# Yahoo! UI Library

### paginator 2.7.0

Yahoo! UI Library > paginator > Paginator.js (source view)
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    (function () {
    /**
     * The Paginator widget provides a set of controls to navigate through paged
     * data.
     *
     * @module paginator
     * @uses YAHOO.util.EventProvider
     * @uses YAHOO.util.AttributeProvider
     */

    /**
     * Instantiate a Paginator, passing a configuration object to the contructor.
     * The configuration object should contain the following properties:
     * <ul>
     *   <li>rowsPerPage : <em>n</em> (int)</li>
     *   <li>totalRecords : <em>n</em> (int or Paginator.VALUE_UNLIMITED)</li>
     *   <li>containers : <em>id | el | arr</em> (HTMLElement reference, its id, or an array of either)</li>
     * </ul>
     *
     * @namespace YAHOO.widget
     * @class Paginator
     * @constructor
     * @param config {Object} Object literal to set instance and ui component
     * configuration.
     */
    function Paginator(config) {
        var UNLIMITED = Paginator.VALUE_UNLIMITED,
            lang      = YAHOO.lang,
            attrib, initialPage, records, perPage, startIndex;

        config = lang.isObject(config) ? config : {};

        this.initConfig();

        this.initEvents();

        // Set the basic config keys first
        this.set('rowsPerPage',config.rowsPerPage,true);
        if (Paginator.isNumeric(config.totalRecords)) {
            this.set('totalRecords',config.totalRecords,true);
        }

        this.initUIComponents();

        // Update the other config values
        for (attrib in config) {
            if (lang.hasOwnProperty(config,attrib)) {
                this.set(attrib,config[attrib],true);
            }
        }

        // Calculate the initial record offset
        initialPage = this.get('initialPage');
        records     = this.get('totalRecords');
        perPage     = this.get('rowsPerPage');
        if (initialPage > 1 && perPage !== UNLIMITED) {
            startIndex = (initialPage - 1) * perPage;
            if (records === UNLIMITED || startIndex < records) {
                this.set('recordOffset',startIndex,true);
            }
        }
    }

    // Static members
    YAHOO.lang.augmentObject(Paginator, {
        /**
         * Incrementing index used to give instances unique ids.
         * @static
         * @property id
         * @type number
         * @private
         */
        id : 0,

        /**
         * Base of id strings used for ui components.
         * @static
         * @property ID_BASE
         * @type string
         * @private
         */
        ID_BASE : 'yui-pg',

        /**
         * Used to identify unset, optional configurations, or used explicitly in
         * the case of totalRecords to indicate unlimited pagination.
         * @static
         * @property VALUE_UNLIMITED
         * @type number
         * @final
         */
        VALUE_UNLIMITED : -1,

        /**
         * Default template used by Paginator instances.  Update this if you want
         * all new Paginators to use a different default template.
         * @static
         * @property TEMPLATE_DEFAULT
         * @type string
         */
        TEMPLATE_DEFAULT : "{FirstPageLink} {PreviousPageLink} {PageLinks} {NextPageLink} {LastPageLink}",

        /**
         * Common alternate pagination format, including page links, links for
         * previous, next, first and last pages as well as a rows-per-page
         * dropdown.  Offered as a convenience.
         * @static
         * @property TEMPLATE_ROWS_PER_PAGE
         * @type string
         */
        TEMPLATE_ROWS_PER_PAGE : "{FirstPageLink} {PreviousPageLink} {PageLinks} {NextPageLink} {LastPageLink} {RowsPerPageDropdown}",

        /**
         * Storage object for UI Components
         * @static
         * @property ui
         */
        ui : {},

        /**
         * Similar to YAHOO.lang.isNumber, but allows numeric strings.  This is
         * is used for attribute validation in conjunction with getters that return
         * numbers.
         *
         * @method isNumeric
         * @param v {Number|String} value to be checked for number or numeric string
         * @returns {Boolean} true if the input is coercable into a finite number
         * @static
         */
        isNumeric : function (v) {
            return isFinite(+v);
        },

        /**
         * Return a number or null from input
         *
         * @method toNumber
         * @param n {Number|String} a number or numeric string
         * @return Number
         * @static
         */
        toNumber : function (n) {
            return isFinite(+n) ? +n : null;
        }

    },true);

    // Instance members and methods
    Paginator.prototype = {

        // Instance members

        /**
         * Array of nodes in which to render pagination controls.  This is set via
         * the &quot;containers&quot; attribute.
         * @property _containers
         * @type Array(HTMLElement)
         * @private
         */
        _containers : [],

        /**
         * Flag used to indicate multiple attributes are being updated via setState
         * @property _batch
         * @type boolean
         * @protected
         */
        _batch : false,

        /**
         * Used by setState to indicate when a page change has occurred
         * @property _pageChanged
         * @type boolean
         * @protected
         */
        _pageChanged : false,

        /**
         * Temporary state cache used by setState to keep track of the previous
         * state for eventual pageChange event firing
         * @property _state
         * @type Object
         * @protected
         */
        _state : null,

        // Instance methods

        /**
         * Initialize the Paginator's attributes (see YAHOO.util.Element class
         * AttributeProvider).
         * @method initConfig
         * @private
         */
        initConfig : function () {

            var UNLIMITED = Paginator.VALUE_UNLIMITED,
                l         = YAHOO.lang;

            /**
             * REQUIRED. Number of records constituting a &quot;page&quot;
             * @attribute rowsPerPage
             * @type integer
             */
            this.setAttributeConfig('rowsPerPage', {
                value     : 0,
                validator : Paginator.isNumeric,
                setter    : Paginator.toNumber
            });

            /**
             * REQUIRED. Node references or ids of nodes in which to render the
             * pagination controls.
             * @attribute containers
             * @type {string|HTMLElement|Array(string|HTMLElement)}
             */
            this.setAttributeConfig('containers', {
                value     : null,
                validator : function (val) {
                    if (!l.isArray(val)) {
                        val = [val];
                    }
                    for (var i = 0, len = val.length; i < len; ++i) {
                        if (l.isString(val[i]) ||
                            (l.isObject(val[i]) && val[i].nodeType === 1)) {
                            continue;
                        }
                        return false;
                    }
                    return true;
                },
                method : function (val) {
                    val = YAHOO.util.Dom.get(val);
                    if (!l.isArray(val)) {
                        val = [val];
                    }
                    this._containers = val;
                }
            });

            /**
             * Total number of records to paginate through
             * @attribute totalRecords
             * @type integer
             * @default 0
             */
            this.setAttributeConfig('totalRecords', {
                value     : 0,
                validator : Paginator.isNumeric,
                setter    : Paginator.toNumber
            });

            /**
             * Zero based index of the record considered first on the current page.
             * For page based interactions, don't modify this attribute directly;
             * use setPage(n).
             * @attribute recordOffset
             * @type integer
             * @default 0
             */
            this.setAttributeConfig('recordOffset', {
                value     : 0,
                validator : function (val) {
                    var total = this.get('totalRecords');
                    if (Paginator.isNumeric(val)) {
                        val = +val;
                        return total === UNLIMITED || total > val ||
                               (total === 0 && val === 0);
                    }

                    return false;
                },
                setter    : Paginator.toNumber
            });

            /**
             * Page to display on initial paint
             * @attribute initialPage
             * @type integer
             * @default 1
             */
            this.setAttributeConfig('initialPage', {
                value     : 1,
                validator : Paginator.isNumeric,
                setter    : Paginator.toNumber
            });

            /**
             * Template used to render controls.  The string will be used as
             * innerHTML on all specified container nodes.  Bracketed keys
             * (e.g. {pageLinks}) in the string will be replaced with an instance
             * of the so named ui component.
             * @see Paginator.TEMPLATE_DEFAULT
             * @see Paginator.TEMPLATE_ROWS_PER_PAGE
             * @attribute template
             * @type string
             */
            this.setAttributeConfig('template', {
                value : Paginator.TEMPLATE_DEFAULT,
                validator : l.isString
            });

            /**
             * Class assigned to the element(s) containing pagination controls.
             * @attribute containerClass
             * @type string
             * @default 'yui-pg-container'
             */
            this.setAttributeConfig('containerClass', {
                value : 'yui-pg-container',
                validator : l.isString
            });

            /**
             * Display pagination controls even when there is only one page.  Set
             * to false to forgo rendering and/or hide the containers when there
             * is only one page of data.  Note if you are using the rowsPerPage
             * dropdown ui component, visibility will be maintained as long as the
             * number of records exceeds the smallest page size.
             * @attribute alwaysVisible
             * @type boolean
             * @default true
             */
            this.setAttributeConfig('alwaysVisible', {
                value : true,
                validator : l.isBoolean
            });

            /**
             * Update the UI immediately upon interaction.  If false, changeRequest
             * subscribers or other external code will need to explicitly set the
             * new values in the paginator to trigger repaint.
             * @attribute updateOnChange
             * @type boolean
             * @default false
             */
            this.setAttributeConfig('updateOnChange', {
                value     : false,
                validator : l.isBoolean
            });

            // Read only attributes

            /**
             * Unique id assigned to this instance
             * @attribute id
             * @type integer
             * @final
             */
            this.setAttributeConfig('id', {
                value    : Paginator.id++,
                readOnly : true
            });

            /**
             * Indicator of whether the DOM nodes have been initially created
             * @attribute rendered
             * @type boolean
             * @final
             */
            this.setAttributeConfig('rendered', {
                value    : false,
                readOnly : true
            });

        },

        /**
         * Initialize registered ui components onto this instance.
         * @method initUIComponents
         * @private
         */
        initUIComponents : function () {
            var ui = Paginator.ui,
                name,UIComp;
            for (name in ui) {
                if (YAHOO.lang.hasOwnProperty(ui,name)) {
                    UIComp = ui[name];
                    if (YAHOO.lang.isObject(UIComp) &&
                        YAHOO.lang.isFunction(UIComp.init)) {
                        UIComp.init(this);
                    }
                }
            }
        },

        /**
         * Initialize this instance's CustomEvents.
         * @method initEvents
         * @private
         */
        initEvents : function () {
            /**
             * Event fired when the Paginator is initially rendered
             * @event render
             */
            this.createEvent('render');

            /**
             * Event fired when the Paginator is initially rendered
             * @event rendered
             * @deprecated use render event
             */
            this.createEvent('rendered'); // backward compatibility

            /**
             * Event fired when a change in pagination values is requested,
             * either by interacting with the various ui components or via the
             * setStartIndex(n) etc APIs.
             * Subscribers will receive the proposed state as the first parameter.
             * The proposed state object will contain the following keys:
             * <ul>
             *   <li>paginator - the Paginator instance</li>
             *   <li>page</li>
             *   <li>totalRecords</li>
             *   <li>recordOffset - index of the first record on the new page</li>
             *   <li>rowsPerPage</li>
             *   <li>records - array containing [start index, end index] for the records on the new page</li>
             *   <li>before - object literal with all these keys for the current state</li>
             * </ul>
             * @event changeRequest
             */
            this.createEvent('changeRequest');

            /**
             * Event fired when attribute changes have resulted in the calculated
             * current page changing.
             * @event pageChange
             */
            this.createEvent('pageChange');

            /**
             * Event that fires before the destroy event.
             * @event beforeDestroy
             */
            this.createEvent('beforeDestroy');

            /**
             * Event used to trigger cleanup of ui components
             * @event destroy
             */
            this.createEvent('destroy');

            this._selfSubscribe();
        },

        /**
         * Subscribes to instance attribute change events to automate certain
         * behaviors.
         * @method _selfSubscribe
         * @protected
         */
        _selfSubscribe : function () {
            // Listen for changes to totalRecords and alwaysVisible
            this.subscribe('totalRecordsChange',this.updateVisibility,this,true);
            this.subscribe('alwaysVisibleChange',this.updateVisibility,this,true);

            // Fire the pageChange event when appropriate
            this.subscribe('totalRecordsChange',this._handleStateChange,this,true);
            this.subscribe('recordOffsetChange',this._handleStateChange,this,true);
            this.subscribe('rowsPerPageChange',this._handleStateChange,this,true);

            // Update recordOffset when totalRecords is reduced below
            this.subscribe('totalRecordsChange',this._syncRecordOffset,this,true);
        },

        /**
         * Sets recordOffset to the starting index of the previous page when
         * totalRecords is reduced below the current recordOffset.
         * @method _syncRecordOffset
         * @param e {Event} totalRecordsChange event
         * @protected
         */
        _syncRecordOffset : function (e) {
            var v = e.newValue,rpp,state;
            if (e.prevValue !== v) {
                if (v !== Paginator.VALUE_UNLIMITED) {
                    rpp = this.get('rowsPerPage');

                    if (rpp && this.get('recordOffset') >= v) {
                        state = this.getState({
                            totalRecords : e.prevValue,
                            recordOffset : this.get('recordOffset')
                        });

                        this.set('recordOffset', state.before.recordOffset);
                        this._firePageChange(state);
                    }
                }
            }
        },

        /**
         * Fires the pageChange event when the state attributes have changed in
         * such a way as to locate the current recordOffset on a new page.
         * @method _handleStateChange
         * @param e {Event} the attribute change event
         * @protected
         */
        _handleStateChange : function (e) {
            if (e.prevValue !== e.newValue) {
                var change = this._state || {},
                    state;

                change[e.type.replace(/Change$/,'')] = e.prevValue;
                state = this.getState(change);

                if (state.page !== state.before.page) {
                    if (this._batch) {
                        this._pageChanged = true;
                    } else {
                        this._firePageChange(state);
                    }
                }
            }
        },

        /**
         * Fires a pageChange event in the form of a standard attribute change
         * event with additional properties prevState and newState.
         * @method _firePageChange
         * @param state {Object} the result of getState(oldState)
         * @protected
         */
        _firePageChange : function (state) {
            if (YAHOO.lang.isObject(state)) {
                var current = state.before;
                delete state.before;
                this.fireEvent('pageChange',{
                    type      : 'pageChange',
                    prevValue : state.page,
                    newValue  : current.page,
                    prevState : state,
                    newState  : current
                });
            }
        },

        /**
         * Render the pagination controls per the format attribute into the
         * specified container nodes.
         * @method render
         */
        render : function () {
            if (this.get('rendered')) {
                return;
            }

            // Forgo rendering if only one page and alwaysVisible is off
            var totalRecords   = this.get('totalRecords'),
                Dom            = YAHOO.util.Dom,
                template       = this.get('template'),
                containerClass = this.get('containerClass'),
                i,len,c,id_base,markers,j,jlen,m,mp,name,UIComp,comp;

            if (totalRecords !== Paginator.VALUE_UNLIMITED &&
                totalRecords < this.get('rowsPerPage') &&
                !this.get('alwaysVisible')) {
                return;
            }

            // add marker spans to the template html to indicate drop zones
            // for ui components
            template = template.replace(/\{([a-z0-9_ \-]+)\}/gi,
                '<span class="yui-pg-ui $1"></span>');
            for (i = 0, len = this._containers.length; i < len; ++i) {
                c = this._containers[i];
                // ex. yui-pg0-1 (first paginator, second container)
                id_base = Paginator.ID_BASE + this.get('id') + '-' + i;

                if (!c) {
                    continue;
                }
                // Hide the container while its contents are rendered
                c.style.display = 'none';

                Dom.addClass(c,containerClass);

                // Place the template innerHTML
                c.innerHTML = template;

                // Replace each marker with the ui component's render() output
                markers = Dom.getElementsByClassName('yui-pg-ui','span',c);

                for (j = 0, jlen = markers.length; j < jlen; ++j) {
                    m      = markers[j];
                    mp     = m.parentNode;
                    name   = m.className.replace(/\s*yui-pg-ui\s+/g,'');
                    UIComp = Paginator.ui[name];

                    if (YAHOO.lang.isFunction(UIComp)) {
                        comp = new UIComp(this);
                        if (YAHOO.lang.isFunction(comp.render)) {
                            mp.replaceChild(comp.render(id_base),m);
                        }
                    }
                }

                // Show the container allowing page reflow
                c.style.display = '';
            }

            // Set render attribute manually to support its readOnly contract
            if (this._containers.length) {
                this.setAttributeConfig('rendered',{value:true});

                this.fireEvent('render',this.getState());
                // For backward compatibility
                this.fireEvent('rendered',this.getState());
            }
        },

        /**
         * Removes controls from the page and unhooks events.
         * @method destroy
         */
        destroy : function () {
            this.fireEvent('beforeDestroy');
            this.fireEvent('destroy');

            this.setAttributeConfig('rendered',{value:false});
        },

        /**
         * Hides the containers if there is only one page of data and attribute
         * alwaysVisible is false.  Conversely, it displays the containers if either
         * there is more than one page worth of data or alwaysVisible is turned on.
         * @method updateVisibility
         */
        updateVisibility : function (e) {
            var alwaysVisible = this.get('alwaysVisible'),
                totalRecords,visible,rpp,rppOptions,i,len;

            if (e.type === 'alwaysVisibleChange' || !alwaysVisible) {
                totalRecords = this.get('totalRecords');
                visible      = true;
                rpp          = this.get('rowsPerPage');
                rppOptions   = this.get('rowsPerPageOptions');

                if (YAHOO.lang.isArray(rppOptions)) {
                    for (i = 0, len = rppOptions.length; i < len; ++i) {
                        rpp = Math.min(rpp,rppOptions[i]);
                    }
                }

                if (totalRecords !== Paginator.VALUE_UNLIMITED &&
                    totalRecords <= rpp) {
                    visible = false;
                }

                visible = visible || alwaysVisible;

                for (i = 0, len = this._containers.length; i < len; ++i) {
                    YAHOO.util.Dom.setStyle(this._containers[i],'display',
                        visible ? '' : 'none');
                }
            }
        },

        /**
         * Get the configured container nodes
         * @method getContainerNodes
         * @return {Array} array of HTMLElement nodes
         */
        getContainerNodes : function () {
            return this._containers;
        },

        /**
         * Get the total number of pages in the data set according to the current
         * rowsPerPage and totalRecords values.  If totalRecords is not set, or
         * set to YAHOO.widget.Paginator.VALUE_UNLIMITED, returns
         * YAHOO.widget.Paginator.VALUE_UNLIMITED.
         * @method getTotalPages
         * @return {number}
         */
        getTotalPages : function () {
            var records = this.get('totalRecords'),
                perPage = this.get('rowsPerPage');

            // rowsPerPage not set.  Can't calculate
            if (!perPage) {
                return null;
            }

            if (records === Paginator.VALUE_UNLIMITED) {
                return Paginator.VALUE_UNLIMITED;
            }

            return Math.ceil(records/perPage);
        },

        /**
         * Does the requested page have any records?
         * @method hasPage
         * @param page {number} the page in question
         * @return {boolean}
         */
        hasPage : function (page) {
            if (!YAHOO.lang.isNumber(page) || page < 1) {
                return false;
            }

            var totalPages = this.getTotalPages();

            return (totalPages === Paginator.VALUE_UNLIMITED || totalPages >= page);
        },

        /**
         * Get the page number corresponding to the current record offset.
         * @method getCurrentPage
         * @return {number}
         */
        getCurrentPage : function () {
            var perPage = this.get('rowsPerPage');
            if (!perPage || !this.get('totalRecords')) {
                return 0;
            }
            return Math.floor(this.get('recordOffset') / perPage) + 1;
        },

        /**
         * Are there records on the next page?
         * @method hasNextPage
         * @return {boolean}
         */
        hasNextPage : function () {
            var currentPage = this.getCurrentPage(),
                totalPages  = this.getTotalPages();

            return currentPage && (totalPages === Paginator.VALUE_UNLIMITED || currentPage < totalPages);
        },

        /**
         * Get the page number of the next page, or null if the current page is the
         * last page.
         * @method getNextPage
         * @return {number}
         */
        getNextPage : function () {
            return this.hasNextPage() ? this.getCurrentPage() + 1 : null;
        },

        /**
         * Is there a page before the current page?
         * @method hasPreviousPage
         * @return {boolean}
         */
        hasPreviousPage : function () {
            return (this.getCurrentPage() > 1);
        },

        /**
         * Get the page number of the previous page, or null if the current page
         * is the first page.
         * @method getPreviousPage
         * @return {number}
         */
        getPreviousPage : function () {
            return (this.hasPreviousPage() ? this.getCurrentPage() - 1 : 1);
        },

        /**
         * Get the start and end record indexes of the specified page.
         * @method getPageRecords
         * @param page {number} (optional) The page (current page if not specified)
         * @return {Array} [start_index, end_index]
         */
        getPageRecords : function (page) {
            if (!YAHOO.lang.isNumber(page)) {
                page = this.getCurrentPage();
            }

            var perPage = this.get('rowsPerPage'),
                records = this.get('totalRecords'),
                start, end;

            if (!page || !perPage) {
                return null;
            }

            start = (page - 1) * perPage;
            if (records !== Paginator.VALUE_UNLIMITED) {
                if (start >= records) {
                    return null;
                }
                end = Math.min(start + perPage, records) - 1;
            } else {
                end = start + perPage - 1;
            }

            return [start,end];
        },

        /**
         * Set the current page to the provided page number if possible.
         * @method setPage
         * @param newPage {number} the new page number
         * @param silent {boolean} whether to forcibly avoid firing the
         * changeRequest event
         */
        setPage : function (page,silent) {
            if (this.hasPage(page) && page !== this.getCurrentPage()) {
                if (this.get('updateOnChange') || silent) {
                    this.set('recordOffset', (page - 1) * this.get('rowsPerPage'));
                } else {
                    this.fireEvent('changeRequest',this.getState({'page':page}));
                }
            }
        },

        /**
         * Get the number of rows per page.
         * @method getRowsPerPage
         * @return {number} the current setting of the rowsPerPage attribute
         */
        getRowsPerPage : function () {
            return this.get('rowsPerPage');
        },

        /**
         * Set the number of rows per page.
         * @method setRowsPerPage
         * @param rpp {number} the new number of rows per page
         * @param silent {boolean} whether to forcibly avoid firing the
         * changeRequest event
         */
        setRowsPerPage : function (rpp,silent) {
            if (Paginator.isNumeric(rpp) && +rpp > 0 &&
                +rpp !== this.get('rowsPerPage')) {
                if (this.get('updateOnChange') || silent) {
                    this.set('rowsPerPage',rpp);
                } else {
                    this.fireEvent('changeRequest',
                        this.getState({'rowsPerPage':+rpp}));
                }
            }
        },

        /**
         * Get the total number of records.
         * @method getTotalRecords
         * @return {number} the current setting of totalRecords attribute
         */
        getTotalRecords : function () {
            return this.get('totalRecords');
        },

        /**
         * Set the total number of records.
         * @method setTotalRecords
         * @param total {number} the new total number of records
         * @param silent {boolean} whether to forcibly avoid firing the changeRequest event
         */
        setTotalRecords : function (total,silent) {
            if (Paginator.isNumeric(total) && +total >= 0 &&
                +total !== this.get('totalRecords')) {
                if (this.get('updateOnChange') || silent) {
                    this.set('totalRecords',total);
                } else {
                    this.fireEvent('changeRequest',
                        this.getState({'totalRecords':+total}));
                }
            }
        },

        /**
         * Get the index of the first record on the current page
         * @method getStartIndex
         * @return {number} the index of the first record on the current page
         */
        getStartIndex : function () {
            return this.get('recordOffset');
        },

        /**
         * Move the record offset to a new starting index.  This will likely cause
         * the calculated current page to change.  You should probably use setPage.
         * @method setStartIndex
         * @param offset {number} the new record offset
         * @param silent {boolean} whether to forcibly avoid firing the changeRequest event
         */
        setStartIndex : function (offset,silent) {
            if (Paginator.isNumeric(offset) && +offset >= 0 &&
                +offset !== this.get('recordOffset')) {
                if (this.get('updateOnChange') || silent) {
                    this.set('recordOffset',offset);
                } else {
                    this.fireEvent('changeRequest',
                        this.getState({'recordOffset':+offset}));
                }
            }
        },

        /**
         * Get an object literal describing the current state of the paginator.  If
         * an object literal of proposed values is passed, the proposed state will
         * be returned as an object literal with the following keys:
         * <ul>
         * <li>paginator - instance of the Paginator</li>
         * <li>page - number</li>
         * <li>totalRecords - number</li>
         * <li>recordOffset - number</li>
         * <li>rowsPerPage - number</li>
         * <li>records - [ start_index, end_index ]</li>
         * <li>before - (OPTIONAL) { state object literal for current state }</li>
         * </ul>
         * @method getState
         * @return {object}
         * @param changes {object} OPTIONAL object literal with proposed values
         * Supported change keys include:
         * <ul>
         * <li>rowsPerPage</li>
         * <li>totalRecords</li>
         * <li>recordOffset OR</li>
         * <li>page</li>
         * </ul>
         */
        getState : function (changes) {
            var UNLIMITED = Paginator.VALUE_UNLIMITED,
                M = Math, max = M.max, ceil = M.ceil,
                currentState, state, offset;

            function normalizeOffset(offset,total,rpp) {
                if (offset <= 0 || total === 0) {
                    return 0;
                }
                if (total === UNLIMITED || total > offset) {
                    return offset - (offset % rpp);
                }
                return total - (total % rpp || rpp);
            }

            currentState = {
                paginator    : this,
                totalRecords : this.get('totalRecords'),
                rowsPerPage  : this.get('rowsPerPage'),
                records      : this.getPageRecords()
            };
            currentState.recordOffset = normalizeOffset(
                                            this.get('recordOffset'),
                                            currentState.totalRecords,
                                            currentState.rowsPerPage);
            currentState.page = ceil(currentState.recordOffset /
                                     currentState.rowsPerPage) + 1;

            if (!changes) {
                return currentState;
            }

            state = {
                paginator    : this,
                before       : currentState,

                rowsPerPage  : changes.rowsPerPage || currentState.rowsPerPage,
                totalRecords : (Paginator.isNumeric(changes.totalRecords) ?
                                    max(changes.totalRecords,UNLIMITED) :
                                    +currentState.totalRecords)
            };

            if (state.totalRecords === 0) {
                state.recordOffset =
                state.page         = 0;
            } else {
                offset = Paginator.isNumeric(changes.page) ?
                            (changes.page - 1) * state.rowsPerPage :
                            Paginator.isNumeric(changes.recordOffset) ?
                                +changes.recordOffset :
                                currentState.recordOffset;

                state.recordOffset = normalizeOffset(offset,
                                        state.totalRecords,
                                        state.rowsPerPage);

                state.page = ceil(state.recordOffset / state.rowsPerPage) + 1;
            }

            state.records = [ state.recordOffset,
                              state.recordOffset + state.rowsPerPage - 1 ];

            // limit upper index to totalRecords - 1
            if (state.totalRecords !== UNLIMITED &&
                state.recordOffset < state.totalRecords && state.records &&
                state.records[1] > state.totalRecords - 1) {
                state.records[1] = state.totalRecords - 1;
            }

            return state;
        },

        /**
         * Convenience method to facilitate setting state attributes rowsPerPage,
         * totalRecords, recordOffset in batch.  Also supports calculating
         * recordOffset from state.page if state.recordOffset is not provided.
         * Fires only a single pageChange event, if appropriate.
         * This will not fire a changeRequest event.
         * @method setState
         * @param state {Object} Object literal of attribute:value pairs to set
         */
        setState : function (state) {
            if (YAHOO.lang.isObject(state)) {
                // get flux state based on current state with before state as well
                this._state = this.getState({});

                // use just the state props from the input obj
                state = {
                    page         : state.page,
                    rowsPerPage  : state.rowsPerPage,
                    totalRecords : state.totalRecords,
                    recordOffset : state.recordOffset
                };

                // calculate recordOffset from page if recordOffset not specified.
                // not using lang.isNumber for support of numeric strings
                if (state.page && state.recordOffset === undefined) {
                    state.recordOffset = (state.page - 1) *
                        (state.rowsPerPage || this.get('rowsPerPage'));
                }

                this._batch = true;
                this._pageChanged = false;

                for (var k in state) {
                    if (state.hasOwnProperty(k)) {
                        this.set(k,state[k]);
                    }
                }

                this._batch = false;

                if (this._pageChanged) {
                    this._pageChanged = false;

                    this._firePageChange(this.getState(this._state));
                }
            }
        }
    };

    YAHOO.lang.augmentProto(Paginator, YAHOO.util.AttributeProvider);

    YAHOO.widget.Paginator = Paginator;
    })();

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