Add ability to extend fileReference completion for particular references

platform/analysis-impl/src/com/intellij/psi/impl/source/resolve/reference/impl/providers/FileReferenceResolver.java

@@ -1,10 +1,29 @@
+/*
+ * Copyright 2000-2016 JetBrains s.r.o.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
 package com.intellij.psi.impl.source.resolve.reference.impl.providers;
 
 import com.intellij.psi.PsiFileSystemItem;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
+import java.util.Collection;
+
 public interface FileReferenceResolver {
   @Nullable
   PsiFileSystemItem resolveFileReference(@NotNull FileReference reference, @NotNull String name);
+
+  Collection<Object> getVariants(@NotNull FileReference reference);
 }

platform/lang-impl/src/com/intellij/psi/impl/source/resolve/reference/impl/providers/FileReferenceCompletionImpl.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2000-2013 JetBrains s.r.o.
+ * Copyright 2000-2016 JetBrains s.r.o.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -26,6 +26,7 @@ import com.intellij.psi.util.PsiUtilCore;
 import com.intellij.util.ArrayUtil;
 import com.intellij.util.CommonProcessors;
 import com.intellij.util.FilteringProcessor;
+import com.intellij.util.containers.ContainerUtil;
 import gnu.trove.THashSet;
 import gnu.trove.TObjectHashingStrategy;
 import org.jetbrains.annotations.NotNull;
@@ -76,17 +77,23 @@ public class FileReferenceCompletionImpl extends FileReferenceCompletion {
           FileReference.getOriginalFile(fileSystemItem));
       }
     };
+    
+    List<Object> additionalItems = ContainerUtil.newArrayList();
     for (PsiFileSystemItem context : reference.getContexts()) {
       for (final PsiElement child : context.getChildren()) {
         if (child instanceof PsiFileSystemItem) {
           processor.execute((PsiFileSystemItem)child);
         }
       }
+      if (context instanceof FileReferenceResolver) {
+        additionalItems.addAll(((FileReferenceResolver)context).getVariants(reference));
+      }
     }
+
     final THashSet<PsiElement> set = new THashSet<PsiElement>(collector.getResults(), VARIANTS_HASHING_STRATEGY);
     final PsiElement[] candidates = PsiUtilCore.toPsiElementArray(set);
 
-    final Object[] variants = new Object[candidates.length];
+    final Object[] variants = new Object[candidates.length + additionalItems.size()];
     for (int i = 0; i < candidates.length; i++) {
       PsiElement candidate = candidates[i];
       Object item = reference.createLookupItem(candidate);
@@ -95,10 +102,14 @@ public class FileReferenceCompletionImpl extends FileReferenceCompletion {
       }
       variants[i] = item;
     }
+    
+    for (int i = 0; i < additionalItems.size(); i++) {
+      variants[i + candidates.length] = additionalItems.get(i);
+    }
     if (!reference.getFileReferenceSet().isUrlEncoded()) {
       return variants;
     }
-    List<Object> encodedVariants = new ArrayList<Object>(variants.length);
+    List<Object> encodedVariants = new ArrayList<Object>(variants.length + additionalItems.size());
     for (int i = 0; i < candidates.length; i++) {
       final PsiElement element = candidates[i];
       if (element instanceof PsiNamedElement) {
@@ -116,6 +127,7 @@ public class FileReferenceCompletionImpl extends FileReferenceCompletion {
         }
       }
     }
+    encodedVariants.addAll(additionalItems);
     return ArrayUtil.toObjectArray(encodedVariants);
   }
 }

xml/xml-psi-impl/src/com/intellij/psi/impl/source/html/HtmlFileImpl.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2000-2009 JetBrains s.r.o.
+ * Copyright 2000-2016 JetBrains s.r.o.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -31,6 +31,9 @@ import com.intellij.psi.xml.XmlElementType;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
+import java.util.Collection;
+import java.util.Collections;
+
 /**
  * @author maxim
  */
@@ -91,4 +94,9 @@ public class HtmlFileImpl extends XmlFileImpl implements FileReferenceResolver {
       return getManager().findFile(childFile);
     }
   }
+
+  @Override
+  public Collection<Object> getVariants(@NotNull FileReference reference) {
+    return Collections.emptyList();
+  }
 }