pos);
64 }
65 size_t Length(absl::string_view delimiter) { return delimiter.length(); }
66};
67
68// Finds using absl::string_view::find_first_of(), therefore the length of the
69// found delimiter is 1.
70struct AnyOfPolicy {
71 size_t Find(absl::string_view text, absl::string_view delimiter, size_t pos) {
72 return text.find_first_of(delimiter, pos);
73 }
74 size_t Length(absl::string_view /* delimiter */) { return 1; }
75};
76
77} // namespace
78
79//
80// ByString
81//
82
83ByString::ByString(absl::string_view sp) : delimiter_(sp) {}
84
85absl::string_view ByString::Find(absl::string_view text, size_t pos) const {
86 if (delimiter_.length() == 1) {
87 // Much faster to call find on a single character than on an
88 // absl::string_view.
89 size_t found_pos = text.find(delimiter_[0], pos);
90 if (found_pos == absl::string_view::npos)
91 return absl::string_view(text.data() + text.size(), 0);
92 return text.substr(found_pos, 1);
93 }
94 return GenericFind(text, delimiter_, pos, LiteralPolicy());
95}
96
97//
98// ByChar
99//
100
101absl::string_view ByChar::Find(absl::string_view text, size_t pos) const {
102 size_t found_pos = text.find(c_, pos);
103 if (found_pos == absl::string_view::npos)
104 return absl::string_view(text.data() + text.size(), 0);
105 return text.substr(found_pos, 1);
106}
107
108//
109// ByAnyChar
110//
111
112ByAnyChar::ByAnyChar(absl::string_view sp) : delimiters_(sp) {}
113
114absl::string_view ByAnyChar::Find(absl::string_view text, size_t pos) const {
115 return GenericFind(text, delimiters_, pos, AnyOfPolicy());
116}
117
118//
119// ByLength
120//
121ByLength::ByLength(ptrdiff_t length) : length_(length) {
122 ABSL_RAW_CHECK(length > 0, "");
123}
124
125absl::string_view ByLength::Find(absl::string_view text,
126 size_t pos) const {
127 pos = std::min(pos, text.size()); // truncate `pos`
128 absl::string_view substr = text.substr(pos);
129 // If the std::string is shorter than the chunk size we say we
130 // "can't find the delimiter" so this will be the last chunk.
131 if (substr.length() <= static_cast<size_t>(length_))
132 return absl::string_view(text.data() + text.size(), 0);
133
134 return absl::string_view(substr.data() + length_, 0);
135}
136
137} // namespace absl
138