悔棋的实现

悔棋功能通过一个栈结构来实现：每走一步，就将当前棋盘状态 push 进栈；需要悔棋时，从栈中 pop 出上一步的状态并恢复。

/**
                 * map stack is provide a stack to regret
                 */
                
                
                
                MAX_STEP = 4;// max step of stack save map
                // you can change value to modify the stack capacity
                
                var MapStack = cc.Class.extend({
                    stack: null,//inner data structrue
                    index: null,// cursor of stack
                    ctor: function () {
                        this.stack = new Array(MAX_STEP);
                        this.index = 0;
                        for (var i = 0; i < MAX_STEP; i++) this.stack[i] = 0;
                
                    },
                
                    /** clear the stack
                     * @warning this will not remove data so,please use pop or
                         * push to operation this stack not use this.stack...
                     * */
                    clear: function () {
                        this.index = 0;
                    },
                
                    /** push a member into stack
                     * @param arg the member
                     * @warning please use deep copy to push member
                     */
                    push: function (arg) {
                        if (this.index == MAX_STEP) {// full
                            for (var i = 0; i < MAX_STEP - 1; i++) {
                                this.stack[i] = this.stack[i + 1];
                            }
                            this.index = MAX_STEP - 1;
                        }
                
                        this.stack[this.index] = arg;
                        this.index++;
                        cc.log("map stack push:" + arg);
                
                    },
                    /**pop a member and return the member which is pop
                     * @return member which is pop
                     */
                    pop: function () {
                        if (this.index > 0) {
                            var ret = this.stack[this.index - 1];
                            this.index--;
                            return ret;
                        }
                        return null;
                    },
                    /**return the stack'stop member
                     * @return the top member of the stack's top
                     */
                    top: function () {
                        if (this.index > 0) return this.stack[this.index - 1];
                        return null;
                    }
                });