aureooms/js-lifo

import Node from './Node' ;

/**
 * NodeStack#peek only valid if NodeStack#empty is false.
 * NodeStack#pop only valid if NodeStack#empty is false.
 */

export default function NodeStack ( ) {

    this.top = null ;

}

NodeStack.prototype.empty = function ( ) {

    return this.top === null ;

} ;

/**
 * Only valid if NodeStack#empty is false.
 */

NodeStack.prototype.peek = function ( ) {

    return this.top.value ;

} ;

NodeStack.prototype.push = function ( value ) {

    this.top = new Node( value , this.top ) ;

} ;

/**
 * Only valid if NodeStack#empty is false.
 */

NodeStack.prototype.pop = function ( ) {

    const value = this.top.value ;

    this.top = this.top.next ;

    return value ;

} ;