text:
// Copyright (c) IPython Development Team.
// Distributed under the terms of the Modified BSD License.

/**
 * @module notebook
 */
define([
    'base/js/namespace',
    'jquery',
    'base/js/utils',
    'base/js/dialog',
    'notebook/js/cell',
    'notebook/js/textcell',
    'notebook/js/codecell',
    'services/config',
    'services/sessions/session',
    'notebook/js/celltoolbar',
    'components/marked/lib/marked',
    'codemirror/lib/codemirror',
    'codemirror/addon/runmode/runmode',
    'notebook/js/mathjaxutils',
    'base/js/keyboard',
    'notebook/js/tooltip',
    'notebook/js/celltoolbarpresets/default',
    'notebook/js/celltoolbarpresets/rawcell',
    'notebook/js/celltoolbarpresets/slideshow',
    'notebook/js/celltoolbarpresets/presentation',
    'notebook/js/scrollmanager',
], function (
    IPython,
    $,
    utils,
    dialog,
    cellmod,
    textcell,
    codecell,
    configmod,
    session,
    celltoolbar,
    marked,
    CodeMirror,
    runMode,
    mathjaxutils,
    keyboard,
    tooltip,
    default_celltoolbar,
    rawcell_celltoolbar,
    slideshow_celltoolbar,
    presentation_celltoolbar,
    scrollmanager
    ) {
    "use strict";

    /**
     * Contains and manages cells.
     *
     * @class Notebook
     * @param {string}          selector
     * @param {object}          options - Dictionary of keyword arguments.
     * @param {jQuery}          options.events - selector of Events
     * @param {KeyboardManager} options.keyboard_manager
     * @param {Contents}        options.contents
     * @param {SaveWidget}      options.save_widget
     * @param {object}          options.config
     * @param {string}          options.base_url
     * @param {string}          options.notebook_path
     * @param {string}          options.notebook_name
     */
    var Notebook = function (selector, options) {
        this.config = options.config;
        this.class_config = new configmod.ConfigWithDefaults(this.config,
                                        Notebook.options_default, 'Notebook');
        this.base_url = options.base_url;
        this.notebook_path = options.notebook_path;
        this.notebook_name = options.notebook_name;
        this.events = options.events;
        this.keyboard_manager = options.keyboard_manager;
        this.contents = options.contents;
        this.save_widget = options.save_widget;
        this.tooltip = new tooltip.Tooltip(this.events);
        this.ws_url = options.ws_url;
        this._session_starting = false;

        //  Create default scroll manager.
        this.scroll_manager = new scrollmanager.ScrollManager(this);

        // TODO: This code smells (and the other `= this` line a couple lines down)
        // We need a better way to deal with circular instance references.
        this.keyboard_manager.notebook = this;
        this.save_widget.notebook = this;

        mathjaxutils.init();

        if (marked) {
            marked.setOptions({
                gfm : true,
                tables: true,
                // FIXME: probably want central config for CodeMirror theme when we have js config
                langPrefix: "cm-s-ipython language-",
                highlight: function(code, lang, callback) {
                    if (!lang) {
                        // no language, no highlight
                        if (callback) {
                            callback(null, code);
                            return;
                        } else {
                            return code;
                        }
                    }
                    utils.requireCodeMirrorMode(lang, function (spec) {
                        var el = document.createElement("div");
                        var mode = CodeMirror.getMode({}, spec);
                        if (!mode) {
                            console.log("No CodeMirror mode: " + lang);
                            callback(null, code);
                            return;
                        }
                        try {
                            CodeMirror.runMode(code, spec, el);
                            callback(null, el.innerHTML);
                        } catch (err) {
                            console.log("Failed to highlight " + lang + " code", err);
                            callback(err, code);
                        }
                    }, function (err) {
                        console.log("No CodeMirror mode: " + lang);
                        callback(err, code);
                    });
                }
            });
        }

        this.element = $(selector);
        this.element.scroll();
        this.element.data("notebook", this);
        this.next_prompt_number = 1;
        this.session = null;
        this.kernel = null;
        this.clipboard = null;
        this.undelete_backup = null;
        this.undelete_index = null;
        this.undelete_below = false;
        this.paste_enabled = false;
        this.writable = false;
        // It is important to start out in command mode to match the intial mode
        // of the KeyboardManager.
        this.mode = 'command';
        this.set_dirty(false);
        this.metadata = {};
        this._checkpoint_after_save = false;
        this.last_checkpoint = null;
        this.checkpoints = [];
        this.autosave_interval = 0;
        this.autosave_timer = null;
        // autosave *at most* every two minutes
        this.minimum_autosave_interval = 120000;
        this.notebook_name_blacklist_re = /[\/\\:]/;
        this.nbformat = 4; // Increment this when changing the nbformat
        this.nbformat_minor = this.current_nbformat_minor = 0; // Increment this when changing the nbformat
        this.codemirror_mode = 'text/x-scala';
        this.create_elements();
        this.bind_events();
        this.kernel_selector = null;
        this.dirty = null;
        this.trusted = null;
        this._fully_loaded = false;

        // Trigger cell toolbar registration.
        default_celltoolbar.register(this);
        presentation_celltoolbar.register(this);

        // these are not used in spark-notebook
        // rawcell_celltoolbar.register(this);
        // slideshow_celltoolbar.register(this);

        // prevent assign to miss-typed properties.
        Object.seal(this);
    };

    Notebook.options_default = {
        // can be any cell type, or the special values of
        // 'above', 'below', or 'selected' to get the value from another cell.
        default_cell_type: 'code'
    };

    /**
     * Create an HTML and CSS representation of the notebook.
     */
    Notebook.prototype.create_elements = function () {
        var that = this;
        this.element.attr('tabindex','-1');
        this.container = $("<div/>").addClass("container").attr("id", "notebook-container");
        // 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 end_space = $('<div/>').addClass('end_space');
        end_space.dblclick(function (e) {
            var ncells = that.ncells();
            that.insert_cell_below('code',ncells-1);
        });
        this.element.append(this.container);
        this.container.after(end_space);
    };

    /**
     * Bind JavaScript events: key presses and custom IPython events.
     */
    Notebook.prototype.bind_events = function () {
        var that = this;

        this.events.on('set_next_input.Notebook', function (event, data) {
            if (data.replace) {
                data.cell.set_text(data.text);
                data.cell.clear_output();
            } else {
                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;
        });

        this.events.on('unrecognized_cell.Cell', function () {
            that.warn_nbformat_minor();
        });

        this.events.on('unrecognized_output.OutputArea', function () {
            that.warn_nbformat_minor();
        });

        this.events.on('set_dirty.Notebook', function (event, data) {
            that.dirty = data.value;
        });

        this.events.on('trust_changed.Notebook', function (event, trusted) {
            that.trusted = trusted;
        });

        this.events.on('select.Cell', function (event, data) {
            var index = that.find_cell_index(data.cell);
            that.select(index);
        });

        this.events.on('edit_mode.Cell', function (event, data) {
            that.handle_edit_mode(data.cell);
        });

        this.events.on('command_mode.Cell', function (event, data) {
            that.handle_command_mode(data.cell);
        });

        this.events.on('spec_changed.Kernel', function(event, data) {
            that.metadata.kernelspec =
                {name: data.name, display_name: data.spec.display_name};
            // start session if the current session isn't already correct
            if (!(this.session && this.session.kernel && this.session.kernel.name === data.name)) {
                that.start_session(data.name);
            }
        });

        this.events.on('kernel_ready.Kernel', function(event, data) {
            var kinfo = data.kernel.info_reply;
            if (!kinfo.language_info) {
                delete that.metadata.language_info;
                return;
            }
            var langinfo = kinfo.language_info;
            that.metadata.language_info = langinfo;
            // Mode 'null' should be plain, unhighlighted text.
            var cm_mode = langinfo.codemirror_mode || langinfo.name || 'text/x-scala';
            that.set_codemirror_mode(cm_mode);
        });

        var collapse_time = function (time) {
            var app_height = $('#ipython-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) {
            var time = (extrap !== undefined) ? ((extrap.duration !== undefined ) ? extrap.duration : 'fast') : 'fast';
            collapse_time(time);
        });

        var expand_time = function (time) {
            var app_height = $('#ipython-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) {
            var time = (extrap !== undefined) ? ((extrap.duration !== undefined ) ? extrap.duration : 'fast') : 'fast';
            expand_time(time);
        });

        // Firefox 22 broke $(window).on("beforeunload")
        // I'm not sure why or how.
        window.onbeforeunload = function (e) {
            // TODO: Make killing the kernel configurable.
            var kill_kernel = false;
            if (kill_kernel) {
                that.session.delete();
            }
            // if we are autosaving, trigger an autosave on nav-away.
            // still warn, because if we don't the autosave may fail.
            if (that.dirty) {
                if ( that.autosave_interval ) {
                    // schedule autosave in a timeout
                    // this gives you a chance to forcefully discard changes
                    // by reloading the page if you *really* want to.
                    // the timer doesn't start until you *dismiss* the dialog.
                    setTimeout(function () {
                        if (that.dirty) {
                            that.save_notebook();
                        }
                    }, 1000);
                    return "Autosave in progress, latest changes may be lost.";
                } else {
                    return "Unsaved changes will be lost.";
                }
            }
            // Null is the *only* return value that will make the browser not
            // pop up the "don't leave" dialog.
            return null;
        };
    };

    /**
     * Trigger a warning dialog about missing functionality from newer minor versions
     */
    Notebook.prototype.warn_nbformat_minor = function (event) {
        var v = 'v' + this.nbformat + '.';
        var orig_vs = v + this.nbformat_minor;
        var this_vs = v + this.current_nbformat_minor;
        var msg = "This notebook is version " + orig_vs + ", but we only fully support up to " +
        this_vs + ".  You can still work with this notebook, but cell and output types " +
        "introduced in later notebook versions will not be available.";

        dialog.modal({
            notebook: this,
            keyboard_manager: this.keyboard_manager,
            title : "Newer Notebook",
            body : msg,
            buttons : {
                OK : {
                    "class" : "btn-danger"
                }
            }
        });
    };

    /**
     * Set the dirty flag, and trigger the set_dirty.Notebook event
     */
    Notebook.prototype.set_dirty = function (value) {
        if (value === undefined) {
            value = true;
        }
        if (this.dirty === value) {
            return;
        }
        this.events.trigger('set_dirty.Notebook', {value: value});
    };

    /**
     * Scroll the top of the page to a given cell.
     *
     * @param {integer}  index - An index of the cell to view
     * @param {integer}  time - Animation time in milliseconds
     * @return {integer} Pixel offset from the top of the container
     */
    Notebook.prototype.scroll_to_cell = function (index, time) {
        var cells = this.get_cells();
        time = time || 0;
        index = Math.min(cells.length-1,index);
        index = Math.max(0             ,index);
        var scroll_value = cells[index].element.position().top-cells[0].element.position().top ;
        this.scroll_manager.element.animate({scrollTop:scroll_value}, time);
        return scroll_value;
    };

    /**
     * Scroll to the bottom of the page.
     */
    Notebook.prototype.scroll_to_bottom = function () {
        this.scroll_manager.element.animate({scrollTop:this.element.get(0).scrollHeight}, 0);
    };

    /**
     * Scroll to the top of the page.
     */
    Notebook.prototype.scroll_to_top = function () {
        this.scroll_manager.element.animate({scrollTop:0}, 0);
    };

    // Edit Notebook metadata

    /**
     * Display a dialog that allows the user to edit the Notebook's metadata.
     */
    Notebook.prototype.edit_metadata = function () {
        var that = this;
        dialog.edit_metadata({
            md: this.metadata,
            callback: function (md) {
                that.metadata = md;
                that.save_notebook();
            },
            name: 'Notebook',
            notebook: this,
            keyboard_manager: this.keyboard_manager});
    };

    // Cell indexing, retrieval, etc.

    /**
     * Get all cell elements in the notebook.
     *
     * @return {jQuery} A selector of all cell elements
     */
    Notebook.prototype.get_cell_elements = function () {
        return this.container.find(".cell").not('.cell .cell');
    };

    /**
     * Get a particular cell element.
     *
     * @param {integer} index An index of a cell to select
     * @return {jQuery} A selector of the given 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;
    };

    /**
     * Try to get a particular cell by msg_id.
     *
     * @param {string} msg_id A message UUID
     * @return {Cell} Cell or null if no cell was found.
     */
    Notebook.prototype.get_msg_cell = function (msg_id) {
        return codecell.CodeCell.msg_cells[msg_id] || null;
    };

    /**
     * Count the cells in this notebook.
     *
     * @return {integer} The number of cells in this notebook
     */
    Notebook.prototype.ncells = function () {
        return this.get_cell_elements().length;
    };

    /**
     * Get all Cell objects in this notebook.
     *
     * @return {Array} This notebook's Cell objects
     */
    Notebook.prototype.get_cells = function () {
        // TODO: we are often calling cells as cells()[i], which we should optimize
        // to cells(i) or a new method.
        return this.get_cell_elements().toArray().map(function (e) {
            return $(e).data("cell");
        });
    };

    /**
     * Get a Cell objects from this notebook.
     *
     * @param {integer} index - An index of a cell to retrieve
     * @return {Cell} Cell or null if no cell was found.
     */
    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;
    };

    /**
     * Get the cell below a given cell.
     *
     * @param {Cell} cell
     * @return {Cell} the next cell or null if no cell was found.
     */
    Notebook.prototype.get_next_cell = function (cell) {
        var result = null;
        var index = this.find_cell_index(cell);
        if (this.is_valid_cell_index(index+1)) {
            result = this.get_cell(index+1);
        }
        return result;
    };

    /**
     * Get the cell above a given cell.
     *
     * @param {Cell} cell
     * @return {Cell} The previous cell or null if no cell was found.
     */
    Notebook.prototype.get_prev_cell = function (cell) {
        var result = null;
        var index = this.find_cell_index(cell);
        if (index !== null && index > 0) {
            result = this.get_cell(index-1);
        }
        return result;
    };

    /**
     * Get the numeric index of a given cell.
     *
     * @param {Cell} cell
     * @return {integer} The cell's numeric index or null if no cell was found.
     */
    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;
    };

    /**
     * Return given index if defined, or the selected index if not.
     *
     * @param {integer} [index] - A cell's index
     * @return {integer} cell index
     */
    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;
    };

    /**
     * Get the currently selected cell.
     *
     * @return {Cell} The selected cell
     */
    Notebook.prototype.get_selected_cell = function () {
        var index = this.get_selected_index();
        return this.get_cell(index);
    };

    /**
     * Check whether a cell index is valid.
     *
     * @param {integer} index - A cell index
     * @return boolean return true if the index is valid, false otherwise
     */
    Notebook.prototype.is_valid_cell_index = function (index) {
        return index !== null && index >= 0 && index < this.ncells();
    };

    /**
     * Get the index of the currently selected cell.
     *
     * @return {integer} The selected cell's numeric index
     */
    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.

    /**
     * Programmatically select a cell.
     *
     * @param {integer} index - A cell's index
     * @return {Notebook} This notebook
     */
    Notebook.prototype.select = function (index) {
        if (this.is_valid_cell_index(index)) {
            var sindex = this.get_selected_index();
            if (sindex !== null && index !== sindex) {
                // If we are about to select a different cell, make sure we are
                // first in command mode.
                if (this.mode !== 'command') {
                    this.command_mode();
                }
                this.get_cell(sindex).unselect();
            }
            var cell = this.get_cell(index);
            cell.select();
            if (cell.cell_type === 'heading') {
                this.events.trigger('selected_cell_type_changed.Notebook',
                    {'cell_type':cell.cell_type,level:cell.level}
                );
            } else {
                this.events.trigger('selected_cell_type_changed.Notebook',
                    {'cell_type':cell.cell_type}
                );
            }
        }
        return this;
    };

    /**
     * Programmatically select the next cell.
     *
     * @return {Notebook} This notebook
     */
    Notebook.prototype.select_next = function () {
        var index = this.get_selected_index();
        this.select(index+1);
        return this;
    };

    /**
     * Programmatically select the previous cell.
     *
     * @return {Notebook} This notebook
     */
    Notebook.prototype.select_prev = function () {
        var index = this.get_selected_index();
        this.select(index-1);
        return this;
    };

    // Edit/Command mode

    /**
     * Gets the index of the cell that is in edit mode.
     *
     * @return {integer} index
     */
    Notebook.prototype.get_edit_index = function () {
        var result = null;
        this.get_cell_elements().filter(function (index) {
            if ($(this).data("cell").mode === 'edit') {
                result = index;
            }
        });
        return result;
    };

    /**
     * Handle when a a cell blurs and the notebook should enter command mode.
     *
     * @param {Cell} [cell] - Cell to enter command mode on.
     */
    Notebook.prototype.handle_command_mode = function (cell) {
        if (this.mode !== 'command') {
            cell.command_mode();
            this.mode = 'command';
            this.events.trigger('command_mode.Notebook');
            this.keyboard_manager.command_mode();
        }
    };

    /**
     * Make the notebook enter command mode.
     */
    Notebook.prototype.command_mode = function () {
        var cell = this.get_cell(this.get_edit_index());
        if (cell && this.mode !== 'command') {
            // We don't call cell.command_mode, but rather call cell.focus_cell()
            // which will blur and CM editor and trigger the call to
            // handle_command_mode.
            cell.focus_cell();
        }
    };

    /**
     * Handle when a cell fires it's edit_mode event.
     *
     * @param {Cell} [cell] Cell to enter edit mode on.
     */
    Notebook.prototype.handle_edit_mode = function (cell) {
        if (cell && this.mode !== 'edit') {
            cell.edit_mode();
            this.mode = 'edit';
            this.events.trigger('edit_mode.Notebook');
            this.keyboard_manager.edit_mode();
        }
    };

    /**
     * Make a cell enter edit mode.
     */
    Notebook.prototype.edit_mode = function () {
        var cell = this.get_selected_cell();
        if (cell && this.mode !== 'edit') {
            cell.unrender();
            cell.focus_editor();
        }
    };

    /**
     * Focus the currently selected cell.
     */
    Notebook.prototype.focus_cell = function () {
        var cell = this.get_selected_cell();
        if (cell === null) {return;}  // No cell is selected
        cell.focus_cell();
    };

    // Cell movement

    /**
     * Move given (or selected) cell up and select it.
     *
     * @param {integer} [index] - cell index
     * @return {Notebook} This notebook
     */
    Notebook.prototype.move_cell_up = function (index) {
        var i = this.index_or_selected(index);
        if (this.is_valid_cell_index(i) && 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);
                var cell = this.get_selected_cell();
                cell.focus_cell();
            }
            this.set_dirty(true);
        }
        return this;
    };

    /**
     * Move given (or selected) cell down and select it.
     *
     * @param {integer} [index] - cell index
     * @return {Notebook} This notebook
     */
    Notebook.prototype.move_cell_down = function (index) {
        var i = this.index_or_selected(index);
        if (this.is_valid_cell_index(i) && this.is_valid_cell_index(i+1)) {
            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);
                var cell = this.get_selected_cell();
                cell.focus_cell();
            }
        }
        this.set_dirty();
        return this;
    };

    // Insertion, deletion.

    /**
     * Delete a cell from the notebook without any precautions
     * Needed to reload checkpoints and other things like that.
     *
     * @param {integer} [index] - cell's numeric index
     * @return {Notebook} This notebook
     */
    Notebook.prototype._unsafe_delete_cell = function (index) {
        var i = this.index_or_selected(index);
        var cell = this.get_cell(i);

        $('#undelete_cell').addClass('disabled');
        if (this.is_valid_cell_index(i)) {
            var old_ncells = this.ncells();
            var ce = this.get_cell_element(i);
            ce.remove();
            this.set_dirty(true);
        }
        return this;
    };

    /**
     * Delete a cell from the notebook.
     *
     * @param {integer} [index] - cell's numeric index
     * @return {Notebook} This notebook
     */
    Notebook.prototype.delete_cell = function (index) {
        var i = this.index_or_selected(index);
        var cell = this.get_cell(i);
        if (!cell.is_deletable()) {
            return this;
        }

        this.undelete_backup = cell.toJSON();
        $('#undelete_cell').removeClass('disabled');
        if (this.is_valid_cell_index(i)) {
            var old_ncells = this.ncells();
            var ce = this.get_cell_element(i);
            ce.remove();
            if (i === 0) {
                // Always make sure we have at least one cell.
                if (old_ncells === 1) {
                    this.insert_cell_below('code');
                }
                this.select(0);
                this.undelete_index = 0;
                this.undelete_below = false;
            } else if (i === old_ncells-1 && i !== 0) {
                this.select(i-1);
                this.undelete_index = i - 1;
                this.undelete_below = true;
            } else {
                this.select(i);
                this.undelete_index = i;
                this.undelete_below = false;
            }
            this.events.trigger('delete.Cell', {'cell': cell, 'index': i});
            this.set_dirty(true);
        }
        return this;
    };

    /**
     * Restore the most recently deleted cell.
     */
    Notebook.prototype.undelete_cell = function() {
        if (this.undelete_backup !== null && this.undelete_index !== null) {
            var current_index = this.get_selected_index();
            if (this.undelete_index < current_index) {
                current_index = current_index + 1;
            }
            if (this.undelete_index >= this.ncells()) {
                this.select(this.ncells() - 1);
            }
            else {
                this.select(this.undelete_index);
            }
            var cell_data = this.undelete_backup;
            var new_cell = null;
            if (this.undelete_below) {
                new_cell = this.insert_cell_below(cell_data.cell_type);
            } else {
                new_cell = this.insert_cell_above(cell_data.cell_type);
            }
            new_cell.fromJSON(cell_data);
            if (this.undelete_below) {
                this.select(current_index+1);
            } else {
                this.select(current_index);
            }
            this.undelete_backup = null;
            this.undelete_index = null;
        }
        $('#undelete_cell').addClass('disabled');
    };

    /**
     * Insert a cell so that after insertion the cell is at given index.
     *
     * If cell type is not provided, it will default to the type of the
     * currently active cell.
     *
     * Similar to insert_above, but index parameter is mandatory.
     *
     * Index will be brought back into the accessible range [0,n].
     *
     * @param {string} [type] - in ['code','markdown', 'raw'], defaults to 'code'
     * @param {integer} [index] - a valid index where to insert cell
     * @return {Cell|null} created cell or null
     */
    Notebook.prototype.insert_cell_at_index = function(type, index){

        var ncells = this.ncells();
        index = Math.min(index, ncells);
        index = Math.max(index, 0);
        var cell = null;
        type = type || this.class_config.get_sync('default_cell_type');
        if (type === 'above') {
            if (index > 0) {
                type = this.get_cell(index-1).cell_type;
            } else {
                type = 'code';
            }
        } else if (type === 'below') {
            if (index < ncells) {
                type = this.get_cell(index).cell_type;
            } else {
                type = 'code';
            }
        } else if (type === 'selected') {
            type = this.get_selected_cell().cell_type;
        }

        if (ncells === 0 || this.is_valid_cell_index(index) || index === ncells) {
            var cell_options = {
                events: this.events,
                config: this.config,
                keyboard_manager: this.keyboard_manager,
                notebook: this,
                tooltip: this.tooltip
            };
            switch(type) {
            case 'code':
                cell = new codecell.CodeCell(this.kernel, cell_options);
                cell.set_input_prompt();
                break;
            case 'markdown':
                cell = new textcell.MarkdownCell(cell_options);
                break;
            case 'raw':
                cell = new textcell.RawCell(cell_options);
                break;
            default:
                console.log("Unrecognized cell type: ", type, cellmod);
                cell = new cellmod.UnrecognizedCell(cell_options);
            }

            if(this._insert_element_at_index(cell.element,index)) {
                cell.render();
                this.events.trigger('create.Cell', {'cell': cell, 'index': index});
                cell.refresh();
                // We used to select the cell after we refresh it, but there
                // are now cases were this method is called where select is
                // not appropriate. The selection logic should be handled by the
                // caller of the the top level insert_cell methods.
                this.set_dirty(true);
            }
        }
        return cell;

    };

    /**
     * Insert an element at given cell index.
     *
     * @param {HTMLElement} element - a cell element
     * @param {integer}     [index] - a valid index where to inser cell
     * @returns {boolean}   success
     */
    Notebook.prototype._insert_element_at_index = function(element, index){
        if (element === undefined){
            return false;
        }

        var ncells = this.ncells();

        if (ncells === 0) {
            // special case append if empty
            this.container.append(element);
        } else if ( ncells === index ) {
            // special case append it the end, but not empty
            this.get_cell_element(index-1).after(element);
        } else if (this.is_valid_cell_index(index)) {
            // otherwise always somewhere to append to
            this.get_cell_element(index).before(element);
        } else {
            return false;
        }

        if (this.undelete_index !== null && index <= this.undelete_index) {
            this.undelete_index = this.undelete_index + 1;
            this.set_dirty(true);
        }
        return true;
    };

    /**
     * Insert a cell of given type above given index, or at top
     * of notebook if index smaller than 0.
     *
     * @param {string}     [type] - cell type
     * @param {integer}    [index] - defaults to the currently selected cell
     * @return {Cell|null} handle to created cell or null
     */
    Notebook.prototype.insert_cell_above = function (type, index) {
        index = this.index_or_selected(index);
        return this.insert_cell_at_index(type, index);
    };

    /**
     * Insert a cell of given type below given index, or at bottom
     * of notebook if index greater than number of cells
     *
     * @param {string}     [type] - cell type
     * @param {integer}    [index] - defaults to the currently selected cell
     * @return {Cell|null} handle to created cell or null
     */
    Notebook.prototype.insert_cell_below = function (type, index) {
        index = this.index_or_selected(index);
        return this.insert_cell_at_index(type, index+1);
    };

    /**
     * Insert cell at end of notebook
     *
     * @param {string} type - cell type
     * @return {Cell|null} handle to created cell or null
     */
    Notebook.prototype.insert_cell_at_bottom = function (type){
        var len = this.ncells();
        return this.insert_cell_below(type,len-1);
    };

    /**
     * Turn a cell into a code cell.
     *
     * @param {integer} [index] - cell index
     */
    Notebook.prototype.to_code = function (index) {
        var i = this.index_or_selected(index);
        if (this.is_valid_cell_index(i)) {
            var source_cell = this.get_cell(i);
            if (!(source_cell instanceof codecell.CodeCell)) {
                var target_cell = this.insert_cell_below('code',i);
                var text = source_cell.get_text();
                if (text === source_cell.placeholder) {
                    text = '';
                }
                //metadata
                target_cell.metadata = source_cell.metadata;

                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_cell.element.remove();
                this.select(i);
                var cursor = source_cell.code_mirror.getCursor();
                target_cell.code_mirror.setCursor(cursor);
                this.set_dirty(true);
            }
        }
    };

    /**
     * Turn a cell into a Markdown cell.
     *
     * @param {integer} [index] - cell index
     */
    Notebook.prototype.to_markdown = function (index) {
        var i = this.index_or_selected(index);
        if (this.is_valid_cell_index(i)) {
            var source_cell = this.get_cell(i);

            if (!(source_cell instanceof textcell.MarkdownCell)) {
                var target_cell = this.insert_cell_below('markdown',i);
                var text = source_cell.get_text();

                if (text === source_cell.placeholder) {
                    text = '';
                }
                // metadata
                target_cell.metadata = source_cell.metadata;
                // We must show the editor before setting its contents
                target_cell.unrender();
                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_cell.element.remove();
                this.select(i);
                if ((source_cell instanceof textcell.TextCell) && source_cell.rendered) {
                    target_cell.render();
                }
                var cursor = source_cell.code_mirror.getCursor();
                target_cell.code_mirror.setCursor(cursor);
                this.set_dirty(true);
            }
        }
    };

    /**
     * Turn a cell into a raw text cell.
     *
     * @param {integer} [index] - cell index
     */
    Notebook.prototype.to_raw = function (index) {
        var i = this.index_or_selected(index);
        if (this.is_valid_cell_index(i)) {
            var target_cell = null;
            var source_cell = this.get_cell(i);

            if (!(source_cell instanceof textcell.RawCell)) {
                target_cell = this.insert_cell_below('raw',i);
                var text = source_cell.get_text();
                if (text === source_cell.placeholder) {
                    text = '';
                }
                //metadata
                target_cell.metadata = source_cell.metadata;
                // We must show the editor before setting its contents
                target_cell.unrender();
                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_cell.element.remove();
                this.select(i);
                var cursor = source_cell.code_mirror.getCursor();
                target_cell.code_mirror.setCursor(cursor);
                this.set_dirty(true);
            }
        }
    };

    /**
     * Warn about heading cell support removal.
     */
    Notebook.prototype._warn_heading = function () {
        dialog.modal({
            notebook: this,
            keyboard_manager: this.keyboard_manager,
            title : "Use markdown headings",
            body : $("<p/>").text(
                'IPython no longer uses special heading cells. ' +
                'Instead, write your headings in Markdown cells using # characters:'
            ).append($('<pre/>').text(
                '## This is a level 2 heading'
            )),
            buttons : {
                "OK" : {}
            }
        });
    };

    /**
     * Turn a cell into a heading containing markdown cell.
     *
     * @param {integer} [index] - cell index
     * @param {integer} [level] - heading level (e.g., 1 for h1)
     */
    Notebook.prototype.to_heading = function (index, level) {
        this.to_markdown(index);
        level = level || 1;
        var i = this.index_or_selected(index);
        if (this.is_valid_cell_index(i)) {
            var cell = this.get_cell(i);
            cell.set_heading_level(level);
            this.set_dirty(true);
        }
    };

    // Cut/Copy/Paste

    /**
     * Enable the UI elements for pasting cells.
     */
    Notebook.prototype.enable_paste = function () {
        var that = this;
        if (!this.paste_enabled) {
            $('#paste_cell_replace').removeClass('disabled')
                .on('click', function () {that.paste_cell_replace();});
            $('#paste_cell_above').removeClass('disabled')
                .on('click', function () {that.paste_cell_above();});
            $('#paste_cell_below').removeClass('disabled')
                .on('click', function () {that.paste_cell_below();});
            this.paste_enabled = true;
        }
    };

    /**
     * Disable the UI elements for pasting cells.
     */
    Notebook.prototype.disable_paste = function () {
        if (this.paste_enabled) {
            $('#paste_cell_replace').addClass('disabled').off('click');
            $('#paste_cell_above').addClass('disabled').off('click');
            $('#paste_cell_below').addClass('disabled').off('click');
            this.paste_enabled = false;
        }
    };

    /**
     * Cut a cell.
     */
    Notebook.prototype.cut_cell = function () {
        this.copy_cell();
        this.delete_cell();
    };

    /**
     * Copy a cell.
     */
    Notebook.prototype.copy_cell = function () {
        var cell = this.get_selected_cell();
        this.clipboard = cell.toJSON();
        // remove undeletable status from the copied cell
        if (this.clipboard.metadata.deletable !== undefined) {
            delete this.clipboard.metadata.deletable;
        }
        this.enable_paste();
    };

    /**
     * Replace the selected cell with the cell in the clipboard.
     */
    Notebook.prototype.paste_cell_replace = 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);
            var 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));
        }
    };

    /**
     * Paste a cell from the clipboard above the selected 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);
            new_cell.focus_cell();
        }
    };

    /**
     * Paste a cell from the clipboard below the selected cell.
     */
    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);
            new_cell.focus_cell();
        }
    };

    // Split/merge

    /**
     * Split the selected cell into two cells.
     */
    Notebook.prototype.split_cell = function () {
        var cell = this.get_selected_cell();
        if (cell.is_splittable()) {
            var texta = cell.get_pre_cursor();
            var textb = cell.get_post_cursor();
            cell.set_text(textb);
            var new_cell = this.insert_cell_above(cell.cell_type);
            // Unrender the new cell so we can call set_text.
            new_cell.unrender();
            new_cell.set_text(texta);
        }
    };

    /**
     * Merge the selected cell into the cell above it.
     */
    Notebook.prototype.merge_cell_above = function () {
        var index = this.get_selected_index();
        var cell = this.get_cell(index);
        var render = cell.rendered;
        if (!cell.is_mergeable()) {
            return;
        }
        if (index > 0) {
            var upper_cell = this.get_cell(index-1);
            if (!upper_cell.is_mergeable()) {
                return;
            }
            var upper_text = upper_cell.get_text();
            var text = cell.get_text();
            if (cell instanceof codecell.CodeCell) {
                cell.set_text(upper_text+'\n'+text);
            } else {
                cell.unrender(); // Must unrender before we set_text.
                cell.set_text(upper_text+'\n\n'+text);
                if (render) {
                    // The rendered state of the final cell should match
                    // that of the original selected cell;
                    cell.render();
                }
            }
            this.delete_cell(index-1);
            this.select(this.find_cell_index(cell));
        }
    };

    /**
     * Merge the selected cell into the cell below it.
     */
    Notebook.prototype.merge_cell_below = function () {
        var index = this.get_selected_index();
        var cell = this.get_cell(index);
        var render = cell.rendered;
        if (!cell.is_mergeable()) {
            return;
        }
        if (index < this.ncells()-1) {
            var lower_cell = this.get_cell(index+1);
            if (!lower_cell.is_mergeable()) {
                return;
            }
            var lower_text = lower_cell.get_text();
            var text = cell.get_text();
            if (cell instanceof codecell.CodeCell) {
                cell.set_text(text+'\n'+lower_text);
            } else {
                cell.unrender(); // Must unrender before we set_text.
                cell.set_text(text+'\n\n'+lower_text);
                if (render) {
                    // The rendered state of the final cell should match
                    // that of the original selected cell;
                    cell.render();
                }
            }
            this.delete_cell(index+1);
            this.select(this.find_cell_index(cell));
        }
    };

    // Cell collapsing and output clearing

    /**
     * Hide a cell's output.
     *
     * @param {integer} index - cell index
     */
    Notebook.prototype.collapse_output = function (index) {
        var i = this.index_or_selected(index);
        var cell = this.get_cell(i);
        if (cell !== null && (cell instanceof codecell.CodeCell)) {
            cell.collapse_output();
            this.set_dirty(true);
        }
    };

    /**
     * Hide each code cell's output area.
     */
    Notebook.prototype.collapse_all_output = function () {
        this.get_cells().map(function (cell, i) {
            if (cell instanceof codecell.CodeCell) {
                cell.collapse_output();
            }
        });
        // this should not be set if the `collapse` key is removed from nbformat
        this.set_dirty(true);
    };

    /**
     * Show a cell's output.
     *
     * @param {integer} index - cell index
     */
    Notebook.prototype.expand_output = function (index) {
        var i = this.index_or_selected(index);
        var cell = this.get_cell(i);
        if (cell !== null && (cell instanceof codecell.CodeCell)) {
            cell.expand_output();
            this.set_dirty(true);
        }
    };

    /**
     * Expand each code cell's output area, and remove scrollbars.
     */
    Notebook.prototype.expand_all_output = function () {
        this.get_cells().map(function (cell, i) {
            if (cell instanceof codecell.CodeCell) {
                cell.expand_output();
            }
        });
        // this should not be set if the `collapse` key is removed from nbformat
        this.set_dirty(true);
    };

    /**
     * Clear the selected CodeCell's output area.
     *
     * @param {integer} index - cell index
     */
    Notebook.prototype.clear_output = function (index) {
        var i = this.index_or_selected(index);
        var cell = this.get_cell(i);
        if (cell !== null && (cell instanceof codecell.CodeCell)) {
            cell.clear_output();
            this.set_dirty(true);
        }
    };

    /**
     * Clear each code cell's output area.
     */
    Notebook.prototype.clear_all_output = function () {
        this.get_cells().map(function (cell, i) {
            if (cell instanceof codecell.CodeCell) {
                cell.clear_output();
            }
        });
        this.set_dirty(true);
    };

    /**
     * Scroll the selected CodeCell's output area.
     *
     * @param {integer} index - cell index
     */
    Notebook.prototype.scroll_output = function (index) {
        var i = this.index_or_selected(index);
        var cell = this.get_cell(i);
        if (cell !== null && (cell instanceof codecell.CodeCell)) {
            cell.scroll_output();
            this.set_dirty(true);
        }
    };

    /**
     * Expand each code cell's output area and add a scrollbar for long output.
     */
    Notebook.prototype.scroll_all_output = function () {
        this.get_cells().map(function (cell, i) {
            if (cell instanceof codecell.CodeCell) {
                cell.scroll_output();
            }
        });
        // this should not be set if the `collapse` key is removed from nbformat
        this.set_dirty(true);
    };

    /**
     * Toggle whether a cell's output is collapsed or expanded.
     *
     * @param {integer} index - cell index
     */
    Notebook.prototype.toggle_output = function (index) {
        var i = this.index_or_selected(index);
        var cell = this.get_cell(i);
        if (cell !== null && (cell instanceof codecell.CodeCell)) {
            cell.toggle_output();
            this.set_dirty(true);
        }
    };

    /**
     * Toggle a cell's input
     *
     * @param {integer} index - cell index
     */
    Notebook.prototype.toggle_input = function (index) {
        var i = this.index_or_selected(index);
        var cell = this.get_cell(i);
        if (cell !== null && (cell instanceof codecell.CodeCell)) {
            cell.toggle_input();
            this.set_dirty(true);
        }
    };

    /**
     * Toggle the output of all cells.
     */
    Notebook.prototype.toggle_all_input = function () {
        this.get_cells().map(function (cell, i) {
            if (cell instanceof codecell.CodeCell) {
                cell.toggle_input();
            }
        });
        // this should not be set if the `collapse` key is removed from nbformat
        this.set_dirty(true);
    };

    /**
     * Toggle a cell's output stram
     *
     * @param {integer} index - cell index
     */
    Notebook.prototype.toggle_output_stream = function (index) {
        var i = this.index_or_selected(index);
        var cell = this.get_cell(i);
        if (cell !== null && (cell instanceof codecell.CodeCell)) {
            cell.toggle_output_stream();
            this.set_dirty(true);
        }
    };

    /**
     * Toggle the output of all cells.
     */
    Notebook.prototype.toggle_all_output_stream = function () {
        this.get_cells().map(function (cell, i) {
            if (cell instanceof codecell.CodeCell) {
                cell.toggle_output_stream();
            }
        });
        // this should not be set if the `collapse` key is removed from nbformat
        this.set_dirty(true);
    };

    /**
     * Toggle the output of all cells.
     */
    Notebook.prototype.toggle_all_output = function () {
        this.get_cells().map(function (cell, i) {
            if (cell instanceof codecell.CodeCell) {
                cell.toggle_output();
            }
        });
        // this should not be set if the `collapse` key is removed from nbformat
        this.set_dirty(true);
    };

    /**
     * Toggle a scrollbar for long cell outputs.
     *
     * @param {integer} index - cell index
     */
    Notebook.prototype.toggle_output_scroll = function (index) {
        var i = this.index_or_selected(index);
        var cell = this.get_cell(i);
        if (cell !== null && (cell instanceof codecell.CodeCell)) {
            cell.toggle_output_scroll();
            this.set_dirty(true);
        }
    };

    /**
     * Toggle the scrolling of long output on all cells.
     */
    Notebook.prototype.toggle_all_output_scroll = function () {
        this.get_cells().map(function (cell, i) {
            if (cell instanceof codecell.CodeCell) {
                cell.toggle_output_scroll();
            }
        });
        // this should not be set if the `collapse` key is removed from nbformat
        this.set_dirty(true);
    };

    // Other cell functions: line numbers, ...

    /**
     * Toggle line numbers in the selected cell's input area.
     */
    Notebook.prototype.cell_toggle_line_numbers = function() {
        this.get_selected_cell().toggle_line_numbers();
    };

    /**
     * Set the codemirror mode for all code cells, including the default for
     * new code cells.
     */
    Notebook.prototype.set_codemirror_mode = function(newmode){
        if (newmode === this.codemirror_mode) {
            return;
        }
        this.codemirror_mode = newmode;
        codecell.CodeCell.options_default.cm_config.mode = newmode;

        var that = this;
        utils.requireCodeMirrorMode(newmode, function (spec) {
            that.get_cells().map(function(cell, i) {
                if (cell.cell_type === 'code'){
                    cell.code_mirror.setOption('mode', spec);
                    // This is currently redundant, because cm_config ends up as
                    // codemirror's own .options object, but I don't want to
                    // rely on that.
                    cell.cm_config.mode = spec;
                }
            });
        });
    };

    // Session related things

    /**
     * Start a new session and set it on each code cell.
     */
    Notebook.prototype.start_session = function (kernel_name) {
        if (this._session_starting) {
            throw new session.SessionAlreadyStarting();
        }
        this._session_starting = true;

        var options = {
            base_url: this.base_url,
            ws_url: this.ws_url,
            notebook_path: this.notebook_path,
            notebook_name: this.notebook_name,
            kernel_name: kernel_name,
            notebook: this
        };

        var success = $.proxy(this._session_started, this);
        var failure = $.proxy(this._session_start_failed, this);

        if (this.session !== null) {
            this.session.restart(options, success, failure);
        } else {
            this.session = new session.Session(options);
            this.session.start(success, failure);
        }
    };

    /**
     * Once a session is started, link the code cells to the kernel and pass the
     * comm manager to the widget manager.
     */
    Notebook.prototype._session_started = function (){
        this._session_starting = false;
        this.kernel = this.session.kernel;
        var ncells = this.ncells();
        for (var i=0; i<ncells; i++) {
            var cell = this.get_cell(i);
            if (cell instanceof codecell.CodeCell) {
                cell.set_kernel(this.session.kernel);
            }
        }
    };

    /**
     * Called when the session fails to start.
     */
    Notebook.prototype._session_start_failed = function(jqxhr, status, error){
        this._session_starting = false;
        utils.log_ajax_error(jqxhr, status, error);
    };

    /**
     * Prompt the user to restart the IPython kernel.
     */
    Notebook.prototype.restart_kernel = function () {
        var that = this;
        dialog.modal({
            notebook: this,
            keyboard_manager: this.keyboard_manager,
            title : "Restart kernel or continue running?",
            body : $("<p/>").text(
                'Do you want to restart the current kernel?  You will lose all variables defined in it.'
            ),
            buttons : {
                "Continue running" : {},
                "Restart" : {
                    "class" : "btn-danger",
                    "click" : function() {
                        that.kernel.restart();
                    }
                }
            }
        });
    };

    /**
     * Execute or render cell outputs and go into command mode.
     */
    Notebook.prototype.execute_cell = function () {
        // mode = shift, ctrl, alt
        var cell = this.get_selected_cell();

        cell.execute();
        this.command_mode();
        this.set_dirty(true);
    };

    /**
     * Execute or render cell outputs and insert a new cell below.
     */
    Notebook.prototype.execute_cell_and_insert_below = function () {
        var cell = this.get_selected_cell();
        var cell_index = this.find_cell_index(cell);

        cell.execute();

        // If we are at the end always insert a new cell and return
        if (cell_index === (this.ncells()-1)) {
            this.command_mode();
            this.insert_cell_below();
            this.select(cell_index+1);
            this.edit_mode();
            this.scroll_to_bottom();
            this.set_dirty(true);
            return;
        }

        this.command_mode();
        this.insert_cell_below();
        this.select(cell_index+1);
        this.edit_mode();
        this.set_dirty(true);
    };

    /**
     * Execute or render cell outputs and select the next cell.
     */
    Notebook.prototype.execute_cell_and_select_below = function () {

        var cell = this.get_selected_cell();
        var cell_index = this.find_cell_index(cell);

        cell.execute();

        // If we are at the end always insert a new cell and return
        if (cell_index === (this.ncells()-1)) {
            this.command_mode();
            this.insert_cell_below();
            this.select(cell_index+1);
            this.edit_mode();
            this.scroll_to_bottom();
            this.set_dirty(true);
            return;
        }

        this.command_mode();
        this.select(cell_index+1);
        this.focus_cell();
        this.set_dirty(true);
    };

    /**
     * Execute all cells below the selected cell.
     */
    Notebook.prototype.execute_cells_below = function () {
        this.execute_cell_range(this.get_selected_index(), this.ncells());
        this.scroll_to_bottom();
    };

    /**
     * Execute all cells above the selected cell.
     */
    Notebook.prototype.execute_cells_above = function () {
        this.execute_cell_range(0, this.get_selected_index());
    };

    /**
     * Execute all cells.
     */
    Notebook.prototype.execute_all_cells = function () {
        this.execute_cell_range(0, this.ncells());
        this.scroll_to_bottom();
    };

    /**
     * Execute a contiguous range of cells.
     *
     * @param {integer} start - index of the first cell to execute (inclusive)
     * @param {integer} end - index of the last cell to execute (exclusive)
     */
    Notebook.prototype.execute_cell_range = function (start, end) {
        this.command_mode();
        for (var i=start; i<end; i++) {
            this.select(i);
            this.execute_cell();
        }
    };

    // Persistance and loading

    /**
     * Getter method for this notebook's name.
     *
     * @return {string} This notebook's name (excluding file extension)
     */
    Notebook.prototype.get_notebook_name = function () {
        var nbname = this.notebook_name;
        if (nbname.indexOf(".snb") !== -1) {
            nbname = nbname.substring(0,nbname.length-".snb".length);
        }
        return nbname;
    };

    /**
     * Setter method for this notebook's name.
     *
     * @param {string} name
     */
    Notebook.prototype.set_notebook_name = function (name) {
        var parent = utils.url_path_split(this.notebook_path)[0];
        this.notebook_name = name;
        this.notebook_path = utils.url_path_join(parent, name);
    };

    /**
     * Check that a notebook's name is valid.
     *
     * @param {string} nbname - A name for this notebook
     * @return {boolean} True if the name is valid, false if invalid
     */
    Notebook.prototype.test_notebook_name = function (nbname) {
        nbname = nbname || '';
        if (nbname.length>0 && !this.notebook_name_blacklist_re.test(nbname)) {
            return true;
        } else {
            return false;
        }
    };

    /**
     * Load a notebook from JSON (.snb).
     *
     * @param {object} data - JSON representation of a notebook
     */
    Notebook.prototype.fromJSON = function (data) {

        var content = data.content;
        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._unsafe_delete_cell(0);
        }
        // Save the metadata and name.
        this.metadata = content.metadata;
        this.notebook_name = data.name;
        this.notebook_path = data.path;
        var trusted = true;

        // Set the codemirror mode from language_info metadata
        if (this.metadata.language_info !== undefined) {
            var langinfo = this.metadata.language_info;
            // Mode 'null' should be plain, unhighlighted text.
            var cm_mode = langinfo.codemirror_mode || langinfo.name || 'text/x-scala';
            this.set_codemirror_mode(cm_mode);
        }

        var new_cells = content.cells;
        ncells = new_cells.length;
        var cell_data = null;
        var new_cell = null;
        for (i=0; i<ncells; i++) {
            cell_data = new_cells[i];
            new_cell = this.insert_cell_at_index(cell_data.cell_type, i);
            new_cell.fromJSON(cell_data);
            if (new_cell.cell_type === 'code' && !new_cell.output_area.trusted) {
                trusted = false;
            }
        }
        if (trusted !== this.trusted) {
            this.trusted = trusted;
            this.events.trigger("trust_changed.Notebook", trusted);
        }
    };

    /**
     * Dump this notebook into a JSON-friendly object.
     *
     * @return {object} A JSON-friendly representation of this notebook.
     */
    Notebook.prototype.toJSON = function () {
        // remove the conversion indicator, which only belongs in-memory
        delete this.metadata.orig_nbformat;
        delete this.metadata.orig_nbformat_minor;

        var cells = this.get_cells();
        var ncells = cells.length;
        var cell_array = new Array(ncells);
        var trusted = true;
        for (var i=0; i<ncells; i++) {
            var cell = cells[i];
            if (cell.cell_type === 'code' && !cell.output_area.trusted) {
                trusted = false;
            }
            cell_array[i] = cell.toJSON();
        }
        var data = {
            cells: cell_array,
            metadata: this.metadata,
            nbformat: this.nbformat,
            nbformat_minor: this.nbformat_minor
        };
        if (trusted !== this.trusted) {
            this.trusted = trusted;
            this.events.trigger("trust_changed.Notebook", trusted);
        }
        return data;
    };

    /**
     * Start an autosave timer which periodically saves the notebook.
     *
     * @param {integer} interval - the autosave interval in milliseconds
     */
    Notebook.prototype.set_autosave_interval = function (interval) {
        var that = this;
        // clear previous interval, so we don't get simultaneous timers
        if (this.autosave_timer) {
            clearInterval(this.autosave_timer);
        }
        if (!this.writable) {
            // disable autosave if not writable
            interval = 0;
        }

        this.autosave_interval = this.minimum_autosave_interval = interval;
        if (interval) {
            this.autosave_timer = setInterval(function() {
                if (that.dirty) {
                    that.save_notebook();
                }
            }, interval);
            this.events.trigger("autosave_enabled.Notebook", interval);
        } else {
            this.autosave_timer = null;
            this.events.trigger("autosave_disabled.Notebook");
        }
    };

    /**
     * Save this notebook on the server. This becomes a notebook instance's
     * .save_notebook method *after* the entire notebook has been loaded.
     */
    Notebook.prototype.save_notebook = function () {
        if (!this._fully_loaded) {
            this.events.trigger('notebook_save_failed.Notebook',
                new Error("Load failed, save is disabled")
            );
            return;
        } else if (!this.writable) {
            this.events.trigger('notebook_save_failed.Notebook',
                new Error("Notebook is read-only")
            );
            return;
        }

        // Trigger an event before save, which allows listeners to modify
        // the notebook as needed.
        this.events.trigger('before_save.Notebook');

        // Create a JSON model to be sent to the server.
        var model = {
            type : "notebook",
            content : this.toJSON()
        };
        // time the ajax call for autosave tuning purposes.
        var start =  new Date().getTime();

        var that = this;
        return this.contents.save(this.notebook_path, model).then(
                $.proxy(this.save_notebook_success, this, start),
                function (error) {
                    that.events.trigger('notebook_save_failed.Notebook', error);
                }
            );
    };

    /**
     * Success callback for saving a notebook.
     *
     * @param {integer} start - Time when the save request start
     * @param {object}  data - JSON representation of a notebook
     */
    Notebook.prototype.save_notebook_success = function (start, data) {
        this.set_dirty(false);
        if (data.message) {
            // save succeeded, but validation failed.
            var body = $("<div>");
            var title = "Notebook validation failed";

            body.append($("<p>").text(
                "The save operation succeeded," +
                " but the notebook does not appear to be valid." +
                " The validation error was:"
            )).append($("<div>").addClass("validation-error").append(
                $("<pre>").text(data.message)
            ));
            dialog.modal({
                notebook: this,
                keyboard_manager: this.keyboard_manager,
                title: title,
                body: body,
                buttons : {
                    OK : {
                        "class" : "btn-primary"
                    }
                }
            });
        }
        this.events.trigger('notebook_saved.Notebook');
        this._update_autosave_interval(start);
        if (this._checkpoint_after_save) {
            this.create_checkpoint();
            this._checkpoint_after_save = false;
        }
    };

    /**
     * Update the autosave interval based on the duration of the last save.
     *
     * @param {integer} timestamp - when the save request started
     */
    Notebook.prototype._update_autosave_interval = function (start) {
        var duration = (new Date().getTime() - start);
        if (this.autosave_interval) {
            // new save interval: higher of 10x save duration or parameter (default 30 seconds)
            var interval = Math.max(10 * duration, this.minimum_autosave_interval);
            // round to 10 seconds, otherwise we will be setting a new interval too often
            interval = 10000 * Math.round(interval / 10000);
            // set new interval, if it's changed
            if (interval !== this.autosave_interval) {
                this.set_autosave_interval(interval);
            }
        }
    };

    /**
     * Explicitly trust the output of this notebook.
     */
    Notebook.prototype.trust_notebook = function () {
        var body = $("<div>").append($("<p>")
            .text("A trusted IPython notebook may execute hidden malicious code ")
            .append($("<strong>")
                .append(
                    $("<em>").text("when you open it")
                )
            ).append(".").append(
                " Selecting trust will immediately reload this notebook in a trusted state."
            ).append(
                " For more information, see the "
            ).append($("<a>").attr("href", "http://ipython.org/ipython-doc/2/notebook/security.html")
                .text("IPython security documentation")
            ).append(".")
        );

        var nb = this;
        dialog.modal({
            notebook: this,
            keyboard_manager: this.keyboard_manager,
            title: "Trust this notebook?",
            body: body,

            buttons: {
                Cancel : {},
                Trust : {
                    class : "btn-danger",
                    click : function () {
                        var cells = nb.get_cells();
                        for (var i = 0; i < cells.length; i++) {
                            var cell = cells[i];
                            if (cell.cell_type === 'code') {
                                cell.output_area.trusted = true;
                            }
                        }
                        nb.events.on('notebook_saved.Notebook', function () {
                            window.location.reload();
                        });
                        nb.save_notebook();
                    }
                }
            }
        });
    };

    /**
     * Make a copy of the current notebook.
     */
    Notebook.prototype.copy_notebook = function () {
        var that = this;
        var base_url = this.base_url;
        var w = window.open();
        var parent = utils.url_path_split(this.notebook_path)[0];
        this.contents.copy(this.notebook_path, parent).then(
            function (data) {
                w.location = utils.url_join_encode(
                    base_url, 'notebooks', data.path
                );
            },
            function(error) {
                w.close();
                that.events.trigger('notebook_copy_failed', error);
            }
        );
    };

    /**
     * Ensure a filename has the right extension
     * Returns the filename with the appropriate extension, appending if necessary.
     */
    Notebook.prototype.ensure_extension = function (name) {
        if (!name.match(/\.snb$/)) {
            name = name + ".snb";
        }
        return name;
    };

    /**
     * Rename the notebook.
     * @param  {string} new_name
     * @return {Promise} promise that resolves when the notebook is renamed.
     */
    Notebook.prototype.rename = function (new_name) {
        new_name = this.ensure_extension(new_name);

        var that = this;
        var parent = utils.url_path_split(this.notebook_path)[0];
        var new_path = utils.url_path_join(parent, new_name);
        return this.contents.rename(this.notebook_path, new_path).then(
            function (json) {
                that.notebook_name = json.name;
                that.metadata.name = json.name;
                that.notebook_path = json.path;
                that.session.rename_notebook(json.path);
                that.events.trigger('notebook_renamed.Notebook', json);
            }
        );
    };

    /**
     * Delete this notebook
     */
    Notebook.prototype.delete = function () {
        this.contents.delete(this.notebook_path);
    };

    /**
     * Request a notebook's data from the server.
     *
     * @param {string} notebook_path - A notebook to load
     */
    Notebook.prototype.load_notebook = function (notebook_path) {
        var that = this;
        this.notebook_path = notebook_path;
        this.notebook_name = utils.url_path_split(this.notebook_path)[1];
        this.events.trigger('notebook_loading.Notebook');
        this.contents.get(notebook_path, {type: 'notebook'}).then(
            $.proxy(this.load_notebook_success, this),
            $.proxy(this.load_notebook_error, this)
        );
    };

    /**
     * Success callback for loading a notebook from the server.
     *
     * Load notebook data from the JSON response.
     *
     * @param {object} data JSON representation of a notebook
     */
    Notebook.prototype.load_notebook_success = function (data) {
        var failed, msg;
        try {
            this.fromJSON(data);
        } catch (e) {
            failed = e;
            console.log("Notebook failed to load from JSON:", e);
        }
        if (failed || data.message) {
            // *either* fromJSON failed or validation failed
            var body = $("<div>");
            var title;
            if (failed) {
                title = "Notebook failed to load";
                body.append($("<p>").text(
                    "The error was: "
                )).append($("<div>").addClass("js-error").text(
                    failed.toString()
                )).append($("<p>").text(
                    "See the error console for details."
                ));
            } else {
                title = "Notebook validation failed";
            }

            if (data.message) {
                if (failed) {
                    msg = "The notebook also failed validation:";
                } else {
                    msg = "An invalid notebook may not function properly." +
                    " The validation error was:";
                }
                body.append($("<p>").text(
                    msg
                )).append($("<div>").addClass("validation-error").append(
                    $("<pre>").text(data.message)
                ));
            }

            dialog.modal({
                notebook: this,
                keyboard_manager: this.keyboard_manager,
                title: title,
                body: body,
                buttons : {
                    OK : {
                        "class" : "btn-primary"
                    }
                }
            });
        }
        if (this.ncells() === 0) {
            this.insert_cell_below('code');
            this.edit_mode(0);
        } else {
            this.select(0);
            this.handle_command_mode(this.get_cell(0));
        }
        this.set_dirty(false);
        this.scroll_to_top();
        this.writable = data.writable || false;
        var nbmodel = data.content;
        var orig_nbformat = nbmodel.metadata.orig_nbformat;
        var orig_nbformat_minor = nbmodel.metadata.orig_nbformat_minor;
        if (orig_nbformat !== undefined && nbmodel.nbformat !== orig_nbformat) {
            var src;
            if (nbmodel.nbformat > orig_nbformat) {
                src = " an older notebook format ";
            } else {
                src = " a newer notebook format ";
            }

            msg = "This notebook has been converted from" + src +
            "(v"+orig_nbformat+") to the current notebook " +
            "format (v"+nbmodel.nbformat+"). The next time you save this notebook, the " +
            "current notebook format will be used.";

            if (nbmodel.nbformat > orig_nbformat) {
                msg += " Older versions of IPython may not be able to read the new format.";
            } else {
                msg += " Some features of the original notebook may not be available.";
            }
            msg += " To preserve the original version, close the " +
                "notebook without saving it.";
            dialog.modal({
                notebook: this,
                keyboard_manager: this.keyboard_manager,
                title : "Notebook converted",
                body : msg,
                buttons : {
                    OK : {
                        class : "btn-primary"
                    }
                }
            });
        } else if (this.nbformat_minor < nbmodel.nbformat_minor) {
            this.nbformat_minor = nbmodel.nbformat_minor;
        }

        if (this.session === null) {
            var kernel_name;
            if (this.metadata.kernelspec) {
                var kernelspec = this.metadata.kernelspec || {};
                kernel_name = kernelspec.name;
            } else {
                kernel_name = utils.get_url_param('kernel_name');
            }
            if (kernel_name) {
                // setting kernel_name here triggers start_session
                this.kernel_selector.set_kernel(kernel_name);
            } else {
                // start a new session with the server's default kernel
                // spec_changed events will fire after kernel is loaded
                this.start_session();
            }
        }
        // load our checkpoint list
        this.list_checkpoints();

        // load toolbar state
        if (this.metadata.celltoolbar) {
            celltoolbar.CellToolbar.global_show();
            celltoolbar.CellToolbar.activate_preset(this.metadata.celltoolbar);
        } else {
            celltoolbar.CellToolbar.global_hide();
        }

        if (!this.writable) {
            this.set_autosave_interval(0);
            this.events.trigger('notebook_read_only.Notebook');
        }

        // now that we're fully loaded, it is safe to restore save functionality
        this._fully_loaded = true;
        this.events.trigger('notebook_loaded.Notebook');
    };

    Notebook.prototype.set_kernelselector = function(k_selector){
        this.kernel_selector = k_selector;
    };

    /**
     * Failure callback for loading a notebook from the server.
     *
     * @param {Error} error
     */
    Notebook.prototype.load_notebook_error = function (error) {
        this.events.trigger('notebook_load_failed.Notebook', error);
        var msg;
        if (error.name === utils.XHR_ERROR && error.xhr.status === 500) {
            utils.log_ajax_error(error.xhr, error.xhr_status, error.xhr_error);
            msg = "An unknown error occurred while loading this notebook. " +
            "This version can load notebook formats " +
            "v" + this.nbformat + " or earlier. See the server log for details.";
        } else {
            msg = error.message;
        }
        dialog.modal({
            notebook: this,
            keyboard_manager: this.keyboard_manager,
            title: "Error loading notebook",
            body : msg,
            buttons : {
                "OK": {}
            }
        });
    };

    /*********************  checkpoint-related  ********************/

    /**
     * Save the notebook then immediately create a checkpoint.
     */
    Notebook.prototype.save_checkpoint = function () {
        this._checkpoint_after_save = true;
        this.save_notebook();
    };

    /**
     * Add a checkpoint for this notebook.
     */
    Notebook.prototype.add_checkpoint = function (checkpoint) {
        var found = false;
        for (var i = 0; i < this.checkpoints.length; i++) {
            var existing = this.checkpoints[i];
            if (existing.id === checkpoint.id) {
                found = true;
                this.checkpoints[i] = checkpoint;
                break;
            }
        }
        if (!found) {
            this.checkpoints.push(checkpoint);
        }
        this.last_checkpoint = this.checkpoints[this.checkpoints.length - 1];
    };

    /**
     * List checkpoints for this notebook.
     */
    Notebook.prototype.list_checkpoints = function () {
        var that = this;
        this.contents.list_checkpoints(this.notebook_path).then(
            $.proxy(this.list_checkpoints_success, this),
            function(error) {
                that.events.trigger('list_checkpoints_failed.Notebook', error);
            }
        );
    };

    /**
     * Success callback for listing checkpoints.
     *
     * @param {object} data - JSON representation of a checkpoint
     */
    Notebook.prototype.list_checkpoints_success = function (data) {
        this.checkpoints = data;
        if (data.length) {
            this.last_checkpoint = data[data.length - 1];
        } else {
            this.last_checkpoint = null;
        }
        this.events.trigger('checkpoints_listed.Notebook', [data]);
    };

    /**
     * Create a checkpoint of this notebook on the server from the most recent save.
     */
    Notebook.prototype.create_checkpoint = function () {
        var that = this;
        this.contents.create_checkpoint(this.notebook_path).then(
            $.proxy(this.create_checkpoint_success, this),
            function (error) {
                that.events.trigger('checkpoint_failed.Notebook', error);
            }
        );
    };

    /**
     * Success callback for creating a checkpoint.
     *
     * @param {object} data - JSON representation of a checkpoint
     */
    Notebook.prototype.create_checkpoint_success = function (data) {
        this.add_checkpoint(data);
        this.events.trigger('checkpoint_created.Notebook', data);
    };

    /**
     * Display the restore checkpoint dialog
     * @param  {string} checkpoint ID
     */
    Notebook.prototype.restore_checkpoint_dialog = function (checkpoint) {
        var that = this;
        checkpoint = checkpoint || this.last_checkpoint;
        if ( ! checkpoint ) {
            console.log("restore dialog, but no checkpoint to restore to!");
            return;
        }
        var body = $('<div/>').append(
            $('<p/>').addClass("p-space").text(
                "Are you sure you want to revert the notebook to " +
                "the latest checkpoint?"
            ).append(
                $("<strong/>").text(
                    " This cannot be undone."
                )
            )
        ).append(
            $('<p/>').addClass("p-space").text("The checkpoint was last updated at:")
        ).append(
            $('<p/>').addClass("p-space").text(
                Date(checkpoint.last_modified)
            ).css("text-align", "center")
        );

        dialog.modal({
            notebook: this,
            keyboard_manager: this.keyboard_manager,
            title : "Revert notebook to checkpoint",
            body : body,
            buttons : {
                Revert : {
                    class : "btn-danger",
                    click : function () {
                        that.restore_checkpoint(checkpoint.id);
                    }
                },
                Cancel : {}
                }
        });
    };

    /**
     * Restore the notebook to a checkpoint state.
     *
     * @param {string} checkpoint ID
     */
    Notebook.prototype.restore_checkpoint = function (checkpoint) {
        this.events.trigger('notebook_restoring.Notebook', checkpoint);
        var that = this;
        this.contents.restore_checkpoint(this.notebook_path, checkpoint).then(
            $.proxy(this.restore_checkpoint_success, this),
            function (error) {
                that.events.trigger('checkpoint_restore_failed.Notebook', error);
            }
        );
    };

    /**
     * Success callback for restoring a notebook to a checkpoint.
     */
    Notebook.prototype.restore_checkpoint_success = function () {
        this.events.trigger('checkpoint_restored.Notebook');
        this.load_notebook(this.notebook_path);
    };

    /**
     * Delete a notebook checkpoint.
     *
     * @param {string} checkpoint ID
     */
    Notebook.prototype.delete_checkpoint = function (checkpoint) {
        this.events.trigger('notebook_restoring.Notebook', checkpoint);
        var that = this;
        this.contents.delete_checkpoint(this.notebook_path, checkpoint).then(
            $.proxy(this.delete_checkpoint_success, this),
            function (error) {
                that.events.trigger('checkpoint_delete_failed.Notebook', error);
            }
        );
    };

    /**
     * Success callback for deleting a notebook checkpoint.
     */
    Notebook.prototype.delete_checkpoint_success = function () {
        this.events.trigger('checkpoint_deleted.Notebook');
        this.load_notebook(this.notebook_path);
    };

    // For backwards compatability.
    IPython.Notebook = Notebook;

    return {'Notebook': Notebook};
});


text:
#import "CDVVibration.h"

@implementation CDVVibration

- (void)vibrate:(CDVInvokedUrlCommand*)command
{
    AudioServicesPlaySystemSound(kSystemSoundID_Vibrate);
}

@end

redpajama_set_name: RedPajamaGithub


text:
<?php
require( "../xajax_core/xajax.inc.php" );

function callScript( )
{
    $response=new xajaxResponse();
    $value2="this is a string";
    $response->call( "myJSFunction", "arg1", 9432.12, array
        (
        "myKey" => "some value",
        "key2" => $value2
        ));

    return $response;
}

function callOtherScript( )
{
    $response=new xajaxResponse();
    $response->call( "myOtherJSFunction" );
    return $response;
}

$xajax=new xajax();
//$xajax->setFlag("debug", true);
$xajax->registerFunction( "callScript" );
$xajax->registerFunction( "callOtherScript" );
$xajax->processRequest();
?>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

        <title>call Script Test | xajax Tests</title>

        <?php $xajax->printJavascript( "../" ) ?>

xajax Tests

call Script Test

            Howdy.

            <input type = "button" value = "Click Me" onclick = "xajax_callScript()" />

            <input type = "button" value = "or Click Me" onclick = "xajax_callOtherScript()" />

            Result:

[blank]

            Expecting:

arg1 and 9532.12
        some value | this is a string


text:
/* AUTO-GENERATED FILE.  DO NOT MODIFY.
 *
 * This class was automatically generated by the
 * aapt tool from the resource data it found.  It
 * should not be modified by hand.
 */

package course.examples.ui.tablayout;

public final class R {
    public static final class attr {
    }
    public static final class drawable {
        public static final int ic_launcher=0x7f020000;
        public static final int image1=0x7f020001;
        public static final int image10=0x7f020002;
        public static final int image11=0x7f020003;
        public static final int image12=0x7f020004;
        public static final int image2=0x7f020005;
        public static final int image3=0x7f020006;
        public static final int image4=0x7f020007;
        public static final int image5=0x7f020008;
        public static final int image6=0x7f020009;
        public static final int image7=0x7f02000a;
        public static final int image8=0x7f02000b;
        public static final int image9=0x7f02000c;
        public static final int sample_0=0x7f02000d;
        public static final int sample_1=0x7f02000e;
        public static final int sample_2=0x7f02000f;
        public static final int sample_3=0x7f020010;
        public static final int sample_4=0x7f020011;
        public static final int sample_5=0x7f020012;
        public static final int sample_6=0x7f020013;
        public static final int sample_7=0x7f020014;
    }
    public static final class id {
        public static final int fragment_container=0x7f050002;
        public static final int frame=0x7f050001;
        public static final int gridview=0x7f050000;
    }
    public static final class layout {
        public static final int grid_fragment=0x7f030000;
        public static final int main=0x7f030001;
    }
    public static final class string {
        public static final int app_name=0x7f040000;
        public static final int xxxxx_string=0x7f040001;
    }
}


text:
layout: documentation
title: Extension FAQ
---

# Frequently Asked Questions

These are some common issues and questions with writing extensions.

<!-- [TOC] -->

## Why is my file not produced / my action never executed?

Bazel only executes the actions needed to produce the *requested* output files.

* If the file you want has a label, you can request it directly:
  `bazel build //pkg:myfile.txt`

* If the file is in an output group of the target, you may need to specify that
  output group on the command line:
  `bazel build //pkg:mytarget --output_groups=foo`

* If you want the file to be built automatically whenever your target is
  mentioned on the command line, add it to your rule's default outputs by
  returning a [`DefaultInfo`](lib/globals.html#DefaultInfo) provider.

See the [Rules page](rules.md#requesting-output-files) for more information.

## Why is my implementation function not executed?

Bazel analyzes only the targets that are requested for the build. You should
either name the target on the command line, or something that depends on the
target.

## A file is missing when my action or binary is executed

Make sure that 1) the file has been registered as an input to the action or
binary, and 2) the script or tool being executed is accessing the file using the
correct path.

For actions, you declare inputs by passing them to the `ctx.actions.*` function
that creates the action. The proper path for the file can be obtained using
[`File.path`](lib/File.html#path).

For binaries (the executable outputs run by a `bazel run` or `bazel test`
command), you declare inputs by including them in the
[runfiles](rules.md#runfiles). Instead of using the `path` field, use
[`File.short_path`](lib/File.html#short_path), which is file's path relative to
the runfiles directory in which the binary executes.

## How can I control which files are built by `bazel build //pkg:mytarget`?

Use the [`DefaultInfo`](lib/globals.html#DefaultInfo) provider to
[set the default outputs](rules.md#requesting-output-files).

## How can I run a program or do file I/O as part of my build?

A tool can be declared as a target, just like any other part of your build, and
run during the execution phase to help build other targets. To create an action
that runs a tool, use [`ctx.actions.run`](lib/actions.html#run) and pass in the
tool as the `executable` parameter.

During the loading and analysis phases, a tool *cannot* run, nor can you perform
file I/O. This means that tools and file contents (except the contents of BUILD
and .bzl files) cannot affect how the target and action graphs get created.

## What if I need to access the same structured data both before and during the execution phase?

You can format the structured data as a .bzl file. You can `load()` the file to
access it during the loading and analysis phases. You can pass it as an input or
runfile to actions and executables that need it during the execution phase.

## How should I document Skylark code?

For rules and rule attributes, you can pass a docstring literal (possibly
triple-quoted) to the `doc` parameter of `rule` or `attr.*()`. For helper
functions and macros, use a triple-quoted docstring literal following the format
given [here](skylint.md#docstrings). Rule implementation functions generally do
not need their own docstring.

Using string literals in the expected places makes it easier for automated
tooling to extract documentation. Feel free to use standard non-string comments
wherever it may help the reader of your code.


text:
var edu = edu || {};
edu.common = edu.common || {};
edu.common.de = edu.common.de || {};

edu.common.de.FieldManager =
  (function() {
    var instance;

    function init() {
      var fieldMap = {};

      var register = function(args) {
        if (!args.name) {
          throw "Field name is either empty or undefined";
        }

        if (!args.displayName) {
          throw "Field display name is either empty or undefined";
        }

        if (!args.fieldCtor) {
          throw "Field initialization function undefined";
        }

        fieldMap[args.name] = args;
      };

      var getField = function(name, params) {
        var fieldDetail = fieldMap[name];
        if (!fieldDetail) {
          return null;
        }

        return new fieldDetail.fieldCtor(params);
      };

      var getFieldList = function() {
        var result = [];
        for (var k in fieldMap) {
          var fieldDetail = fieldMap[k];
          result.push({name: fieldDetail.name, displayName: fieldDetail.displayName});
        }

        return result;
      };

      return {
        register: register,
        getField: getField,
        getFieldList: getFieldList
      };
    };

    return {
      getInstance: function() {
        if (!instance) {
          instance = init();
        }

        return instance;
      }
    };
  })();