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// Copyright 2018-2023 the Deno authors. All rights reserved. MIT license.
import { Buffer } from "../io/buffer.ts";import { writeAll } from "./write_all.ts";import { Reader } from "../types.d.ts";
/** Create a `Reader` from an iterable of `Uint8Array`s. * * ```ts *      import { readerFromIterable } from "https://deno.land/std@$STD_VERSION/streams/reader_from_iterable.ts"; *      import { copy } from "https://deno.land/std@$STD_VERSION/streams/copy.ts"; * *      const file = await Deno.open("metrics.txt", { write: true }); *      const reader = readerFromIterable((async function* () { *        while (true) { *          await new Promise((r) => setTimeout(r, 1000)); *          const message = `data: ${JSON.stringify(Deno.metrics())}\n\n`; *          yield new TextEncoder().encode(message); *        } *      })()); *      await copy(reader, file); * ``` */export function readerFromIterable(  iterable: Iterable<Uint8Array> | AsyncIterable<Uint8Array>,): Reader {  const iterator: Iterator<Uint8Array> | AsyncIterator<Uint8Array> =    (iterable as AsyncIterable<Uint8Array>)[Symbol.asyncIterator]?.() ??      (iterable as Iterable<Uint8Array>)[Symbol.iterator]?.();  const buffer = new Buffer();  return {    async read(p: Uint8Array): Promise<number | null> {      if (buffer.length == 0) {        const result = await iterator.next();        if (result.done) {          return null;        } else {          if (result.value.byteLength <= p.byteLength) {            p.set(result.value);            return result.value.byteLength;          }          p.set(result.value.subarray(0, p.byteLength));          await writeAll(buffer, result.value.subarray(p.byteLength));          return p.byteLength;        }      } else {        const n = await buffer.read(p);        if (n == null) {          return this.read(p);        }        return n;      }    },  };}