SamJakob

const { promisify } = require('util');
const exec = promisify(require('child_process').exec);

/** Returns a random byte as a floating-point decimal between 0 and 1. */
async function random() {
	const payload = await exec(`gpg-connect-agent "SCD RANDOM 1" /bye`);
	const randomBytes = payload.stdout.split('\n')[0].substr(2);

	const buffer = Buffer.from(randomBytes, 'utf-8');
	const number = buffer.readUIntBE(0, 1);

SamJakob

/// This class extends [SizedBox] whilst implementing [PreferredSizeWidget]
/// based on the defined size. This allows the use of [SizedBox] in places
/// where [PreferredSizeWidget] is required, such as in [AppBar.preferredSize].
class PreferredSizedBox extends SizedBox implements PreferredSizeWidget {
  const PreferredSizedBox({super.key});

  const PreferredSizedBox.shrink({super.key, super.child}) : super.shrink();
  const PreferredSizedBox.expand({super.key, super.child}) : super.expand();
  PreferredSizedBox.fromSize({super.key, super.child, super.size})
      : super.fromSize();

SamJakob

/**
 * This is a TypeScript version of the `Completer` class from Dart.
 *
 * A `Completer` provides a future that can be imperatively concluded (once and
 * only once) with either `#complete` or `#completeError`.
 * Once the completer has completed (or errored), the future will be resolved
 * with the specified value.
 *
 * This is trivially implemented by instantiating a Promise and capturing the
 * resolve and reject functions.

SamJakob

/// An extension that adds the [chunked] method to a [Stream] of [List]s, to
/// allow dividing that [Stream] of (potentially) arbitrarily sized [List]s into
/// a stream of fixed sized [List]s.
extension ChunkedStream<T> on Stream<List<T>> {
  /// Convert the stream to a chunked stream, where each chunk is of the given
  /// [size]. The size of each chunk must be at least one, but the size may be
  /// any number larger than one (if the stream is finished before a chunk is
  /// finished, that chunk is returned as-is).
  Stream<List<T>> chunked(final int size) async* {
    if (size < 1) {