michael@0: /* This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this
michael@0:  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: "use strict";
michael@0: 
michael@0: // **********
michael@0: // Title: utils.js
michael@0: 
michael@0: this.EXPORTED_SYMBOLS = ["Point", "Rect", "Range", "Subscribable", "Utils", "MRUList"];
michael@0: 
michael@0: // #########
michael@0: const Ci = Components.interfaces;
michael@0: const Cu = Components.utils;
michael@0: 
michael@0: Cu.import("resource://gre/modules/Services.jsm");
michael@0: 
michael@0: // ##########
michael@0: // Class: Point
michael@0: // A simple point.
michael@0: //
michael@0: // Constructor: Point
michael@0: // If a is a Point, creates a copy of it. Otherwise, expects a to be x,
michael@0: // and creates a Point with it along with y. If either a or y are omitted,
michael@0: // 0 is used in their place.
michael@0: this.Point = function Point(a, y) {
michael@0:   if (Utils.isPoint(a)) {
michael@0:     this.x = a.x;
michael@0:     this.y = a.y;
michael@0:   } else {
michael@0:     this.x = (Utils.isNumber(a) ? a : 0);
michael@0:     this.y = (Utils.isNumber(y) ? y : 0);
michael@0:   }
michael@0: };
michael@0: 
michael@0: Point.prototype = {
michael@0:   // ----------
michael@0:   // Function: toString
michael@0:   // Prints [Point (x,y)] for debug use
michael@0:   toString: function Point_toString() {
michael@0:     return "[Point (" + this.x + "," + this.y + ")]";
michael@0:   },
michael@0: 
michael@0:   // ----------
michael@0:   // Function: distance
michael@0:   // Returns the distance from this point to the given <Point>.
michael@0:   distance: function Point_distance(point) {
michael@0:     var ax = this.x - point.x;
michael@0:     var ay = this.y - point.y;
michael@0:     return Math.sqrt((ax * ax) + (ay * ay));
michael@0:   }
michael@0: };
michael@0: 
michael@0: // ##########
michael@0: // Class: Rect
michael@0: // A simple rectangle. Note that in addition to the left and width, it also has
michael@0: // a right property; changing one affects the others appropriately. Same for the
michael@0: // vertical properties.
michael@0: //
michael@0: // Constructor: Rect
michael@0: // If a is a Rect, creates a copy of it. Otherwise, expects a to be left,
michael@0: // and creates a Rect with it along with top, width, and height.
michael@0: this.Rect = function Rect(a, top, width, height) {
michael@0:   // Note: perhaps 'a' should really be called 'rectOrLeft'
michael@0:   if (Utils.isRect(a)) {
michael@0:     this.left = a.left;
michael@0:     this.top = a.top;
michael@0:     this.width = a.width;
michael@0:     this.height = a.height;
michael@0:   } else {
michael@0:     this.left = a;
michael@0:     this.top = top;
michael@0:     this.width = width;
michael@0:     this.height = height;
michael@0:   }
michael@0: };
michael@0: 
michael@0: Rect.prototype = {
michael@0:   // ----------
michael@0:   // Function: toString
michael@0:   // Prints [Rect (left,top,width,height)] for debug use
michael@0:   toString: function Rect_toString() {
michael@0:     return "[Rect (" + this.left + "," + this.top + "," +
michael@0:             this.width + "," + this.height + ")]";
michael@0:   },
michael@0: 
michael@0:   get right() this.left + this.width,
michael@0:   set right(value) {
michael@0:     this.width = value - this.left;
michael@0:   },
michael@0: 
michael@0:   get bottom() this.top + this.height,
michael@0:   set bottom(value) {
michael@0:     this.height = value - this.top;
michael@0:   },
michael@0: 
michael@0:   // ----------
michael@0:   // Variable: xRange
michael@0:   // Gives you a new <Range> for the horizontal dimension.
michael@0:   get xRange() new Range(this.left, this.right),
michael@0: 
michael@0:   // ----------
michael@0:   // Variable: yRange
michael@0:   // Gives you a new <Range> for the vertical dimension.
michael@0:   get yRange() new Range(this.top, this.bottom),
michael@0: 
michael@0:   // ----------
michael@0:   // Function: intersects
michael@0:   // Returns true if this rectangle intersects the given <Rect>.
michael@0:   intersects: function Rect_intersects(rect) {
michael@0:     return (rect.right > this.left &&
michael@0:             rect.left < this.right &&
michael@0:             rect.bottom > this.top &&
michael@0:             rect.top < this.bottom);
michael@0:   },
michael@0: 
michael@0:   // ----------
michael@0:   // Function: intersection
michael@0:   // Returns a new <Rect> with the intersection of this rectangle and the give <Rect>,
michael@0:   // or null if they don't intersect.
michael@0:   intersection: function Rect_intersection(rect) {
michael@0:     var box = new Rect(Math.max(rect.left, this.left), Math.max(rect.top, this.top), 0, 0);
michael@0:     box.right = Math.min(rect.right, this.right);
michael@0:     box.bottom = Math.min(rect.bottom, this.bottom);
michael@0:     if (box.width > 0 && box.height > 0)
michael@0:       return box;
michael@0: 
michael@0:     return null;
michael@0:   },
michael@0: 
michael@0:   // ----------
michael@0:   // Function: contains
michael@0:   // Returns a boolean denoting if the <Rect> or <Point> is contained inside
michael@0:   // this rectangle.
michael@0:   //
michael@0:   // Parameters
michael@0:   //  - A <Rect> or a <Point>
michael@0:   contains: function Rect_contains(a) {
michael@0:     if (Utils.isPoint(a))
michael@0:       return (a.x > this.left &&
michael@0:               a.x < this.right &&
michael@0:               a.y > this.top &&
michael@0:               a.y < this.bottom);
michael@0: 
michael@0:     return (a.left >= this.left &&
michael@0:             a.right <= this.right &&
michael@0:             a.top >= this.top &&
michael@0:             a.bottom <= this.bottom);
michael@0:   },
michael@0: 
michael@0:   // ----------
michael@0:   // Function: center
michael@0:   // Returns a new <Point> with the center location of this rectangle.
michael@0:   center: function Rect_center() {
michael@0:     return new Point(this.left + (this.width / 2), this.top + (this.height / 2));
michael@0:   },
michael@0: 
michael@0:   // ----------
michael@0:   // Function: size
michael@0:   // Returns a new <Point> with the dimensions of this rectangle.
michael@0:   size: function Rect_size() {
michael@0:     return new Point(this.width, this.height);
michael@0:   },
michael@0: 
michael@0:   // ----------
michael@0:   // Function: position
michael@0:   // Returns a new <Point> with the top left of this rectangle.
michael@0:   position: function Rect_position() {
michael@0:     return new Point(this.left, this.top);
michael@0:   },
michael@0: 
michael@0:   // ----------
michael@0:   // Function: area
michael@0:   // Returns the area of this rectangle.
michael@0:   area: function Rect_area() {
michael@0:     return this.width * this.height;
michael@0:   },
michael@0: 
michael@0:   // ----------
michael@0:   // Function: inset
michael@0:   // Makes the rect smaller (if the arguments are positive) as if a margin is added all around
michael@0:   // the initial rect, with the margin widths (symmetric) being specified by the arguments.
michael@0:   //
michael@0:   // Paramaters
michael@0:   //  - A <Point> or two arguments: x and y
michael@0:   inset: function Rect_inset(a, b) {
michael@0:     if (Utils.isPoint(a)) {
michael@0:       b = a.y;
michael@0:       a = a.x;
michael@0:     }
michael@0: 
michael@0:     this.left += a;
michael@0:     this.width -= a * 2;
michael@0:     this.top += b;
michael@0:     this.height -= b * 2;
michael@0:   },
michael@0: 
michael@0:   // ----------
michael@0:   // Function: offset
michael@0:   // Moves (translates) the rect by the given vector.
michael@0:   //
michael@0:   // Paramaters
michael@0:   //  - A <Point> or two arguments: x and y
michael@0:   offset: function Rect_offset(a, b) {
michael@0:     if (Utils.isPoint(a)) {
michael@0:       this.left += a.x;
michael@0:       this.top += a.y;
michael@0:     } else {
michael@0:       this.left += a;
michael@0:       this.top += b;
michael@0:     }
michael@0:   },
michael@0: 
michael@0:   // ----------
michael@0:   // Function: equals
michael@0:   // Returns true if this rectangle is identical to the given <Rect>.
michael@0:   equals: function Rect_equals(rect) {
michael@0:     return (rect.left == this.left &&
michael@0:             rect.top == this.top &&
michael@0:             rect.width == this.width &&
michael@0:             rect.height == this.height);
michael@0:   },
michael@0: 
michael@0:   // ----------
michael@0:   // Function: union
michael@0:   // Returns a new <Rect> with the union of this rectangle and the given <Rect>.
michael@0:   union: function Rect_union(a) {
michael@0:     var newLeft = Math.min(a.left, this.left);
michael@0:     var newTop = Math.min(a.top, this.top);
michael@0:     var newWidth = Math.max(a.right, this.right) - newLeft;
michael@0:     var newHeight = Math.max(a.bottom, this.bottom) - newTop;
michael@0:     var newRect = new Rect(newLeft, newTop, newWidth, newHeight);
michael@0: 
michael@0:     return newRect;
michael@0:   },
michael@0: 
michael@0:   // ----------
michael@0:   // Function: copy
michael@0:   // Copies the values of the given <Rect> into this rectangle.
michael@0:   copy: function Rect_copy(a) {
michael@0:     this.left = a.left;
michael@0:     this.top = a.top;
michael@0:     this.width = a.width;
michael@0:     this.height = a.height;
michael@0:   }
michael@0: };
michael@0: 
michael@0: // ##########
michael@0: // Class: Range
michael@0: // A physical interval, with a min and max.
michael@0: //
michael@0: // Constructor: Range
michael@0: // Creates a Range with the given min and max
michael@0: this.Range = function Range(min, max) {
michael@0:   if (Utils.isRange(min) && !max) { // if the one variable given is a range, copy it.
michael@0:     this.min = min.min;
michael@0:     this.max = min.max;
michael@0:   } else {
michael@0:     this.min = min || 0;
michael@0:     this.max = max || 0;
michael@0:   }
michael@0: };
michael@0: 
michael@0: Range.prototype = {
michael@0:   // ----------
michael@0:   // Function: toString
michael@0:   // Prints [Range (min,max)] for debug use
michael@0:   toString: function Range_toString() {
michael@0:     return "[Range (" + this.min + "," + this.max + ")]";
michael@0:   },
michael@0: 
michael@0:   // Variable: extent
michael@0:   // Equivalent to max-min
michael@0:   get extent() {
michael@0:     return (this.max - this.min);
michael@0:   },
michael@0: 
michael@0:   set extent(extent) {
michael@0:     this.max = extent - this.min;
michael@0:   },
michael@0: 
michael@0:   // ----------
michael@0:   // Function: contains
michael@0:   // Whether the <Range> contains the given <Range> or value or not.
michael@0:   //
michael@0:   // Parameters
michael@0:   //  - a number or <Range>
michael@0:   contains: function Range_contains(value) {
michael@0:     if (Utils.isNumber(value))
michael@0:       return value >= this.min && value <= this.max;
michael@0:     if (Utils.isRange(value))
michael@0:       return value.min >= this.min && value.max <= this.max;
michael@0:     return false;
michael@0:   },
michael@0: 
michael@0:   // ----------
michael@0:   // Function: overlaps
michael@0:   // Whether the <Range> overlaps with the given <Range> value or not.
michael@0:   //
michael@0:   // Parameters
michael@0:   //  - a number or <Range>
michael@0:   overlaps: function Range_overlaps(value) {
michael@0:     if (Utils.isNumber(value))
michael@0:       return this.contains(value);
michael@0:     if (Utils.isRange(value))
michael@0:       return !(value.max < this.min || this.max < value.min);
michael@0:     return false;
michael@0:   },
michael@0: 
michael@0:   // ----------
michael@0:   // Function: proportion
michael@0:   // Maps the given value to the range [0,1], so that it returns 0 if the value is <= the min,
michael@0:   // returns 1 if the value >= the max, and returns an interpolated "proportion" in (min, max).
michael@0:   //
michael@0:   // Parameters
michael@0:   //  - a number
michael@0:   //  - (bool) smooth? If true, a smooth tanh-based function will be used instead of the linear.
michael@0:   proportion: function Range_proportion(value, smooth) {
michael@0:     if (value <= this.min)
michael@0:       return 0;
michael@0:     if (this.max <= value)
michael@0:       return 1;
michael@0: 
michael@0:     var proportion = (value - this.min) / this.extent;
michael@0: 
michael@0:     if (smooth) {
michael@0:       // The ease function ".5+.5*Math.tanh(4*x-2)" is a pretty
michael@0:       // little graph. It goes from near 0 at x=0 to near 1 at x=1
michael@0:       // smoothly and beautifully.
michael@0:       // http://www.wolframalpha.com/input/?i=.5+%2B+.5+*+tanh%28%284+*+x%29+-+2%29
michael@0:       let tanh = function tanh(x) {
michael@0:         var e = Math.exp(x);
michael@0:         return (e - 1/e) / (e + 1/e);
michael@0:       };
michael@0: 
michael@0:       return .5 - .5 * tanh(2 - 4 * proportion);
michael@0:     }
michael@0: 
michael@0:     return proportion;
michael@0:   },
michael@0: 
michael@0:   // ----------
michael@0:   // Function: scale
michael@0:   // Takes the given value in [0,1] and maps it to the associated value on the Range.
michael@0:   //
michael@0:   // Parameters
michael@0:   //  - a number in [0,1]
michael@0:   scale: function Range_scale(value) {
michael@0:     if (value > 1)
michael@0:       value = 1;
michael@0:     if (value < 0)
michael@0:       value = 0;
michael@0:     return this.min + this.extent * value;
michael@0:   }
michael@0: };
michael@0: 
michael@0: // ##########
michael@0: // Class: Subscribable
michael@0: // A mix-in for allowing objects to collect subscribers for custom events.
michael@0: this.Subscribable = function Subscribable() {
michael@0:   this.subscribers = null;
michael@0: };
michael@0: 
michael@0: Subscribable.prototype = {
michael@0:   // ----------
michael@0:   // Function: addSubscriber
michael@0:   // The given callback will be called when the Subscribable fires the given event.
michael@0:   addSubscriber: function Subscribable_addSubscriber(eventName, callback) {
michael@0:     try {
michael@0:       Utils.assertThrow(typeof callback == "function", "callback must be a function");
michael@0:       Utils.assertThrow(eventName && typeof eventName == "string",
michael@0:           "eventName must be a non-empty string");
michael@0:     } catch(e) {
michael@0:       Utils.log(e);
michael@0:       return;
michael@0:     }
michael@0: 
michael@0:     if (!this.subscribers)
michael@0:       this.subscribers = {};
michael@0: 
michael@0:     if (!this.subscribers[eventName])
michael@0:       this.subscribers[eventName] = [];
michael@0: 
michael@0:     let subscribers = this.subscribers[eventName];
michael@0:     if (subscribers.indexOf(callback) == -1)
michael@0:       subscribers.push(callback);
michael@0:   },
michael@0: 
michael@0:   // ----------
michael@0:   // Function: removeSubscriber
michael@0:   // Removes the subscriber associated with the event for the given callback.
michael@0:   removeSubscriber: function Subscribable_removeSubscriber(eventName, callback) {
michael@0:     try {
michael@0:       Utils.assertThrow(typeof callback == "function", "callback must be a function");
michael@0:       Utils.assertThrow(eventName && typeof eventName == "string",
michael@0:           "eventName must be a non-empty string");
michael@0:     } catch(e) {
michael@0:       Utils.log(e);
michael@0:       return;
michael@0:     }
michael@0: 
michael@0:     if (!this.subscribers || !this.subscribers[eventName])
michael@0:       return;
michael@0: 
michael@0:     let subscribers = this.subscribers[eventName];
michael@0:     let index = subscribers.indexOf(callback);
michael@0: 
michael@0:     if (index > -1)
michael@0:       subscribers.splice(index, 1);
michael@0:   },
michael@0: 
michael@0:   // ----------
michael@0:   // Function: _sendToSubscribers
michael@0:   // Internal routine. Used by the Subscribable to fire events.
michael@0:   _sendToSubscribers: function Subscribable__sendToSubscribers(eventName, eventInfo) {
michael@0:     try {
michael@0:       Utils.assertThrow(eventName && typeof eventName == "string",
michael@0:           "eventName must be a non-empty string");
michael@0:     } catch(e) {
michael@0:       Utils.log(e);
michael@0:       return;
michael@0:     }
michael@0: 
michael@0:     if (!this.subscribers || !this.subscribers[eventName])
michael@0:       return;
michael@0: 
michael@0:     let subsCopy = this.subscribers[eventName].concat();
michael@0:     subsCopy.forEach(function (callback) {
michael@0:       try {
michael@0:         callback(this, eventInfo);
michael@0:       } catch(e) {
michael@0:         Utils.log(e);
michael@0:       }
michael@0:     }, this);
michael@0:   }
michael@0: };
michael@0: 
michael@0: // ##########
michael@0: // Class: Utils
michael@0: // Singelton with common utility functions.
michael@0: this.Utils = {
michael@0:   // ----------
michael@0:   // Function: toString
michael@0:   // Prints [Utils] for debug use
michael@0:   toString: function Utils_toString() {
michael@0:     return "[Utils]";
michael@0:   },
michael@0: 
michael@0:   // ___ Logging
michael@0:   useConsole: true, // as opposed to dump
michael@0:   showTime: false,
michael@0: 
michael@0:   // ----------
michael@0:   // Function: log
michael@0:   // Prints the given arguments to the JavaScript error console as a message.
michael@0:   // Pass as many arguments as you want, it'll print them all.
michael@0:   log: function Utils_log() {
michael@0:     var text = this.expandArgumentsForLog(arguments);
michael@0:     var prefix = this.showTime ? Date.now() + ': ' : '';
michael@0:     if (this.useConsole)    
michael@0:       Services.console.logStringMessage(prefix + text);
michael@0:     else
michael@0:       dump(prefix + text + '\n');
michael@0:   },
michael@0: 
michael@0:   // ----------
michael@0:   // Function: error
michael@0:   // Prints the given arguments to the JavaScript error console as an error.
michael@0:   // Pass as many arguments as you want, it'll print them all.
michael@0:   error: function Utils_error() {
michael@0:     var text = this.expandArgumentsForLog(arguments);
michael@0:     var prefix = this.showTime ? Date.now() + ': ' : '';
michael@0:     if (this.useConsole)    
michael@0:       Cu.reportError(prefix + "tabview error: " + text);
michael@0:     else
michael@0:       dump(prefix + "TABVIEW ERROR: " + text + '\n');
michael@0:   },
michael@0: 
michael@0:   // ----------
michael@0:   // Function: trace
michael@0:   // Prints the given arguments to the JavaScript error console as a message,
michael@0:   // along with a full stack trace.
michael@0:   // Pass as many arguments as you want, it'll print them all.
michael@0:   trace: function Utils_trace() {
michael@0:     var text = this.expandArgumentsForLog(arguments);
michael@0: 
michael@0:     // cut off the first line of the stack trace, because that's just this function.
michael@0:     let stack = Error().stack.split("\n").slice(1);
michael@0: 
michael@0:     // if the caller was assert, cut out the line for the assert function as well.
michael@0:     if (stack[0].indexOf("Utils_assert(") == 0)
michael@0:       stack.splice(0, 1);
michael@0: 
michael@0:     this.log('trace: ' + text + '\n' + stack.join("\n"));
michael@0:   },
michael@0: 
michael@0:   // ----------
michael@0:   // Function: assert
michael@0:   // Prints a stack trace along with label (as a console message) if condition is false.
michael@0:   assert: function Utils_assert(condition, label) {
michael@0:     if (!condition) {
michael@0:       let text;
michael@0:       if (typeof label != 'string')
michael@0:         text = 'badly formed assert';
michael@0:       else
michael@0:         text = "tabview assert: " + label;
michael@0: 
michael@0:       this.trace(text);
michael@0:     }
michael@0:   },
michael@0: 
michael@0:   // ----------
michael@0:   // Function: assertThrow
michael@0:   // Throws label as an exception if condition is false.
michael@0:   assertThrow: function Utils_assertThrow(condition, label) {
michael@0:     if (!condition) {
michael@0:       let text;
michael@0:       if (typeof label != 'string')
michael@0:         text = 'badly formed assert';
michael@0:       else
michael@0:         text = "tabview assert: " + label;
michael@0: 
michael@0:       // cut off the first line of the stack trace, because that's just this function.
michael@0:       let stack = Error().stack.split("\n").slice(1);
michael@0: 
michael@0:       throw text + "\n" + stack.join("\n");
michael@0:     }
michael@0:   },
michael@0: 
michael@0:   // ----------
michael@0:   // Function: expandObject
michael@0:   // Prints the given object to a string, including all of its properties.
michael@0:   expandObject: function Utils_expandObject(obj) {
michael@0:     var s = obj + ' = {';
michael@0:     for (let prop in obj) {
michael@0:       let value;
michael@0:       try {
michael@0:         value = obj[prop];
michael@0:       } catch(e) {
michael@0:         value = '[!!error retrieving property]';
michael@0:       }
michael@0: 
michael@0:       s += prop + ': ';
michael@0:       if (typeof value == 'string')
michael@0:         s += '\'' + value + '\'';
michael@0:       else if (typeof value == 'function')
michael@0:         s += 'function';
michael@0:       else
michael@0:         s += value;
michael@0: 
michael@0:       s += ', ';
michael@0:     }
michael@0:     return s + '}';
michael@0:   },
michael@0: 
michael@0:   // ----------
michael@0:   // Function: expandArgumentsForLog
michael@0:   // Expands all of the given args (an array) into a single string.
michael@0:   expandArgumentsForLog: function Utils_expandArgumentsForLog(args) {
michael@0:     var that = this;
michael@0:     return Array.map(args, function(arg) {
michael@0:       return typeof arg == 'object' ? that.expandObject(arg) : arg;
michael@0:     }).join('; ');
michael@0:   },
michael@0: 
michael@0:   // ___ Misc
michael@0: 
michael@0:   // ----------
michael@0:   // Function: isLeftClick
michael@0:   // Given a DOM mouse event, returns true if it was for the left mouse button.
michael@0:   isLeftClick: function Utils_isLeftClick(event) {
michael@0:     return event.button == 0;
michael@0:   },
michael@0: 
michael@0:   // ----------
michael@0:   // Function: isMiddleClick
michael@0:   // Given a DOM mouse event, returns true if it was for the middle mouse button.
michael@0:   isMiddleClick: function Utils_isMiddleClick(event) {
michael@0:     return event.button == 1;
michael@0:   },
michael@0: 
michael@0:   // ----------
michael@0:   // Function: isRightClick
michael@0:   // Given a DOM mouse event, returns true if it was for the right mouse button.
michael@0:   isRightClick: function Utils_isRightClick(event) {
michael@0:     return event.button == 2;
michael@0:   },
michael@0: 
michael@0:   // ----------
michael@0:   // Function: isDOMElement
michael@0:   // Returns true if the given object is a DOM element.
michael@0:   isDOMElement: function Utils_isDOMElement(object) {
michael@0:     return object instanceof Ci.nsIDOMElement;
michael@0:   },
michael@0: 
michael@0:   // ----------
michael@0:   // Function: isValidXULTab
michael@0:   // A xulTab is valid if it has not been closed,
michael@0:   // and it has not been removed from the DOM
michael@0:   // Returns true if the tab is valid.
michael@0:   isValidXULTab: function Utils_isValidXULTab(xulTab) {
michael@0:     return !xulTab.closing && xulTab.parentNode;
michael@0:   },
michael@0: 
michael@0:   // ----------
michael@0:   // Function: isNumber
michael@0:   // Returns true if the argument is a valid number.
michael@0:   isNumber: function Utils_isNumber(n) {
michael@0:     return typeof n == 'number' && !isNaN(n);
michael@0:   },
michael@0: 
michael@0:   // ----------
michael@0:   // Function: isRect
michael@0:   // Returns true if the given object (r) looks like a <Rect>.
michael@0:   isRect: function Utils_isRect(r) {
michael@0:     return (r &&
michael@0:             this.isNumber(r.left) &&
michael@0:             this.isNumber(r.top) &&
michael@0:             this.isNumber(r.width) &&
michael@0:             this.isNumber(r.height));
michael@0:   },
michael@0: 
michael@0:   // ----------
michael@0:   // Function: isRange
michael@0:   // Returns true if the given object (r) looks like a <Range>.
michael@0:   isRange: function Utils_isRange(r) {
michael@0:     return (r &&
michael@0:             this.isNumber(r.min) &&
michael@0:             this.isNumber(r.max));
michael@0:   },
michael@0: 
michael@0:   // ----------
michael@0:   // Function: isPoint
michael@0:   // Returns true if the given object (p) looks like a <Point>.
michael@0:   isPoint: function Utils_isPoint(p) {
michael@0:     return (p && this.isNumber(p.x) && this.isNumber(p.y));
michael@0:   },
michael@0: 
michael@0:   // ----------
michael@0:   // Function: isPlainObject
michael@0:   // Check to see if an object is a plain object (created using "{}" or "new Object").
michael@0:   isPlainObject: function Utils_isPlainObject(obj) {
michael@0:     // Must be an Object.
michael@0:     // Make sure that DOM nodes and window objects don't pass through, as well
michael@0:     if (!obj || Object.prototype.toString.call(obj) !== "[object Object]" ||
michael@0:        obj.nodeType || obj.setInterval) {
michael@0:       return false;
michael@0:     }
michael@0: 
michael@0:     // Not own constructor property must be Object
michael@0:     const hasOwnProperty = Object.prototype.hasOwnProperty;
michael@0: 
michael@0:     if (obj.constructor &&
michael@0:        !hasOwnProperty.call(obj, "constructor") &&
michael@0:        !hasOwnProperty.call(obj.constructor.prototype, "isPrototypeOf")) {
michael@0:       return false;
michael@0:     }
michael@0: 
michael@0:     // Own properties are enumerated firstly, so to speed up,
michael@0:     // if last one is own, then all properties are own.
michael@0: 
michael@0:     var key;
michael@0:     for (key in obj) {}
michael@0: 
michael@0:     return key === undefined || hasOwnProperty.call(obj, key);
michael@0:   },
michael@0: 
michael@0:   // ----------
michael@0:   // Function: isEmptyObject
michael@0:   // Returns true if the given object has no members.
michael@0:   isEmptyObject: function Utils_isEmptyObject(obj) {
michael@0:     for (let name in obj)
michael@0:       return false;
michael@0:     return true;
michael@0:   },
michael@0: 
michael@0:   // ----------
michael@0:   // Function: copy
michael@0:   // Returns a copy of the argument. Note that this is a shallow copy; if the argument
michael@0:   // has properties that are themselves objects, those properties will be copied by reference.
michael@0:   copy: function Utils_copy(value) {
michael@0:     if (value && typeof value == 'object') {
michael@0:       if (Array.isArray(value))
michael@0:         return this.extend([], value);
michael@0:       return this.extend({}, value);
michael@0:     }
michael@0:     return value;
michael@0:   },
michael@0: 
michael@0:   // ----------
michael@0:   // Function: merge
michael@0:   // Merge two array-like objects into the first and return it.
michael@0:   merge: function Utils_merge(first, second) {
michael@0:     Array.forEach(second, function(el) Array.push(first, el));
michael@0:     return first;
michael@0:   },
michael@0: 
michael@0:   // ----------
michael@0:   // Function: extend
michael@0:   // Pass several objects in and it will combine them all into the first object and return it.
michael@0:   extend: function Utils_extend() {
michael@0: 
michael@0:     // copy reference to target object
michael@0:     let target = arguments[0] || {};
michael@0:     // Deep copy is not supported
michael@0:     if (typeof target === "boolean") {
michael@0:       this.assert(false, "The first argument of extend cannot be a boolean." +
michael@0:           "Deep copy is not supported.");
michael@0:       return target;
michael@0:     }
michael@0: 
michael@0:     // Back when this was in iQ + iQ.fn, so you could extend iQ objects with it.
michael@0:     // This is no longer supported.
michael@0:     let length = arguments.length;
michael@0:     if (length === 1) {
michael@0:       this.assert(false, "Extending the iQ prototype using extend is not supported.");
michael@0:       return target;
michael@0:     }
michael@0: 
michael@0:     // Handle case when target is a string or something
michael@0:     if (typeof target != "object" && typeof target != "function") {
michael@0:       target = {};
michael@0:     }
michael@0: 
michael@0:     for (let i = 1; i < length; i++) {
michael@0:       // Only deal with non-null/undefined values
michael@0:       let options = arguments[i];
michael@0:       if (options != null) {
michael@0:         // Extend the base object
michael@0:         for (let name in options) {
michael@0:           let copy = options[name];
michael@0: 
michael@0:           // Prevent never-ending loop
michael@0:           if (target === copy)
michael@0:             continue;
michael@0: 
michael@0:           if (copy !== undefined)
michael@0:             target[name] = copy;
michael@0:         }
michael@0:       }
michael@0:     }
michael@0: 
michael@0:     // Return the modified object
michael@0:     return target;
michael@0:   },
michael@0: 
michael@0:   // ----------
michael@0:   // Function: attempt
michael@0:   // Tries to execute a number of functions. Returns immediately the return
michael@0:   // value of the first non-failed function without executing successive
michael@0:   // functions, or null.
michael@0:   attempt: function Utils_attempt() {
michael@0:     let args = arguments;
michael@0: 
michael@0:     for (let i = 0; i < args.length; i++) {
michael@0:       try {
michael@0:         return args[i]();
michael@0:       } catch (e) {}
michael@0:     }
michael@0: 
michael@0:     return null;
michael@0:   }
michael@0: };
michael@0: 
michael@0: // ##########
michael@0: // Class: MRUList
michael@0: // A most recently used list.
michael@0: //
michael@0: // Constructor: MRUList
michael@0: // If a is an array of entries, creates a copy of it.
michael@0: this.MRUList = function MRUList(a) {
michael@0:   if (Array.isArray(a))
michael@0:     this._list = a.concat();
michael@0:   else
michael@0:     this._list = [];
michael@0: };
michael@0: 
michael@0: MRUList.prototype = {
michael@0:   // ----------
michael@0:   // Function: toString
michael@0:   // Prints [List (entry1, entry2, ...)] for debug use
michael@0:   toString: function MRUList_toString() {
michael@0:     return "[List (" + this._list.join(", ") + ")]";
michael@0:   },
michael@0: 
michael@0:   // ----------
michael@0:   // Function: update
michael@0:   // Updates/inserts the given entry as the most recently used one in the list.
michael@0:   update: function MRUList_update(entry) {
michael@0:     this.remove(entry);
michael@0:     this._list.unshift(entry);
michael@0:   },
michael@0: 
michael@0:   // ----------
michael@0:   // Function: remove
michael@0:   // Removes the given entry from the list.
michael@0:   remove: function MRUList_remove(entry) {
michael@0:     let index = this._list.indexOf(entry);
michael@0:     if (index > -1)
michael@0:       this._list.splice(index, 1);
michael@0:   },
michael@0: 
michael@0:   // ----------
michael@0:   // Function: peek
michael@0:   // Returns the most recently used entry.  If a filter exists, gets the most 
michael@0:   // recently used entry which matches the filter.
michael@0:   peek: function MRUList_peek(filter) {
michael@0:     let match = null;
michael@0:     if (filter && typeof filter == "function")
michael@0:       this._list.some(function MRUList_peek_getEntry(entry) {
michael@0:         if (filter(entry)) {
michael@0:           match = entry
michael@0:           return true;
michael@0:         }
michael@0:         return false;
michael@0:       });
michael@0:     else 
michael@0:       match = this._list.length > 0 ? this._list[0] : null;
michael@0: 
michael@0:     return match;
michael@0:   },
michael@0: };
michael@0: