data-forge-beta/build/lib/iterators/distinct-iterator.js

JavaScript data transformation and analysis toolkit inspired by Pandas and LINQ.

"use strict";
//
// An iterator that iterates the only distinct elements of another iterable.
//
Object.defineProperty(exports, "__esModule", { value: true });
var DistinctIterator = /** @class */ (function () {
    function DistinctIterator(iterable, selector) {
        this.valuesAlreadySeen = new Set();
        this.iterator = iterable[Symbol.iterator]();
        this.selector = selector;
    }
    DistinctIterator.prototype.next = function () {
        while (true) {
            var result = this.iterator.next();
            if (result.done) {
                return { done: true };
            }
            var potentialOutput = void 0;
            if (this.selector) {
                potentialOutput = this.selector(result.value);
            }
            else {
                potentialOutput = result.value;
            }
            if (this.valuesAlreadySeen.has(potentialOutput)) {
                // Already seen this value.
                // Skip it and continue to next item.
                continue;
            }
            this.valuesAlreadySeen.add(potentialOutput);
            return {
                done: false,
                value: result.value,
            };
        }
    };
    return DistinctIterator;
}());
exports.DistinctIterator = DistinctIterator;
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