allow customization of stub root for multi-root psi files (CR-IC-1700)

platform/core-api/src/com/intellij/psi/FileViewProvider.java

@@ -100,4 +100,7 @@ public interface FileViewProvider extends Cloneable, UserDataHolder {
 
   @NotNull
   FileViewProvider createCopy(@NotNull VirtualFile copy);
+
+  @NotNull
+  PsiFile getStubBindingRoot();
 }

platform/core-impl/src/com/intellij/psi/DummyHolderViewProvider.java

@@ -162,6 +162,12 @@ public class DummyHolderViewProvider extends UserDataHolderBase implements FileV
     throw new RuntimeException("Clone is not supported for DummyHolderProviders. Use DummyHolder clone directly.");
   }
 
+  @NotNull
+  @Override
+  public PsiFile getStubBindingRoot() {
+    return getPsi(getBaseLanguage());
+  }
+
   @Override
   public PsiElement findElementAt(final int offset) {
     final LeafElement element = ((PsiFileImpl)getPsi(getBaseLanguage())).calcTreeElement().findLeafElementAt(offset);

platform/core-impl/src/com/intellij/psi/SingleRootFileViewProvider.java

@@ -578,4 +578,12 @@ public class SingleRootFileViewProvider extends UserDataHolderBase implements Fi
       return myModificationStamp;
     }
   }
+
+  @NotNull
+  @Override
+  public PsiFile getStubBindingRoot() {
+    final PsiFile psi = getPsi(getBaseLanguage());
+    assert psi != null;
+    return psi;
+  }
 }

platform/core-impl/src/com/intellij/psi/impl/source/PsiFileImpl.java

@@ -257,7 +257,7 @@ public abstract class PsiFileImpl extends ElementBase implements PsiFileEx, PsiF
     }
   }
 
-  protected List<Pair<StubBasedPsiElementBase, CompositeElement>> calcStubAstBindings(final ASTNode root, final Document cachedDocument) {
+  private List<Pair<StubBasedPsiElementBase, CompositeElement>> calcStubAstBindings(final ASTNode root, final Document cachedDocument) {
     final StubTree stubTree = derefStub();
     if (stubTree == null) {
       return Collections.emptyList();
@@ -695,6 +695,12 @@ public abstract class PsiFileImpl extends ElementBase implements PsiFileEx, PsiF
     final VirtualFile vFile = getVirtualFile();
     if (!(vFile instanceof VirtualFileWithId)) return null;
 
+    final PsiFile stubBindingRoot = getViewProvider().getStubBindingRoot();
+    if (stubBindingRoot != this) {
+      LOG.error("Attempted to create stubs for non-root file: " + this + ", stub binding root: " + stubBindingRoot);
+      return null;
+    }
+
     ObjectStubTree tree = StubTreeLoader.getInstance().readOrBuild(getProject(), vFile, this);
     if (!(tree instanceof StubTree)) return null;
     StubTree stubHolder = (StubTree)tree;

platform/core-impl/src/com/intellij/psi/stubs/StubTreeBuilder.java

@@ -56,6 +56,7 @@ public class StubTreeBuilder {
         final IFileElementType type = LanguageParserDefinitions.INSTANCE.forLanguage(l).getFileNodeType();
 
         PsiFile psi = inputData.getPsiFile();
+        psi = psi.getViewProvider().getStubBindingRoot();
         CharSequence contentAsText = inputData.getContentAsText();
         psi.putUserData(IndexingDataKeys.FILE_TEXT_CONTENT_KEY, contentAsText);
 

platform/indexing-impl/src/com/intellij/psi/stubs/StubProcessingHelperBase.java

@@ -34,10 +34,11 @@ public abstract class StubProcessingHelperBase {
   public <Psi extends PsiElement> boolean processStubsInFile(final Project project, final VirtualFile file, StubIdList value, final Processor<? super Psi> processor) {
     StubTree stubTree = null;
 
-    final PsiFile _psifile = PsiManager.getInstance(project).findFile(file);
+    PsiFile _psifile = PsiManager.getInstance(project).findFile(file);
     PsiFileWithStubSupport psiFile = null;
 
     if (_psifile != null && !(_psifile instanceof PsiPlainTextFile)) {
+      _psifile = _psifile.getViewProvider().getStubBindingRoot();
       if (_psifile instanceof PsiFileWithStubSupport) {
         psiFile = (PsiFileWithStubSupport)_psifile;
         stubTree = psiFile.getStubTree();