@blueprintjs/core
Version:
Core styles & components
86 lines (79 loc) • 2.64 kB
text/typescript
/*
* Copyright 2018 Palantir Technologies, Inc. All rights reserved.
*
* Licensed under the terms of the LICENSE file distributed with this project.
*/
import { isFunction } from "../utils";
/*
Understanding the types here:
`<Object, Key, ...Args, Return>`
`{ [k in K]?: (a: A) => R }`: This is a MAPPED TYPE that enforces that keys `K`
are all optional member functions with the given signature. The type `k` is only
used in the mapping definition.
`K extends keyof T`: A subset of the keys of the object `T`. The mapped type
above then imposes a restriction on the _values_ of these keys in `T`. Note that
`safeInvokeMember` only supports a single key, so the subset here has exactly
one item.
*/
/**
* Safely invoke the member function with no arguments, if the object
* exists and the given key is indeed a function, and return its value.
* Otherwise, return `undefined`.
*/
export function safeInvokeMember<T extends { [k in K]?: () => R }, K extends keyof T, R = void>(
obj: T | undefined,
key: K,
): R | undefined;
/**
* Safely invoke the member function with one argument, if the object
* exists and the given key is indeed a function, and return its value.
* Otherwise, return `undefined`.
*
* ```js
* // example usage
* safeInvokeMember(this.props.inputProps, "onChange", evt);
* ```
*/
export function safeInvokeMember<T extends { [k in K]?: (a: A) => R }, K extends keyof T, A, R = void>(
obj: T | undefined,
key: K,
arg1: A,
): R | undefined;
/**
* Safely invoke the member function with two arguments, if the object
* exists and the given key is indeed a function, and return its value.
* Otherwise, return `undefined`.
*/
export function safeInvokeMember<T extends { [k in K]?: (a: A, b: B) => R }, K extends keyof T, A, B, R = void>(
obj: T | undefined,
key: K,
arg1: A,
arg2: B,
): R | undefined;
/**
* Safely invoke the member function with three arguments, if the object
* exists and the given key is indeed a function, and return its value.
* Otherwise, return undefined.
*/
export function safeInvokeMember<
T extends { [k in K]?: (a: A, b: B, c: C) => R },
K extends keyof T,
A,
B,
C,
R = void
>(obj: T | undefined, key: K, arg1: A, arg2: B, arg3: C): R | undefined;
// tslint:disable-next-line:ban-types
export function safeInvokeMember<T extends { [P in K]?: Function }, K extends keyof T>(
obj: T | null | undefined,
key: K,
...args: any[]
) {
if (obj != null) {
const member = obj[key];
if (isFunction(member)) {
return member(...args);
}
}
return undefined;
}