Unwrap: function parameter (KT-14788)

#KT-14788 Fixed

idea/src/org/jetbrains/kotlin/idea/codeInsight/unwrap/KotlinFunctionParameterUnwrapper.kt

@@ -0,0 +1,30 @@
+/*
+ * Copyright 2000-2018 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license
+ * that can be found in the license/LICENSE.txt file.
+ */
+
+package org.jetbrains.kotlin.idea.codeInsight.unwrap
+
+import com.intellij.psi.PsiElement
+import org.jetbrains.kotlin.psi.KtCallExpression
+import org.jetbrains.kotlin.psi.KtValueArgument
+import org.jetbrains.kotlin.psi.psiUtil.getStrictParentOfType
+
+class KotlinFunctionParameterUnwrapper(key: String) : KotlinUnwrapRemoveBase(key) {
+
+    override fun isApplicableTo(element: PsiElement): Boolean {
+        if (element !is KtCallExpression) return false
+        if (element.valueArguments.size != 1) return false
+        val argument = element.parent as? KtValueArgument ?: return false
+        if (argument.getStrictParentOfType<KtCallExpression>() == null) return false
+        return true
+    }
+
+    override fun doUnwrap(element: PsiElement?, context: Context?) {
+        val function = element as? KtCallExpression ?: return
+        val argument = element.valueArguments.firstOrNull()?.getArgumentExpression() ?: return
+        context?.extractFromExpression(argument, function)
+        context?.delete(function)
+    }
+
+}

idea/src/org/jetbrains/kotlin/idea/codeInsight/unwrap/KotlinUnwrapDescriptor.java

@@ -34,6 +34,7 @@ public class KotlinUnwrapDescriptor extends UnwrapDescriptorBase {
                 new KotlinUnwrappers.KotlinFinallyUnwrapper("unwrap.expression"),
                 new KotlinUnwrappers.KotlinFinallyRemover("remove.expression"),
                 new KotlinLambdaUnwrapper("unwrap.expression"),
+                new KotlinFunctionParameterUnwrapper("unwrap.expression")
         };
     }
 }