media/formats/webm/webm_webvtt_parser.cc

   1 // Copyright 2014 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "media/formats/webm/webm_webvtt_parser.h"
   6
   7 namespace media {
   8
   9 void WebMWebVTTParser::Parse(const uint8* payload, int payload_size,
  10                              std::string* id,
  11                              std::string* settings,
  12                              std::string* content) {
  13   WebMWebVTTParser parser(payload, payload_size);
  14   parser.Parse(id, settings, content);
  15 }
  16
  17 WebMWebVTTParser::WebMWebVTTParser(const uint8* payload, int payload_size)
  18     : ptr_(payload),
  19       ptr_end_(payload + payload_size) {
  20 }
  21
  22 void WebMWebVTTParser::Parse(std::string* id,
  23                              std::string* settings,
  24                              std::string* content) {
  25   ParseLine(id);
  26   ParseLine(settings);
  27   content->assign(ptr_, ptr_end_);
  28 }
  29
  30 bool WebMWebVTTParser::GetByte(uint8* byte) {
  31   if (ptr_ >= ptr_end_)
  32     return false;  // indicates end-of-stream
  33
  34   *byte = *ptr_++;
  35   return true;
  36 }
  37
  38 void WebMWebVTTParser::UngetByte() {
  39   --ptr_;
  40 }
  41
  42 void WebMWebVTTParser::ParseLine(std::string* line) {
  43   line->clear();
  44
  45   // Consume characters from the stream, until we reach end-of-line.
  46
  47   // The WebVTT spec states that lines may be terminated in any of the following
  48   // three ways:
  49   //  LF
  50   //  CR
  51   //  CR LF
  52
  53   // The spec is here:
  54   //  http://wiki.webmproject.org/webm-metadata/temporal-metadata/webvtt-in-webm
  55
  56   enum {
  57     kLF = '\x0A',
  58     kCR = '\x0D'
  59   };
  60
  61   for (;;) {
  62     uint8 byte;
  63
  64     if (!GetByte(&byte) || byte == kLF)
  65       return;
  66
  67     if (byte == kCR) {
  68       if (GetByte(&byte) && byte != kLF)
  69         UngetByte();
  70
  71       return;
  72     }
  73
  74     line->push_back(byte);
  75   }
  76 }
  77
  78 }  // namespace media