46 lines
1.7 KiB
TypeScript
46 lines
1.7 KiB
TypeScript
// License: LGPL-3.0-or-later
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// from https://github.com/mtraynham/lodash-joins/blob/c252b462981562451d85d1e09c8f273ce7fe06c5/lib/hash/hashInnerJoin.ts
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import groupBy from 'lodash/groupBy';
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import has from 'lodash/has';
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import map from 'lodash/map';
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import reduceRight from 'lodash/reduceRight';
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import {Accessor, Merger} from '../typings';
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import {toStringAccessor} from './util';
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/**
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* Hash inner join
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*/
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export default function hashInnerJoin<LeftRow, RightRow, Key, MergeResult>(
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a: LeftRow[],
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aAccessor: Accessor<LeftRow, Key>,
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b: RightRow[],
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bAccessor: Accessor<RightRow, Key>,
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merger: Merger<LeftRow, RightRow, MergeResult>
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): MergeResult[] {
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if (a.length < 1 || b.length < 1) {
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return [];
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}
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const leftAccessor: Accessor<LeftRow, string> = toStringAccessor(aAccessor),
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rightAccessor: Accessor<RightRow, string> = toStringAccessor(bAccessor);
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let index: {[key: string]: (LeftRow | RightRow)[]},
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key: string;
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if (a.length < b.length) {
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index = groupBy(a, leftAccessor);
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return reduceRight(b, (previous: MergeResult[], bDatum: RightRow) => {
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key = rightAccessor(bDatum);
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if (has(index, key)) {
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return map(index[key], (aDatum: LeftRow) => merger(aDatum, bDatum)).concat(previous);
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}
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return previous;
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}, []);
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}
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index = groupBy(b, rightAccessor);
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return reduceRight(a, (previous: MergeResult[], aDatum: LeftRow) => {
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key = leftAccessor(aDatum);
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if (has(index, key)) {
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return map(index[key], (bDatum: RightRow) => merger(aDatum, bDatum)).concat(previous);
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}
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return previous;
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}, []);
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}
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