From 5b6c41cdef413bd5c5df388895ec642c05ea4435 Mon Sep 17 00:00:00 2001
From: Aleksey Pivovarov <AMPivovarov@gmail.com>
Date: Tue, 25 Aug 2015 15:02:52 +0300
Subject: [PATCH] merge: fix NPE if UndoManager not found

---
 .../intellij/diff/merge/TextMergeTool.java    | 42 ++++++++-----------
 1 file changed, 17 insertions(+), 25 deletions(-)

diff --git a/platform/diff-impl/src/com/intellij/diff/merge/TextMergeTool.java b/platform/diff-impl/src/com/intellij/diff/merge/TextMergeTool.java
index 26e58ddabf0e..a82a03b741c4 100644
--- a/platform/diff-impl/src/com/intellij/diff/merge/TextMergeTool.java
+++ b/platform/diff-impl/src/com/intellij/diff/merge/TextMergeTool.java
@@ -200,6 +200,7 @@ public class TextMergeTool implements MergeTool {
 
     public class MyThreesideViewer extends ThreesideTextDiffViewerEx {
       @NotNull private final ModifierProvider myModifierProvider;
+      @Nullable private final UndoManager myUndoManager;
 
       // all changes - both applied and unapplied ones
       @NotNull private final List<TextMergeChange> myAllMergeChanges = new ArrayList<TextMergeChange>();
@@ -217,14 +218,17 @@ public class TextMergeTool implements MergeTool {
         super(context, request);
 
         myModifierProvider = new ModifierProvider();
+        myUndoManager = getProject() != null ? UndoManager.getInstance(getProject()) : UndoManager.getGlobalInstance();
 
         DiffUtil.registerAction(new ApplySelectedChangesAction(Side.LEFT, true), myPanel);
         DiffUtil.registerAction(new ApplySelectedChangesAction(Side.RIGHT, true), myPanel);
         DiffUtil.registerAction(new IgnoreSelectedChangesAction(Side.LEFT, true), myPanel);
         DiffUtil.registerAction(new IgnoreSelectedChangesAction(Side.RIGHT, true), myPanel);
 
-        new UndoRedoAction(true).register();
-        new UndoRedoAction(false).register();
+        if (myUndoManager != null) {
+          new UndoRedoAction(true).register();
+          new UndoRedoAction(false).register();
+        }
       }
 
       @Override
@@ -333,10 +337,9 @@ public class TextMergeTool implements MergeTool {
           @Override
           public void run() {
             outputDocument.setText(baseDocument.getCharsSequence());
-            UndoManager undoManager = getProject() != null ? UndoManager.getInstance(getProject()) : UndoManager.getGlobalInstance();
-            if (undoManager != null) {
+            if (myUndoManager != null) {
               DocumentReference ref = DocumentReferenceManager.getInstance().create(outputDocument);
-              undoManager.nonundoableActionPerformed(ref, false);
+              myUndoManager.nonundoableActionPerformed(ref, false);
             }
           }
         });
@@ -513,10 +516,10 @@ public class TextMergeTool implements MergeTool {
           }
         }
 
-        if (!corruptedStates.isEmpty()) {
+        if (!corruptedStates.isEmpty() && myUndoManager != null) {
           // document undo is registered inside onDocumentChange, so our undo() will be called after its undo().
           // thus thus we can avoid checks for isUndoInProgress() (to avoid modification of the same TextMergeChange by this listener)
-          UndoManager.getInstance(getProject()).undoableActionPerformed(new BasicUndoableAction(getEditor(ThreeSide.BASE).getDocument()) {
+          myUndoManager.undoableActionPerformed(new BasicUndoableAction(getEditor(ThreeSide.BASE).getDocument()) {
             @Override
             public void undo() throws UnexpectedUndoException {
               enterBulkChangeUpdateBlock();
@@ -701,10 +704,7 @@ public class TextMergeTool implements MergeTool {
         }
 
         private void registerUndoRedo(final boolean undo) {
-          Project project = getProject();
-          if (project == null) {
-            return;
-          }
+          if (myUndoManager == null) return;
 
           List<TextMergeChange> affectedChanges = getAffectedChanges();
           final List<TextMergeChange.State> states = new ArrayList<TextMergeChange.State>(affectedChanges.size());
@@ -712,7 +712,7 @@ public class TextMergeTool implements MergeTool {
             states.add(change.storeState());
           }
 
-          UndoManager.getInstance(project).undoableActionPerformed(new BasicUndoableAction(myDocument) {
+          myUndoManager.undoableActionPerformed(new BasicUndoableAction(myDocument) {
             @Override
             public void undo() throws UnexpectedUndoException {
               if (undo) restoreStates(states);
@@ -1185,22 +1185,20 @@ public class TextMergeTool implements MergeTool {
 
         @Override
         public void update(AnActionEvent e) {
-          UndoManager undoManager = getUndoManager();
+          assert myUndoManager != null;
           TextEditor textEditor = getTextEditor();
-
-          e.getPresentation().setEnabled(myUndo ? undoManager.isUndoAvailable(textEditor) : undoManager.isRedoAvailable(textEditor));
+          e.getPresentation().setEnabled(myUndo ? myUndoManager.isUndoAvailable(textEditor) : myUndoManager.isRedoAvailable(textEditor));
         }
 
         @Override
         public void actionPerformed(AnActionEvent e) {
-          UndoManager undoManager = getUndoManager();
+          assert myUndoManager != null;
           TextEditor textEditor = getTextEditor();
-
           if (myUndo) {
-            undoManager.undo(textEditor);
+            myUndoManager.undo(textEditor);
           }
           else {
-            undoManager.redo(textEditor);
+            myUndoManager.redo(textEditor);
           }
         }
 
@@ -1209,12 +1207,6 @@ public class TextMergeTool implements MergeTool {
           EditorEx editor = getEditor(ThreeSide.BASE);
           return TextEditorProvider.getInstance().getTextEditor(editor);
         }
-
-        @NotNull
-        private UndoManager getUndoManager() {
-          Project project = getProject();
-          return project != null ? UndoManager.getInstance(project) : UndoManager.getGlobalInstance();
-        }
       }
 
       private class MyDividerPaintable implements DiffDividerDrawUtil.DividerPaintable {