Refactoring: make "unnecessary variable" inspection applicability-based

idea/src/org/jetbrains/kotlin/idea/inspections/UnnecessaryVariableInspection.kt

@@ -16,12 +16,10 @@
 
 package org.jetbrains.kotlin.idea.inspections
 
-import com.intellij.codeInspection.LocalQuickFix
-import com.intellij.codeInspection.ProblemDescriptor
-import com.intellij.codeInspection.ProblemHighlightType
-import com.intellij.codeInspection.ProblemsHolder
+import com.intellij.codeInspection.*
+import com.intellij.openapi.editor.Editor
 import com.intellij.openapi.project.Project
-import com.intellij.psi.PsiElementVisitor
+import com.intellij.psi.PsiElement
 import com.intellij.psi.search.LocalSearchScope
 import com.intellij.psi.search.searches.ReferencesSearch
 import org.jetbrains.kotlin.descriptors.FunctionDescriptor
@@ -35,29 +33,37 @@ import org.jetbrains.kotlin.resolve.BindingContext.DECLARATION_TO_DESCRIPTOR
 import org.jetbrains.kotlin.resolve.BindingContext.REFERENCE_TARGET
 import org.jetbrains.kotlin.resolve.DescriptorToSourceUtils
 
-class UnnecessaryVariableInspection : AbstractKotlinInspection() {
+class UnnecessaryVariableInspection : AbstractApplicabilityBasedInspection<KtProperty>() {
 
-    override fun buildVisitor(holder: ProblemsHolder, isOnTheFly: Boolean): PsiElementVisitor =
+    override fun buildVisitor(holder: ProblemsHolder, isOnTheFly: Boolean, session: LocalInspectionToolSession): KtVisitorVoid =
             object : KtVisitorVoid() {
                 override fun visitProperty(property: KtProperty) {
                     super.visitProperty(property)
-
-                    val nameIdentifier = property.nameIdentifier ?: return
-                    val status = statusFor(property) ?: return
-                    holder.registerProblem(
-                            nameIdentifier,
-                            when (status) {
-                                Status.RETURN_ONLY ->
-                                    "Variable used only in following return and can be inlined"
-                                Status.EXACT_COPY ->
-                                    "Variable is an exact copy of another variable and can be inlined"
-                            },
-                            ProblemHighlightType.GENERIC_ERROR_OR_WARNING,
-                            InlineVariableFix()
-                    )
+                    visitTargetElement(property, holder, isOnTheFly)
                 }
             }
 
+    override fun isApplicable(element: KtProperty) = statusFor(element) != null
+
+    override fun inspectionTarget(element: KtProperty) = element.nameIdentifier ?: element
+
+    override fun inspectionText(element: KtProperty) = when (statusFor(element)) {
+        Status.RETURN_ONLY ->
+            "Variable used only in following return and can be inlined"
+        Status.EXACT_COPY ->
+            "Variable is an exact copy of another variable and can be inlined"
+        else -> ""
+    }
+
+    override val defaultFixText = "Inline variable"
+
+    override val startFixInWriteAction = false
+
+    override fun applyTo(element: PsiElement, project: Project, editor: Editor?) {
+        val property = element.getParentOfType<KtProperty>(strict = false) ?: return
+        KotlinInlineValHandler().inlineElement(project, editor, property)
+    }
+
     companion object {
         private enum class Status {
             RETURN_ONLY,
@@ -108,21 +114,5 @@ class UnnecessaryVariableInspection : AbstractKotlinInspection() {
                 else -> null
             }
         }
-
-        fun isActiveFor(property: KtProperty) = statusFor(property) != null
-    }
-
-    class InlineVariableFix : LocalQuickFix {
-
-        override fun getName() = "Inline variable"
-
-        override fun getFamilyName() = name
-
-        override fun startInWriteAction() = false
-
-        override fun applyFix(project: Project, descriptor: ProblemDescriptor) {
-            val property = descriptor.psiElement.getParentOfType<KtProperty>(strict = true) ?: return
-            KotlinInlineValHandler().inlineElement(project, property.findExistingEditor(), property)
-        }
     }
 }

idea/src/org/jetbrains/kotlin/idea/j2k/J2kPostProcessings.kt

@@ -36,7 +36,6 @@ import org.jetbrains.kotlin.idea.intentions.branchedTransformations.intentions.I
 import org.jetbrains.kotlin.idea.intentions.branchedTransformations.isTrivialStatementBody
 import org.jetbrains.kotlin.idea.quickfix.RemoveModifierFix
 import org.jetbrains.kotlin.idea.quickfix.RemoveUselessCastFix
-import org.jetbrains.kotlin.idea.refactoring.inline.KotlinInlineValHandler
 import org.jetbrains.kotlin.idea.references.mainReference
 import org.jetbrains.kotlin.lexer.KtTokens
 import org.jetbrains.kotlin.psi.*
@@ -80,7 +79,7 @@ object J2KPostProcessingRegistrar {
         _processings.add(RemoveRedundantCastToNullableProcessing())
         registerInspectionBasedProcessing(ReplacePutWithAssignmentInspection())
         _processings.add(UseExpressionBodyProcessing())
-        _processings.add(UnnecessaryVariableProcessing())
+        registerInspectionBasedProcessing(UnnecessaryVariableInspection())
 
         registerIntentionBasedProcessing(FoldInitializerAndIfToElvisIntention())
 
@@ -317,21 +316,6 @@ object J2KPostProcessingRegistrar {
         }
     }
 
-    private class UnnecessaryVariableProcessing : J2kPostProcessing {
-        // Refactoring
-        override val writeActionNeeded = false
-
-        override fun createAction(element: KtElement, diagnostics: Diagnostics): (() -> Unit)? {
-            if (element !is KtProperty) return null
-
-            if (!UnnecessaryVariableInspection.isActiveFor(element)) return null
-
-            return {
-                KotlinInlineValHandler(withPrompt = false).inlineElement(element.project, element.findExistingEditor(), element)
-            }
-        }
-    }
-
     private class RemoveRedundantCastToNullableProcessing : J2kPostProcessing {
         override val writeActionNeeded = true