# guppy.js

    var Mousetrap = require('../lib/mousetrap/mousetrap.min.js');
    var katex = require('../lib/katex/katex-modified.min.js');
    var Engine = require('./engine.js');
    var Utils = require('./utils.js');
    var Symbols = require('./symbols.js');
    var Settings = require('./settings.js');
    var Doc = require('./doc.js');

    /**
       @class
       @classdesc An instance of Guppy.  Calling `Guppy(id)` with the ID of
       an existing editor will simply return that instance.
       @param {string} id - The string ID of the element that should be converted to an editor.
       @param {Object} [config] - The configuration options for this instance
       @param {Object} [config.events] - A dictionary of events.
       Available events are as specified in Guppy.init.  Values in this
       dictionary will, for this instance of the editor, override events
       specified through Guppy.init.
       @param {Object} [config.settings] - A dictionary of settings.
       Values in this dictionary will override any global settings
       specified in `Guppy.init`.  This dictionary takes the same keys as
       the `config.settings` dictionary passed to `Guppy.init`.  See that
       function's documentation for the complete list.
       @constructor
    */
    var Guppy = function(id, config){
        if(Guppy.instances[id]){
            if(Guppy.instances[id].ready){
                return Guppy.instances[id];
            }
            return null;
        }
        var self = this;
        config = config || {};
        var settings = config['settings'] || {};

        this.id = id;
        var guppy_div = document.getElementById(id);

        var tab_idx = Guppy.max_tabIndex || 0;
        guppy_div.tabIndex = tab_idx;
        Guppy.max_tabIndex = tab_idx+1;

        var buttons = settings['buttons'] || Settings.config.settings['buttons'];
        this.buttons_div = document.createElement("div");
        this.buttons_div.setAttribute("class","guppy_buttons");
        if(buttons){
            for(var i = 0; i < buttons.length; i++){
                if(buttons[i] == "osk" && Settings.osk){
                    Guppy.make_button("icons/keyboard.png", this.buttons_div, function() {
                        if(Settings.osk.guppy == self){ Settings.osk.detach(self); }
                        else{ Settings.osk.attach(self); }});
                }
                else if(buttons[i] == "settings") Guppy.make_button("icons/settings.png", this.buttons_div, function(){ Settings.toggle("settings", self); });
                else if(buttons[i] == "symbols") Guppy.make_button("icons/symbols.png", this.buttons_div, function(){ Settings.toggle("symbols", self); });
                else if(buttons[i] == "controls") Guppy.make_button("icons/help.png", this.buttons_div, function(){ Settings.toggle("controls", self); });
            }
        }

        this.editor_active = true;
        //this.empty_content = settings['empty_content'] || "\\red{[?]}"
        this.editor = guppy_div;
        this.blacklist = [];
        this.autoreplace = true;
        this.ready = false;

        Guppy.instances[guppy_div.id] = this;

        config['parent'] = self;

        /**   @member {Engine} */
        this.engine = new Engine(config);
        this.temp_cursor = {"node":null,"caret":0}
        this.editor.addEventListener("keydown",Guppy.key_down, false);
        this.editor.addEventListener("keyup",Guppy.key_up, false);
        this.editor.addEventListener("focus", function() { Guppy.kb.alt_down = false; if(self.activate) self.activate();}, false);
        if(Guppy.ready && !this.ready){
            this.ready = true;
            this.engine.fire_event("ready");
            this.render(true);
        }
        this.deactivate();
        this.recompute_locations_paths();
    }

    Guppy.instances = {};
    Guppy.ready = false;
    Guppy.Doc = Doc;
    Guppy.active_guppy = null;
    Guppy.Symbols = Symbols;

    Guppy.make_button = function(url, parent, cb){
        var b = document.createElement("img");
        b.setAttribute("class","guppy-button");
        b.setAttribute("src", Settings.config.path + "/" + url);
        parent.appendChild(b);
        if(cb){
            b.addEventListener("mouseup", function(e){
                cb(e);
                if(e.cancelBubble!=null) e.cancelBubble = true;
                if(e.stopPropagation) e.stopPropagation();
                e.preventDefault();
                return false;
            }, false);
        }
        return b;
    }

    /**
        Add a symbol to all instances of the editor
        @memberof Guppy
        @param {string} name - The name of the symbol to add.  This is
        also the string that will be autoreplaced with the symbol.
        @param {Object} symbol - If `template` is present, this is just
        the template arguments.  Otherwise, it is the complete symbol
        specification
        @param {Object} symbol.output - Key/value pairs where the key is
        the output type (such as "latex" or "asciimath") and the value is
        the string by which the output will be rendered in that format.
        In this string, {$n} will be substituted with the rendering of the
        nth argument.  If the nth argument is a d-dimensional list, then
        the argument should be specified as {$n{sep_1}{sep_2}...{sep_d}}
        where sep_i will be the separator used to separate entries in the
        ith dimension.  Note that keys are not necessary to describe the
        AST or plain-text outputs.
        @param {Array} symbol.keys - A list of strings representing
        keystrokes that can be used to trigger the insertion of this
        symbol.  For example, `"^" or `"shift+up"` for the `exponential`
        symbol.
        @param {Object} symbol.attrs - A specification of the attributes
        of the symbol
        @param {string} symbol.attrs.type - A longer description of the
        symbol type, suitable for searching and text rendering.
        @param {string} symbol.attrs.group - The group in which to place
        this symbol (for OSK)
        @param {Object} [symbol.input] - If the symbol should subsume part
        of the existing content of the editor (as in, for example, the
        case of exponent), this object will contain the (1-based) index of
        the argument in which that content should be placed.
        @param {Object} [symbol.ast] - Modifies the default construction
        of an entry in the AST for this symbol.
        @param {Object} [symbol.ast.type="operator"] - The type of symbol
        for AST purposes.  Can be "name" (meaning this symbol represents
        a variable, as in the case of pi), "number" (meaning this symbol
        is a literal value), "operator" (meaning this symbol is a
        function or otherwise takes arguments (as in cos or +), or
        "pass" (meaning this symbol's first argument will be used as its
        AST entry, as in the case of brackets/parentheses).
        @param {Object[]} [symbol.args] - A list of specifications, one
        for each argument
        @param {string} [symbol.args.down] - The index of the argument
        to jump to when the "down" arrow is pressed in this argument
        @param {string} [symbol.args.up] - The index of the argument
        to jump to when the "up" arrow is pressed in this argument
        @param {string} [symbol.args.small="no"] - "yes" if the symbol is
        small (as in an exponent)
        @param {string} [symbol.args.name] - The name of this particular
        argument (suitable for searching)
        @param {string} [symbol.args.bracket="no"] - "yes" if brackets
        should automatically be rendered around this argument when they
        might be needed to disambiguate.
        @param {string} [symbol.args.delete] - If present, when the
        "backspace" key is pressed at the beginning of this argument,
        the symbol will be deleted and replaced with the argument whose
        index is specified in this parameter.  For example, the second
        argument of an exponent has this value set to "1", so that when
        the exponent is deleted, the base remains.
        @param {string} [symbol.args.mode="math"] - Change the mode of an
        argument.  Can be "text" (meaning the argument will be editable
        as and rendered as plain text), "symbol" (meaning the argument
        will specify a symbol name and will complete to an actual symbol
        when this is entered--only used for the backslash symbol), or
        "math" (the default)
        @param {string} [symbol.args.is_bracket="no"] - Set to "yes" if
        the symbol is itself a bracket/parenthesis equivalent.
        @param {string} [template] - The name of the template to use
    */
    Guppy.add_global_symbol = function(name, symbol, template){
        if(template){
            symbol = Symbols.make_template_symbol(template, name, symbol);
        }
        Symbols.symbols[name] = JSON.parse(JSON.stringify(symbol));
        for(var i in Guppy.instances){
            Guppy.instances[i].engine.symbols[name] = JSON.parse(JSON.stringify(symbol));
        }
    }

    /**
        Remove a symbol from all instances of the editor
        @memberof Guppy
        @param {string} name - The name of the symbol to remove
    */
    Guppy.remove_global_symbol = function(name){
        if(Symbols.symbols[name]){
            delete Symbols.symbols[name]
            for(var i in Guppy.instances){
                if(Guppy.instances[i].engine.symbols[name]){
                    delete Guppy.instances[i].engine.symbols[name];
                }
            }
        }
    }

    /**
       Initialise global settings for all instances of the editor.  Most
       of these can be overridden for specific instances later.  Should be
       called before instantiating the Guppy class.
       @static
       @memberof Guppy
       @param {Object} config - The configuration options for this instance
       @param {string[]} [config.symbols] - A list of URLs for symbol JSON files to request
       @param {string} [config.path="/lib/guppy"] - The path to the guppy build folder.
       @param {GuppyOSK} [config.osk] - A GuppyOSK object to use for the on-screen keyboard if one is desired
       @param {Object} [config.events] - A dictionary of events
       @param {function} [config.events.ready] - Called when the instance is ready to render things.
       @param {function} [config.events.change] - Called when the editor's content changes.  Argument will be a dictionary with keys `old` and `new` containing the old and new documents, respectively.
       @param {function} [config.events.left_end] - Called when the cursor is at the left-most point and a command is received to move the cursor to the left (e.g., via the left arrow key).  Argument will be null.
       @param {function} [config.events.left_end] - Called when the cursor is at the right-most point and a command is received to move the cursor to the right (e.g., via the right arrow key).  Argument will be null.
       @param {function} [config.events.done] - Called when the enter key is pressed in the editor.
       @param {function} [config.events.completion] - Called when the editor outputs tab completion
       options.  Argument is a dictionary with the key `candidates`, a
       list of the options for tab-completion.
       @param {function} [config.events.debug] - Called when the editor outputs some debug information.
       Argument is a dictionary with the key `message`.
       @param {function} [config.events.error] - Called when the editor receives an error.  Argument is
       a dictionary with the key `message`.
       @param {function} [config.events.focus] - Called when the editor is focused or unfocused.
       Argument will have a single key `focused` which will be `true`
       or `false` according to whether the editor is newly focused or
       newly unfocused (respectively).
       @param {Object} [config.settings] - A dictionary of settings
       @param {string} [config.settings.xml_content=<m><e/></m>] - An XML
       string with which to initialise the editor's state.
       @param {string} [config.settings.autoreplace="auto"] - Determines
       whether or not to autoreplace typed text with the corresponding
       symbols when possible.
       @param {string} [config.settings.blank_caret=""] - A LaTeX string
       that specifies what the caret should look like when in a blank
       spot.  If `""`, the default caret is used.
       @param {string} [config.settings.empty_content=\color{red}{[?]}] - A
       LaTeX string that will be displayed when the editor is both
       inactive and contains no content.
       @param {string[]} [config.settings.blacklist=[]] - A list of string
       symbol names, corresponding to symbols that should not be
       allowed in this instance of the editor.
       @param {string[]} [config.settings.buttons=["osk","settings","symbols","controls"]] - A list of strings corresponding to the helper buttons that should be displayed in the editor when focused.
       @param {string} [config.settings.cliptype] - A string, either
       "text" or "latex".  If this option is present, when text is
       placed onto the editor clipboard, the contents of the editor
       will be rendered into either plain text or LaTeX (depending on
       the value of this option) and an attempt will be made to copy
       the result to the system clipboard.
       @param {function} [config.callback] - A function to be called when
       initialisation is complete.
    */
    Guppy.init = function(config){
        var all_ready = function(){
            Settings.init(Symbols.symbols);
            Guppy.register_keyboard_handlers();
            for(var i in Guppy.instances){
                Guppy.instances[i].ready = true;
                Guppy.instances[i].render(true);

                // Set backend symbols
                Guppy.instances[i].engine.symbols = JSON.parse(JSON.stringify(Symbols.symbols));

                // Set backend settings
                // for(var s in Settings.config.settings){
                //     Guppy.instances[i].engine.settings[s] = JSON.parse(JSON.stringify(Settings.config.settings[s]));
                // }

                // Set backend events
                for(var e in Settings.config.events){
                    Guppy.instances[i].engine.events[e] = Settings.config.events[e];
                }
            }
            Engine.ready = true;
            for(var j in Guppy.instances){
                Guppy.instances[j].engine.ready = true;
                Guppy.instances[j].engine.fire_event("ready");
            }
    	if(config.callback) config.callback();
        }
        if(config.settings){
            var settings = JSON.parse(JSON.stringify(config.settings));
            for(var s in settings){
                Settings.config.settings[s] = settings[s];
            }
        }
        if(config.events){
            Settings.config.events = config.events;
        }
        if(config.osk){
    	Guppy.OSK = config.osk;
            Settings.osk = config.osk;
            if(config.osk.config.attach == "focus"){
                var f = Settings.config.events["focus"];
                Settings.config.events["focus"] = function(e){
                    if(f) f(e);
                    if(e.focused) config.osk.attach(e.target);
                    else config.osk.detach(e.target);
                };
            }
        }
        if(config.path){
            Settings.config.path = config.path;
        }
        if(config.symbols){
            var symbols = config.symbols;
            if(!(Array.isArray(symbols))){
                symbols = [symbols];
            }
            var calls = [];
            for(var i = 0; i < symbols.length; i++){
                var x = function outer(j){
                    return function(callback){
                        var req = new XMLHttpRequest();
                        req.onload = function(){
                            var syms = JSON.parse(this.responseText);
                            Symbols.add_symbols(syms);
                            callback();
                        };
                        req.open("get", symbols[j], true);
                        req.send();
                    }
                }(i);
                calls.push(x);
            }
            calls.push(all_ready);
            var j = 0;
            var cb = function(){
                j += 1;
                if(j < calls.length) calls[j](cb);
            }
            if(calls.length > 0) calls[0](cb);
        }
        else{
            all_ready();
        }
    }

    Guppy.prototype.is_changed = function(){
        var bb = this.editor.getElementsByClassName("katex")[0];
        if(!bb) return;
        var rect = bb.getBoundingClientRect();
        var ans = null;
        if(this.bounding_box)
            ans = this.bounding_box.top != rect.top || this.bounding_box.bottom != rect.bottom || this.bounding_box.right != rect.right || this.bounding_box.left != rect.left;
        else
            ans = true;
        this.bounding_box = rect;
        return ans;
    }

    Guppy.prototype.recompute_locations_paths = function(){
        var ans = [];
        var bb = this.editor.getElementsByClassName("katex")[0];
        if(!bb) return;
        var rect = bb.getBoundingClientRect();
        ans.push({'path':'all',
                  'top':rect.top,
                  'bottom':rect.bottom,
                  'left':rect.left,
                  'right':rect.right});
        var elts = this.editor.getElementsByClassName("guppy_elt");
        for(var i = 0; i < elts.length; i++){
            var elt = elts[i];
            if(elt.nodeName == "mstyle") continue;
            rect = elt.getBoundingClientRect();
            if(rect.top == 0 && rect.bottom == 0 && rect.left == 0 && rect.right == 0) continue;
            var cl = elt.classList;
            for(var j = 0; j < cl.length; j++){
                if(cl[j].indexOf("guppy_loc") == 0){
                    ans.push({'path':cl[j],
                              'top':rect.top,
                              'bottom':rect.bottom,
                              'left':rect.left,
                              'right':rect.right,
                              'mid_x':(rect.left+rect.right)/2,
                              'mid_y':(rect.bottom+rect.top)/2,
                              'blank':(' '+elt.className+' ').indexOf(' guppy_blank ') >= 0});
                    break;
                }
            }
        }
        this.boxes = ans;
    }

    Guppy.get_loc = function(x,y,current_node,current_caret){
        var g = Guppy.active_guppy;
        var min_dist = -1;
        var mid_dist = 0;
        var pos = "";
        var opt = null;
        var cur = null;
        var car = null;
        // check if we go to first or last element
        var bb = g.editor.getElementsByClassName("katex")[0];
        if(!bb) return;
        if(current_node){
            var current_path = Utils.path_to(current_node);
            var current_pos = parseInt(current_path.substring(current_path.lastIndexOf("e")+1));
        }

        var boxes = g.boxes;
        if(!boxes) return;
        if(current_node){
            current_path = current_path.replace(/e[0-9]+$/,"e");
            var boxes2 = [];
            for(var i = 0; i < boxes.length; i++){
                if(boxes[i].path == "all") continue;
                var loc = boxes[i].path.substring(0,boxes[i].path.lastIndexOf("_"));
                loc = loc.replace(/e[0-9]+$/,"e");
                if(loc == current_path){
                    boxes2.push(boxes[i]);
                }
            }
            boxes = boxes2;
        }
        if(!boxes) return;
        for(var j = 0; j < boxes.length; j++){
            var box = boxes[j];
            if(box.path == "all"){
                if(!opt) opt = {'path':'guppy_loc_m_e1_0'};
                continue;
            }
            var xdist = Math.max(box.left - x, x - box.right, 0)
            var ydist = Math.max(box.top - y, y - box.bottom, 0)
            var dist = Math.sqrt(xdist*xdist + ydist*ydist);
            if(min_dist == -1 || dist < min_dist){
                min_dist = dist;
                mid_dist = x - box.mid_x;
                opt = box;
            }
        }
        loc = opt.path.substring("guppy_loc".length);
        loc = loc.replace(/_/g,"/");
        loc = loc.replace(/([0-9]+)(?=.*?\/)/g,"[$1]");
        cur = g.engine.doc.xpath_node(loc.substring(0,loc.lastIndexOf("/")), g.engine.doc.root());
        car = parseInt(loc.substring(loc.lastIndexOf("/")+1));
        // Check if we want the cursor before or after the element
        if(mid_dist > 0 && !(opt.blank)){
            car++;
        }
        var ans = {"current":cur,"caret":car,"pos":pos};
        if(current_node && opt){
            var opt_pos = parseInt(opt.path.substring(opt.path.lastIndexOf("e")+1,opt.path.lastIndexOf("_")));
            if(opt_pos < current_pos) pos = "left";
            else if(opt_pos > current_pos) pos = "right";
            else if(car < current_caret) pos = "left";
            else if(car > current_caret) pos = "right";
            if(pos) ans['pos'] = pos;
            else ans['pos'] = "none";
        }
        return ans;
    }

    Guppy.mouse_up = function(){
        Guppy.kb.is_mouse_down = false;
        var g = Guppy.active_guppy;
        if(g) g.render(true);
    }

    Guppy.mouse_down = function(e){
        if(e.target.getAttribute("class") == "guppy-button") return;
        var n = e.target;
        Guppy.kb.is_mouse_down = true;
        while(n != null){
            if(n.id in Guppy.instances){
                e.preventDefault();
                var prev_active = Guppy.active_guppy;
                for(var i in Guppy.instances){
                    if(i != n.id) Guppy.instances[i].deactivate();
                    Guppy.active_guppy = Guppy.instances[n.id];
                    Guppy.active_guppy.activate();
                }
                var g = Guppy.active_guppy;
                var b = Guppy.active_guppy.engine;
                g.space_caret = 0;
                if(prev_active == g){
                    if(e.shiftKey){
                        g.select_to(e.clientX, e.clientY, true);
                    }
                    else {
                        var loc = Guppy.get_loc(e.clientX,e.clientY);
                        if(!loc) return;
                        b.current = loc.current;
                        b.caret = loc.caret;
                        b.sel_status = Engine.SEL_NONE;
                    }
                    g.render(true);
                }
                return;
            }
            if(n.classList && n.classList.contains("guppy_osk")){
                return;
            }
            n = n.parentNode;
        }
        Guppy.active_guppy = null;
        for(var j in Guppy.instances){
            Guppy.instances[j].deactivate();
        }
    }

    Guppy.mouse_move = function(e){
        var g = Guppy.active_guppy;
        if(!g) return;
        if(!Guppy.kb.is_mouse_down){
            var bb = g.editor;
            var rect = bb.getBoundingClientRect();
            if((e.clientX < rect.left || e.clientX > rect.right) || (e.clientY > rect.bottom || e.clientY < rect.top)){
                g.temp_cursor = {"node":null,"caret":0};
            }
            else{
                var loc = Guppy.get_loc(e.clientX,e.clientY);
                if(!loc) return;
                g.temp_cursor = {"node":loc.current,"caret":loc.caret};
            }
            g.render(g.is_changed());
        }
        else{
            g.select_to(e.clientX,e.clientY, true);
            g.render(g.is_changed());
        }
    }

    Guppy.prototype.select_to = function(x, y, mouse){
        var sel_caret = this.engine.caret;
        var sel_cursor = this.engine.current;
        if(this.engine.sel_status == Engine.SEL_CURSOR_AT_START){
            sel_cursor = this.engine.sel_end.node;
            sel_caret = this.engine.sel_end.caret;
        }
        else if(this.engine.sel_status == Engine.SEL_CURSOR_AT_END){
            sel_cursor = this.engine.sel_start.node;
            sel_caret = this.engine.sel_start.caret;
        }
        var loc = Guppy.get_loc(x,y,sel_cursor,sel_caret);
        if(!loc) return;
        this.engine.select_to(loc, sel_cursor, sel_caret, mouse);
    }

    window.addEventListener("mousedown",Guppy.mouse_down, true);
    window.addEventListener("mouseup",Guppy.mouse_up, true);
    window.addEventListener("mousemove",Guppy.mouse_move, false);

    Guppy.prototype.render_node = function(t){
        // All the interesting work is done by transform.  This function just adds in the cursor and selection-start cursor
        var output = "";
        if(t == "render"){
            var root = this.engine.doc.root();
            this.engine.add_paths(root,"m");
            this.engine.temp_cursor = this.temp_cursor;
            this.engine.add_classes_cursors(root);
            this.engine.current.setAttribute("current","yes");
            if(this.temp_cursor.node) this.temp_cursor.node.setAttribute("temp","yes");
            output = this.engine.get_content("latex",true);
            this.engine.remove_cursors_classes(root);
            output = output.replace(new RegExp('&amp;','g'), '&');
            return output;
        }
        else{
            output = this.engine.get_content(t);
        }
        return output
    }

    /**
        Render the document
        @memberof Guppy
        @param {boolean} [updated=false] - Whether there have been visible
        changes to the document (i.e. that affect the positions of
        elements)
    */
    Guppy.prototype.render = function(updated){
        if(!this.editor_active && this.engine.doc.is_blank()){
            katex.render(this.engine.setting("empty_content"),this.editor);
            this.editor.appendChild(this.buttons_div);
            return;
        }
        var tex = this.render_node("render");
        katex.render(tex,this.editor);
        this.editor.appendChild(this.buttons_div);
        if(updated){
            this.recompute_locations_paths();
        }
    }

    /**
        Get the content of the editor as LaTeX
        @memberof Guppy
    */
    Guppy.prototype.latex = function(){
        return this.engine.get_content("latex");
    }

    /**
        Get the content of the editor as XML
        @memberof Guppy
    */
    Guppy.prototype.xml = function(){
        return this.engine.get_content("xml");
    }

    /**
        Get the content of the editor as a syntax tree, serialised using JSON
        @memberof Guppy
    */
    Guppy.prototype.syntax_tree = function(){
        return this.engine.get_content("ast");
    }

    /**
        Get the content of the editor as a list of equations, serialised
        using JSON.  For example, `x < y = z` will be returned as `[["<", [["var", "x"], ["var", "y"]]],["=", [["var", "y"], ["var", "z"]]]]
        @memberof Guppy
    */
    Guppy.prototype.equations = function(){
        return this.engine.get_content("eqns");
    }

    /**
        Get the content of the editor in a parseable text format.
        @memberof Guppy
    */
    Guppy.prototype.text = function(){
        return this.engine.get_content("text");
    }

    /**
        Get the content of the editor in AsciiMath.
        @memberof Guppy
    */
    Guppy.prototype.asciimath = function(){
        return this.engine.get_content("asciimath");
    }

    /**
        Get the Doc object representing the editor's contents.
        @memberof Guppy
    */
    Guppy.prototype.doc = function(){
        return this.engine.doc;
    }

    /**
        Get the content of the editor as a Javascript function, with
        user-supplied interpretations of the various symbols.  If not
        supplied, default interpretations will be given for the following
        symbols: `*,+,/,-,^,sqrt,sin,cos,tan,log`
        @param {Object} [evaluators] - An object with a key for each
        possible symbol type ("exponential", "integral", etc.)
        whose values are functions.  These functions take in a single
        argument, `args`, which is an array of that symbol's arguments,
        and should return a function that takes in an object argument
        `vars`.  In this inner function, to compute e.g. the sum of the
        first and second arguments, you would do
        `args[0](vars)+args[1](vars)`.  This function should return the
        result of that symbol's operation.
        @returns {function(Object)} - Returns a function that takes in an
        object with a key for each variable in the expression and whose
        values are the values that will be passed in for those variables.
        In addition, this function is augmented with a `vars` member which
        is a list of the variables that appear in the expression.
        @memberof Guppy
    */
    Guppy.prototype.func = function(evaluators){
        var res = this.engine.get_content("function", evaluators);
        var f = res['function'];
        f.vars = res.vars;
        return f;
    }

    /**
        Recursively evaluate the syntax tree of the editor's contents using specified functions.
        @param {Object} [evaluators] - An object with a key for each
        possible symbol type ("exponential", "integral", etc.)
        whose values are functions that will be applied whenever that
        symbol is encountered in the syntax tree.  These functions take a
        single argument, `args`, which is a list of the results of
        evaluating that symbol's arguments.
        @returns - Whatever the `evaluators` function for the root symbol
        in the syntax tree returns.
        @memberof Guppy
    */
    Guppy.prototype.evaluate = function(evaluators){
        return this.engine.doc.evaluate(evaluators);
    }

    /**
        Get a list of the symbols used in the document, in order of
        appearance, with each kind of symbol appearing only once.  For
        example, a document representing `sin(x^3)+sqrt(x^2+x)` will
        have symbols `["sin","exponential","square_root"]`.
        @param {String[]} [groups] - A list of the groups whose symbols
        may be included in the output.  If absent, all symbols in the
        document will be returned.
        @memberof Guppy
    */
    Guppy.prototype.symbols_used = function(groups){
        return this.engine.doc.get_symbols(groups);
    }

    /**
        Get a list of the variable names used in the document.
        @memberof Guppy
    */
    Guppy.prototype.vars = function(){
        return this.engine.get_content("function").vars;
    }

    /**
        Set the content of the document from text in the format outputted by `guppy.text()`.
        @param {String} text - A string representing the document to import.
        @memberof Guppy
    */
    Guppy.prototype.import_text = function(text){
        return this.engine.import_text(text);
    }

    /**
        Set the content of the document from input text in "semantic
        LaTeX" format.  That is, all functions are represented as
        `\funcname{arg1}{arg2}`.  For example,
        `\defintegral{1}{2}{x^2}{x}`.
        @param {String} text - A string representing the document to import.
        @memberof Guppy
    */
    Guppy.prototype.import_latex = function(text){
        return this.engine.import_latex(text);
    }

    /**
        Set the content of the document from XML in the format outputted
        by `guppy.xml()`.
        @param {String} xml - An XML string representing the document to
        import.
        @memberof Guppy
    */
    Guppy.prototype.import_xml = function(xml){
        return this.engine.set_content(xml);
    }

    /**
        Import a syntax tree from a JSON object formatted as outputted by `guppy.syntax_tree()`.
        @param {Object} tree - A JSON object representing the syntax tree to import.
        @memberof Guppy
    */
    Guppy.prototype.import_syntax_tree = function(tree){
        return this.engine.import_ast(tree);
    }

    /**
        Focus this instance of the editor
        @memberof Guppy
    */
    Guppy.prototype.activate = function(){
        Guppy.active_guppy = this;
        this.editor_active = true;
        this.editor.className = this.editor.className.replace(new RegExp('(\\s|^)guppy_inactive(\\s|$)'),' guppy_active ');
        this.editor.focus();
        if(this.ready){
            this.render(true);
            this.engine.fire_event("focus",{"focused":true});
        }
    }

    /**
        Unfocus this instance of the editor
        @memberof Guppy
    */
    Guppy.prototype.deactivate = function(){
        this.editor_active = false;
        var r1 = new RegExp('(?:\\s|^)guppy_active(?:\\s|$)');
        var r2 = new RegExp('(?:\\s|^)guppy_inactive(?:\\s|$)');
        if(this.editor.className.match(r1)){
            this.editor.className = this.editor.className.replace(r1,' guppy_inactive ');
        }
        else if(!this.editor.className.match(r2)){
            this.editor.className += ' guppy_inactive ';
        }
        Guppy.kb.shift_down = false;
        Guppy.kb.ctrl_down = false;
        Guppy.kb.alt_down = false;
        if(this.ready){
            this.render();
            this.engine.fire_event("focus",{"focused":false});
        }
    }

    // Keyboard stuff

    Guppy.kb = {};

    Guppy.kb.is_mouse_down = false;

    /* keyboard behaviour definitions */

    // keys aside from 0-9,a-z,A-Z
    Guppy.kb.k_chars = {
        "+":"+",
        "-":"-",
        "*":"*",
        ".":".",
        "shift+/":"/",
        "shift+=":"+",
    };
    Guppy.kb.k_text = {
        "/":"/",
        "*":"*",
        "(":"(",
        ")":")",
        "<":"<",
        ">":">",
        "|":"|",
        "!":"!",
        ",":",",
        ".":".",
        ";":";",
        "=":"=",
        "[":"[",
        "]":"]",
        "@":"@",
        "'":"'",
        "`":"`",
        ":":":",
        "\"":"\"",
        "shift+/":"?",
        "space":" ",
    };
    Guppy.kb.k_controls = {
        "up":"up",
        "down":"down",
        "right":"right",
        "left":"left",
        "alt+k":"up",
        "alt+j":"down",
        "alt+l":"right",
        "alt+h":"left",
        "space":"spacebar",
        "home":"home",
        "end":"end",
        "backspace":"backspace",
        "del":"delete_key",
        "mod+a":"sel_all",
        "mod+c":"sel_copy",
        "mod+x":"sel_cut",
        "mod+v":"sel_paste",
        "mod+z":"undo",
        "mod+y":"redo",
        "enter":"done",
        "mod+shift+right":"list_extend_copy_right",
        "mod+shift+left":"list_extend_copy_left",
        ",":"list_extend_right",
        ";":"list_extend_down",
        "mod+right":"list_extend_right",
        "mod+left":"list_extend_left",
        "mod+up":"list_extend_up",
        "mod+down":"list_extend_down",
        "mod+shift+up":"list_extend_copy_up",
        "mod+shift+down":"list_extend_copy_down",
        "mod+backspace":"list_remove",
        "mod+shift+backspace":"list_remove_row",
        "shift+left":"sel_left",
        "shift+right":"sel_right",
        ")":"right_paren",
        "\\":"backslash",
        "tab":"tab"
    };

    // Will populate keyboard shortcuts for symbols from symbol files
    Guppy.kb.k_syms = {};

    var i = 0;

    // letters

    for(i = 65; i <= 90; i++){
        Guppy.kb.k_chars[String.fromCharCode(i).toLowerCase()] = String.fromCharCode(i).toLowerCase();
        Guppy.kb.k_chars['shift+'+String.fromCharCode(i).toLowerCase()] = String.fromCharCode(i).toUpperCase();
    }

    // numbers

    for(i = 48; i <= 57; i++)
        Guppy.kb.k_chars[String.fromCharCode(i)] = String.fromCharCode(i);

    Guppy.register_keyboard_handlers = function(){
        Mousetrap.addKeycodes({173: '-'}); // Firefox's special minus (needed for _ = sub binding)
        var i, name;
        // Pull symbol shortcuts from Symbols:
        for(name in Symbols.symbols){
    	var s = Symbols.symbols[name];
    	if(s.keys)
                    for(i = 0; i < s.keys.length; i++)
                    Guppy.kb.k_syms[s.keys[i]] = s.attrs.type;
        }
        for(i in Guppy.kb.k_chars)
            Mousetrap.bind(i,function(i){ return function(){
                if(!Guppy.active_guppy) return true;
                Guppy.active_guppy.temp_cursor.node = null;
                if(Utils.is_text(Guppy.active_guppy.engine.current) && Guppy.kb.k_text[i]){
                    Guppy.active_guppy.engine.insert_string(Guppy.kb.k_text[i]);
                }
                else{
                    Guppy.active_guppy.engine.insert_string(Guppy.kb.k_chars[i]);
                }
                Guppy.active_guppy.render(true);
                return false;
            }}(i));
        for(i in Guppy.kb.k_syms)
            Mousetrap.bind(i,function(i){ return function(){
                if(!Guppy.active_guppy) return true;
                Guppy.active_guppy.temp_cursor.node = null;
                // We always want to skip using this symbol insertion if
                // we are in text mode, and additionally we want only to
                // insert the corresponding text if there is an overriding
                // text representation in Guppy.kb.k_text
                if(Utils.is_text(Guppy.active_guppy.engine.current)){
                    if(Guppy.kb.k_text[i]) Guppy.active_guppy.engine.insert_string(Guppy.kb.k_text[i]);
                }
                else{
                    Guppy.active_guppy.engine.space_caret = 0;
                    //Guppy.active_guppy.engine.insert_symbol(Guppy.kb.k_syms[i]);
                    Guppy.active_guppy.engine.insert_symbol(Symbols.lookup_type(Guppy.kb.k_syms[i]));
                }
                Guppy.active_guppy.render(true);
                return false;
            }}(i));
        for(i in Guppy.kb.k_controls)
            Mousetrap.bind(i,function(i){ return function(){
                if(!Guppy.active_guppy) return true;
                // We want to skip using this control sequence only if there is an overriding text representation in Guppy.kb.k_text
                if(Utils.is_text(Guppy.active_guppy.engine.current) && Guppy.kb.k_text[i]){
                    Guppy.active_guppy.engine.insert_string(Guppy.kb.k_text[i]);
                }
                else{
                    Guppy.active_guppy.engine.space_caret = 0;
                    Guppy.active_guppy.engine[Guppy.kb.k_controls[i]]();
                    Guppy.active_guppy.temp_cursor.node = null;
                }
                Guppy.active_guppy.render(["up","down","right","left","home","end","sel_left","sel_right"].indexOf(i) < 0);
                //Guppy.active_guppy.render(false);
                return false;
            }}(i));
        for(i in Guppy.kb.k_text)
            if(!(Guppy.kb.k_chars[i] || Guppy.kb.k_syms[i] || Guppy.kb.k_controls[i])){
                Mousetrap.bind(i,function(i){ return function(){
                    if(!Guppy.active_guppy) return true;
                    Guppy.active_guppy.temp_cursor.node = null;
                    if(Utils.is_text(Guppy.active_guppy.engine.current)){
                        Guppy.active_guppy.engine.insert_string(Guppy.kb.k_text[i]);
                        Guppy.active_guppy.render(true);
                    }
                    return false;
                }}(i));
            }
    }

    module.exports = Guppy;