addFold must not throw if new fold is inside the existing one

lib/ace/edit_session/fold.js

@@ -74,6 +74,42 @@ var Fold = exports.Fold = function(range, placeholder) {
         return fold;
     };
 
+    this.addSubFold = function(fold) {
+        if (this.range.isEequal(fold))
+            return this;
+
+        if (!this.range.containsRange(fold))
+            throw "A fold can't intersect already existing fold" + fold.range + this.range;
+
+        var row = fold.range.start.row, column = fold.range.start.column;
+        for (var i = 0, cmp = -1; i < this.subFolds.length; i++) {
+            cmp = this.subFolds[i].range.compare(row, column);
+            if (cmp != 1)
+                break;
+        }
+        var afterStart = this.subFolds[i];
+
+        if (cmp == 0)
+            return afterStart.addSubFold(fold)
+
+        // cmp == -1
+        var row = fold.range.end.row, column = fold.range.end.column;
+        for (var j = i, cmp = -1; j < this.subFolds.length; j++) {
+            cmp = this.subFolds[j].range.compare(row, column);
+            if (cmp != 1)
+                break;
+        }
+        var afterEnd = this.subFolds[j];
+
+        if (cmp == 0)
+            throw "A fold can't intersect already existing fold" + fold.range + this.range;
+
+        var consumedFolds = this.subFolds.splice(i, j - i, fold)
+        fold.setFoldLine(this.foldLine);
+
+        return fold;
+    }
+
 }).call(Fold.prototype);
 
 });

lib/ace/edit_session/fold_line.js

@@ -41,7 +41,7 @@ define(function(require, exports, module) {
 var Range = require("../range").Range;
 
 /**
- * If the an array is passed in, the folds are expected to be sorted already.
+ * If an array is passed in, the folds are expected to be sorted already.
  */
 function FoldLine(foldData, folds) {
     this.foldData = foldData;

lib/ace/edit_session/folding.js

@@ -247,6 +247,8 @@ function Folding() {
         else
             fold = new Fold(range, placeholder);
 
+        this.$clipRangeToDocument(fold.range);
+
         var startRow = fold.start.row;
         var startColumn = fold.start.column;
         var endRow = fold.end.row;
@@ -259,29 +261,18 @@ function Folding() {
         if (startRow == endRow && endColumn - startColumn < 2)
             throw "The range has to be at least 2 characters width";
 
-        var existingFold = this.getFoldAt(startRow, startColumn, 1);
+        var startFold = this.getFoldAt(startRow, startColumn, 1);
+        var endFold = this.getFoldAt(endRow, endColumn, -1);
+        if (startFold && endFold == startFold)
+            return startFold.addSubFold(fold);
+
         if (
-            existingFold
-            && existingFold.range.isEnd(endRow, endColumn)
-            && existingFold.range.isStart(startRow, startColumn)
+            (startFold && !startFold.range.isStart(startRow, startColumn))
+            || (endFold && !endFold.range.isEnd(endRow, endColumn))
         ) {
-            return fold;
+            throw "A fold can't intersect already existing fold" + fold.range + startFold.range;
         }
 
-        existingFold = this.getFoldAt(startRow, startColumn, 1);
-        if (existingFold && !existingFold.range.isStart(startRow, startColumn))
-            throw "A fold can't start inside of an already existing fold";
-
-        existingFold = this.getFoldAt(endRow, endColumn, -1);
-        if (existingFold && !existingFold.range.isEnd(endRow, endColumn))
-            throw "A fold can't end inside of an already existing fold";
-
-        if (endRow >= this.doc.getLength())
-            throw "End of fold is outside of the document.";
-
-        if (endColumn > this.getLine(endRow).length || startColumn > this.getLine(startRow).length)
-            throw "End of fold is outside of the document.";
-
         // Check if there are folds in the range we create the new fold for.
         var folds = this.getFoldsInRange(fold.range);
         if (folds.length > 0) {