65 lines
1.7 KiB
JavaScript
65 lines
1.7 KiB
JavaScript
import {InternMap} from "internmap";
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import identity from "./identity.js";
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export default function group(values, ...keys) {
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return nest(values, identity, identity, keys);
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}
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export function groups(values, ...keys) {
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return nest(values, Array.from, identity, keys);
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}
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function flatten(groups, keys) {
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for (let i = 1, n = keys.length; i < n; ++i) {
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groups = groups.flatMap(g => g.pop().map(([key, value]) => [...g, key, value]));
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}
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return groups;
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}
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export function flatGroup(values, ...keys) {
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return flatten(groups(values, ...keys), keys);
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}
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export function flatRollup(values, reduce, ...keys) {
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return flatten(rollups(values, reduce, ...keys), keys);
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}
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export function rollup(values, reduce, ...keys) {
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return nest(values, identity, reduce, keys);
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}
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export function rollups(values, reduce, ...keys) {
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return nest(values, Array.from, reduce, keys);
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}
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export function index(values, ...keys) {
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return nest(values, identity, unique, keys);
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}
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export function indexes(values, ...keys) {
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return nest(values, Array.from, unique, keys);
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}
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function unique(values) {
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if (values.length !== 1) throw new Error("duplicate key");
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return values[0];
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}
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function nest(values, map, reduce, keys) {
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return (function regroup(values, i) {
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if (i >= keys.length) return reduce(values);
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const groups = new InternMap();
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const keyof = keys[i++];
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let index = -1;
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for (const value of values) {
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const key = keyof(value, ++index, values);
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const group = groups.get(key);
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if (group) group.push(value);
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else groups.set(key, [value]);
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}
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for (const [key, values] of groups) {
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groups.set(key, regroup(values, i));
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}
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return map(groups);
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})(values, 0);
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}
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