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/*
* Copyright (C) 2013, Opera Software ASA. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above
* copyright notice, this list of conditions and the following disclaimer
* in the documentation and/or other materials provided with the
* distribution.
* * Neither the name of Google Inc. nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "config.h"
#include "BufferedLineReader.h"
#include <wtf/unicode/CharacterNames.h>
namespace WebCore {
std::optional<String> BufferedLineReader::nextLine()
{
if (m_maybeSkipLF) {
// We ran out of data after a CR (U+000D), which means that we may be
// in the middle of a CRLF pair. If the next character is a LF (U+000A)
// then skip it, and then (unconditionally) return the buffered line.
if (!m_buffer.isEmpty()) {
if (m_buffer.currentCharacter() == newlineCharacter)
m_buffer.advancePastNewline();
m_maybeSkipLF = false;
}
// If there was no (new) data available, then keep m_maybeSkipLF set,
// and fall through all the way down to the EOS check at the end of the function.
}
bool shouldReturnLine = false;
bool checkForLF = false;
while (!m_buffer.isEmpty()) {
UChar character = m_buffer.currentCharacter();
m_buffer.advance();
if (character == newlineCharacter || character == carriageReturn) {
// We found a line ending. Return the accumulated line.
shouldReturnLine = true;
checkForLF = (character == carriageReturn);
break;
}
// NULs are transformed into U+FFFD (REPLACEMENT CHAR.) in step 1 of
// the WebVTT parser algorithm.
if (character == '\0')
character = replacementCharacter;
m_lineBuffer.append(character);
}
if (checkForLF) {
// May be in the middle of a CRLF pair.
if (!m_buffer.isEmpty()) {
if (m_buffer.currentCharacter() == newlineCharacter)
m_buffer.advancePastNewline();
} else {
// Check for the newline on the next call (unless we reached EOS, in
// which case we'll return the contents of the line buffer, and
// reset state for the next line.)
m_maybeSkipLF = true;
}
}
if (isAtEndOfStream()) {
// We've reached the end of the stream proper. Emit a line if the
// current line buffer is non-empty. (Note that if shouldReturnLine is
// set already, we want to return a line nonetheless.)
shouldReturnLine |= !m_lineBuffer.isEmpty();
}
if (shouldReturnLine) {
auto line = m_lineBuffer.toString();
m_lineBuffer.clear();
return WTFMove(line);
}
ASSERT(m_buffer.isEmpty());
return std::nullopt;
}
} // namespace WebCore
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