Custom wlxml names in label widget
[fnpeditor.git] / modules / documentCanvas / canvas / canvas.js
index 3f6599a..a8ff8d4 100644 (file)
@@ -1,12 +1,15 @@
 define([
 'libs/jquery-1.9.1.min',
 'libs/underscore-min',
 define([
 'libs/jquery-1.9.1.min',
 'libs/underscore-min',
-'modules/documentCanvas/canvas/documentElement'
-], function($, _, documentElement) {
+'libs/backbone-min',
+'modules/documentCanvas/canvas/documentElement',
+'modules/documentCanvas/canvas/utils'
+], function($, _, Backbone, documentElement, utils) {
     
 'use strict';
 
 var Canvas = function(wlxml, publisher) {
     
 'use strict';
 
 var Canvas = function(wlxml, publisher) {
+    this.eventBus = _.extend({}, Backbone.Events);
     this.loadWlxml(wlxml);
     this.publisher = publisher ? publisher : function() {};
 };
     this.loadWlxml(wlxml);
     this.publisher = publisher ? publisher : function() {};
 };
@@ -18,78 +21,317 @@ $.extend(Canvas.prototype, {
         if(d) {
             this.wrapper = $('<div>').addClass('canvas-wrapper').attr('contenteditable', true);
             this.wrapper.append(d);
         if(d) {
             this.wrapper = $('<div>').addClass('canvas-wrapper').attr('contenteditable', true);
             this.wrapper.append(d);
-            
+            var canvas = this;
+
             this.wrapper.find('*').replaceWith(function() {
                 var currentTag = $(this);
                 if(currentTag.attr('wlxml-tag'))
                     return;
             this.wrapper.find('*').replaceWith(function() {
                 var currentTag = $(this);
                 if(currentTag.attr('wlxml-tag'))
                     return;
-                var element = documentElement.DocumentNodeElement.createDOM({
+
+                var meta = {}, others = {};
+                for(var i = 0; i < this.attributes.length; i++) {
+                    var attr = this.attributes[i];
+                    if(attr.name.substr(0, 5) === 'meta-')
+                        meta[attr.name.substr(5)] = attr.value;
+                    else if(attr.name !== 'class')
+                        others[attr.name] = attr.value;
+                }
+
+                var element = documentElement.DocumentNodeElement.create({
                     tag: currentTag.prop('tagName').toLowerCase(),
                     tag: currentTag.prop('tagName').toLowerCase(),
-                    klass: currentTag.attr('class')
+                    klass: currentTag.attr('class'),
+                    meta: meta,
+                    others: others,
+                    rawChildren: currentTag.contents()
+                }, canvas);
+
+                ['orig-before', 'orig-after', 'orig-begin', 'orig-end'].forEach(function(attr) {
+                    element.data(attr, '');
                 });
                 });
-
-                element.append(currentTag.contents());
-                return element;
+                return element.dom();
             });
 
             });
 
+            var FIRST_CONTENT_INDEX = 0;
+
+            // @@ TODO - refactor!
+            var getNode = function(element) {
+                return element.children('[document-element-content]');
+            }
+
             this.wrapper.find(':not(iframe)').addBack().contents()
                 .filter(function() {return this.nodeType === Node.TEXT_NODE})
                 .each(function() {
 
             this.wrapper.find(':not(iframe)').addBack().contents()
                 .filter(function() {return this.nodeType === Node.TEXT_NODE})
                 .each(function() {
 
-                    var el = $(this);
-                    
                     // TODO: use DocumentElement API
                     // TODO: use DocumentElement API
-                    var spanParent = el.parent().attr('wlxml-tag') === 'span',
-                        spanBefore = el.prev().length > 0  && $(el.prev()[0]).attr('wlxml-tag') === 'span',
-                        spanAfter = el.next().length > 0 && $(el.next()[0]).attr('wlxml-tag') === 'span';
-                        
-                    if(spanParent || spanBefore || spanAfter) {
-                        var startSpace = /\s/g.test(this.data.substr(0,1));
-                        var endSpace = /\s/g.test(this.data.substr(-1)) && this.data.length > 1;
-                        var trimmed = $.trim(this.data);
-                        this.data = (startSpace && (spanParent || spanBefore) ? ' ' : '')
-                                    + trimmed
-                                    + (endSpace && (spanParent || spanAfter) ? ' ' : '');
 
 
+                    var el = $(this),
+                        text = {original: el.text(), trimmed: $.trim(el.text())},
+                        elParent = el.parent(),
+                        hasSpanParent = elParent.attr('wlxml-tag') === 'span',
+                        hasSpanBefore = el.prev().length > 0  && getNode($(el.prev()[0])).attr('wlxml-tag') === 'span',
+                        hasSpanAfter = el.next().length > 0 && getNode($(el.next()[0])).attr('wlxml-tag') === 'span';
+
+                    if(el.parent().hasClass('canvas-widget'))
+                        return true; // continue
+
+                    var addInfo = function(toAdd, where) {
+                        var parentContents = elParent.contents(),
+                            idx = parentContents.index(el[0]),
+                            prev = idx > FIRST_CONTENT_INDEX ? parentContents[idx-1] : null,
+                            next = idx < parentContents.length - 1 ? parentContents[idx+1] : null,
+                            target, key;
+
+                        if(where === 'above') {
+                            target = prev ? $(prev) : elParent.parent();
+                            key = prev ? 'orig-after' : 'orig-begin';
+                        } else if(where === 'below') {
+                            target = next ? $(next) : elParent.parent();
+                            key = next ? 'orig-before' : 'orig-end';
+                        } else { throw new Object;}
+
+                        target.data(key, toAdd);
+                    }
+
+                    text.transformed = text.trimmed;
+                    
+                    if(hasSpanParent || hasSpanBefore || hasSpanAfter) {
+                        var startSpace = /\s/g.test(text.original.substr(0,1)),
+                            endSpace = /\s/g.test(text.original.substr(-1)) && text.original.length > 1;
+                        text.transformed = (startSpace && (hasSpanParent || hasSpanBefore) ? ' ' : '')
+                                    + text.trimmed
+                                    + (endSpace && (hasSpanParent || hasSpanAfter) ? ' ' : '');
                     } else {
                     } else {
-                        var oldLength = this.data.length;
-                        this.data = $.trim(this.data);
-                        if(this.data.length === 0 && oldLength > 0 && el.parent().contents().length === 1)
-                            this.data = ' ';
-                        if(this.data.length === 0) {
-                            $(this).remove();
-                            return true; // continue
+                        if(text.trimmed.length === 0 && text.original.length > 0 && elParent.contents().length === 1)
+                            text.transformed = ' ';
+                    }
+
+                    if(!text.transformed) {
+                        addInfo(text.original, 'below');
+                        el.remove();
+                        return true; // continue
+                    }
+
+                    if(text.transformed !== text.original) {
+                        if(!text.trimmed) {
+                            addInfo(text.original, 'below');
+                        } else {
+                            var startingMatch = text.original.match(/^\s+/g),
+                                endingMatch = text.original.match(/\s+$/g),
+                                startingWhiteSpace = startingMatch ? startingMatch[0] : null,
+                                endingWhiteSpace = endingMatch ? endingMatch[0] : null;
+
+                            if(endingWhiteSpace) {
+                                if(text.transformed[text.transformed.length - 1] === ' ' && endingWhiteSpace[0] === ' ')
+                                    endingWhiteSpace = endingWhiteSpace.substr(1);
+                                addInfo(endingWhiteSpace, 'below');
+                            }
+
+                            if(startingWhiteSpace) {
+                                if(text.transformed[0] === ' ' && startingWhiteSpace[startingWhiteSpace.length-1] === ' ')
+                                    startingWhiteSpace = startingWhiteSpace.substr(0, startingWhiteSpace.length -1);
+                                addInfo(startingWhiteSpace, 'above');
+                            }
                         }
                     }
 
                         }
                     }
 
-                    var element = documentElement.DocumentTextElement.create({text: this.data});
-                    $(this).replaceWith(element.dom());
+                    var element = documentElement.DocumentTextElement.create({text: text.transformed});
+                    el.replaceWith(element.dom());
                 });
             
             this.d = this.wrapper.children(0);
 
                 });
             
             this.d = this.wrapper.children(0);
 
-            var canvas = this;
+            var KEYS = {
+                ENTER: 13,
+                ARROW_LEFT: 37,
+                ARROW_UP: 38,
+                ARROW_RIGHT: 39,
+                ARROW_DOWN: 40,
+                BACKSPACE: 8,
+                DELETE: 46,
+                X: 88
+            }
+
+            this.wrapper.on('keyup', function(e) {
+                if(e.which >= 37 && e.which <= 40) {
+                    var element = canvas.getCursor().getPosition().element,
+                        caretTo = false;
+                    if(!element) {
+                        // Chrome hack
+                        var direction;
+                        if(e.which === KEYS.ARROW_LEFT  || e.which === KEYS.ARROW_UP) {
+                            direction = 'above';
+                            caretTo = 'end';
+                        } else {
+                            direction = 'below';
+                            caretTo = 'start';
+                        }
+                        element = canvas.getDocumentElement(utils.nearestInDocumentOrder('[document-text-element]:visible', direction, window.getSelection().focusNode));
+                    }
+                    canvas.setCurrentElement(element, {caretTo: caretTo});
+                }
+            });
+         
             this.wrapper.on('keydown', function(e) {
             this.wrapper.on('keydown', function(e) {
-                if(e.which === 13) { 
+                var cursor = canvas.getCursor(),
+                    position = canvas.getCursor().getPosition(),
+                    element = position.element;
+                if(e.which >= 37 && e.which <= 40) {
+
+                    if(element && (element instanceof documentElement.DocumentTextElement)) {
+                        if(element.isEmpty()) {
+                            var direction, caretTo;
+                            if(e.which === KEYS.ARROW_LEFT  || e.which === KEYS.ARROW_UP) {
+                                direction = 'above';
+                                caretTo = 'end';
+                            } else {
+                                direction = 'below';
+                                caretTo = 'start';
+                            }
+                            var el = canvas.getDocumentElement(utils.nearestInDocumentOrder('[document-text-element]', direction, window.getSelection().focusNode))
+                            canvas.setCurrentElement(element, {caretTo: caretTo});
+                        } else {
+                            var txt = element.dom().contents()[0].data;
+                            if(e.which === KEYS.ARROW_LEFT && position.offset > 1 && txt.charAt(position.offset-2) === utils.unicode.ZWS) {
+                                e.preventDefault();
+                                canvas._moveCaretToTextElement(element, position.offset-2);
+                            }
+                            if(e.which === KEYS.ARROW_RIGHT && position.offset < txt.length - 1 && txt.charAt(position.offset+1) === utils.unicode.ZWS) {
+                                e.preventDefault();
+                                canvas._moveCaretToTextElement(element, position.offset+2);
+                            }
+                        }
+                    }
+
+
+                }
+
+                var selectsWholeTextElement = function() {
+                    if(cursor.isSelecting() && cursor.getSelectionStart().offsetAtBeginning && cursor.getSelectionEnd().offsetAtEnd)
+                        return true;
+                    return false;
+                }
+
+                if(e.which === KEYS.X && e.ctrlKey && selectsWholeTextElement()) {
+                    e.preventDefault();
+                }
+
+                if(e.which === KEYS.BACKSPACE || e.which === KEYS.DELETE) {
+                    if(cursor.isSelecting() && !cursor.isSelectingWithinElement()) {
+                        e.preventDefault();
+                        return;
+                    }
+                        
+                    var cursorAtOperationEdge = position.offsetAtBeginning;
+                    if(e.which === KEYS.DELETE) {
+                        cursorAtOperationEdge = position.offsetAtEnd;
+                    }
+
+                    if(element.getText().length === 1 || selectsWholeTextElement()) {
+                        e.preventDefault();
+                        element.setText('');
+                    }
+                    else if(element.isEmpty()) {
+
+                        var direction = 'above',
+                            caretTo = 'end';
+                            
+                        if(e.which === KEYS.DELETE) {
+                            direction = 'below';
+                            caretTo = 'start';
+                        }
+
+                        e.preventDefault();
+
+                        var parent = element.parent(),
+                            grandParent = parent ? parent.parent() : null,
+                            goto;
+                        if(parent.children().length === 1) {
+                            if(grandParent && grandParent.children().length === 1) {
+                                goto = grandParent.append({text: ''});
+                            } else {
+                                goto = canvas.getDocumentElement(utils.nearestInDocumentOrder('[document-text-element]', direction, element.dom()[0]));
+                            }
+                            parent.detach();
+                        } else {
+                            goto = canvas.getDocumentElement(utils.nearestInDocumentOrder('[document-text-element]', direction, element.dom()[0]));
+                            element.detach();
+                        }
+                        canvas.setCurrentElement(goto, {caretTo: caretTo});
+                    }
+                    else if(cursorAtOperationEdge) {
+                        // todo
+                        e.preventDefault();
+                    }
+                }
+
+                if(e.which === KEYS.ENTER) {
                     e.preventDefault();
                     var cursor = canvas.getCursor();
                     if(!cursor.isSelecting()) {
                     e.preventDefault();
                     var cursor = canvas.getCursor();
                     if(!cursor.isSelecting()) {
-                        var position = cursor.getPosition();
-                        position.element.split({offset: position.offset});
+                        var position = cursor.getPosition(),
+                            element = position.element;
+
+                        if(!(element.parent().parent())) {
+                            return false; // top level element is unsplittable
+                        }
+
+                        var elements = position.element.split({offset: position.offset}),
+                            newEmpty,
+                            goto;
+
+                        if(position.offsetAtBeginning)
+                            newEmpty = elements.first;
+                        else if(position.offsetAtEnd)
+                            newEmpty = elements.second;
+                        if(newEmpty) {
+                            goto = newEmpty.append(documentElement.DocumentTextElement.create({text: ''}, this));
+                            canvas.setCurrentElement(goto);
+                        }
                     }
                 }
             });
 
                     }
                 }
             });
 
-            this.wrapper.on('keyup', function(e) {
-                if(e.which >= 37 && e.which <= 40)
-                    canvas.setCurrentElement(canvas.getCursor().getPosition().element, {caretTo: false})
+            this.wrapper.on('click', '[document-node-element], [document-text-element]', function(e) {
+                e.stopPropagation();
+                canvas.setCurrentElement(canvas.getDocumentElement(e.currentTarget), {caretTo: false});
             });
 
             });
 
-            this.wrapper.on('click', '[wlxml-tag], [wlxml-text]', function(e) {
+            var observer = new MutationObserver(function(mutations) {
+                mutations.forEach(function(mutation) {
+                    if(documentElement.DocumentTextElement.isContentContainer(mutation.target) && mutation.target.data === '')
+                        mutation.target.data = utils.unicode.ZWS;
+                });
+            });
+            var config = { attributes: false, childList: false, characterData: true, subtree: true, characterDataOldValue: true};
+            observer.observe(this.d[0], config);
+
+
+            this.wrapper.on('mouseover', '[document-node-element], [document-text-element]', function(e) {
+                var el = canvas.getDocumentElement(e.currentTarget);
+                if(!el)
+                    return;
+                e.stopPropagation();
+                if(el instanceof documentElement.DocumentTextElement)
+                    el = el.parent();
+                el.toggleLabel(true);
+            });
+            this.wrapper.on('mouseout', '[document-node-element], [document-text-element]', function(e) {
+                var el = canvas.getDocumentElement(e.currentTarget);
+                if(!el)
+                    return;
                 e.stopPropagation();
                 e.stopPropagation();
-                canvas.setCurrentElement(canvas.getDocumentElement(e.target), {caretTo: false});
+                if(el instanceof documentElement.DocumentTextElement)
+                    el = el.parent();
+                el.toggleLabel(false);
             });
 
             });
 
+            this.eventBus.on('elementToggled', function(toggle, element) {
+                if(!toggle) {
+                    element = canvas.getDocumentElement(utils.nearestInDocumentOrder('[document-text-element]:visible', 'above', element.dom()[0]));
+                    canvas.setCurrentElement(element);
+                }
+            })
+
         } else {
             this.d = null;
         }
         } else {
             this.d = null;
         }
@@ -145,6 +387,59 @@ $.extend(Canvas.prototype, {
             wrapperElement.after({text: suffixOutside});
         return wrapperElement;
     },
             wrapperElement.after({text: suffixOutside});
         return wrapperElement;
     },
+
+    wrapElements: function(params) {
+        if(!(params.element1.parent().sameNode(params.element2.parent())))
+            return;
+
+        var parent = params.element1.parent(),
+            parentChildren = parent.children(),
+            wrapper = documentElement.DocumentNodeElement.create({
+                tag: params._with.tag,
+                klass: params._with.klass}),
+            idx1 = parent.childIndex(params.element1),
+            idx2 = parent.childIndex(params.element2);
+
+        if(idx1 > idx2) {
+            var tmp = idx1;
+            idx1 = idx2;
+            idx2 = tmp;
+        }
+
+        var insertingMethod, insertingTarget;
+        if(idx1 === 0) {
+            insertingMethod = 'prepend';
+            insertingTarget = parent;
+        } else {
+            insertingMethod = 'after';
+            insertingTarget = parentChildren[idx1-1];
+        }
+
+        for(var i = idx1; i <= idx2; i++) {
+            wrapper.append(parentChildren[i].detach());
+        }
+
+        insertingTarget[insertingMethod](wrapper);
+        return wrapper;
+    },
+
+    getSiblingParents: function(params) {
+        var parents1 = [params.element1].concat(params.element1.parents()).reverse(),
+            parents2 = [params.element2].concat(params.element2.parents()).reverse(),
+            noSiblingParents = null;
+
+        if(parents1.length === 0 || parents2.length === 0 || !(parents1[0].sameNode(parents2[0])))
+            return noSiblingParents;
+
+        var i;
+        for(i = 0; i < Math.min(parents1.length, parents2.length); i++) {
+            if(parents1[i].sameNode(parents2[i]))
+                continue;
+            break;
+        }
+        return {element1: parents1[i], element2: parents2[i]};
+    },
+
     getDocumentElement: function(from) {
         if(from instanceof HTMLElement || from instanceof Text) {
            return documentElement.DocumentElement.fromHTMLElement(from, this);
     getDocumentElement: function(from) {
         if(from instanceof HTMLElement || from instanceof Text) {
            return documentElement.DocumentElement.fromHTMLElement(from, this);
@@ -156,19 +451,9 @@ $.extend(Canvas.prototype, {
 
     list: {},
 
 
     list: {},
 
-
-
-    highlightElement: function(element) {
-        this.wrapper.find('.highlighted-element').removeClass('highlighted-element');
-        element.dom().addClass('highlighted-element');
-    },
-
-    dimElement: function(element) {
-        element.dom().removeClass('highlighted-element');
-    },
     
     getCurrentNodeElement: function() {
     
     getCurrentNodeElement: function() {
-        return this.getDocumentElement(this.wrapper.find('.current-node-element')[0]);
+        return this.getDocumentElement(this.wrapper.find('.current-node-element').parent()[0]);
     },
 
     getCurrentTextElement: function() {
     },
 
     getCurrentTextElement: function() {
@@ -196,7 +481,7 @@ $.extend(Canvas.prototype, {
                 element.dom().addClass('current-text-element');
             } else {
                 this.wrapper.find('.current-node-element').removeClass('current-node-element')
                 element.dom().addClass('current-text-element');
             } else {
                 this.wrapper.find('.current-node-element').removeClass('current-node-element')
-                element.dom().addClass('current-node-element');
+                element._container().addClass('current-node-element');
                 this.publisher('currentElementChanged', element);
             }
         }.bind(this);
                 this.publisher('currentElementChanged', element);
             }
         }.bind(this);
@@ -216,7 +501,7 @@ $.extend(Canvas.prototype, {
             if(params.caretTo || !textElementToLand.sameNode(this.getCursor().getPosition().element))
                 this._moveCaretToTextElement(textElementToLand, params.caretTo); // as method on element?
             if(!(textElementToLand.sameNode(currentTextElement)))
             if(params.caretTo || !textElementToLand.sameNode(this.getCursor().getPosition().element))
                 this._moveCaretToTextElement(textElementToLand, params.caretTo); // as method on element?
             if(!(textElementToLand.sameNode(currentTextElement)))
-                this.publisher('currentTextElementSet', element);
+                this.publisher('currentTextElementSet', textElementToLand);
         } else {
             document.getSelection().removeAllRanges();
         }
         } else {
             document.getSelection().removeAllRanges();
         }
@@ -253,6 +538,13 @@ $.extend(Canvas.prototype, {
     setCursorPosition: function(position) {
         if(position.element)
             this._moveCaretToTextElement(position.element, position.offset);
     setCursorPosition: function(position) {
         if(position.element)
             this._moveCaretToTextElement(position.element, position.offset);
+    },
+
+    toXML: function() {
+        var parent = $('<div>'),
+            parts = this.doc().toXML(0);
+        parent.append(parts);
+        return parent.html();
     }
 });
 
     }
 });
 
@@ -414,18 +706,48 @@ $.extend(Cursor.prototype, {
     getSelectionAnchor: function() {
         return this.getSelectionBoundry('anchor');
     },
     getSelectionAnchor: function() {
         return this.getSelectionBoundry('anchor');
     },
+    getSelectionFocus: function() {
+        return this.getSelectionBoundry('focus');
+    },
     getSelectionBoundry: function(which) {
         var selection = window.getSelection(),
             anchorElement = this.canvas.getDocumentElement(selection.anchorNode),
             focusElement = this.canvas.getDocumentElement(selection.focusNode);
         
     getSelectionBoundry: function(which) {
         var selection = window.getSelection(),
             anchorElement = this.canvas.getDocumentElement(selection.anchorNode),
             focusElement = this.canvas.getDocumentElement(selection.focusNode);
         
-        if(anchorElement instanceof documentElement.DocumentNodeElement || focusElement instanceof documentElement.DocumentNodeElement)
+        var getOffset = function(where) {
+            var toret, node;
+            if(where === 'anchor') {
+                node = selection.anchorNode;
+                toret = selection.anchorOffset;
+            } else {
+                node = selection.focusNode;
+                toret = selection.focusOffset;
+            }
+                        
+            if(toret === 1 && node.data.charAt(0) === utils.unicode.ZWS)
+                toret = 0;
+            else if((toret === node.data.length - 1) && (node.data.charAt(node.data.length - 1) === utils.unicode.ZWS))
+                toret++;
+            return toret;
+        }
+
+        if((!anchorElement) || (anchorElement instanceof documentElement.DocumentNodeElement) || (!focusElement) || focusElement instanceof documentElement.DocumentNodeElement)
             return {};
 
         if(which === 'anchor') {
             return {
                 element: anchorElement,
             return {};
 
         if(which === 'anchor') {
             return {
                 element: anchorElement,
-                offset: selection.anchorOffset
+                offset: getOffset('anchor'),
+                offsetAtBeginning: getOffset('anchor') === 0,
+                offsetAtEnd: selection.anchorNode.data.length === getOffset('anchor')
+            };
+        }
+        if(which === 'focus') {
+            return {
+                element: focusElement,
+                offset: getOffset('focus'),
+                offsetAtBeginning: getOffset('focus') === 0,
+                offsetAtEnd: selection.focusNode.data.length === getOffset('focus')
             };
         }
         
             };
         }
         
@@ -438,36 +760,39 @@ $.extend(Cursor.prototype, {
             if(anchorFirst) {
                 if(which === 'start') {
                     element = anchorElement;
             if(anchorFirst) {
                 if(which === 'start') {
                     element = anchorElement;
-                    offset = selection.anchorOffset;
+                    offset = getOffset('anchor')
                 }
                 else if(which === 'end') {
                     element = focusElement,
                 }
                 else if(which === 'end') {
                     element = focusElement,
-                    offset = selection.focusOffset;
+                    offset = getOffset('focus')
                 }
             } else {
                 if(which === 'start') {
                     element = focusElement,
                 }
             } else {
                 if(which === 'start') {
                     element = focusElement,
-                    offset = selection.focusOffset
+                    offset = getOffset('focus')
                 }
                 else if(which === 'end') {
                     element = anchorElement;
                 }
                 else if(which === 'end') {
                     element = anchorElement;
-                    offset = selection.anchorOffset;
+                    offset = getOffset('anchor')
                 }
             }
         } else {
                 }
             }
         } else {
-            // TODO: Handle order
+            // TODO: Handle order via https://developer.mozilla.org/en-US/docs/Web/API/Node.compareDocumentPosition
             if(which === 'start') {
                 element = anchorElement;
             if(which === 'start') {
                 element = anchorElement;
-                offset = selection.anchorOffset
+                offset = getOffset('anchor')
             } else {
                 element = focusElement;
             } else {
                 element = focusElement;
-                offset = selection.focusOffset
+                offset = getOffset('focus')
             }
         }
 
             }
         }
 
+        var nodeLen = (element.sameNode(focusElement) ? selection.focusNode : selection.anchorNode).length;
         return {
             element: element,
         return {
             element: element,
-            offset: offset
+            offset: offset,
+            offsetAtBeginning: offset === 0,
+            offsetAtEnd: nodeLen === offset
         }
     }
 })
         }
     }
 })