J2K: generating of elvis operators instead of if's

idea/src/org/jetbrains/kotlin/idea/intentions/branchedTransformations/intentions/IfThenToElvisIntention.kt

@@ -60,6 +60,11 @@ public class IfThenToElvisIntention : JetSelfTargetingIntention<JetIfExpression>
     }
 
     override fun applyTo(element: JetIfExpression, editor: Editor) {
+        val elvis = applyTo(element)
+        elvis.inlineLeftSideIfApplicableWithPrompt(editor)
+    }
+
+    public fun applyTo(element: JetIfExpression): JetBinaryExpression {
         val condition = element.getCondition() as JetBinaryExpression
 
         val thenClause = checkNotNull(element.getThen(), "The then clause cannot be null")
@@ -80,7 +85,6 @@ public class IfThenToElvisIntention : JetSelfTargetingIntention<JetIfExpression>
         assert(resultingExpression is JetBinaryExpression,
                "Unexpected expression type: ${resultingExpression?.javaClass}, expected JetBinaryExpression, element = '${element.getText()}'")
 
-        val elvis = resultingExpression as JetBinaryExpression
-        elvis.inlineLeftSideIfApplicableWithPrompt(editor)
+        return resultingExpression as JetBinaryExpression
     }
 }

idea/src/org/jetbrains/kotlin/idea/j2k/J2kPostProcessor.kt

@@ -22,6 +22,7 @@ import org.jetbrains.kotlin.diagnostics.Errors
 import org.jetbrains.kotlin.idea.caches.resolve.analyzeFullyAndGetResult
 import org.jetbrains.kotlin.idea.intentions.RemoveExplicitTypeArguments
 import org.jetbrains.kotlin.idea.intentions.SimplifyNegatedBinaryExpressionIntention
+import org.jetbrains.kotlin.idea.intentions.branchedTransformations.intentions.IfThenToElvisIntention
 import org.jetbrains.kotlin.idea.intentions.branchedTransformations.intentions.IfThenToSafeAccessIntention
 import org.jetbrains.kotlin.idea.quickfix.RemoveRightPartOfBinaryExpressionFix
 import org.jetbrains.kotlin.j2k.PostProcessor
@@ -69,9 +70,20 @@ public class J2kPostProcessor(override val contextToAnalyzeIn: PsiElement) : Pos
             override fun visitIfExpression(expression: JetIfExpression) {
                 super.visitIfExpression(expression)
 
-                val intention = IfThenToSafeAccessIntention()
-                if (intention.isApplicableTo(expression)) {
-                    intention.applyTo(expression)
+                run {
+                    val intention = IfThenToSafeAccessIntention()
+                    if (intention.isApplicableTo(expression)) {
+                        intention.applyTo(expression)
+                        return
+                    }
+                }
+
+                run {
+                    val intention = IfThenToElvisIntention()
+                    if (intention.isApplicableTo(expression)) {
+                        intention.applyTo(expression)
+                        return
+                    }
                 }
             }
         })

j2k/testData/fileOrElement/codeSimplifications/IfToElvis.java

@@ -0,0 +1,5 @@
+class C {
+    String foo(String s) {
+        return s != null ? s : "";
+    }
+}

j2k/testData/fileOrElement/codeSimplifications/IfToElvis.kt

@@ -0,0 +1,5 @@
+class C {
+    fun foo(s: String?): String {
+        return s ?: ""
+    }
+}

j2k/tests/org/jetbrains/kotlin/j2k/JavaToKotlinConverterForWebDemoTestGenerated.java

@@ -982,6 +982,12 @@ public class JavaToKotlinConverterForWebDemoTestGenerated extends AbstractJavaTo
             JetTestUtils.assertAllTestsPresentByMetadata(this.getClass(), new File("j2k/testData/fileOrElement/codeSimplifications"), Pattern.compile("^(.+)\\.java$"), true);
         }
 
+        @TestMetadata("IfToElvis.java")
+        public void testIfToElvis() throws Exception {
+            String fileName = JetTestUtils.navigationMetadata("j2k/testData/fileOrElement/codeSimplifications/IfToElvis.java");
+            doTest(fileName);
+        }
+
         @TestMetadata("IfToSafeCall.java")
         public void testIfToSafeCall() throws Exception {
             String fileName = JetTestUtils.navigationMetadata("j2k/testData/fileOrElement/codeSimplifications/IfToSafeCall.java");

j2k/tests/org/jetbrains/kotlin/j2k/JavaToKotlinConverterSingleFileTestGenerated.java

@@ -982,6 +982,12 @@ public class JavaToKotlinConverterSingleFileTestGenerated extends AbstractJavaTo
             JetTestUtils.assertAllTestsPresentByMetadata(this.getClass(), new File("j2k/testData/fileOrElement/codeSimplifications"), Pattern.compile("^(.+)\\.java$"), true);
         }
 
+        @TestMetadata("IfToElvis.java")
+        public void testIfToElvis() throws Exception {
+            String fileName = JetTestUtils.navigationMetadata("j2k/testData/fileOrElement/codeSimplifications/IfToElvis.java");
+            doTest(fileName);
+        }
+
         @TestMetadata("IfToSafeCall.java")
         public void testIfToSafeCall() throws Exception {
             String fileName = JetTestUtils.navigationMetadata("j2k/testData/fileOrElement/codeSimplifications/IfToSafeCall.java");