data-collectors/lib/transformers/distinct.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("../collections/toArray");
class DistinctCollector extends collector_1.BaseCollector {
    constructor(keyer, collector) {
        super();
        this.keyer = keyer;
        this.collector = collector;
    }
    supply() {
        return {
            keys: new Map(),
            items: []
        };
    }
    accumulate(container, item) {
        const key = this.keyer(item);
        if (!container.keys.has(key)) {
            container.keys.set(key, container.items.length);
            container.items.push([key, item]);
        }
    }
    combine(container1, container2) {
        const keys = new Map(container1.keys);
        const items = container1.items.slice();
        for (let [key, item] of container2.items) {
            if (!keys.has(key)) {
                keys.set(key, items.length);
                items.push([key, item]);
            }
        }
        return { keys, items };
    }
    finish(container) {
        const subContainer = this.collector.supply();
        for (let [_, item] of container.items) {
            this.collector.accumulate(subContainer, item);
        }
        return this.collector.finish(subContainer);
    }
}
exports.DistinctCollector = DistinctCollector;
function distinct(keyer, collector) {
    return new DistinctCollector(keyer || (x => x), collector || toArray_1.toArray());
}
exports.distinct = distinct;
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