    /**
     * This class provides an abstract grid editing plugin on selected {@link Ext.grid.column.Column columns}.
     * The editable columns are specified by providing an {@link Ext.grid.column.Column#editor editor}
     * in the {@link Ext.grid.column.Column column configuration}.
     *
     * **Note:** This class should not be used directly. See {@link Ext.grid.plugin.CellEditing} and
     * {@link Ext.grid.plugin.RowEditing}.
     */
    Ext.define('Ext.grid.plugin.Editing', {
        alias: 'editing.editing',

        requires: [
            'Ext.grid.column.Column',
            'Ext.util.KeyNav'
        ],

        mixins: {
            observable: 'Ext.util.Observable'
        },

        /**
         * @cfg {Number} clicksToEdit
         * The number of clicks on a grid required to display the editor.
         */
        clicksToEdit: 2,

        // private
        defaultFieldXType: 'textfield',

        // cell, row, form
        editStyle: '',

        constructor: function(config) {
            var me = this;
            Ext.apply(me, config);

            me.addEvents(
                // Doc'ed in separate editing plugins
                'beforeedit',

                // Doc'ed in separate editing plugins
                'edit',

                // Doc'ed in separate editing plugins
                'validateedit'
            );
            me.mixins.observable.constructor.call(me);
            // TODO: Deprecated, remove in 5.0
            me.relayEvents(me, ['afteredit'], 'after');
        },

        // private
        init: function(grid) {
            var me = this;

            me.grid = grid;
            me.view = grid.view;
            me.initEvents();
            me.mon(grid, 'reconfigure', me.onReconfigure, me);
            me.onReconfigure();

            grid.relayEvents(me, ['beforeedit', 'edit', 'validateedit']);
            // Marks the grid as editable, so that the SelectionModel
            // can make appropriate decisions during navigation
            grid.isEditable = true;
            grid.editingPlugin = grid.view.editingPlugin = me;
        },

        /**
         * Fires after the grid is reconfigured
         * @private
         */
        onReconfigure: function(){
            this.initFieldAccessors(this.view.getGridColumns());
        },

        /**
         * @private
         * AbstractComponent calls destroy on all its plugins at destroy time.
         */
        destroy: function() {
            var me = this,
                grid = me.grid,
                headerCt = grid.headerCt,
                events = grid.events;

            Ext.destroy(me.keyNav);
            me.removeFieldAccessors(grid.getView().getGridColumns());

            // Clear all listeners from all our events, clear all managed listeners we added to other Observables
            me.clearListeners();

            delete me.grid.editingPlugin;
            delete me.grid.view.editingPlugin;
            delete me.grid;
            delete me.view;
            delete me.editor;
            delete me.keyNav;
        },

        // private
        getEditStyle: function() {
            return this.editStyle;
        },

        // private
        initFieldAccessors: function(column) {
            var me = this;

            if (Ext.isArray(column)) {
                Ext.Array.forEach(column, me.initFieldAccessors, me);
                return;
            }

            // Augment the Header class to have a getEditor and setEditor method
            // Important: Only if the header does not have its own implementation.
            Ext.applyIf(column, {
                getEditor: function(record, defaultField) {
                    return me.getColumnField(this, defaultField);
                },

                setEditor: function(field) {
                    me.setColumnField(this, field);
                }
            });
        },

        // private
        removeFieldAccessors: function(column) {
            var me = this;

            if (Ext.isArray(column)) {
                Ext.Array.forEach(column, me.removeFieldAccessors, me);
                return;
            }

            delete column.getEditor;
            delete column.setEditor;
        },

        // private
        // remaps to the public API of Ext.grid.column.Column.getEditor
        getColumnField: function(columnHeader, defaultField) {
            var field = columnHeader.field;

            if (!field && columnHeader.editor) {
                field = columnHeader.editor;
                delete columnHeader.editor;
            }

            if (!field && defaultField) {
                field = defaultField;
            }

            if (field) {
                if (Ext.isString(field)) {
                    field = { xtype: field };
                }
                if (Ext.isObject(field) && !field.isFormField) {
                    field = Ext.ComponentManager.create(field, this.defaultFieldXType);
                    columnHeader.field = field;
                }

                Ext.apply(field, {
                    name: columnHeader.dataIndex
                });

                return field;
            }
        },

        // private
        // remaps to the public API of Ext.grid.column.Column.setEditor
        setColumnField: function(column, field) {
            if (Ext.isObject(field) && !field.isFormField) {
                field = Ext.ComponentManager.create(field, this.defaultFieldXType);
            }
            column.field = field;
        },

        // private
        initEvents: function() {
            var me = this;
            me.initEditTriggers();
            me.initCancelTriggers();
        },

        // @abstract
        initCancelTriggers: Ext.emptyFn,

        // private
        initEditTriggers: function() {
            var me = this,
                view = me.view,
                clickEvent = me.clicksToEdit === 1 ? 'click' : 'dblclick';

            // Start editing
            me.mon(view, 'cell' + clickEvent, me.startEditByClick, me);
            view.on('render', function() {
                me.keyNav = Ext.create('Ext.util.KeyNav', view.el, {
                    enter: me.onEnterKey,
                    esc: me.onEscKey,
                    scope: me
                });
            }, me, { single: true });
        },

        // private
        onEnterKey: function(e) {
            var me = this,
                grid = me.grid,
                selModel = grid.getSelectionModel(),
                record,
                columnHeader = grid.headerCt.getHeaderAtIndex(0);

            // Calculate editing start position from SelectionModel
            // CellSelectionModel
            if (selModel.getCurrentPosition) {
                pos = selModel.getCurrentPosition();
                record = grid.store.getAt(pos.row);
                columnHeader = grid.headerCt.getHeaderAtIndex(pos.column);
            }
            // RowSelectionModel
            else {
                record = selModel.getLastSelected();
            }
            me.startEdit(record, columnHeader);
        },

        // private
        onEscKey: function(e) {
            this.cancelEdit();
        },

        // private
        startEditByClick: function(view, cell, colIdx, record, row, rowIdx, e) {
            this.startEdit(record, view.getHeaderAtIndex(colIdx));
        },

        /**
         * @private
         * @template
         * Template method called before editing begins.
         * @param {Object} context The current editing context
         * @return {Boolean} Return false to cancel the editing process
         */
        beforeEdit: Ext.emptyFn,

        /**
         * Starts editing the specified record, using the specified Column definition to define which field is being edited.
         * @param {Ext.data.Model/Number} record The Store data record which backs the row to be edited, or index of the record in Store.
         * @param {Ext.grid.column.Column/Number} columnHeader The Column object defining the column to be edited, or index of the column.
         */
        startEdit: function(record, columnHeader) {
            var me = this,
                context = me.getEditingContext(record, columnHeader);

            if (me.beforeEdit(context) === false || me.fireEvent('beforeedit', context) === false || context.cancel) {
                return false;
            }

            me.context = context;
            me.editing = true;
        },

        /**
         * @private
         * Collects all information necessary for any subclasses to perform their editing functions.
         * @param record
         * @param columnHeader
         * @returns {Object} The editing context based upon the passed record and column
         */
        getEditingContext: function(record, columnHeader) {
            var me = this,
                grid = me.grid,
                store = grid.store,
                rowIdx,
                colIdx,
                view = grid.getView(),
                value;

            // If they'd passed numeric row, column indices, look them up.
            if (Ext.isNumber(record)) {
                rowIdx = record;
                record = store.getAt(rowIdx);
            } else {
                rowIdx = store.indexOf(record);
            }
            if (Ext.isNumber(columnHeader)) {
                colIdx = columnHeader;
                columnHeader = grid.headerCt.getHeaderAtIndex(colIdx);
            } else {
                colIdx = columnHeader.getIndex();
            }

            value = record.get(columnHeader.dataIndex);
            return {
                grid: grid,
                record: record,
                field: columnHeader.dataIndex,
                value: value,
                row: view.getNode(rowIdx),
                column: columnHeader,
                rowIdx: rowIdx,
                colIdx: colIdx
            };
        },

        /**
         * Cancels any active edit that is in progress.
         */
        cancelEdit: function() {
            this.editing = false;
        },

        /**
         * Completes the edit if there is an active edit in progress.
         */
        completeEdit: function() {
            var me = this;

            if (me.editing && me.validateEdit()) {
                me.fireEvent('edit', me.context);
            }

            delete me.context;
            me.editing = false;
        },

        // @abstract
        validateEdit: function() {
            var me = this,
                context = me.context;

            return me.fireEvent('validateedit', me, context) !== false && !context.cancel;
        }
    });