sequency/lib/reduceIndexed.js

Functional sequences for processing iterable data in JavaScript

Object.defineProperty(exports, "__esModule", { value: true });
exports.ReduceIndexed = void 0;
var ReduceIndexed = /** @class */ (function () {
    function ReduceIndexed() {
    }
    /**
     * Reduces the whole sequence to a single value by invoking `operation` with each element
     * from left to right. For every invocation of the operation `acc` is the result of the last
     * invocation. For the first invocation of the operation `acc` is the first element of the
     * sequence. In addition the `index` of the current element is also passed to the operation.
     *
     * @param {(index: number, acc: S, element: T) => S} operation
     * @returns {S}
     */
    ReduceIndexed.prototype.reduceIndexed = function (operation) {
        var first = this.iterator.next();
        if (first.done) {
            throw new Error("Cannot reduce empty sequence");
        }
        var index = 1;
        var result = first.value;
        for (var item = this.iterator.next(); !item.done; item = this.iterator.next()) {
            result = operation(index, result, item.value);
            index++;
        }
        return result;
    };
    return ReduceIndexed;
}());
exports.ReduceIndexed = ReduceIndexed;
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