@reflet/express/dist/array-manipulation.js

Well-defined and well-typed express decorators

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
exports.flatMapFast = void 0;
function flatMapFast(array, mapper) {
    // wrapping the original array to avoid mutating it.
    const flattened = [array];
    // usual loop, but, don't put `i++` in third clause
    // because it won't increment it when the element is an array.
    for (let i = 0; i < flattened.length;) {
        const value = flattened[i];
        // if the element is an array then we'll put its contents
        // into `flattened` replacing the current element.
        if (Array.isArray(value)) {
            if (value.length > 0) {
                // to provide the `value` array to splice()
                // we need to add the splice() args to its front,
                // these args tell it to splice at `i` and delete what's at `i`.
                value.unshift(i, 1);
                // in-place change
                flattened.splice.apply(flattened, value);
                // take (i, 1) back off the `value` front so it remains "unchanged".
                value.splice(0, 2);
            }
            else {
                // remove an empty array from `flattened`
                flattened.splice(i, 1);
            }
            // we don't do `i++` because we want it to re-evaluate the new element
            // at `i` in case it is an array, or we deleted an empty array at `i`.
        }
        else {
            // it's not an array so map the value and move on to the next element.
            /* istanbul ignore else - unused */
            if (mapper) {
                flattened[i] = mapper(value);
            }
            i++;
        }
    }
    return flattened;
}
exports.flatMapFast = flatMapFast;