upsert



Maps for emplace, TC39
proposal-upsert implementation.

Table of Contents

- Install
- Usage
- Insert
- Just insert
- Update
- Just update
- Emplaceable
- EmplaceableMap
- EmplaceableWeakMap
- Polyfill
- API
- Contributing
- License

Install

deno.land:

``ts
import * as mod from "https://deno.land/x/upsert/mod.ts";
`

npm:

`bash
npm i @miyauci/upsert
`

Usage

Add a value to a map like if it does not already have something at key, and
will also update an existing value at key.

`ts
import { emplace } from "https://deno.land/x/upsert/mod.ts";
import { assert } from "https://deno.land/std/testing/asserts.ts";

declare const map: Map;
declare const key: string;

const result = emplace(map, key, {
insert: () => 0,
update: (existing) => ++existing,
});
assert(map.has(key));
`

$3

Add the entry if the key does not exist.

`ts
import { emplace } from "https://deno.land/x/upsert/mod.ts";
import { assert } from "https://deno.land/std/testing/asserts.ts";
import {
assertType,
type IsExact,
} from "https://deno.land/std/testing/types.ts";

declare const map: Map;
declare const key: string;
declare const value: number;

const result = emplace(map, key, { insert: () => value });

assert(map.has(key));
assertType>(true);
`

#### Just insert

If only inserting is required, insert is available.

`ts
import { insert } from "https://deno.land/x/upsert/mod.ts";
import { assertEquals } from "https://deno.land/std/testing/asserts.ts";

declare const key: string;
declare const value: number;
const map = new Map();

insert(map, key, () => value);

assertEquals(map, new Map([[key, value]]));
`

$3

Update the entry if the key exists.

`ts
import { emplace } from "https://deno.land/x/upsert/mod.ts";
import { assert } from "https://deno.land/std/testing/asserts.ts";
import {
assertType,
type IsExact,
} from "https://deno.land/std/testing/types.ts";

declare const map: Map;
declare const key: string;

const result = emplace(map, key, { update: (existing) => ++existing });

assertType>(true);
`

#### Just update

If only updating is required, update is available.

`ts
import { update } from "https://deno.land/x/upsert/mod.ts";
import { assertEquals } from "https://deno.land/std/testing/asserts.ts";

declare const key: string;
const map = new Map([[key, 0]]);

update(map, key, (existing) => ++existing);

assertEquals(map, new Map([[key, 1]]));
`

$3

Mixin for emplace.

`ts
import { emplaceable } from "https://deno.land/x/upsert/mod.ts";
import { assert } from "https://deno.land/std/testing/asserts.ts";

class MyMap extends emplaceable(Map) {}

assert(MyMap.prototype.emplace);
`

decorator style:

> note In TypeScript, decorators do not yet affect types.

`ts
import {
type Emplaceable,
emplaceable,
} from "https://deno.land/x/upsert/mod.ts";
import { assert } from "https://deno.land/std/testing/asserts.ts";

@emplaceable
class MyMap extends Map {}
interface MyMap extends Emplaceable {}

assert(MyMap.prototype.emplace);
`

$3

Map with Emplaceable implementation.

`ts
import { EmplaceableMap } from "https://deno.land/x/upsert/mod.ts";
import {
assert,
assertInstanceOf,
} from "https://deno.land/std/testing/asserts.ts";

const map = new EmplaceableMap();

assertInstanceOf(map, Map);
assert(map.emplace);
`

$3

WeakMap with Emplaceable implementation.

`ts
import { EmplaceableWeakMap } from "https://deno.land/x/upsert/mod.ts";
import {
assert,
assertInstanceOf,
} from "https://deno.land/std/testing/asserts.ts";

const weakMap = new EmplaceableWeakMap();

assertInstanceOf(weakMap, WeakMap);
assert(weakMap.emplace);
`

$3

Polyfill affects the global object. You must be very careful when using it.

`ts
import "https://deno.land/x/upsert/polyfill.ts";
import { assert } from "https://deno.land/std/testing/asserts.ts";

assert(Map.prototype.emplace);
assert(WeakMap.prototype.emplace);
``

API

See deno doc for all APIs.

Contributing

See contributing.

License

MIT © 2023 Tomoki Miyauchi