/* * 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