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x/evt/tools/reducers/diff.ts

šŸ’§EventEmitter's typesafe replacement
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import { ReduceArguments, toReduceArguments } from "./reduceify.ts";import { contains } from "./contains.ts";import { removeDuplicates } from "./removeDuplicates.ts";import { id } from "https://deno.land/x/tsafe@v1.1.0/id.ts";
export type ArrDiff<T> = { added: readonly T[]; removed: readonly T[];}
const areStrictEqual = (e1: unknown, e2: unknown) => e1 === e2;
/** WARNING: Providing areEquals significantly impact performances */export function arrDiff<ArrOf>( arr: readonly ArrOf[], newArr: readonly ArrOf[], areEquals: (e1: ArrOf, e2: ArrOf) => boolean = areStrictEqual): ArrDiff<ArrOf> {
const arrDiff = { "added": id<ArrOf[]>([]), "removed": id<ArrOf[]>([]) };
if ( arr.length === newArr.length && arr.every((elem, i) => areEquals(elem, newArr[i])) ) { return arrDiff; }
if (areEquals !== areStrictEqual) {
return { "added": newArr .reduce(...removeDuplicates<ArrOf>(areEquals)) .filter(newEntry => !arr.reduce(...contains<ArrOf>(entry => areEquals(entry, newEntry)))), "removed": arr .reduce(...removeDuplicates<ArrOf>(areEquals)) .filter(entry => !newArr.reduce(...contains<ArrOf>(newEntry => areEquals(newEntry, entry)))) };
}
const arrAsSet = new Set<ArrOf>(arr); const newArrAsSet = new Set(newArr);
arrAsSet.forEach(elem => {
if (newArrAsSet.has(elem)) { return; }
arrDiff.removed.push(elem);
});
newArrAsSet.forEach(elem => {
if (arrAsSet.has(elem)) { return; }
arrDiff.added.push(elem);
});
return arrDiff;
}
export function diff<ArrOf>( newArr: readonly ArrOf[], areEquals?: (e1: ArrOf, e2: ArrOf) => boolean): ReduceArguments<ArrOf, ArrDiff<ArrOf>> { return toReduceArguments(arrDiff, newArr, areEquals);}
export function diffFactory({ areEquals }: { areEquals: <T>(e1: T, e2: T) => boolean; }) { return { "diff": <ArrOf>(newArr: readonly ArrOf[]) => diff<ArrOf>(newArr, areEquals) };}