shaka-player/lib/hls/hls_classes.js

DASH/EME video player library

/**
 * @license
 * Copyright 2016 Google Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

goog.provide('shaka.hls.Attribute');
goog.provide('shaka.hls.Playlist');
goog.provide('shaka.hls.PlaylistType');
goog.provide('shaka.hls.Segment');
goog.provide('shaka.hls.Tag');

goog.require('goog.asserts');


/**
 * Creates an HLS playlist object.
 *
 * @param {string} absoluteUri An absolute, final URI after redirects.
 * @param {!shaka.hls.PlaylistType} type
 * @param {!Array.<shaka.hls.Tag>} tags
 * @param {!Array.<shaka.hls.Segment>=} segments
 *
 * @constructor
 * @struct
 */
shaka.hls.Playlist = function(absoluteUri, type, tags, segments) {
  /**
   * An absolute, final URI after redirects.
   *
   * @const {string}
   */
  this.absoluteUri = absoluteUri;

  /** @const {shaka.hls.PlaylistType} */
  this.type = type;

  /** @const {!Array.<!shaka.hls.Tag>} */
  this.tags = tags;

  /** @const {Array.<!shaka.hls.Segment>} */
  this.segments = segments || null;
};


/**
 * @enum {number}
 */
shaka.hls.PlaylistType = {
  MASTER: 0,
  MEDIA: 1,
};


/**
 * Creates an HLS tag object.
 *
 * @param {number} id
 * @param {string} name
 * @param {!Array.<shaka.hls.Attribute>} attributes
 * @param {?string=} value
 *
 * @constructor
 * @struct
 */
shaka.hls.Tag = function(id, name, attributes, value = null) {
  /** @const {number} */
  this.id = id;

  /** @const {string} */
  this.name = name;

  /** @const {Array.<shaka.hls.Attribute>} */
  this.attributes = attributes;

  /** @const {?string} */
  this.value = value;
};


/**
 * Create the string representation of the tag.
 *
 * For the DRM system - the full tag needs to be passed down to the CDM.  There
 * are two ways of doing this (1) save the original tag or (2) recreate the tag.
 * As in some cases (like in tests) the tag never existed in string form, it
 * is far easier to recreate the tag from the parsed form.
 *
 * @return {string}
 * @override
 */
shaka.hls.Tag.prototype.toString = function() {
  /**
   * @param {shaka.hls.Attribute} attr
   * @return {string}
   */
  let attrToStr = function(attr) {
    const isNumericAttr = !isNaN(Number(attr.value));

    const value = (isNumericAttr ? attr.value : '"' + attr.value + '"');

    return attr.name + '=' + value;
  };


  // A valid tag can only follow 1 of 4 patterns.
  //  1) <NAME>:<VALUE>
  //  2) <NAME>:<ATTRIBUTE LIST>
  //  3) <NAME>
  //  4) <NAME>:<VALUE>,<ATTRIBUTE_LIST>

  let tagStr = '#' + this.name;
  const appendages = this.attributes ? this.attributes.map(attrToStr) : [];

  if (this.value) {
    appendages.unshift(this.value);
  }

  if (appendages.length > 0) {
    tagStr += ':' + appendages.join(',');
  }

  return tagStr;
};


/**
 * Creates an HLS attribute object.
 *
 * @param {string} name
 * @param {string} value
 *
 * @constructor
 * @struct
 */
shaka.hls.Attribute = function(name, value) {
  /** @const {string} */
  this.name = name;

  /** @const {string} */
  this.value = value;
};


/**
 * Adds an attribute to an HLS Tag.
 *
 * @param {!shaka.hls.Attribute} attribute
 */
shaka.hls.Tag.prototype.addAttribute = function(attribute) {
  this.attributes.push(attribute);
};


/**
 * Gets the first attribute of the tag with a specified name.
 *
 * @param {string} name
 * @return {?shaka.hls.Attribute} attribute
 */
shaka.hls.Tag.prototype.getAttribute = function(name) {
  let attributes = this.attributes.filter(function(attr) {
    return attr.name == name;
  });

  goog.asserts.assert(attributes.length < 2,
                      'A tag should not have multiple attributes ' +
                      'with the same name!');

  if (attributes.length) {
    return attributes[0];
  } else {
    return null;
  }
};


/**
 * Gets the value of the first attribute of the tag with a specified name.
 * If not found, returns an optional default value.
 *
 * @param {string} name
 * @param {string=} defaultValue
 * @return {?string}
 */
shaka.hls.Tag.prototype.getAttributeValue = function(name, defaultValue) {
  let attribute = this.getAttribute(name);
  return attribute ? attribute.value : (defaultValue || null);
};


/**
 * Creates an HLS segment object.
 *
 * @param {string} absoluteUri An absolute URI.
 * @param {!Array.<shaka.hls.Tag>} tags
 *
 * @constructor
 * @struct
 */
shaka.hls.Segment = function(absoluteUri, tags) {
  /** @const {!Array.<shaka.hls.Tag>} */
  this.tags = tags;

  /**
   * An absolute URI.
   *
   * @const {string}
   */
  this.absoluteUri = absoluteUri;
};