abozhilov / es-iter Goto Github PK

    // Current
    static range (start, end, step) {
        return new Iter(function* () {
            let s = toInteger(start),
                e = toInteger(end);

            if (typeof end == 'undefined') {
                e = s;
                s = 0;
            }

            let k = toInteger(step) || (s < e ? 1 : -1)

            if (k > 0) {
                while (s < e) {
                    yield s;
                    s += k;
                }
            }
            else {
                while (s > e) {
                    yield s;
                    s += k;
                }        
            }
        });
    }

    // Proposed
    static * range(start, end, step=undefined) {
        // step = undefined signals that `step` is optional
        if (start === undefined || end === undefined) {
            throw new Error('Need at least two arguments');
        }
        start = toInteger(start);
        end = toInteger(end);
        step = toInteger(step) || (start < end ? 1 : -1);
        if (step >= 0) {
            while (start < end) {
                yield start;
                start += step;
            }
        }
        else {
            while (start > end) {
                yield start;
                start += step;
            }
        }
    }

  new Iter(...).collect(Array);
  new Iter(...).collect(String);
  new Iter(...).collect(Map);
  new Iter(...).collect(Set);

collect(Class) {
    const iter = Iter.getIterator(this);

    // Array and subclasses.
    if (Class === Array || Class.prototype instanceof Array) {
        return Class.from(iter);
    }

    if (Class === Object) {
        const result = {};

        for (const [key, value] of iter) {
            result[key] = value;
        }

        return result;
    }

    if (Class === String) {
        return this.collect(Array).join('');
    }

    // Map, Set, WeakMap, WeakSet and custom types.
    return new Class(iter);
}

foo(start, end, step?)

foo(start, end[, step])

Iter.range(start=0, end=Infinity, step=1)