add seek()

Author: jsimpson

README.md

@@ -5,7 +5,7 @@ A Deno module helper class that wraps around [DataView](https://developer.mozill
 ## Usage
 
 ```typescript
-import { BinaryReader } from "https://deno.land/x/[email protected].3/mod.ts";
+import { BinaryReader } from "https://deno.land/x/[email protected].4/mod.ts";
 
 const filename = "some-file.bin";
 const file = Deno.openSync(filename);

binary_reader.ts

@@ -20,6 +20,18 @@ export class BinaryReader {
     this.#position -= numBytes;
   }
 
+  /**
+   * Moves the buffer/DataView byteOffset to the specified position.
+   * @param position The position to move the buffer/DataView to.
+   */
+  seek(position: number): void {
+    if (position > this.buffer.length) {
+      return;
+    }
+
+    this.#position = position;
+  }
+
   /**
    * Returns the current position in the buffer.
    */

binary_reader_test.ts

@@ -363,3 +363,21 @@ Deno.test(
     assertEquals(data, [0x48, 0x65, 0x6C, 0x6C]);
   },
 );
+
+Deno.test(
+  "seek",
+  function (): void {
+    const buffer = new ArrayBuffer(4);
+    const array = new Uint8Array(buffer);
+
+    array[0] = 0x48;
+    array[1] = 0x65;
+    array[2] = 0x6C;
+    array[3] = 0x6C;
+
+    const binaryReader = new BinaryReader(array);
+    assertEquals(binaryReader.position, 0);
+    binaryReader.seek(3);
+    assertEquals(binaryReader.position, 3);
+  },
+);