Added checking for emptiness of cell below.

IPython/frontend/html/notebook/static/js/notebook.js

@@ -1,1295 +1,1295
 //----------------------------------------------------------------------------
 //  Copyright (C) 2008-2011  The IPython Development Team
 //
 //  Distributed under the terms of the BSD License.  The full license is in
 //  the file COPYING, distributed as part of this software.
 //----------------------------------------------------------------------------
 
 //============================================================================
 // Notebook
 //============================================================================
 
 var IPython = (function (IPython) {
 
     var utils = IPython.utils;
     var key   = IPython.utils.keycodes;
 
     var Notebook = function (selector) {
         this.read_only = IPython.read_only;
         this.element = $(selector);
         this.element.scroll();
         this.element.data("notebook", this);
         this.next_prompt_number = 1;
         this.kernel = null;
         this.clipboard = null;
         this.paste_enabled = false;
         this.dirty = false;
         this.metadata = {};
         // single worksheet for now
         this.worksheet_metadata = {};
         this.control_key_active = false;
         this.notebook_id = null;
         this.notebook_name = null;
         this.notebook_name_blacklist_re = /[\/\\:]/;
         this.nbformat = 3 // Increment this when changing the nbformat
         this.nbformat_minor = 0 // Increment this when changing the nbformat
         this.style();
         this.create_elements();
         this.bind_events();
     };
 
 
     Notebook.prototype.style = function () {
         $('div#notebook').addClass('border-box-sizing');
     };
 
 
     Notebook.prototype.create_elements = function () {
         // We add this end_space div to the end of the notebook div to:
         // i) provide a margin between the last cell and the end of the notebook
         // ii) to prevent the div from scrolling up when the last cell is being
         // edited, but is too low on the page, which browsers will do automatically.
         var that = this;
         var end_space = $('<div/>').addClass('end_space').height("30%");
         end_space.dblclick(function (e) {
             if (that.read_only) return;
             var ncells = that.ncells();
             that.insert_cell_below('code',ncells-1);
         });
         this.element.append(end_space);
         $('div#notebook').addClass('border-box-sizing');
     };
 
 
     Notebook.prototype.bind_events = function () {
         var that = this;
 
         $([IPython.events]).on('set_next_input.Notebook', function (event, data) {
             var index = that.find_cell_index(data.cell);
             var new_cell = that.insert_cell_below('code',index);
             new_cell.set_text(data.text);
             that.dirty = true;
         });
 
         $([IPython.events]).on('set_dirty.Notebook', function (event, data) {
             that.dirty = data.value;
         });
 
         $([IPython.events]).on('select.Cell', function (event, data) {
             var index = that.find_cell_index(data.cell);
             that.select(index);
         });
 
 
         $(document).keydown(function (event) {
             // console.log(event);
             if (that.read_only) return true;
             
             // Save (CTRL+S) or (AppleKey+S) 
             //metaKey = applekey on mac
             if ((event.ctrlKey || event.metaKey) && event.keyCode==83) { 
                 that.save_notebook();
                 event.preventDefault();
                 return false;
             } else if (event.which === key.ESC) {
                 // Intercept escape at highest level to avoid closing 
                 // websocket connection with firefox
                 event.preventDefault();
             } else if (event.which === key.SHIFT) {
                 // ignore shift keydown
                 return true;
             }
             if (event.which === key.UPARROW && !event.shiftKey) {
                 var cell = that.get_selected_cell();
                 if (cell.at_top()) {
                     event.preventDefault();
                     that.select_prev();
                 };
             } else if (event.which === key.DOWNARROW && !event.shiftKey) {
                 var cell = that.get_selected_cell();
                 if (cell.at_bottom()) {
                     event.preventDefault();
                     that.select_next();
                 };
             } else if (event.which === key.ENTER && event.shiftKey) {
                 that.execute_selected_cell();
                 return false;
             } else if (event.which === key.ENTER && event.altKey) {
                 // Execute code cell, and insert new in place
                 that.execute_selected_cell();
                  // Only insert a new cell, if we ended up in an already populated cell
-                if (that.get_selected_cell().toJSON().input !== "") {
+                if (/\S/.test(that.get_selected_cell().toJSON().input) == true) {
                     that.insert_cell_above('code');
                 }
                 return false;
             } else if (event.which === key.ENTER && event.ctrlKey) {
                 that.execute_selected_cell({terminal:true});
                 return false;
             } else if (event.which === 77 && event.ctrlKey && that.control_key_active == false) {
                 that.control_key_active = true;
                 return false;
             } else if (event.which === 88 && that.control_key_active) {
                 // Cut selected cell = x
                 that.cut_cell();
                 that.control_key_active = false;
                 return false;
             } else if (event.which === 67 && that.control_key_active) {
                 // Copy selected cell = c
                 that.copy_cell();
                 that.control_key_active = false;
                 return false;
             } else if (event.which === 86 && that.control_key_active) {
                 // Paste selected cell = v
                 that.paste_cell();
                 that.control_key_active = false;
                 return false;
             } else if (event.which === 68 && that.control_key_active) {
                 // Delete selected cell = d
                 that.delete_cell();
                 that.control_key_active = false;
                 return false;
             } else if (event.which === 65 && that.control_key_active) {
                 // Insert code cell above selected = a
                 that.insert_cell_above('code');
                 that.control_key_active = false;
                 return false;
             } else if (event.which === 66 && that.control_key_active) {
                 // Insert code cell below selected = b
                 that.insert_cell_below('code');
                 that.control_key_active = false;
                 return false;
             } else if (event.which === 89 && that.control_key_active) {
                 // To code = y
                 that.to_code();
                 that.control_key_active = false;
                 return false;
             } else if (event.which === 77 && that.control_key_active) {
                 // To markdown = m
                 that.to_markdown();
                 that.control_key_active = false;
                 return false;
             } else if (event.which === 84 && that.control_key_active) {
                 // To Raw = t
                 that.to_raw();
                 that.control_key_active = false;
                 return false;
             } else if (event.which === 49 && that.control_key_active) {
                 // To Heading 1 = 1
                 that.to_heading(undefined, 1);
                 that.control_key_active = false;
                 return false;
             } else if (event.which === 50 && that.control_key_active) {
                 // To Heading 2 = 2
                 that.to_heading(undefined, 2);
                 that.control_key_active = false;
                 return false;
             } else if (event.which === 51 && that.control_key_active) {
                 // To Heading 3 = 3
                 that.to_heading(undefined, 3);
                 that.control_key_active = false;
                 return false;
             } else if (event.which === 52 && that.control_key_active) {
                 // To Heading 4 = 4
                 that.to_heading(undefined, 4);
                 that.control_key_active = false;
                 return false;
             } else if (event.which === 53 && that.control_key_active) {
                 // To Heading 5 = 5
                 that.to_heading(undefined, 5);
                 that.control_key_active = false;
                 return false;
             } else if (event.which === 54 && that.control_key_active) {
                 // To Heading 6 = 6
                 that.to_heading(undefined, 6);
                 that.control_key_active = false;
                 return false;
             } else if (event.which === 79 && that.control_key_active) {
                 // Toggle output = o
                 if (event.shiftKey){
                     that.toggle_output_scroll();
                 } else {
                     that.toggle_output();
                 }
                 that.control_key_active = false;
                 return false;
             } else if (event.which === 83 && that.control_key_active) {
                 // Save notebook = s
                 that.save_notebook();
                 that.control_key_active = false;
                 return false;
             } else if (event.which === 74 && that.control_key_active) {
                 // Move cell down = j
                 that.move_cell_down();
                 that.control_key_active = false;
                 return false;
             } else if (event.which === 75 && that.control_key_active) {
                 // Move cell up = k
                 that.move_cell_up();
                 that.control_key_active = false;
                 return false;
             } else if (event.which === 80 && that.control_key_active) {
                 // Select previous = p
                 that.select_prev();
                 that.control_key_active = false;
                 return false;
             } else if (event.which === 78 && that.control_key_active) {
                 // Select next = n
                 that.select_next();
                 that.control_key_active = false;
                 return false;
             } else if (event.which === 76 && that.control_key_active) {
                 // Toggle line numbers = l
                 that.cell_toggle_line_numbers();
                 that.control_key_active = false;
                 return false;
             } else if (event.which === 73 && that.control_key_active) {
                 // Interrupt kernel = i
                 that.kernel.interrupt();
                 that.control_key_active = false;
                 return false;
             } else if (event.which === 190 && that.control_key_active) {
                 // Restart kernel = .  # matches qt console
                 that.restart_kernel();
                 that.control_key_active = false;
                 return false;
             } else if (event.which === 72 && that.control_key_active) {
                 // Show keyboard shortcuts = h
                 IPython.quick_help.show_keyboard_shortcuts();
                 that.control_key_active = false;
                 return false;
             } else if (that.control_key_active) {
                 that.control_key_active = false;
                 return true;
             };
             return true;
         });
 
         var collapse_time = function(time){
             var app_height = $('div#main_app').height(); // content height
             var splitter_height = $('div#pager_splitter').outerHeight(true);
             var new_height = app_height - splitter_height;
             that.element.animate({height : new_height + 'px'}, time);
         }
 
         this.element.bind('collapse_pager', function (event,extrap) {
             time = (extrap != undefined) ? ((extrap.duration != undefined ) ? extrap.duration : 'fast') : 'fast';
             collapse_time(time);
         });
 
         var expand_time = function(time) {
             var app_height = $('div#main_app').height(); // content height
             var splitter_height = $('div#pager_splitter').outerHeight(true);
             var pager_height = $('div#pager').outerHeight(true);
             var new_height = app_height - pager_height - splitter_height; 
             that.element.animate({height : new_height + 'px'}, time);
         }
 
         this.element.bind('expand_pager', function (event, extrap) {
             time = (extrap != undefined) ? ((extrap.duration != undefined ) ? extrap.duration : 'fast') : 'fast';
             expand_time(time);
         });
 
         $(window).bind('beforeunload', function () {
             // TODO: Make killing the kernel configurable.
             var kill_kernel = false;
             if (kill_kernel) {
                 that.kernel.kill();
             }
             if (that.dirty && ! that.read_only) {
                 return "You have unsaved changes that will be lost if you leave this page.";
             };
             // Null is the *only* return value that will make the browser not
             // pop up the "don't leave" dialog.
             return null;
         });
     };
 
 
     Notebook.prototype.scroll_to_bottom = function () {
         this.element.animate({scrollTop:this.element.get(0).scrollHeight}, 0);
     };
 
 
     Notebook.prototype.scroll_to_top = function () {
         this.element.animate({scrollTop:0}, 0);
     };
 
 
     // Cell indexing, retrieval, etc.
 
     Notebook.prototype.get_cell_elements = function () {
         return this.element.children("div.cell");
     };
 
 
     Notebook.prototype.get_cell_element = function (index) {
         var result = null;
         var e = this.get_cell_elements().eq(index);
         if (e.length !== 0) {
             result = e;
         }
         return result;
     };
 
 
     Notebook.prototype.ncells = function (cell) {
         return this.get_cell_elements().length;
     };
 
 
     // TODO: we are often calling cells as cells()[i], which we should optimize
     // to cells(i) or a new method.
     Notebook.prototype.get_cells = function () {
         return this.get_cell_elements().toArray().map(function (e) {
             return $(e).data("cell");
         });
     };
 
 
     Notebook.prototype.get_cell = function (index) {
         var result = null;
         var ce = this.get_cell_element(index);
         if (ce !== null) {
             result = ce.data('cell');
         }
         return result;
     }
 
 
     Notebook.prototype.get_next_cell = function (cell) {
         var result = null;
         var index = this.find_cell_index(cell);
         if (index !== null && index < this.ncells()) {
             result = this.get_cell(index+1);
         }
         return result;
     }
 
 
     Notebook.prototype.get_prev_cell = function (cell) {
         var result = null;
         var index = this.find_cell_index(cell);
         if (index !== null && index > 1) {
             result = this.get_cell(index-1);
         }
         return result;
     }
 
     Notebook.prototype.find_cell_index = function (cell) {
         var result = null;
         this.get_cell_elements().filter(function (index) {
             if ($(this).data("cell") === cell) {
                 result = index;
             };
         });
         return result;
     };
 
 
     Notebook.prototype.index_or_selected = function (index) {
         var i;
         if (index === undefined || index === null) {
             i = this.get_selected_index();
             if (i === null) {
                 i = 0;
             }
         } else {
             i = index;
         }
         return i;
     };
 
 
     Notebook.prototype.get_selected_cell = function () {
         var index = this.get_selected_index();
         return this.get_cell(index);
     };
 
 
     Notebook.prototype.is_valid_cell_index = function (index) {
         if (index !== null && index >= 0 && index < this.ncells()) {
             return true;
         } else {
             return false;
         };
     }
 
     Notebook.prototype.get_selected_index = function () {
         var result = null;
         this.get_cell_elements().filter(function (index) {
             if ($(this).data("cell").selected === true) {
                 result = index;
             };
         });
         return result;
     };
 
 
     // Cell selection.
 
     Notebook.prototype.select = function (index) {
         if (index !== undefined && index >= 0 && index < this.ncells()) {
             sindex = this.get_selected_index()
             if (sindex !== null && index !== sindex) {
                 this.get_cell(sindex).unselect();
             };
             var cell = this.get_cell(index)
             cell.select();
             if (cell.cell_type === 'heading') {
                 $([IPython.events]).trigger('selected_cell_type_changed.Notebook',
                     {'cell_type':cell.cell_type,level:cell.level}
                 );
             } else {
                 $([IPython.events]).trigger('selected_cell_type_changed.Notebook',
                     {'cell_type':cell.cell_type}
                 );
             };
         };
         return this;
     };
 
 
     Notebook.prototype.select_next = function () {
         var index = this.get_selected_index();
         if (index !== null && index >= 0 && (index+1) < this.ncells()) {
             this.select(index+1);
         };
         return this;
     };
 
 
     Notebook.prototype.select_prev = function () {
         var index = this.get_selected_index();
         if (index !== null && index >= 0 && (index-1) < this.ncells()) {
             this.select(index-1);
         };
         return this;
     };
 
 
     // Cell movement
 
     Notebook.prototype.move_cell_up = function (index) {
         var i = this.index_or_selected();
         if (i !== null && i < this.ncells() && i > 0) {
             var pivot = this.get_cell_element(i-1);
             var tomove = this.get_cell_element(i);
             if (pivot !== null && tomove !== null) {
                 tomove.detach();
                 pivot.before(tomove);
                 this.select(i-1);
             };
         };
         this.dirty = true;
         return this;
     };
 
 
     Notebook.prototype.move_cell_down = function (index) {
         var i = this.index_or_selected();
         if (i !== null && i < (this.ncells()-1) && i >= 0) {
             var pivot = this.get_cell_element(i+1);
             var tomove = this.get_cell_element(i);
             if (pivot !== null && tomove !== null) {
                 tomove.detach();
                 pivot.after(tomove);
                 this.select(i+1);
             };
         };
         this.dirty = true;
         return this;
     };
 
 
     Notebook.prototype.sort_cells = function () {
         // This is not working right now. Calling this will actually crash
         // the browser. I think there is an infinite loop in here...
         var ncells = this.ncells();
         var sindex = this.get_selected_index();
         var swapped;
         do {
             swapped = false;
             for (var i=1; i<ncells; i++) {
                 current = this.get_cell(i);
                 previous = this.get_cell(i-1);
                 if (previous.input_prompt_number > current.input_prompt_number) {
                     this.move_cell_up(i);
                     swapped = true;
                 };
             };
         } while (swapped);
         this.select(sindex);
         return this;
     };
 
     // Insertion, deletion.
 
     Notebook.prototype.delete_cell = function (index) {
         var i = this.index_or_selected(index);
         if (this.is_valid_cell_index(i)) {
             var ce = this.get_cell_element(i);
             ce.remove();
             if (i === (this.ncells())) {
                 this.select(i-1);
             } else {
                 this.select(i);
             };
             this.dirty = true;
         };
         return this;
     };
 
 
     Notebook.prototype.insert_cell_below = function (type, index) {
         // type = ('code','html','markdown')
         // index = cell index or undefined to insert below selected
         index = this.index_or_selected(index);
         var cell = null;
         if (this.ncells() === 0 || this.is_valid_cell_index(index)) {
             if (type === 'code') {
                 cell = new IPython.CodeCell(this.kernel);
                 cell.set_input_prompt();
             } else if (type === 'markdown') {
                 cell = new IPython.MarkdownCell();
             } else if (type === 'html') {
                 cell = new IPython.HTMLCell();
             } else if (type === 'raw') {
                 cell = new IPython.RawCell();
             } else if (type === 'heading') {
                 cell = new IPython.HeadingCell();
             };
             if (cell !== null) {
                 if (this.ncells() === 0) {
                     this.element.find('div.end_space').before(cell.element);
                 } else if (this.is_valid_cell_index(index)) {
                     this.get_cell_element(index).after(cell.element);
                 };
                 cell.render();
                 this.select(this.find_cell_index(cell));
                 this.dirty = true;
                 return cell;
             };
         };
         return cell;
     };
 
 
     Notebook.prototype.insert_cell_above = function (type, index) {
         // type = ('code','html','markdown')
         // index = cell index or undefined to insert above selected
         index = this.index_or_selected(index);
         var cell = null;
         if (this.ncells() === 0 || this.is_valid_cell_index(index)) {
             if (type === 'code') {
                 cell = new IPython.CodeCell(this.kernel);
                 cell.set_input_prompt();
             } else if (type === 'markdown') {
                 cell = new IPython.MarkdownCell();
             } else if (type === 'html') {
                 cell = new IPython.HTMLCell();
             } else if (type === 'raw') {
                 cell = new IPython.RawCell();
             } else if (type === 'heading') {
                 cell = new IPython.HeadingCell();
             };
             if (cell !== null) {
                 if (this.ncells() === 0) {
                     this.element.find('div.end_space').before(cell.element);
                 } else if (this.is_valid_cell_index(index)) {
                     this.get_cell_element(index).before(cell.element);
                 };
                 cell.render();
                 this.select(this.find_cell_index(cell));
                 this.dirty = true;
                 return cell;
             };
         };
         return cell;
     };
 
 
     Notebook.prototype.to_code = function (index) {
         var i = this.index_or_selected(index);
         if (this.is_valid_cell_index(i)) {
             var source_element = this.get_cell_element(i);
             var source_cell = source_element.data("cell");
             if (!(source_cell instanceof IPython.CodeCell)) {
                 target_cell = this.insert_cell_below('code',i);
                 var text = source_cell.get_text();
                 if (text === source_cell.placeholder) {
                     text = '';
                 }
                 target_cell.set_text(text);
                 // make this value the starting point, so that we can only undo
                 // to this state, instead of a blank cell
                 target_cell.code_mirror.clearHistory();
                 source_element.remove();
                 this.dirty = true;
             };
         };
     };
 
 
     Notebook.prototype.to_markdown = function (index) {
         var i = this.index_or_selected(index);
         if (this.is_valid_cell_index(i)) {
             var source_element = this.get_cell_element(i);
             var source_cell = source_element.data("cell");
             if (!(source_cell instanceof IPython.MarkdownCell)) {
                 target_cell = this.insert_cell_below('markdown',i);
                 var text = source_cell.get_text();
                 if (text === source_cell.placeholder) {
                     text = '';
                 };
                 // The edit must come before the set_text.
                 target_cell.edit();
                 target_cell.set_text(text);
                 // make this value the starting point, so that we can only undo
                 // to this state, instead of a blank cell
                 target_cell.code_mirror.clearHistory();
                 source_element.remove();
                 this.dirty = true;
             };
         };
     };
 
 
     Notebook.prototype.to_html = function (index) {
         var i = this.index_or_selected(index);
         if (this.is_valid_cell_index(i)) {
             var source_element = this.get_cell_element(i);
             var source_cell = source_element.data("cell");
             var target_cell = null;
             if (!(source_cell instanceof IPython.HTMLCell)) {
                 target_cell = this.insert_cell_below('html',i);
                 var text = source_cell.get_text();
                 if (text === source_cell.placeholder) {
                     text = '';
                 };
                 // The edit must come before the set_text.
                 target_cell.edit();
                 target_cell.set_text(text);
                 // make this value the starting point, so that we can only undo
                 // to this state, instead of a blank cell
                 target_cell.code_mirror.clearHistory();
                 source_element.remove();
                 this.dirty = true;
             };
         };
     };
 
 
     Notebook.prototype.to_raw = function (index) {
         var i = this.index_or_selected(index);
         if (this.is_valid_cell_index(i)) {
             var source_element = this.get_cell_element(i);
             var source_cell = source_element.data("cell");
             var target_cell = null;
             if (!(source_cell instanceof IPython.RawCell)) {
                 target_cell = this.insert_cell_below('raw',i);
                 var text = source_cell.get_text();
                 if (text === source_cell.placeholder) {
                     text = '';
                 };
                 // The edit must come before the set_text.
                 target_cell.edit();
                 target_cell.set_text(text);
                 // make this value the starting point, so that we can only undo
                 // to this state, instead of a blank cell
                 target_cell.code_mirror.clearHistory();
                 source_element.remove();
                 this.dirty = true;
             };
         };
     };
 
 
     Notebook.prototype.to_heading = function (index, level) {
         level = level || 1;
         var i = this.index_or_selected(index);
         if (this.is_valid_cell_index(i)) {
             var source_element = this.get_cell_element(i);
             var source_cell = source_element.data("cell");
             var target_cell = null;
             if (source_cell instanceof IPython.HeadingCell) {
                 source_cell.set_level(level);
             } else {
                 target_cell = this.insert_cell_below('heading',i);
                 var text = source_cell.get_text();
                 if (text === source_cell.placeholder) {
                     text = '';
                 };
                 // The edit must come before the set_text.
                 target_cell.set_level(level);
                 target_cell.edit();
                 target_cell.set_text(text);
                 // make this value the starting point, so that we can only undo
                 // to this state, instead of a blank cell
                 target_cell.code_mirror.clearHistory();
                 source_element.remove();
                 this.dirty = true;
             };
             $([IPython.events]).trigger('selected_cell_type_changed.Notebook',
                 {'cell_type':'heading',level:level}
             );
         };
     };
 
 
     // Cut/Copy/Paste
 
     Notebook.prototype.enable_paste = function () {
         var that = this;
         if (!this.paste_enabled) {
             $('#paste_cell').removeClass('ui-state-disabled')
                 .on('click', function () {that.paste_cell();});
             $('#paste_cell_above').removeClass('ui-state-disabled')
                 .on('click', function () {that.paste_cell_above();});
             $('#paste_cell_below').removeClass('ui-state-disabled')
                 .on('click', function () {that.paste_cell_below();});
             this.paste_enabled = true;
         };
     };
 
 
     Notebook.prototype.disable_paste = function () {
         if (this.paste_enabled) {
             $('#paste_cell').addClass('ui-state-disabled').off('click');
             $('#paste_cell_above').addClass('ui-state-disabled').off('click');
             $('#paste_cell_below').addClass('ui-state-disabled').off('click');
             this.paste_enabled = false;
         };
     };
 
 
     Notebook.prototype.cut_cell = function () {
         this.copy_cell();
         this.delete_cell();
     }
 
     Notebook.prototype.copy_cell = function () {
         var cell = this.get_selected_cell();
         this.clipboard = cell.toJSON();
         this.enable_paste();
     };
 
 
     Notebook.prototype.paste_cell = function () {
         if (this.clipboard !== null && this.paste_enabled) {
             var cell_data = this.clipboard;
             var new_cell = this.insert_cell_above(cell_data.cell_type);
             new_cell.fromJSON(cell_data);
             old_cell = this.get_next_cell(new_cell);
             this.delete_cell(this.find_cell_index(old_cell));
             this.select(this.find_cell_index(new_cell));
         };
     };
 
 
     Notebook.prototype.paste_cell_above = function () {
         if (this.clipboard !== null && this.paste_enabled) {
             var cell_data = this.clipboard;
             var new_cell = this.insert_cell_above(cell_data.cell_type);
             new_cell.fromJSON(cell_data);
         };
     };
 
 
     Notebook.prototype.paste_cell_below = function () {
         if (this.clipboard !== null && this.paste_enabled) {
             var cell_data = this.clipboard;
             var new_cell = this.insert_cell_below(cell_data.cell_type);
             new_cell.fromJSON(cell_data);
         };
     };
 
 
     // Split/merge
 
     Notebook.prototype.split_cell = function () {
         // Todo: implement spliting for other cell types.
         var cell = this.get_selected_cell();
         if (cell.is_splittable()) {
             texta = cell.get_pre_cursor();
             textb = cell.get_post_cursor();
             if (cell instanceof IPython.CodeCell) {
                 cell.set_text(texta);
                 var new_cell = this.insert_cell_below('code');
                 new_cell.set_text(textb);
             } else if (cell instanceof IPython.MarkdownCell) {
                 cell.set_text(texta);
                 cell.render();
                 var new_cell = this.insert_cell_below('markdown');
                 new_cell.edit(); // editor must be visible to call set_text
                 new_cell.set_text(textb);
                 new_cell.render();
             } else if (cell instanceof IPython.HTMLCell) {
                 cell.set_text(texta);
                 cell.render();
                 var new_cell = this.insert_cell_below('html');
                 new_cell.edit(); // editor must be visible to call set_text
                 new_cell.set_text(textb);
                 new_cell.render();
             };
         };
     };
 
 
     Notebook.prototype.merge_cell_above = function () {
         var index = this.get_selected_index();
         var cell = this.get_cell(index);
         if (index > 0) {
             upper_cell = this.get_cell(index-1);
             upper_text = upper_cell.get_text();
             text = cell.get_text();
             if (cell instanceof IPython.CodeCell) {
                 cell.set_text(upper_text+'\n'+text);
             } else if (cell instanceof IPython.MarkdownCell || cell instanceof IPython.HTMLCell) {
                 cell.edit();
                 cell.set_text(upper_text+'\n'+text);
                 cell.render();
             };
             this.delete_cell(index-1);
             this.select(this.find_cell_index(cell));
         };
     };
 
 
     Notebook.prototype.merge_cell_below = function () {
         var index = this.get_selected_index();
         var cell = this.get_cell(index);
         if (index < this.ncells()-1) {
             lower_cell = this.get_cell(index+1);
             lower_text = lower_cell.get_text();
             text = cell.get_text();
             if (cell instanceof IPython.CodeCell) {
                 cell.set_text(text+'\n'+lower_text);
             } else if (cell instanceof IPython.MarkdownCell || cell instanceof IPython.HTMLCell) {
                 cell.edit();
                 cell.set_text(text+'\n'+lower_text);
                 cell.render();
             };
             this.delete_cell(index+1);
             this.select(this.find_cell_index(cell));
         };
     };
 
 
     // Cell collapsing and output clearing
 
     Notebook.prototype.collapse = function (index) {
         var i = this.index_or_selected(index);
         this.get_cell(i).collapse();
         this.dirty = true;
     };
 
 
     Notebook.prototype.expand = function (index) {
         var i = this.index_or_selected(index);
         this.get_cell(i).expand();
         this.dirty = true;
     };
 
 
     Notebook.prototype.toggle_output = function (index) {
         var i = this.index_or_selected(index);
         this.get_cell(i).toggle_output();
         this.dirty = true;
     };
 
 
     Notebook.prototype.toggle_output_scroll = function (index) {
         var i = this.index_or_selected(index);
         this.get_cell(i).toggle_output_scroll();
     };
 
 
     Notebook.prototype.collapse_all_output = function () {
         var ncells = this.ncells();
         var cells = this.get_cells();
         for (var i=0; i<ncells; i++) {
             if (cells[i] instanceof IPython.CodeCell) {
                 cells[i].output_area.collapse();
             }
         };
         // this should not be set if the `collapse` key is removed from nbformat
         this.dirty = true;
     };
 
 
     Notebook.prototype.scroll_all_output = function () {
         var ncells = this.ncells();
         var cells = this.get_cells();
         for (var i=0; i<ncells; i++) {
             if (cells[i] instanceof IPython.CodeCell) {
                 cells[i].output_area.expand();
                 cells[i].output_area.scroll_if_long(20);
             }
         };
         // this should not be set if the `collapse` key is removed from nbformat
         this.dirty = true;
     };
 
 
     Notebook.prototype.expand_all_output = function () {
         var ncells = this.ncells();
         var cells = this.get_cells();
         for (var i=0; i<ncells; i++) {
             if (cells[i] instanceof IPython.CodeCell) {
                 cells[i].output_area.expand();
                 cells[i].output_area.unscroll_area();
             }
         };
         // this should not be set if the `collapse` key is removed from nbformat
         this.dirty = true;
     };
 
 
     Notebook.prototype.clear_all_output = function () {
         var ncells = this.ncells();
         var cells = this.get_cells();
         for (var i=0; i<ncells; i++) {
             if (cells[i] instanceof IPython.CodeCell) {
                 cells[i].clear_output(true,true,true);
                 // Make all In[] prompts blank, as well
                 // TODO: make this configurable (via checkbox?)
                 cells[i].set_input_prompt();
             }
         };
         this.dirty = true;
     };
 
 
     // Other cell functions: line numbers, ...
 
     Notebook.prototype.cell_toggle_line_numbers = function() {
         this.get_selected_cell().toggle_line_numbers();
     };
 
     // Kernel related things
 
     Notebook.prototype.start_kernel = function () {
         var base_url = $('body').data('baseKernelUrl') + "kernels";
         this.kernel = new IPython.Kernel(base_url);
         this.kernel.start(this.notebook_id);
         // Now that the kernel has been created, tell the CodeCells about it.
         var ncells = this.ncells();
         for (var i=0; i<ncells; i++) {
             var cell = this.get_cell(i);
             if (cell instanceof IPython.CodeCell) {
                 cell.set_kernel(this.kernel)
             };
         };
     };
 
 
     Notebook.prototype.restart_kernel = function () {
         var that = this;
         var dialog = $('<div/>');
         dialog.html('Do you want to restart the current kernel?  You will lose all variables defined in it.');
         $(document).append(dialog);
         dialog.dialog({
             resizable: false,
             modal: true,
             title: "Restart kernel or continue running?",
             closeText: '',
             buttons : {
                 "Restart": function () {
                     that.kernel.restart();
                     $(this).dialog('close');
                 },
                 "Continue running": function () {
                     $(this).dialog('close');
                 }
             }
         });
     };
 
 
     Notebook.prototype.execute_selected_cell = function (options) {
         // add_new: should a new cell be added if we are at the end of the nb
         // terminal: execute in terminal mode, which stays in the current cell
         default_options = {terminal: false, add_new: true};
         $.extend(default_options, options);
         var that = this;
         var cell = that.get_selected_cell();
         var cell_index = that.find_cell_index(cell);
         if (cell instanceof IPython.CodeCell) {
             cell.execute();
         } else if (cell instanceof IPython.HTMLCell) {
             cell.render();
         }
         if (default_options.terminal) {
             cell.select_all();
         } else {
             if ((cell_index === (that.ncells()-1)) && default_options.add_new) {
                 that.insert_cell_below('code');
                 // If we are adding a new cell at the end, scroll down to show it.
                 that.scroll_to_bottom();
             } else {
                 that.select(cell_index+1);
             };
         };
         this.dirty = true;
     };
 
 
     Notebook.prototype.execute_all_cells = function () {
         var ncells = this.ncells();
         for (var i=0; i<ncells; i++) {
             this.select(i);
             this.execute_selected_cell({add_new:false});
         };
         this.scroll_to_bottom();
     };
 
     // Persistance and loading
 
     Notebook.prototype.get_notebook_id = function () {
         return this.notebook_id;
     };
 
 
     Notebook.prototype.get_notebook_name = function () {
         return this.notebook_name;
     };
 
 
     Notebook.prototype.set_notebook_name = function (name) {
         this.notebook_name = name;
     };
 
 
     Notebook.prototype.test_notebook_name = function (nbname) {
         nbname = nbname || '';
         if (this.notebook_name_blacklist_re.test(nbname) == false && nbname.length>0) {
             return true;
         } else {
             return false;
         };
     };
 
 
     Notebook.prototype.fromJSON = function (data) {
         var ncells = this.ncells();
         var i;
         for (i=0; i<ncells; i++) {
             // Always delete cell 0 as they get renumbered as they are deleted.
             this.delete_cell(0);
         };
         // Save the metadata and name.
         this.metadata = data.metadata;
         this.notebook_name = data.metadata.name;
         // Only handle 1 worksheet for now.
         var worksheet = data.worksheets[0];
         if (worksheet !== undefined) {
             if (worksheet.metadata) {
                 this.worksheet_metadata = worksheet.metadata;
             }
             var new_cells = worksheet.cells;
             ncells = new_cells.length;
             var cell_data = null;
             var new_cell = null;
             for (i=0; i<ncells; i++) {
                 cell_data = new_cells[i];
                 // VERSIONHACK: plaintext -> raw
                 // handle never-released plaintext name for raw cells
                 if (cell_data.cell_type === 'plaintext'){
                     cell_data.cell_type = 'raw';
                 }
                 
                 new_cell = this.insert_cell_below(cell_data.cell_type);
                 new_cell.fromJSON(cell_data);
             };
         };
         if (data.worksheets.length > 1) {
             var dialog = $('<div/>');
             dialog.html("This notebook has " + data.worksheets.length + " worksheets, " +
             "but this version of IPython can only handle the first.  " +
             "If you save this notebook, worksheets after the first will be lost."
             );
             this.element.append(dialog);
             dialog.dialog({
                 resizable: false,
                 modal: true,
                 title: "Multiple worksheets",
                 closeText: "",
                 close: function(event, ui) {$(this).dialog('destroy').remove();},
                 buttons : {
                     "OK": function () {
                         $(this).dialog('close');
                     }
                 },
                 width: 400
             });
         }
     };
 
 
     Notebook.prototype.toJSON = function () {
         var cells = this.get_cells();
         var ncells = cells.length;
         var cell_array = new Array(ncells);
         for (var i=0; i<ncells; i++) {
             cell_array[i] = cells[i].toJSON();
         };
         var data = {
             // Only handle 1 worksheet for now.
             worksheets : [{
                 cells: cell_array,
                 metadata: this.worksheet_metadata
             }],
             metadata : this.metadata
         };
         return data;
     };
 
     Notebook.prototype.save_notebook = function () {
         // We may want to move the name/id/nbformat logic inside toJSON?
         var data = this.toJSON();
         data.metadata.name = this.notebook_name;
         data.nbformat = this.nbformat;
         data.nbformat_minor = this.nbformat_minor;
         // We do the call with settings so we can set cache to false.
         var settings = {
             processData : false,
             cache : false,
             type : "PUT",
             data : JSON.stringify(data),
             headers : {'Content-Type': 'application/json'},
             success : $.proxy(this.save_notebook_success,this),
             error : $.proxy(this.save_notebook_error,this)
         };
         $([IPython.events]).trigger('notebook_saving.Notebook');
         var url = $('body').data('baseProjectUrl') + 'notebooks/' + this.notebook_id;
         $.ajax(url, settings);
     };
 
 
     Notebook.prototype.save_notebook_success = function (data, status, xhr) {
         this.dirty = false;
         $([IPython.events]).trigger('notebook_saved.Notebook');
     };
 
 
     Notebook.prototype.save_notebook_error = function (xhr, status, error_msg) {
         $([IPython.events]).trigger('notebook_save_failed.Notebook');
     };
 
 
     Notebook.prototype.load_notebook = function (notebook_id) {
         var that = this;
         this.notebook_id = notebook_id;
         // We do the call with settings so we can set cache to false.
         var settings = {
             processData : false,
             cache : false,
             type : "GET",
             dataType : "json",
             success : $.proxy(this.load_notebook_success,this),
             error : $.proxy(this.load_notebook_error,this),
         };
         $([IPython.events]).trigger('notebook_loading.Notebook');
         var url = $('body').data('baseProjectUrl') + 'notebooks/' + this.notebook_id;
         $.ajax(url, settings);
     };
 
 
     Notebook.prototype.load_notebook_success = function (data, status, xhr) {
         this.fromJSON(data);
         if (this.ncells() === 0) {
             this.insert_cell_below('code');
         };
         this.dirty = false;
         this.select(0);
         this.scroll_to_top();
         if (data.orig_nbformat !== undefined && data.nbformat !== data.orig_nbformat) {
             msg = "This notebook has been converted from an older " +
             "notebook format (v"+data.orig_nbformat+") to the current notebook " +
             "format (v"+data.nbformat+"). The next time you save this notebook, the " +
             "newer notebook format will be used and older verions of IPython " +
             "may not be able to read it. To keep the older version, close the " +
             "notebook without saving it.";
             var dialog = $('<div/>');
             dialog.html(msg);
             this.element.append(dialog);
             dialog.dialog({
                 resizable: false,
                 modal: true,
                 title: "Notebook converted",
                 closeText: "",
                 close: function(event, ui) {$(this).dialog('destroy').remove();},
                 buttons : {
                     "OK": function () {
                         $(this).dialog('close');
                     }
                 },
                 width: 400
             });
         } else if (data.orig_nbformat_minor !== undefined && data.nbformat_minor !== data.orig_nbformat_minor) {
             var that = this;
             var orig_vs = 'v' + data.nbformat + '.' + data.orig_nbformat_minor;
             var this_vs = 'v' + data.nbformat + '.' + this.nbformat_minor;
             msg = "This notebook is version " + orig_vs + ", but we only fully support up to " +
             this_vs + ".  You can still work with this notebook, but some features " +
             "introduced in later notebook versions may not be available."
             
             var dialog = $('<div/>');
             dialog.html(msg);
             this.element.append(dialog);
             dialog.dialog({
                 resizable: false,
                 modal: true,
                 title: "Newer Notebook",
                 closeText: "",
                 close: function(event, ui) {$(this).dialog('destroy').remove();},
                 buttons : {
                     "OK": function () {
                         $(this).dialog('close');
                     }
                 },
                 width: 400
             });
             
         }
         // Create the kernel after the notebook is completely loaded to prevent
         // code execution upon loading, which is a security risk.
         if (! this.read_only) {
             this.start_kernel();
         }
         $([IPython.events]).trigger('notebook_loaded.Notebook');
     };
 
 
     Notebook.prototype.load_notebook_error = function (xhr, textStatus, errorThrow) {
         if (xhr.status === 500) {
             msg = "An error occurred while loading this notebook. Most likely " +
             "this notebook is in a newer format than is supported by this " +
             "version of IPython. This version can load notebook formats " +
             "v"+this.nbformat+" or earlier.";
             var dialog = $('<div/>');
             dialog.html(msg);
             this.element.append(dialog);
             dialog.dialog({
                 resizable: false,
                 modal: true,
                 title: "Error loading notebook",
                 closeText: "",
                 close: function(event, ui) {$(this).dialog('destroy').remove();},
                 buttons : {
                     "OK": function () {
                         $(this).dialog('close');
                     }
                 },
                 width: 400
             });
         }
     }
     
     IPython.Notebook = Notebook;
 
 
     return IPython;
 
 }(IPython));