data-collectors/lib/collections/groupingBy.js

A collection of composable reduction operations for arbitrary streams of values

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
const collector_1 = require("../collector");
const toArray_1 = require("./toArray");
class GroupingByCollector extends collector_1.BaseCollector {
    constructor(mapper, supplier, collector) {
        super();
        this.mapper = mapper;
        this.supplier = supplier;
        this.collector = collector;
    }
    supply() {
        return new Map();
    }
    accumulate(container, item) {
        const key = this.mapper(item);
        if (!container.get(key)) {
            const subContainer = this.collector.supply();
            container.set(key, subContainer);
            this.collector.accumulate(subContainer, item);
        }
        else {
            this.collector.accumulate(container.get(key), item);
        }
    }
    combine(container1, container2) {
        for (let [key, value] of container2) {
            container1.set(key, this.collector.combine(container1.get(key), value));
        }
        return container1;
    }
    finish(container) {
        let finished = this.supplier();
        for (let [key, value] of container) {
            finished.set(key, this.collector.finish(value));
        }
        return finished;
    }
}
exports.GroupingByCollector = GroupingByCollector;
function groupingBy(mapper, supplier, collector) {
    if (!supplier && !collector) {
        return groupingBy(mapper, () => new Map(), toArray_1.toArray());
    }
    else if (!collector) {
        return groupingBy(mapper, () => new Map(), supplier);
    }
    return new GroupingByCollector(mapper, supplier, collector);
}
exports.groupingBy = groupingBy;
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