Top-level callables are added one by one

idea/ide-common/src/org/jetbrains/kotlin/idea/util/ShadowedDeclarationsFilter.kt

@@ -79,23 +79,27 @@ public class ShadowedDeclarationsFilter(
                 .flatMap { group -> filterEqualSignatureGroup(group) }
     }
 
-    public fun <TDescriptor : DeclarationDescriptor> filterNonImported(
-            declarations: Collection<TDescriptor>,
+    public fun <TDescriptor : DeclarationDescriptor> createNonImportedDeclarationsFilter(
             importedDeclarations: Collection<DeclarationDescriptor>
-    ): Collection<TDescriptor> {
+    ): (Collection<TDescriptor>) -> Collection<TDescriptor> {
         val importedDeclarationsSet = importedDeclarations.toSet()
-        val nonImportedDeclarations = declarations.filter { it !in importedDeclarationsSet }
-
         val importedDeclarationsBySignature = importedDeclarationsSet.groupBy { signature(it) }
 
-        val notShadowed = HashSet<DeclarationDescriptor>()
-        // same signature non-imported declarations from different packages do not shadow each other
-        for ((pair, group) in nonImportedDeclarations.groupBy { signature(it) to packageName(it) }) {
-            val imported = importedDeclarationsBySignature[pair.first]
-            val all = if (imported != null) group + imported else group
-            notShadowed.addAll(filterEqualSignatureGroup(all, descriptorsToImport = group))
+        return filter@ { declarations ->
+            // optimization
+            if (declarations.size == 1 && importedDeclarationsBySignature[signature(declarations.single())] == null) return@filter declarations
+
+            val nonImportedDeclarations = declarations.filter { it !in importedDeclarationsSet }
+
+            val notShadowed = HashSet<DeclarationDescriptor>()
+            // same signature non-imported declarations from different packages do not shadow each other
+            for ((pair, group) in nonImportedDeclarations.groupBy { signature(it) to packageName(it) }) {
+                val imported = importedDeclarationsBySignature[pair.first]
+                val all = if (imported != null) group + imported else group
+                notShadowed.addAll(filterEqualSignatureGroup(all, descriptorsToImport = group))
+            }
+            declarations.filter { it in notShadowed }
         }
-        return declarations.filter { it in notShadowed }
     }
 
     private fun signature(descriptor: DeclarationDescriptor): Any {

idea/idea-completion/src/org/jetbrains/kotlin/idea/completion/BasicCompletionSession.kt

@@ -242,7 +242,10 @@ class BasicCompletionSession(
 
         private fun completeNonImported(lookupElementFactory: LookupElementFactory) {
             if (shouldCompleteTopLevelCallablesFromIndex()) {
-                collector.addDescriptorElements(getTopLevelCallables(), lookupElementFactory, notImported = true)
+                processTopLevelCallables {
+                    collector.addDescriptorElements(it, lookupElementFactory, notImported = true)
+                    flushToResultSet()
+                }
             }
 
             val classKindFilter: ((ClassKind) -> Boolean)?

idea/idea-completion/src/org/jetbrains/kotlin/idea/completion/CompletionSession.kt

@@ -337,7 +337,9 @@ abstract class CompletionSession(
 
         if (shadowedDeclarationsFilter != null) {
             variants = shadowedDeclarationsFilter.filter(variants)
-            notImportedExtensions = shadowedDeclarationsFilter.filterNonImported(notImportedExtensions, variants)
+            notImportedExtensions = shadowedDeclarationsFilter
+                    .createNonImportedDeclarationsFilter<CallableDescriptor>(importedDeclarations = variants)
+                    .invoke(notImportedExtensions)
         }
 
         if (configuration.filterOutJavaGettersAndSetters) {
@@ -394,10 +396,17 @@ abstract class CompletionSession(
         return callTypeAndReceiver.receiver == null
     }
 
-    protected fun getTopLevelCallables(): Collection<CallableDescriptor> {
-        val result = LinkedHashSet<CallableDescriptor>()
-        indicesHelper(true).processTopLevelCallables({ prefixMatcher.prefixMatches(it) }) { result.add(it) }
-        return result.filterShadowedNonImported()
+    protected fun processTopLevelCallables(processor: (CallableDescriptor) -> Unit) {
+        val shadowedFilter = ShadowedDeclarationsFilter.create(bindingContext, resolutionFacade, nameExpression!!, callTypeAndReceiver)
+                ?.createNonImportedDeclarationsFilter<CallableDescriptor>(referenceVariants!!.imported)
+        indicesHelper(true).processTopLevelCallables({ prefixMatcher.prefixMatches(it) }) {
+            if (shadowedFilter != null) {
+                shadowedFilter(listOf(it)).singleOrNull()?.let(processor)
+            }
+            else {
+                processor(it)
+            }
+        }
     }
 
     protected fun CallTypeAndReceiver<*, *>.shouldCompleteCallableExtensions(): Boolean {
@@ -405,11 +414,6 @@ abstract class CompletionSession(
                && this !is CallTypeAndReceiver.IMPORT_DIRECTIVE
     }
 
-    private fun Collection<CallableDescriptor>.filterShadowedNonImported(): Collection<CallableDescriptor> {
-        val filter = ShadowedDeclarationsFilter.create(bindingContext, resolutionFacade, nameExpression!!, callTypeAndReceiver)
-        return if (filter != null) filter.filterNonImported(this, referenceVariants!!.imported) else this
-    }
-
     protected fun addClassesFromIndex(kindFilter: (ClassKind) -> Boolean) {
         AllClassesCompletion(parameters, indicesHelper(true), prefixMatcher, resolutionFacade, kindFilter)
                 .collect(

idea/idea-completion/src/org/jetbrains/kotlin/idea/completion/smart/SmartCompletionSession.kt

@@ -120,8 +120,10 @@ class SmartCompletionSession(configuration: CompletionSessionConfiguration, para
                 }
 
                 if (shouldCompleteTopLevelCallablesFromIndex()) {
-                    getTopLevelCallables().forEach { collector.addElements(filter(it, lookupElementFactory), notImported = true) }
-                    flushToResultSet()
+                    processTopLevelCallables {
+                        collector.addElements(filter(it, lookupElementFactory), notImported = true)
+                        flushToResultSet()
+                    }
                 }
 
                 if (position.getContainingFile() is KtCodeFragment) {