111 lines
2.7 KiB
C++
111 lines
2.7 KiB
C++
/*
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* Copyright (c) Facebook, Inc. and its affiliates.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#pragma once
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namespace folly {
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namespace io {
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namespace detail {
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/*
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* Helper classes for use with CursorBase::readWhile()
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*/
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class CursorStringAppender {
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public:
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void append(ByteRange bytes) {
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str_.append(reinterpret_cast<char const*>(bytes.data()), bytes.size());
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}
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std::string extractString() {
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return std::move(str_);
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}
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private:
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std::string str_;
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};
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class CursorNoopAppender {
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public:
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void append(ByteRange) {}
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};
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template <class Derived, class BufType>
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std::string CursorBase<Derived, BufType>::readTerminatedString(
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char termChar,
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size_t maxLength) {
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size_t bytesRead{0};
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auto keepReading = [&bytesRead, termChar, maxLength](uint8_t byte) {
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if (byte == termChar) {
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return false;
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}
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++bytesRead;
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if (bytesRead >= maxLength) {
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throw std::length_error("string overflow");
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}
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return true;
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};
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auto result = readWhile(keepReading);
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// skip over the terminator character
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if (isAtEnd()) {
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throw_exception<std::out_of_range>("terminator not found");
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}
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skip(1);
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return result;
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}
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template <class Derived, class BufType>
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template <typename Predicate>
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std::string CursorBase<Derived, BufType>::readWhile(
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const Predicate& predicate) {
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CursorStringAppender s;
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readWhile(predicate, s);
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return s.extractString();
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}
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template <class Derived, class BufType>
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template <typename Predicate, typename Output>
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void CursorBase<Derived, BufType>::readWhile(
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const Predicate& predicate,
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Output& out) {
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while (true) {
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auto peeked = peekBytes();
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if (peeked.empty()) {
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return;
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}
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for (size_t idx = 0; idx < peeked.size(); ++idx) {
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if (!predicate(peeked[idx])) {
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peeked.reset(peeked.data(), idx);
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out.append(peeked);
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skip(idx);
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return;
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}
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}
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out.append(peeked);
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skip(peeked.size());
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}
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}
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template <class Derived, class BufType>
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template <typename Predicate>
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void CursorBase<Derived, BufType>::skipWhile(const Predicate& predicate) {
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CursorNoopAppender appender;
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readWhile(predicate, appender);
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}
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} // namespace detail
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} // namespace io
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} // namespace folly
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