Alright file system walker

fs.ts

/*
 * Copyright (C) 2021 Hunter Kohler <jhunterkohler@gmail.com>
 */
import fs from "fs";
import path from "path";

interface WalkdirOptions {
    withFileTypes?: boolean;
    followlinks?: boolean;
    files?: boolean;
    encoding?: BufferEncoding;
    blockdev?: boolean;
    chardev?: boolean;
    dirs?: boolean;
    fifos?: boolean;
    sockets?: boolean;
    symlinks?: boolean;
    maxdepth?: number;
}

/**
 * Walk a directory tree.
 *
 * @param root Start of walk.
 * @param options Walk options.
 */
export async function* walkdirs(
    root: fs.PathLike,
    options?: WalkdirOptions
): AsyncIterator<string> {
    const {
        followlinks = false,
        files = true,
        encoding = "utf8",
        blockdev = true,
        chardev = true,
        dirs = true,
        fifos = true,
        sockets = true,
        symlinks = true,
        maxdepth = Infinity,
    } = options ?? {};

    const dirstack = [{ dirpath: String(root), depth: 0 }];
    const diropts = { withFileTypes: true, encoding } as const;
    const linkopts = { encoding };
    const seen = new Set<string>();

    while (dirstack.length) {
        const { dirpath, depth } = dirstack.pop()!;

        if (depth >= maxdepth) {
            continue;
        }

        const dir: (string | fs.Dirent)[] = await fs.promises.readdir(
            dirpath,
            diropts
        );

        for (const dirent of dir) {
            let filepath: string;
            let stats: fs.Dirent | fs.Stats;

            if (typeof dirent == "string") {
                filepath = dirent;
                stats = await fs.promises.stat(filepath);
            } else {
                filepath = path.join(dirpath, dirent.name);
                stats = dirent;
            }

            /*
             * Stop cycles if symlinks are allowed. (Though I suppose UNIX
             * systems could implement a circular file system haha).
             */
            if (seen.has(filepath)) {
                continue;
            } else {
                seen.add(filepath);
            }

            if (stats.isFile()) {
                if (files) {
                    yield filepath;
                }
            } else if (stats.isDirectory()) {
                if (dirs) {
                    yield filepath;
                }

                dirstack.push({ dirpath: filepath, depth: depth + 1 });
            } else if (stats.isSymbolicLink()) {
                if (symlinks) {
                    yield filepath;
                }

                if (followlinks) {
                    dir.push(await fs.promises.readlink(filepath, linkopts));
                }
            } else if (stats.isBlockDevice()) {
                if (blockdev) {
                    yield filepath;
                }
            } else if (stats.isCharacterDevice()) {
                if (chardev) {
                    yield filepath;
                }
            } else if (stats.isFIFO()) {
                if (fifos) {
                    yield filepath;
                }
            } else if (stats.isSocket()) {
                if (sockets) {
                    yield filepath;
                }
            }
        }
    }
}