fileinput.ts

/*
 * fileinput.ts
 */

import { TextLineStream } from 'https://deno.land/std/streams/mod.ts'

const readableToLines = async function* (
    readable: ReadableStream,
    encoding = 'utf-8',
): AsyncIterable<string> {
    const lines = readable
        .pipeThrough(new TextDecoderStream(encoding))
        .pipeThrough(new TextLineStream())
    for await (const line of lines) {
        yield line
    }
}

export const input = async function* (
    args: string[] = Deno.args,
    encoding = 'utf-8',
): AsyncIterable<string> {
    if (!args.length) {
        const lines = readableToLines(Deno.stdin.readable, encoding)
        for await (const line of lines) {
            yield line
        }
    }
    for (const filename of args) {
        const file = await Deno.open(filename)
        const lines = readableToLines(file.readable, encoding)
        for await (const line of lines) {
            yield line
        }
    }
}

if (import.meta.main) {
    const lines = input()
    let lineno = 0
    for await (const line of lines) {
        console.log(`${++lineno}: ${line}`)
    }
}