https://github.com/eibens/peek
Add a peek function to iterators in TypeScript for Deno.
https://github.com/eibens/peek
deno iterable iterator peek typescript utility
Last synced: 3 months ago
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Add a peek function to iterators in TypeScript for Deno.
- Host: GitHub
- URL: https://github.com/eibens/peek
- Owner: eibens
- License: mit
- Created: 2021-07-10T22:07:58.000Z (almost 4 years ago)
- Default Branch: master
- Last Pushed: 2021-07-11T08:51:36.000Z (almost 4 years ago)
- Last Synced: 2025-02-22T18:48:07.774Z (4 months ago)
- Topics: deno, iterable, iterator, peek, typescript, utility
- Language: TypeScript
- Homepage:
- Size: 4.88 KB
- Stars: 0
- Watchers: 2
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
README
# peek
[peek] implements a peeking iterator in TypeScript for [Deno].
[![License][license-shield]](LICENSE) [![Deno doc][deno-doc-shield]][deno-doc]
[![Deno module][deno-land-shield]][deno-land]
[![Github tag][github-shield]][github] [![Build][build-shield]][build]
[![Code coverage][coverage-shield]][coverage]
# Motivation
A peeking iterator allows one to look at the next item without taking it. This
can be useful if one only wants to consume items while a certain condition is
met. For example, a scheduler algorithm that only schedules tasks within a
certain time window can use a peeking iterator to check whether the event should
be scheduled, otherwise leaving it in the iterator for the next scheduling
cycle.
# [mod.ts](mod.ts)
This module exports all other modules.
# [peeking.ts](peeking.ts)
The `fromIterator` function creates a `PeekingIterator` from a normal `Iterator`
by implementing the `peek` function.
```ts
import {
fromIterator,
PeekingIterator,
} from "https://deno.land/x/peek/peeking.ts";
const peeking: PeekingIterator = fromIterator(
"abc"[Symbol.iterator](),
);
const preview: number = peeking.peek();
console.assert(preview === "a");
// The item is still in the iterator.
const next = peeking.next();
console.assert(next.value === "a");
```
The `fromIterable` function creates a `PeekingIterator` from an `Iterable`.
```ts
import { fromIterable } from "https://deno.land/x/peek/peeking.ts";
const peeking = fromIterable("abc");
console.assert(typeof peeking.peek === "function");
```
# [take_while.ts](take_while.ts)
The `takeWhile` generator function removes items from a `PeekingIterator` as
long as the specified `condition` is met.
```ts
import { fromIterable } from "https://deno.land/x/peek/peeking.ts";
import { takeWhile } from "https://deno.land/x/peek/take_while.ts";
const peeking = fromIterable("abcde");
const abc = takeWhile(peeking, (x) => x !== "d");
console.assert([...abc].join("") === "abc");
```
[peek]: #
[Deno]: https://deno.land
[github]: https://github.com/eibens/peek
[github-shield]: https://img.shields.io/github/v/tag/eibens/peek?label&logo=github
[coverage-shield]: https://img.shields.io/codecov/c/github/eibens/peek?logo=codecov&label
[license-shield]: https://img.shields.io/github/license/eibens/peek?color=informational
[coverage]: https://codecov.io/gh/eibens/peek
[build]: https://github.com/eibens/peek/actions/workflows/ci.yml
[build-shield]: https://img.shields.io/github/workflow/status/eibens/peek/ci?logo=github&label
[deno-doc]: https://doc.deno.land/https/deno.land/x/peek/mod.ts
[deno-doc-shield]: https://img.shields.io/badge/doc-informational?logo=deno
[deno-land]: https://deno.land/x/peek
[deno-land-shield]: https://img.shields.io/badge/x/peek-informational?logo=deno&label