import * as stream from 'stream';

const NEWLINE_REGEX = /\n/g;

/**

* Given a string, yields each part in the string terminated by a newline and

* returns the final part without a newline.

*/

function* yieldLinesFromString(string: string) {

// Strip out carraige returns. We can't simply look for \r\n because git can

// sometimes emit ansi color codes between \r and \n.

string = string.replace(/\r/g, '');

let lastIndex = 0;

let match: RegExpExecArray | null;

while ((match = NEWLINE_REGEX.exec(string))) {

yield string.slice(lastIndex, match.index);

lastIndex = match.index + match[0].length;

}

return string.slice(lastIndex);

}

/**

* Converts a readable stream to an iterator that yields the stream's contents

* line-by-line.

*/

export async function* iterlinesFromReadable(

readable: stream.Readable

): AsyncIterable<string> {

let string: string = '';

for await (const chunk of readable) {

string += (chunk as Buffer).toString();

string = yield* yieldLinesFromString(string);

}

yield string;

}