shaka-packager/packager/media/formats/webvtt/text_readers.cc

123 lines
2.9 KiB
C++

// Copyright 2017 Google Inc. All rights reserved.
//
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file or at
// https://developers.google.com/open-source/licenses/bsd
#include "packager/media/formats/webvtt/text_readers.h"
#include "packager/base/logging.h"
#include "packager/file/file.h"
namespace shaka {
namespace media {
Status FileReader::Open(const std::string& filename,
std::unique_ptr<FileReader>* out) {
const char* kReadOnly = "r";
std::unique_ptr<File, FileCloser> file(
File::Open(filename.c_str(), kReadOnly));
if (!file) {
return Status(error::INVALID_ARGUMENT,
"Could not open input file " + filename);
}
*out = std::unique_ptr<FileReader>(new FileReader(std::move(file)));
return Status::OK;
}
bool FileReader::Next(char* out) {
// TODO(vaage): If file reading performance is poor, change this to buffer
// data and read from the buffer.
return file_->Read(out, 1) == 1;
}
FileReader::FileReader(std::unique_ptr<File, FileCloser> file)
: file_(std::move(file)) {
DCHECK(file_);
}
PeekingReader::PeekingReader(std::unique_ptr<FileReader> source)
: source_(std::move(source)) {}
bool PeekingReader::Next(char* out) {
DCHECK(out);
if (Peek(out)) {
has_cached_next_ = false;
return true;
}
return false;
}
bool PeekingReader::Peek(char* out) {
DCHECK(out);
if (!has_cached_next_ && source_->Next(&cached_next_)) {
has_cached_next_ = true;
}
if (has_cached_next_) {
*out = cached_next_;
return true;
}
return false;
}
LineReader::LineReader(std::unique_ptr<FileReader> source)
: source_(std::move(source)) {}
// Split lines based on https://w3c.github.io/webvtt/#webvtt-line-terminator
bool LineReader::Next(std::string* out) {
DCHECK(out);
out->clear();
bool read_something = false;
char now;
while (source_.Next(&now)) {
read_something = true;
// handle \n
if (now == '\n') {
break;
}
// handle \r and \r\n
if (now == '\r') {
char next;
if (source_.Peek(&next) && next == '\n') {
source_.Next(&next); // Read in the '\n' that was just seen via |Peek|
}
break;
}
out->push_back(now);
}
return read_something;
}
BlockReader::BlockReader(std::unique_ptr<FileReader> source)
: source_(std::move(source)) {}
bool BlockReader::Next(std::vector<std::string>* out) {
DCHECK(out);
out->clear();
bool in_block = false;
// Read through lines until a non-empty line is found. With a non-empty
// line is found, start adding the lines to the output and once an empty
// line if found again, stop adding lines and exit.
std::string line;
while (source_.Next(&line)) {
if (in_block && line.empty()) {
break;
}
if (in_block || !line.empty()) {
out->push_back(line);
in_block = true;
}
}
return in_block;
}
} // namespace media
} // namespace shaka