Fix bug with tee() so that endianness is also copied to teed stream.

Author: codedread

io/bytestream.js

@@ -66,6 +66,11 @@ export class ByteStream {
     this.littleEndian_ = true;
   }
 
+  /** @returns {boolean} Whether the stream is little-endian. */
+  isLittleEndian() {
+    return this.littleEndian_;
+  }
+
   /** Big-Endian is sometimes called Motorola-style. */
   setBigEndian() {
     this.littleEndian_ = false;
@@ -78,13 +83,15 @@ export class ByteStream {
 
   /**
    * Returns how many bytes have been read in the stream since the beginning of time.
+   * @returns {number}
    */
   getNumBytesRead() {
     return this.bytesRead_;
   }
 
   /**
    * Returns how many bytes are currently in the stream left to be read.
+   * @returns {number}
    */
   getNumBytesLeft() {
     const bytesInCurrentPage = (this.bytes.byteLength - this.ptr);
@@ -334,6 +341,10 @@ export class ByteStream {
 
   /**
    * Creates a new ByteStream from this ByteStream that can be read / peeked.
+   * Note that the teed stream is a disconnected copy. If you push more bytes to the original
+   * stream, the copy does not get them.
+   * TODO: Assess whether the above causes more bugs than it avoids. (It would feel weird to me if
+   *       the teed stream shared some state with the original stream.)
    * @returns {ByteStream} A clone of this ByteStream.
    */
   tee() {
@@ -342,6 +353,7 @@ export class ByteStream {
     clone.ptr = this.ptr;
     clone.pages_ = this.pages_.slice();
     clone.bytesRead_ = this.bytesRead_;
+    clone.littleEndian_ = this.littleEndian_;
     return clone;
   }
 }

tests/io-bytestream.spec.js

@@ -255,6 +255,8 @@ describe('bitjs.io.ByteStream', () => {
   it('Tee', () => {
     for (let i = 0; i < 4; ++i) array[i] = 65 + i;
     const stream = new ByteStream(array.buffer);
+    // Set non-default endianness.
+    stream.setBigEndian(true);
 
     const anotherArray = new Uint8Array(4);
     for (let i = 0; i < 4; ++i) anotherArray[i] = 69 + i;
@@ -265,5 +267,6 @@ describe('bitjs.io.ByteStream', () => {
     teed.readBytes(5);
     expect(stream.getNumBytesLeft()).equals(8);
     expect(teed.getNumBytesLeft()).equals(3);
+    expect(teed.isLittleEndian()).equals(stream.isLittleEndian());
   });
 });