40 lines
1.2 KiB
TypeScript
40 lines
1.2 KiB
TypeScript
/**
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* Functions that does nothing (useful for default callbacks)
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*/
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export function nop(...args: any[]): any {
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}
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/**
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* Identity function (returns the sole argument untouched)
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*/
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export function identity<T>(input: T): T {
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return input;
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}
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/**
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* Partially apply fixed arguments to a function with named arguments
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*/
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export function partial<A extends object, PA extends Partial<A>, RA extends any[], R>(fixedargs: PA, func: (args: A, ...rest: RA) => R): (args: Omit<A, keyof PA>, ...rest: RA) => R {
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return (args: Omit<A, keyof PA>, ...rest: RA) => func({ ...fixedargs, ...args } as any, ...rest);
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}
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export type cmpArgs = Readonly<{ key: (item: any) => any, reverse: boolean }>
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export const cmpDefaults: cmpArgs = { key: identity, reverse: false }
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/**
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* Compare operator, that can be used in sort() calls.
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*/
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export function cmp(args?: Partial<cmpArgs>): (a: any, b: any) => number {
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const fargs = { ...cmpDefaults, ...args };
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return (a, b) => {
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const ka = fargs.key(a);
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const kb = fargs.key(b);
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if (ka > kb) {
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return fargs.reverse ? -1 : 1;
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} else if (ka < kb) {
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return fargs.reverse ? 1 : -1;
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} else {
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return 0;
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}
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}
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}
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