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authorGravatar misterg <misterg@google.com>2017-09-19 16:54:40 -0400
committerGravatar misterg <misterg@google.com>2017-09-19 16:54:40 -0400
commitc2e754829628d1e9b7a16b3389cfdace76950fdf (patch)
tree5a7f056f44e27c30e10025113b644f0b3b5801fc /absl/strings/str_split.cc
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+// Copyright 2017 The Abseil Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "absl/strings/str_split.h"
+
+#include <cassert>
+#include <cstdlib>
+#include <cstring>
+#include <iterator>
+#include <limits>
+
+#include "absl/base/internal/raw_logging.h"
+#include "absl/strings/ascii.h"
+
+namespace absl {
+
+namespace {
+
+// This GenericFind() template function encapsulates the finding algorithm
+// shared between the ByString and ByAnyChar delimiters. The FindPolicy
+// template parameter allows each delimiter to customize the actual find
+// function to use and the length of the found delimiter. For example, the
+// Literal delimiter will ultimately use absl::string_view::find(), and the
+// AnyOf delimiter will use absl::string_view::find_first_of().
+template <typename FindPolicy>
+absl::string_view GenericFind(absl::string_view text,
+ absl::string_view delimiter, size_t pos,
+ FindPolicy find_policy) {
+ if (delimiter.empty() && text.length() > 0) {
+ // Special case for empty std::string delimiters: always return a zero-length
+ // absl::string_view referring to the item at position 1 past pos.
+ return absl::string_view(text.begin() + pos + 1, 0);
+ }
+ size_t found_pos = absl::string_view::npos;
+ absl::string_view found(text.end(), 0); // By default, not found
+ found_pos = find_policy.Find(text, delimiter, pos);
+ if (found_pos != absl::string_view::npos) {
+ found = absl::string_view(text.data() + found_pos,
+ find_policy.Length(delimiter));
+ }
+ return found;
+}
+
+// Finds using absl::string_view::find(), therefore the length of the found
+// delimiter is delimiter.length().
+struct LiteralPolicy {
+ size_t Find(absl::string_view text, absl::string_view delimiter, size_t pos) {
+ return text.find(delimiter, pos);
+ }
+ size_t Length(absl::string_view delimiter) { return delimiter.length(); }
+};
+
+// Finds using absl::string_view::find_first_of(), therefore the length of the
+// found delimiter is 1.
+struct AnyOfPolicy {
+ size_t Find(absl::string_view text, absl::string_view delimiter, size_t pos) {
+ return text.find_first_of(delimiter, pos);
+ }
+ size_t Length(absl::string_view /* delimiter */) { return 1; }
+};
+
+} // namespace
+
+//
+// ByString
+//
+
+ByString::ByString(absl::string_view sp) : delimiter_(sp) {}
+
+absl::string_view ByString::Find(absl::string_view text, size_t pos) const {
+ if (delimiter_.length() == 1) {
+ // Much faster to call find on a single character than on an
+ // absl::string_view.
+ size_t found_pos = text.find(delimiter_[0], pos);
+ if (found_pos == absl::string_view::npos)
+ return absl::string_view(text.end(), 0);
+ return text.substr(found_pos, 1);
+ }
+ return GenericFind(text, delimiter_, pos, LiteralPolicy());
+}
+
+//
+// ByChar
+//
+
+absl::string_view ByChar::Find(absl::string_view text, size_t pos) const {
+ size_t found_pos = text.find(c_, pos);
+ if (found_pos == absl::string_view::npos)
+ return absl::string_view(text.end(), 0);
+ return text.substr(found_pos, 1);
+}
+
+//
+// ByAnyChar
+//
+
+ByAnyChar::ByAnyChar(absl::string_view sp) : delimiters_(sp) {}
+
+absl::string_view ByAnyChar::Find(absl::string_view text, size_t pos) const {
+ return GenericFind(text, delimiters_, pos, AnyOfPolicy());
+}
+
+//
+// ByLength
+//
+ByLength::ByLength(ptrdiff_t length) : length_(length) {
+ ABSL_RAW_CHECK(length > 0, "");
+}
+
+absl::string_view ByLength::Find(absl::string_view text,
+ size_t pos) const {
+ pos = std::min(pos, text.size()); // truncate `pos`
+ absl::string_view substr = text.substr(pos);
+ // If the std::string is shorter than the chunk size we say we
+ // "can't find the delimiter" so this will be the last chunk.
+ if (substr.length() <= static_cast<size_t>(length_))
+ return absl::string_view(text.end(), 0);
+
+ return absl::string_view(substr.begin() + length_, 0);
+}
+
+} // namespace absl