Move: Implement Kotlin-specific editor for class name

#KT-13192 Fixed

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

@@ -142,7 +142,7 @@ abstract class CompletionSession(
 
     // LookupElementsCollector instantiation is deferred because virtual call to createSorter uses data from derived classes
     protected val collector: LookupElementsCollector by lazy(LazyThreadSafetyMode.NONE) {
-        LookupElementsCollector(prefixMatcher, parameters, resultSet, createSorter())
+        LookupElementsCollector(prefixMatcher, parameters, resultSet, createSorter(), (file as? KtCodeFragment)?.extraCompletionFilter)
     }
 
     protected val searchScope: GlobalSearchScope = getResolveScope(parameters.originalFile as KtFile)

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

@@ -418,4 +418,6 @@ fun OffsetMap.tryGetOffset(key: OffsetKey): Int? {
     catch(e: Exception) {
         return null
     }
-}
+}
+
+var KtCodeFragment.extraCompletionFilter: ((LookupElement) -> Boolean)? by CopyableUserDataProperty(Key.create("EXTRA_COMPLETION_FILTER"))

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

@@ -159,6 +159,7 @@ object KeywordCompletion {
             CommentFilter(),
             ParentFilter(ClassFilter(KtLiteralStringTemplateEntry::class.java)),
             ParentFilter(ClassFilter(KtConstantExpression::class.java)),
+            FileFilter(ClassFilter(KtTypeCodeFragment::class.java)),
             LeftNeighbour(TextFilter(".")),
             LeftNeighbour(TextFilter("?."))
     ))
@@ -182,6 +183,17 @@ object KeywordCompletion {
         }
     }
 
+    private class FileFilter(filter : ElementFilter) : PositionElementFilter() {
+        init {
+            setFilter(filter)
+        }
+
+        override fun isAcceptable(element : Any?, context : PsiElement?) : Boolean {
+            val file = (element as? PsiElement)?.containingFile
+            return file != null && (filter?.isAcceptable(file, context) ?: true)
+        }
+    }
+
     private fun buildFilter(position: PsiElement): (KtKeywordToken) -> Boolean {
         var parent = position.parent
         var prevParent = position

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

@@ -32,7 +32,8 @@ class LookupElementsCollector(
         private val prefixMatcher: PrefixMatcher,
         private val completionParameters: CompletionParameters,
         resultSet: CompletionResultSet,
-        sorter: CompletionSorter
+        sorter: CompletionSorter,
+        private val filter: ((LookupElement) -> Boolean)?
 ) {
 
     var bestMatchingDegree = Int.MIN_VALUE
@@ -132,7 +133,9 @@ class LookupElementsCollector(
             }
         }
 
-        elements.add(result)
+        if (filter?.invoke(result) ?: true) {
+            elements.add(result)
+        }
 
         val matchingDegree = RealPrefixMatchingWeigher.getBestMatchingDegree(result, prefixMatcher)
         bestMatchingDegree = Math.max(bestMatchingDegree, matchingDegree)