From 99a028b295299c73568ee3f2e37422a5f5df30b0 Mon Sep 17 00:00:00 2001
From: Nicolay Mitropolsky <nicolay.mitropolsky@jetbrains.com>
Date: Wed, 19 Apr 2017 13:32:15 +0300
Subject: [PATCH] `MetaAnnotationUtil.findMetaAnnotations` now is lazy.

---
 .../codeInsight/MetaAnnotationUtil.java       | 25 +++++++++----------
 1 file changed, 12 insertions(+), 13 deletions(-)

diff --git a/java/openapi/src/com/intellij/codeInsight/MetaAnnotationUtil.java b/java/openapi/src/com/intellij/codeInsight/MetaAnnotationUtil.java
index 5b2e63bca38c..911a7d2695be 100644
--- a/java/openapi/src/com/intellij/codeInsight/MetaAnnotationUtil.java
+++ b/java/openapi/src/com/intellij/codeInsight/MetaAnnotationUtil.java
@@ -26,7 +26,6 @@ import com.intellij.psi.search.GlobalSearchScope;
 import com.intellij.psi.search.searches.AnnotatedElementsSearch;
 import com.intellij.psi.search.searches.DirectClassInheritorsSearch;
 import com.intellij.psi.util.*;
-import com.intellij.util.SmartList;
 import com.intellij.util.containers.ConcurrentFactoryMap;
 import com.intellij.util.containers.ContainerUtil;
 import gnu.trove.THashSet;
@@ -35,6 +34,7 @@ import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
 import java.util.*;
+import java.util.stream.Stream;
 
 /**
  * @since 2016.3
@@ -196,20 +196,19 @@ public class MetaAnnotationUtil {
 
 
   @NotNull
-  public static PsiAnnotation[] findMetaAnnotations(@NotNull PsiModifierListOwner listOwner,
-                                                    @NotNull final Collection<String> annotations) {
+  public static Stream<PsiAnnotation> findMetaAnnotations(@NotNull PsiModifierListOwner listOwner,
+                                                          @NotNull final Collection<String> annotations) {
 
-    List<PsiAnnotation> result = new SmartList<>(AnnotationUtil.findAnnotations(listOwner, annotations));
-    final List<PsiClass> resolvedAnnotations = getResolvedClassesInAnnotationsList(listOwner);
-    for (String annotationFQN : annotations) {
-      for (PsiClass psiClass : resolvedAnnotations) {
-        PsiAnnotation annotation = metaAnnotationCached(annotationFQN, psiClass);
-        if (annotation != null)
-          result.add(annotation);
-      }
-    }
+    Stream<PsiAnnotation> directAnnotations = Stream.of(AnnotationUtil.findAnnotations(listOwner, annotations));
 
-    return result.isEmpty() ? PsiAnnotation.EMPTY_ARRAY : result.toArray(new PsiAnnotation[result.size()]);
+    Stream<PsiAnnotation> metannotations =
+      Stream.generate(() -> getResolvedClassesInAnnotationsList(listOwner)).limit(1)
+        .flatMap(e -> e.stream())
+        .flatMap(psiClass -> annotations.stream()
+          .map(annotationFQN -> metaAnnotationCached(annotationFQN, psiClass)))
+        .filter(Objects::nonNull);
+
+    return Stream.concat(directAnnotations, metannotations);
   }