Initial support for scratch files

idea/src/META-INF/extensions/ide.xml

@@ -16,6 +16,11 @@
 
         <extensionPoint qualifiedName="org.jetbrains.kotlin.highlighterExtension"
                         interface="org.jetbrains.kotlin.idea.highlighter.HighlighterExtension"/>
+
+        <extensionPoint name="scratchFileLanguageProvider" beanClass="com.intellij.lang.LanguageExtensionPoint">
+            <with attribute="implementationClass" implements="org.jetbrains.kotlin.idea.scratch.ScratchFileLanguageProvider"/>
+        </extensionPoint>
+
         <extensionPoint qualifiedName="org.jetbrains.kotlin.binaryExtension"
                         interface="org.jetbrains.kotlin.idea.util.KotlinBinaryExtension"/>
         <extensionPoint qualifiedName="org.jetbrains.kotlin.facetValidatorCreator"
@@ -48,5 +53,7 @@
         <idePlatformSupport implementation="org.jetbrains.kotlin.caches.resolve.JvmPlatformSupport"/>
         <idePlatformSupport implementation="org.jetbrains.kotlin.caches.resolve.JsPlatformSupport"/>
         <idePlatformSupport implementation="org.jetbrains.kotlin.caches.resolve.CommonPlatformSupport"/>
+
+        <scratchFileLanguageProvider language="kotlin" implementationClass="org.jetbrains.kotlin.idea.scratch.KtScratchFileLanguageProvider"/>
     </extensions>
 </idea-plugin>

idea/src/META-INF/plugin.xml

@@ -52,6 +52,12 @@
       <interface-class>org.jetbrains.kotlin.idea.completion.CompletionBindingContextProvider</interface-class>
       <implementation-class>org.jetbrains.kotlin.idea.completion.CompletionBindingContextProvider</implementation-class>
     </component>
+    <component>
+      <implementation-class>org.jetbrains.kotlin.idea.scratch.ui.ScratchFileHook</implementation-class>
+    </component>
+    <component>
+      <implementation-class>org.jetbrains.kotlin.idea.scratch.ScratchFileModuleInfoProvider</implementation-class>
+    </component>
   </project-components>
 
   <application-components>

idea/src/org/jetbrains/kotlin/idea/codeInsight/CodeInsightUtils.java

@@ -25,6 +25,7 @@ import com.intellij.psi.util.PsiTreeUtil;
 import com.intellij.psi.util.PsiUtilCore;
 import com.intellij.refactoring.util.CommonRefactoringUtil;
 import com.intellij.util.text.CharArrayUtil;
+import kotlin.collections.ArraysKt;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 import org.jetbrains.kotlin.descriptors.ClassKind;
@@ -361,9 +362,9 @@ public class CodeInsightUtils {
 
 
     @Nullable
-    public static <T> T getTopmostElementAtOffset(@NotNull PsiElement element, int offset, @NotNull Class<T> klass) {
+    public static <T> T getTopmostElementAtOffset(@NotNull PsiElement element, int offset, @NotNull Class<? extends T>... classes) {
         T lastElementOfType = null;
-        if (klass.isInstance(element)) {
+        if (anyIsInstance(element, classes)) {
             lastElementOfType = (T) element;
         }
         do {
@@ -371,7 +372,7 @@ public class CodeInsightUtils {
             if (parent == null || (parent.getTextOffset() < offset) || parent instanceof KtBlockExpression) {
                 break;
             }
-            if (klass.isInstance(parent)) {
+            if (anyIsInstance(parent, classes)) {
                 lastElementOfType = (T) parent;
             }
             element = parent;
@@ -380,4 +381,8 @@ public class CodeInsightUtils {
 
         return lastElementOfType;
     }
+
+    private static <T> boolean anyIsInstance(PsiElement finalElement, @NotNull Class<? extends T>[] klass) {
+        return ArraysKt.any(klass, aClass -> aClass.isInstance(finalElement));
+    }
 }

idea/src/org/jetbrains/kotlin/idea/refactoring/kotlinRefactoringUtil.kt

@@ -321,7 +321,10 @@ fun PsiFile.getLineStartOffset(line: Int): Int? {
         val startOffset = doc.getLineStartOffset(line)
         val element = findElementAt(startOffset) ?: return startOffset
 
-        return PsiTreeUtil.skipSiblingsForward(element, PsiWhiteSpace::class.java, PsiComment::class.java)?.startOffset ?: startOffset
+        if (element is PsiWhiteSpace || element is PsiComment) {
+            return PsiTreeUtil.skipSiblingsForward(element, PsiWhiteSpace::class.java, PsiComment::class.java)?.startOffset ?: startOffset
+        }
+        return startOffset
     }
 
     return null