Abstract Base Classes

Learning again why currently TS doesn't support a way to use `abstract static` unfortunately.

microsoft/TypeScript#34516

Eeps!

src/ArrayFileReader.ts

@@ -28,7 +28,7 @@ class ArrayFileReader extends MediaFileReader {
     );
   }
 
-  override init(callbacks: LoadCallbackType): void {
+  override _init(callbacks: LoadCallbackType): void {
     setTimeout(callbacks.onSuccess, 0);
   }
 

src/MediaFileReader.ts

@@ -14,7 +14,7 @@ import type {
   CharsetType
 } from './FlowTypes';
 
-class MediaFileReader {
+abstract class MediaFileReader {
   _isInitialized: boolean;
   _size: number;
 
@@ -50,17 +50,13 @@ class MediaFileReader {
     }
   }
 
-  _init(callbacks: LoadCallbackType): void {
-    throw new Error("Must implement init function");
-  }
+  abstract _init(callbacks: LoadCallbackType): void;
 
   /**
    * @param range The start and end indexes of the range to load.
    *        Ex: [0, 7] load bytes 0 to 7 inclusive.
    */
-  loadRange(range: [number, number], callbacks: LoadCallbackType): void {
-    throw new Error("Must implement loadRange function");
-  }
+  abstract loadRange(range: [number, number], callbacks: LoadCallbackType): void;
 
   /**
    * @return The size of the file in bytes.
@@ -73,9 +69,7 @@ class MediaFileReader {
     return this._size;
   }
 
-  getByteAt(offset: number): number {
-    throw new Error("Must implement getByteAt function");
-  }
+  abstract getByteAt(offset: number): number;
 
   getBytesAt(offset: number, length: number): Array<number> {
     var bytes = new Array(length);

src/MediaTagReader.ts

@@ -12,7 +12,7 @@ import type {
   TagType
 } from './FlowTypes';
 
-class MediaTagReader {
+abstract class MediaTagReader {
   _mediaFileReader: MediaFileReader;
   _tags: Array<string> | null;
 
@@ -80,19 +80,15 @@ class MediaTagReader {
   /**
    * Load the necessary bytes from the media file.
    */
-  _loadData(
+  abstract _loadData(
     mediaFileReader: MediaFileReader,
     callbacks: LoadCallbackType
-  ): void {
-    throw new Error("Must implement _loadData function");
-  }
+  ): void;
 
   /**
    * Parse the loaded data to read the media tags.
    */
-  _parseData(mediaFileReader: MediaFileReader, tags: Array<string> | null): TagType {
-    throw new Error("Must implement _parseData function");
-  }
+  abstract _parseData(mediaFileReader: MediaFileReader, tags: Array<string> | null): TagType;
 
   _expandShortcutTags(tagsWithShortcuts: Array<string> | null): Array<string> | null {
     if (!tagsWithShortcuts) {