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Diffstat (limited to 'src/web_vtt_reader.cc')
| -rw-r--r-- | src/web_vtt_reader.cc | 157 |
1 files changed, 157 insertions, 0 deletions
diff --git a/src/web_vtt_reader.cc b/src/web_vtt_reader.cc new file mode 100644 index 0000000..2781654 --- /dev/null +++ b/src/web_vtt_reader.cc @@ -0,0 +1,157 @@ +/* + Copyright (C) 2022 Carl Hetherington <cth@carlh.net> + + This program is free software; you can redistribute it and/or modify + it under the terms of the GNU General Public License as published by + the Free Software Foundation; either version 2 of the License, or + (at your option) any later version. + + This program is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + GNU General Public License for more details. + + You should have received a copy of the GNU General Public License + along with this program; if not, write to the Free Software + Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. + +*/ + + +#include "exceptions.h" +#include "subrip_reader.h" +#include "util.h" +#include "web_vtt_reader.h" +#include <boost/algorithm/string.hpp> +#include <boost/algorithm/string_regex.hpp> +#include <boost/bind.hpp> +#include <boost/regex.hpp> +#include <iostream> +#include <vector> + + +using std::function; +using std::string; +using std::vector; +using boost::optional; +using namespace sub; + + +WebVTTReader::WebVTTReader(FILE* file) +{ + this->read(boost::bind(&get_line_file, file)); +} + + +WebVTTReader::WebVTTReader(string subs) +{ + this->read(boost::bind(&get_line_string, &subs)); +} + + +void +WebVTTReader::read(std::function<optional<string> ()> get_line) +{ + enum class State { + /* expecting WEBVTT */ + HEADER, + /* awaiting a NOTE or a subtitle timing line */ + DATA, + /* reading the text of a subtitle */ + SUBTITLE, + /* reading a note */ + NOTE + } state = State::HEADER; + + RawSubtitle rs; + + rs.vertical_position.line = 0; + rs.vertical_position.reference = TOP_OF_SUBTITLE; + + while (true) { + auto line = get_line(); + if (!line) { + break; + } + + trim_right_if(*line, boost::is_any_of("\n\r")); + remove_unicode_bom(line); + + /* Keep some history in case there is an error to report */ + _context.push_back(*line); + if (_context.size() > 5) { + _context.pop_front(); + } + + switch (state) { + case State::HEADER: + if (!boost::starts_with(*line, "WEBVTT")) { + throw WebVTTError("No WEBVTT header found"); + } + state = State::DATA; + break; + case State::DATA: + if (boost::starts_with(*line, "NOTE")) { + state = State::NOTE; + } else if (line->find("-->") != string::npos) { + /* Further trim this line, removing spaces from the end */ + trim_right_if(*line, boost::is_any_of(" ")); + + vector<string> parts; + boost::algorithm::split(parts, *line, boost::algorithm::is_any_of(" "), boost::token_compress_on); + + if (parts.size() != 3 && parts.size() != 7) { + for (int i = 0; i < 2; ++i) { + auto ex = get_line(); + if (ex) { + _context.push_back(*ex); + } + } + throw WebVTTError(*line, "a time line", _context); + } + + string expected; + auto from = SubripReader::convert_time(parts[0], &expected); + if (!from) { + throw WebVTTError(parts[0], expected, _context); + } + rs.from = *from; + + auto to = SubripReader::convert_time(parts[2], &expected); + if (!to) { + throw WebVTTError(parts[2], expected, _context); + } + rs.to = *to; + + rs.vertical_position.line = 0; + state = State::SUBTITLE; + } else if (!line->empty()) { + throw WebVTTError(*line, "a note or time", _context); + } + break; + case State::SUBTITLE: + if (line->empty()) { + state = State::DATA; + } else { + /* Split up this line on unicode "LINE SEPARATOR". This feels hacky but also + * the least unpleasant place to do it. + */ + vector<string> sub_lines; + boost::algorithm::split_regex(sub_lines, *line, boost::regex("\xe2\x80\xa8")); + for (auto sub_line: sub_lines) { + rs.text = sub_line; + _subs.push_back(rs); + rs.vertical_position.line = rs.vertical_position.line.get() + 1; + } + } + break; + case State::NOTE: + if (line->empty()) { + state = State::DATA; + } + break; + } + + } +} + |