feat(cli/unstable): add ProgressBar start() method

cli/unstable_progress_bar.ts

@@ -110,6 +110,7 @@
  * const writer = (await Deno.create("./_tmp/output.txt")).writable.getWriter();
  *
  * const bar = new ProgressBar(Deno.stdout.writable, { max: 100_000 });
+ * bar.start();
  *
  * for await (const buffer of gen) {
  *   bar.add(buffer.length);
@@ -131,6 +132,7 @@
  *     return `${x.styledTime()}${x.progressBar}[${x.value}/${x.max} files]`;
  *   },
  * });
+ * bar.start();
  *
  * for (const x of Array(100)) {
  *   bar.add(1);
@@ -143,10 +145,10 @@
   #unit: string;
   #rate: number;
   #writer: WritableStreamDefaultWriter;
-  #id: number;
-  #startTime: number;
-  #lastTime: number;
-  #lastValue: number;
+  #intervalId?: number;
+  #startTime: number = 0;
+  #lastTime: number = 0;
+  #lastValue: number = 0;
 
   #value: number;
   #max: number;
@@ -204,9 +206,9 @@
     const stream = new TextEncoderStream();
     stream.readable
       .pipeTo(writable, { preventClose: this.#keepOpen })
-      .catch(() => clearInterval(this.#id));
+      .catch(() => clearInterval(this.#intervalId));
     this.#writer = stream.writable.getWriter();
-    this.#id = setInterval(() => this.#print(), 1000);
+    this.#intervalId = setInterval(() => this.#print(), 1000);
     this.#startTime = performance.now();
     this.#lastTime = this.#startTime;
     this.#lastValue = this.#value;
@@ -259,6 +261,25 @@
     this.#value += x;
   }
 
+  /**
+   * Starts the progress bar.
+   *
+   * @example Usage
+   * ```ts ignore
+   * import { ProgressBar } from "@std/cli/unstable-progress-bar";
+   *
+   * const bar = new ProgressBar(Deno.stdout.writable, { max: 1 });
+   * bar.start();
+   * ```
+   */
+  start(): void {
+    if (this.#intervalId) return;
+    this.#intervalId = setInterval(() => this.#print(), 200);
+    this.#startTime = performance.now();
+    this.#lastTime = this.#startTime;
+    this.#lastValue = this.#value;
+  }
+
   /**
    * Ends the progress bar and cleans up any lose ends.
    *
@@ -271,7 +292,7 @@
    * ```
    */
   async end(): Promise<void> {
-    clearInterval(this.#id);
+    clearInterval(this.#intervalId);
     await this.#print()
       .then(() => this.#writer.write(this.#clear ? "\r\u001b[K" : "\n"))
       .then(() => this.#writer.close())

cli/unstable_progress_bar_stream.ts

@@ -55,6 +55,7 @@ export class ProgressBarStream extends TransformStream<Uint8Array, Uint8Array> {
     super({
       start(_controller) {
         bar = new ProgressBar(writable, options);
+        bar.start();
       },
       transform(chunk, controller) {
         bar?.add(chunk.length);

cli/unstable_progress_bar_test.ts

@@ -16,6 +16,7 @@ async function* getData(
 Deno.test("ProgressBar() outputs default result", async () => {
   const { readable, writable } = new TransformStream();
   const bar = new ProgressBar(writable, { max: 10 * 1000 });
+  bar.start();
 
   for await (const a of getData(10, 1000)) bar.add(a.length);
   bar.end().then(() => writable.close());
@@ -65,6 +66,7 @@ Deno.test("ProgressBar() outputs default result", async () => {
 Deno.test("ProgressBar() can handle a readable.cancel() correctly", async () => {
   const { readable, writable } = new TransformStream();
   const bar = new ProgressBar(writable, { max: 10 * 1000 });
+  bar.start();
 
   for await (const a of getData(10, 1000)) bar.add(a.length);
   bar.end();
@@ -78,6 +80,7 @@ Deno.test("ProgressBar() can remove itself when finished", async () => {
     max: 10 * 1000,
     clear: true,
   });
+  bar.start();
 
   for await (const a of getData(10, 1000)) bar.add(a.length);
   bar.end()
@@ -103,6 +106,7 @@ Deno.test("ProgressBar() passes correct values to formatter", async () => {
       return "";
     },
   });
+  bar.start();
 
   for await (const a of getData(10, 1000)) bar.add(a.length);
   bar.end();
@@ -119,7 +123,7 @@ Deno.test("ProgressBar() uses correct unit type", async () => {
       max: 2 ** (10 * ++i),
       keepOpen: false,
     });
-
+    bar.start();
     const decoder = new TextDecoder();
     for await (const buffer of readable) {
       assertEquals(decoder.decode(buffer.subarray(-5, -2)), unit);
@@ -128,3 +132,48 @@ Deno.test("ProgressBar() uses correct unit type", async () => {
     bar.end();
   }
 });
+
+Deno.test("ProgressBar() handles successive start() calls", () => {
+  const { writable } = new TransformStream();
+  const bar = new ProgressBar(writable, { max: 1 });
+  bar.start();
+  bar.start();
+  bar.end();
+});
+
+Deno.test("ProgressBar() handles successive end() calls", () => {
+  const { writable } = new TransformStream();
+  const bar = new ProgressBar(writable, { max: 1 });
+  bar.start();
+  bar.end();
+  bar.end();
+});
+
+Deno.test(
+  "ProgressBar() handles multiple start() and stop() calls",
+  async () => {
+    const { readable, writable } = new TransformStream();
+    const bar = new ProgressBar(writable, { max: 1 });
+    bar.start();
+    bar.add(0.5);
+    bar.end();
+    const decoder = new TextDecoder();
+    for await (const buffer of readable) {
+      assertEquals(
+        decoder.decode(buffer),
+        "\r\x1b[K[00:00] [#########################-------------------------] [0.00/0.00 KiB] ",
+      );
+      break;
+    }
+    bar.start();
+    bar.add(0.5);
+    bar.end();
+    for await (const buffer of readable) {
+      assertEquals(
+        decoder.decode(buffer),
+        "\r\x1b[K[00:00] [#########################-------------------------] [0.00/0.00 KiB] ",
+      );
+      break;
+    }
+  },
+);