smart pointers on import lists should survive adding new imports (IDEA-161409)

java/java-impl/src/com/intellij/psi/impl/smartPointers/JavaAnchorProvider.java

@@ -30,16 +30,14 @@ public class JavaAnchorProvider extends SmartPointerAnchorProvider {
       return null;
     }
 
-    if (element instanceof PsiClass) {
-      if (element instanceof PsiAnonymousClass) {
-        return ((PsiAnonymousClass)element).getBaseClassReference().getReferenceNameElement();
-      } else {
-        return ((PsiClass)element).getNameIdentifier();
-      }
-    } else if (element instanceof PsiMethod) {
-      return ((PsiMethod)element).getNameIdentifier();
-    } else if (element instanceof PsiVariable) {
-      return ((PsiVariable)element).getNameIdentifier();
+    if (element instanceof PsiAnonymousClass) {
+      return ((PsiAnonymousClass)element).getBaseClassReference().getReferenceNameElement();
+    }
+    if (element instanceof PsiClass || element instanceof PsiMethod || element instanceof PsiVariable) {
+      return ((PsiNameIdentifierOwner)element).getNameIdentifier();
+    }
+    if (element instanceof PsiImportList) {
+      return element.getContainingFile();
     }
     return null;
   }
@@ -55,6 +53,9 @@ public class JavaAnchorProvider extends SmartPointerAnchorProvider {
 
       return parent;
     }
+    if (anchor instanceof PsiJavaFile) {
+      return ((PsiJavaFile)anchor).getImportList();
+    }
     return null;
   }
 }

java/java-tests/testSrc/com/intellij/codeInsight/folding/JavaFoldingTest.groovy

@@ -996,7 +996,7 @@ class Foo {
     assertTopLevelFoldRegionsState "[FoldRegion +(49:92), placeholder='otherMethod() → { ', FoldRegion +(113:123), placeholder=' }']"
   }
 
-  public void "disabled - test imports remain collapsed when new item is added at the end"() {
+  public void "test imports remain collapsed when new item is added at the end"() {
     boolean oldValue = CodeInsightSettings.getInstance().ADD_UNAMBIGIOUS_IMPORTS_ON_THE_FLY
     CodeInsightSettings.getInstance().ADD_UNAMBIGIOUS_IMPORTS_ON_THE_FLY = true
     DaemonCodeAnalyzerSettings.getInstance().setImportHintEnabled(true); // tests disable this by default

java/java-tests/testSrc/com/intellij/psi/impl/smartPointers/SmartPsiElementPointersTest.java

@@ -931,4 +931,26 @@ public class SmartPsiElementPointersTest extends CodeInsightTestCase {
     assertFalse(createPointer(clazz).hashCode() == createPointer(clazz.getMethods()[0]).hashCode());
   }
 
+  public void testImportListPointerSurvivesImportAddition() throws Exception {
+    PsiJavaFile file = (PsiJavaFile)createFile("a.java", "import foo.Bar;\nclass Foo {}");
+    SmartPointerEx<PsiImportList> pointer = createPointer(file.getImportList());
+    Document document = file.getViewProvider().getDocument();
+    
+    WriteCommandAction.runWriteCommandAction(myProject, () -> {
+      document.insertString(document.getText().indexOf("class"), "import foo.Goo;\n");
+      PsiDocumentManager.getInstance(myProject).commitAllDocuments();
+    });
+    assertEquals(file.getImportList(), pointer.getElement());
+    assertSize(2, file.getImportList().getImportStatements());
+
+    WriteCommandAction.runWriteCommandAction(myProject, () -> {
+      document.insertString(0, " ");
+      PsiDocumentManager.getInstance(myProject).commitAllDocuments();
+      document.deleteString(0, document.getText().indexOf("\nimport"));
+      PsiDocumentManager.getInstance(myProject).commitAllDocuments();
+    });
+    assertEquals(file.getImportList(), pointer.getElement());
+    assertSize(1, file.getImportList().getImportStatements());
+  }
+
 }

platform/core-impl/src/com/intellij/psi/impl/smartPointers/AnchorElementInfo.java

@@ -36,7 +36,6 @@ class AnchorElementInfo extends SelfElementInfo {
 
   AnchorElementInfo(@NotNull PsiElement anchor, @NotNull PsiFile containingFile, Identikit.ByAnchor identikit) {
     super(containingFile.getProject(), ProperTextRange.create(anchor.getTextRange()), identikit, containingFile, false);
-    assert !(anchor instanceof PsiFile) : "FileElementInfo must be used for file: "+anchor;
     myStubElementTypeAndId = pack(-1, null);
   }
   // will restore by stub index until file tree get loaded

platform/core-impl/src/com/intellij/psi/impl/smartPointers/Identikit.java

@@ -22,6 +22,7 @@ import com.intellij.openapi.util.TextRange;
 import com.intellij.psi.PsiElement;
 import com.intellij.psi.PsiFile;
 import com.intellij.psi.tree.IElementType;
+import com.intellij.psi.tree.IFileElementType;
 import com.intellij.psi.util.PsiTreeUtil;
 import com.intellij.psi.util.PsiUtilCore;
 import com.intellij.util.containers.WeakInterner;
@@ -41,6 +42,8 @@ public abstract class Identikit {
   @NotNull
   public abstract Language getFileLanguage();
 
+  public abstract boolean isForPsiFile();
+
   public static ByType fromPsi(@NotNull PsiElement element, @NotNull Language fileLanguage) {
     return fromTypes(element.getClass(), PsiUtilCore.getElementType(element), fileLanguage);
   }
@@ -156,6 +159,11 @@ public abstract class Identikit {
       return myFileLanguage;
     }
 
+    @Override
+    public boolean isForPsiFile() {
+      return myElementType instanceof IFileElementType;
+    }
+
     private boolean isAcceptable(@NotNull PsiElement element) {
       return myElementClass == element.getClass() && myElementType == PsiUtilCore.getElementType(element);
     }
@@ -204,6 +212,11 @@ public abstract class Identikit {
     public Language getFileLanguage() {
       return myAnchorInfo.getFileLanguage();
     }
+
+    @Override
+    public boolean isForPsiFile() {
+      return myAnchorInfo.isForPsiFile();
+    }
   }
 
 }

platform/core-impl/src/com/intellij/psi/impl/smartPointers/MarkerCache.java

@@ -45,7 +45,7 @@ class MarkerCache {
       o2 = info2.getPsiEndOffset();
       if (o1 != o2) return o1 > o2 ? 1 : -1;
 
-      return (info1.isForInjected() ? 1 : 0) - (info2.isForInjected() ? 1 : 0);
+      return (info1.isGreedy() ? 1 : 0) - (info2.isGreedy() ? 1 : 0);
     }
   };
   private final SmartPointerTracker myPointers;
@@ -83,13 +83,13 @@ class MarkerCache {
     int i = 0;
     while (i < markers.length) {
       SelfElementInfo info = infos.get(i);
-      boolean forInjected = info.isForInjected();
+      boolean greedy = info.isGreedy();
       int start = info.getPsiStartOffset();
       int end = info.getPsiEndOffset();
-      markers[i] = new ManualRangeMarker(start, end, forInjected, forInjected, !forInjected, null);
+      markers[i] = new ManualRangeMarker(start, end, greedy, greedy, !greedy, null);
 
       i++;
-      while (i < markers.length && rangeEquals(infos.get(i), start, end, forInjected)) {
+      while (i < markers.length && rangeEquals(infos.get(i), start, end, greedy)) {
         markers[i] = markers[i - 1];
         i++;
       }
@@ -97,8 +97,8 @@ class MarkerCache {
     return markers;
   }
 
-  private static boolean rangeEquals(SelfElementInfo info, int start, int end, boolean injected) {
-    return start == info.getPsiStartOffset() && end == info.getPsiEndOffset() && injected == info.isForInjected();
+  private static boolean rangeEquals(SelfElementInfo info, int start, int end, boolean greedy) {
+    return start == info.getPsiStartOffset() && end == info.getPsiEndOffset() && greedy == info.isGreedy();
   }
 
   private static UpdatedRanges applyEvents(@NotNull List<DocumentEvent> events, final UpdatedRanges struct) {

platform/core-impl/src/com/intellij/psi/impl/smartPointers/SelfElementInfo.java

@@ -89,8 +89,8 @@ public class SelfElementInfo extends SmartPointerElementInfo {
     return myEndOffset;
   }
 
-  boolean isForInjected() {
-    return myForInjected;
+  boolean isGreedy() {
+    return myForInjected || myIdentikit.isForPsiFile();
   }
 
   @Override