Introduce PackageIndexUtil#packageExists()

Use it in IDELightClassGenerationSupport and PluginDeclarationProviderFactory

idea/idea-analysis/src/org/jetbrains/jet/plugin/caches/resolve/IDELightClassGenerationSupport.java

@@ -179,7 +179,7 @@ public class IDELightClassGenerationSupport extends LightClassGenerationSupport
 
     @Override
     public boolean packageExists(@NotNull FqName fqName, @NotNull GlobalSearchScope scope) {
-        return !JetAllPackagesIndex.getInstance().get(fqName.asString(), project, kotlinSources(scope, project)).isEmpty();
+        return PackageIndexUtil.packageExists(fqName, kotlinSources(scope, project), project);
     }
 
     @NotNull

idea/idea-analysis/src/org/jetbrains/jet/plugin/stubindex/PackageIndexUtil.java

@@ -19,7 +19,10 @@ package org.jetbrains.jet.plugin.stubindex;
 import com.google.common.collect.Sets;
 import com.intellij.openapi.project.Project;
 import com.intellij.openapi.util.Condition;
+import com.intellij.openapi.util.Ref;
 import com.intellij.psi.search.GlobalSearchScope;
+import com.intellij.psi.stubs.StubIndex;
+import com.intellij.util.Processor;
 import com.intellij.util.containers.ContainerUtil;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.jet.lang.psi.JetFile;
@@ -70,6 +73,24 @@ public final class PackageIndexUtil {
         });
     }
 
+    public static boolean packageExists(
+            @NotNull FqName packageFqName,
+            @NotNull GlobalSearchScope searchScope,
+            @NotNull Project project
+    ) {
+        final Ref<Boolean> result = new Ref<Boolean>(false);
+        StubIndex.getInstance().processElements(
+                JetAllPackagesIndex.getInstance().getKey(), packageFqName.asString(), project, searchScope, JetFile.class,
+                new Processor<JetFile>() {
+                    @Override
+                    public boolean process(JetFile file) {
+                        result.set(true);
+                        return false;
+                    }
+                });
+        return result.get();
+    }
+
     private PackageIndexUtil() {
     }
 }

idea/idea-analysis/src/org/jetbrains/jet/plugin/stubindex/resolve/PluginDeclarationProviderFactory.kt

@@ -22,8 +22,8 @@ import org.jetbrains.jet.lang.psi.JetFile
 import org.jetbrains.jet.lang.resolve.lazy.data.JetClassLikeInfo
 import org.jetbrains.jet.lang.resolve.lazy.declarations.*
 import org.jetbrains.jet.lang.resolve.name.FqName
-import org.jetbrains.jet.plugin.stubindex.JetAllPackagesIndex
 import org.jetbrains.jet.storage.StorageManager
+import org.jetbrains.jet.plugin.stubindex.PackageIndexUtil
 
 public class PluginDeclarationProviderFactory(
         private val project: Project,
@@ -49,11 +49,8 @@ public class PluginDeclarationProviderFactory(
     }
 
     private fun getStubBasedPackageMemberDeclarationProvider(name: FqName): PackageMemberDeclarationProvider? {
-        //TODO: better check
-        val files = JetAllPackagesIndex.getInstance().get(name.asString(), project, indexedFilesScope)
-        if (files.isEmpty()) {
-            return null
-        }
+        if (!PackageIndexUtil.packageExists(name, indexedFilesScope, project)) return null
+
         return StubBasedPackageMemberDeclarationProvider(name, project, indexedFilesScope)
     }
 }