// Generator utilities


const Generator = Object.getPrototypeOf(function*() {})


Generator.range = function*(start, end, step=1) {
    let number = start

    function stop() {
        return step >= 0 ? number >= end : number <=end
    }

    while (!stop()) {
        yield number
        number += step
    }
}


Generator.prototype.forEach = function(callback) {
    let index = 0
    for (const item of this) {
        callback(item, index++, this)
    }
}


Generator.prototype.until = function*(condition) {
    for (const item of this) {
        if (!condition(item)) {
            yield item
        } else {
            return
        }
    }
}


Generator.prototype.exhaust = function(n) {
    for (let i = 0; i < n; i++) {
        this.next()
    }
}


Generator.prototype.dropFirst = function*(n) {
    this.exhaust(n)
    yield* this
}


module.exports = Generator