120 lines
2.7 KiB
TypeScript
120 lines
2.7 KiB
TypeScript
|
import { NotFoundError } from '../error/NotFoundError';
|
||
|
|
|
||
|
|
/**
|
||
|
|
* Unset value.
|
||
|
|
*/
|
||
|
|
/* eslint-disable-next-line @typescript-eslint/ban-types */
|
||
|
|
export type Nil = null | undefined;
|
||
|
|
|
||
|
|
/**
|
||
|
|
* Value that may be nil.
|
||
|
|
*/
|
||
|
|
export type Optional<T> = T | Nil;
|
||
|
|
|
||
|
|
/**
|
||
|
|
* Comparison (filter) predicate for a single value.
|
||
|
|
*/
|
||
|
|
export type PredicateC1<TVal> = (val: TVal, idx: number, list: Array<TVal>) => boolean;
|
||
|
|
|
||
|
|
/**
|
||
|
|
* Comparison (sort) predicate for two values.
|
||
|
|
*/
|
||
|
|
export type PredicateC2<TVal> = (pval: TVal, nval: TVal, idx: number, list: Array<TVal>) => number;
|
||
|
|
|
||
|
|
/**
|
||
|
|
* Reduction predicate for two values.
|
||
|
|
*/
|
||
|
|
export type PredicateR2<TVal> = (pval: TVal, nval: TVal, idx: number, list: Array<TVal>) => TVal;
|
||
|
|
|
||
|
|
/* eslint-disable-next-line @typescript-eslint/ban-types */
|
||
|
|
export function isNil<T>(val: Optional<T>): val is Nil {
|
||
|
|
/* eslint-disable-next-line no-null/no-null */
|
||
|
|
return val === null || val === undefined;
|
||
|
|
}
|
||
|
|
|
||
|
|
/**
|
||
|
|
* Calculate the "length" of an array or value.
|
||
|
|
*
|
||
|
|
* Arrays return their length, single values return 1, and nil values return 0.
|
||
|
|
* This counts the number of elements that setOrPush would add.
|
||
|
|
*/
|
||
|
|
export function countOf(val: unknown): number {
|
||
|
|
if (Array.isArray(val)) {
|
||
|
|
return val.length;
|
||
|
|
}
|
||
|
|
|
||
|
|
if (doesExist(val)) {
|
||
|
|
return 1;
|
||
|
|
}
|
||
|
|
|
||
|
|
return 0;
|
||
|
|
}
|
||
|
|
|
||
|
|
export function defaultWhen<TVal>(condition: boolean, ...items: Array<TVal>): TVal {
|
||
|
|
if (condition) {
|
||
|
|
return items[0];
|
||
|
|
} else {
|
||
|
|
return items[1];
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
/**
|
||
|
|
* Remove any null or undefined items from the list.
|
||
|
|
*/
|
||
|
|
export function filterNil<TItem>(list: ArrayLike<Optional<TItem>>): Array<TItem> {
|
||
|
|
return Array.from(list).filter(doesExist);
|
||
|
|
}
|
||
|
|
|
||
|
|
/**
|
||
|
|
* Merge arguments, which may or may not be arrays, into one return that is definitely an array.
|
||
|
|
*/
|
||
|
|
export function mergeList<TItem>(...parts: Array<TItem | Array<TItem>>): Array<TItem> {
|
||
|
|
const out = [];
|
||
|
|
|
||
|
|
for (const part of parts) {
|
||
|
|
if (Array.isArray(part)) {
|
||
|
|
out.push(...part);
|
||
|
|
} else {
|
||
|
|
out.push(part);
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
return out;
|
||
|
|
}
|
||
|
|
|
||
|
|
/**
|
||
|
|
* Find a value matching the given predicate or throw.
|
||
|
|
*/
|
||
|
|
export function mustFind<TVal>(list: Array<Optional<TVal>>, predicate: PredicateC1<TVal>): TVal {
|
||
|
|
const val = filterNil(list).find(predicate);
|
||
|
|
return mustExist(val);
|
||
|
|
}
|
||
|
|
|
||
|
|
/**
|
||
|
|
* Check if a variable is not nil.
|
||
|
|
*/
|
||
|
|
export function doesExist<T>(val: Optional<T>): val is T {
|
||
|
|
return !isNil(val);
|
||
|
|
}
|
||
|
|
|
||
|
|
/**
|
||
|
|
* Assert that a variable is not nil and return the value.
|
||
|
|
*
|
||
|
|
* @throws NotFoundError
|
||
|
|
* @returns val
|
||
|
|
*/
|
||
|
|
export function mustExist<T>(val: Optional<T>): T {
|
||
|
|
if (isNil(val)) {
|
||
|
|
throw new NotFoundError();
|
||
|
|
}
|
||
|
|
|
||
|
|
return val;
|
||
|
|
}
|
||
|
|
|
||
|
|
/**
|
||
|
|
* Return the first value that is not nil.
|
||
|
|
*/
|
||
|
|
export function mustCoalesce<T>(...values: Array<Optional<T>>): T {
|
||
|
|
return mustFind(values, doesExist);
|
||
|
|
}
|