Cache the result of hasTopLevelCallables() for a KtFile

#KT-19885 Fixed

compiler/frontend.java/src/org/jetbrains/kotlin/load/kotlin/PackagePartClassUtils.kt

@@ -20,11 +20,10 @@ import com.intellij.openapi.util.io.FileUtil
 import com.intellij.openapi.vfs.VirtualFile
 import org.jetbrains.annotations.TestOnly
 import org.jetbrains.kotlin.idea.KotlinFileType
-import org.jetbrains.kotlin.lexer.KtTokens
 import org.jetbrains.kotlin.name.FqName
 import org.jetbrains.kotlin.name.Name
 import org.jetbrains.kotlin.name.NameUtils
-import org.jetbrains.kotlin.psi.*
+import org.jetbrains.kotlin.psi.KtFile
 import java.util.*
 
 object PackagePartClassUtils {
@@ -52,15 +51,7 @@ object PackagePartClassUtils {
     }
 
     @JvmStatic fun getFilesWithCallables(files: Collection<KtFile>): List<KtFile> =
-            files.filter { fileHasTopLevelCallables(it) }
-
-    @JvmStatic fun fileHasTopLevelCallables(file: KtFile): Boolean =
-            file.declarations.any {
-                (it is KtProperty ||
-                it is KtNamedFunction ||
-                it is KtScript ||
-                it is KtTypeAlias) && !it.hasModifier(KtTokens.HEADER_KEYWORD)
-            }
+            files.filter { it.hasTopLevelCallables() }
 
     @JvmStatic fun getFilePartShortName(fileName: String): String =
             NameUtils.getPackagePartClassNamePrefix(FileUtil.getNameWithoutExtension(fileName)) + PART_CLASS_NAME_SUFFIX

compiler/frontend/src/org/jetbrains/kotlin/psi/KtFile.kt

@@ -27,6 +27,7 @@ import com.intellij.util.IncorrectOperationException
 import org.jetbrains.kotlin.KtNodeTypes
 import org.jetbrains.kotlin.idea.KotlinFileType
 import org.jetbrains.kotlin.idea.KotlinLanguage
+import org.jetbrains.kotlin.lexer.KtTokens
 import org.jetbrains.kotlin.name.FqName
 import org.jetbrains.kotlin.parsing.KotlinParserDefinition
 import org.jetbrains.kotlin.psi.psiUtil.getChildOfType
@@ -43,8 +44,12 @@ open class KtFile(viewProvider: FileViewProvider, val isCompiled: Boolean) :
         PsiNamedElement,
         PsiModifiableCodeBlock {
 
+    @Volatile
     private var isScript: Boolean? = null
 
+    @Volatile
+    private var hasTopLeveCallables: Boolean? = null
+
     val importList: KtImportList?
         get() = findChildByTypeOrClass(KtStubElementTypes.IMPORT_LIST, KtImportList::class.java)
 
@@ -153,10 +158,25 @@ open class KtFile(viewProvider: FileViewProvider, val isCompiled: Boolean) :
     override fun clearCaches() {
         super.clearCaches()
         isScript = null
+        hasTopLeveCallables = null
     }
 
     fun isScript(): Boolean = stub?.isScript() ?: isScriptByTree
 
+    fun hasTopLevelCallables(): Boolean {
+        hasTopLeveCallables?.let { return it }
+
+        val result = declarations.any {
+            (it is KtProperty ||
+             it is KtNamedFunction ||
+             it is KtScript ||
+             it is KtTypeAlias) && !it.hasModifier(KtTokens.HEADER_KEYWORD)
+        }
+
+        hasTopLeveCallables = result
+        return result
+    }
+
     override fun accept(visitor: PsiElementVisitor) {
         if (visitor is KtVisitor<*, *>) {
             @Suppress("UNCHECKED_CAST")

compiler/light-classes/src/org/jetbrains/kotlin/asJava/classes/KtLightClassForFacade.kt

@@ -37,7 +37,6 @@ import org.jetbrains.kotlin.fileClasses.javaFileFacadeFqName
 import org.jetbrains.kotlin.idea.KotlinLanguage
 import org.jetbrains.kotlin.load.java.structure.LightClassOriginKind
 import org.jetbrains.kotlin.load.kotlin.PackagePartClassUtils
-import org.jetbrains.kotlin.load.kotlin.PackagePartClassUtils.fileHasTopLevelCallables
 import org.jetbrains.kotlin.name.FqName
 import org.jetbrains.kotlin.psi.KtClassOrObject
 import org.jetbrains.kotlin.psi.KtFile
@@ -190,7 +189,7 @@ class KtLightClassForFacade private constructor(
 
     override fun getQualifiedName() = facadeClassFqName.asString()
 
-    override fun isValid() = files.all { it.isValid && fileHasTopLevelCallables(it) && facadeClassFqName == it.javaFileFacadeFqName }
+    override fun isValid() = files.all { it.isValid && it.hasTopLevelCallables() && facadeClassFqName == it.javaFileFacadeFqName }
 
     override fun copy() = KtLightClassForFacade(manager, facadeClassFqName, lightClassDataCache, files)