Insert soft tabs to all insertion points

CHANGELOG.md

@@ -5,6 +5,12 @@ Change Log
 3.8.4 (unreleased)
 --------------------------
 
+### Improvements
+
+- Insert soft tabs to all insertion points when typing the tab key.
+
+
+
 ### Fixes
 
 - Fix an issue on macOS 10.13-14 where the application became instabil with some specific actions when the cursor locates the end of the document.

CotEditor/Sources/EditorTextView.swift

@@ -524,10 +524,16 @@ final class EditorTextView: NSTextView, Themable, CurrentLineHighlighting, Multi
             return
         }
         
-        if self.isAutomaticTabExpansionEnabled {
-            let softTab = self.string.softTab(at: self.rangeForUserTextChange.location, tabWidth: self.tabWidth)
+        // insert soft tab
+        if
+            self.isAutomaticTabExpansionEnabled,
+            let insertionRanges = rangesForUserTextChange as? [NSRange]
+        {
+            let softTabs = insertionRanges
+                .map { self.string.softTab(at: $0.location, tabWidth: self.tabWidth) }
             
-            return super.insertText(softTab, replacementRange: self.rangeForUserTextChange)
+           self.replace(with: softTabs, ranges: insertionRanges, selectedRanges: nil)
+           return
         }
         
         super.insertTab(sender)
@@ -1027,16 +1033,7 @@ final class EditorTextView: NSTextView, Themable, CurrentLineHighlighting, Multi
             let blanks = [String](repeating: "", count: ranges.count - multipleTexts.count)
             let strings = multipleTexts + blanks
             
-            var offset = 0
-            let selectedRanges: [NSRange] = zip(ranges, strings).map { (range, string) in
-                let length = string.length
-                let location = range.lowerBound + offset + length
-                offset += length - range.length
-            
-                return NSRange(location: location, length: 0)
-            }
-            
-            return self.replace(with: strings, ranges: ranges, selectedRanges: selectedRanges)
+            return self.replace(with: strings, ranges: ranges, selectedRanges: nil)
         }
         
         return super.readSelection(from: pboard, type: type)

CotEditor/Sources/NSTextView+TextReplacement.swift

@@ -59,6 +59,28 @@ extension NSTextView {
         if let actionName = actionName {
             self.undoManager?.setActionName(actionName)
         }
+
+        // manually calculate the cursor locations after the replacement for multiple insertions
+        let selectedRanges: [NSRange]? = {
+            // use ones when explicitly specified
+            if let selectedRanges = selectedRanges { return selectedRanges }
+            
+            // let NSTextView culculate by single insertion editing
+            guard
+                let insertionRanges = self.rangesForUserTextChange as? [NSRange],
+                insertionRanges.count > 1,
+                insertionRanges == ranges
+                else { return nil }
+            
+            var offset = 0
+            return zip(ranges, strings).map { (range, string) in
+                let length = string.length
+                let location = range.lowerBound + offset + length
+                offset += length - range.length
+            
+                return NSRange(location: location, length: 0)
+            }
+        }()
         
         textStorage.beginEditing()
         // use a backward enumeration to skip adjustment of applying location