Code improvements in IfThenToElvisIntention

idea/idea-analysis/src/org/jetbrains/kotlin/idea/JetBundle.properties

@@ -246,8 +246,6 @@ if.then.to.double.bang.replace.exception=Replace 'if' expression with '!!' expre
 if.then.to.double.bang.family=Replace 'if' Expression with '!!' Expression
 elvis.to.if.then=Replace elvis expression with 'if' expression
 elvis.to.if.then.family=Replace Elvis Expression with 'if' Expression
-if.then.to.elvis=Replace 'if' expression with elvis expression
-if.then.to.elvis.family=Replace 'if' Expression with Elvis Expression
 safe.access.to.if.then=Replace safe access expression with 'if' expression
 safe.access.to.if.then.family=Replace Safe Access Expression with 'if' Expression
 if.then.to.safe.access=Replace 'if' expression with safe access expression

idea/src/org/jetbrains/kotlin/idea/intentions/IfNullToElvisIntention.kt

@@ -22,6 +22,8 @@ import com.intellij.psi.PsiElement
 import com.intellij.psi.PsiRecursiveElementVisitor
 import org.jetbrains.kotlin.JetNodeTypes
 import org.jetbrains.kotlin.idea.caches.resolve.analyze
+import org.jetbrains.kotlin.idea.intentions.branchedTransformations.expressionComparedToNull
+import org.jetbrains.kotlin.idea.intentions.branchedTransformations.isNullExpression
 import org.jetbrains.kotlin.idea.util.isNothing
 import org.jetbrains.kotlin.lexer.JetTokens
 import org.jetbrains.kotlin.psi.*
@@ -84,14 +86,13 @@ public class IfNullToElvisIntention : JetSelfTargetingOffsetIndependentIntention
 
         val binaryExpression = ifExpression.getCondition() as? JetBinaryExpression ?: return null
         if (binaryExpression.getOperationToken() != JetTokens.EQEQ) return null
-        if (binaryExpression.getRight()?.getNode()?.getElementType() != JetNodeTypes.NULL) return null
-        val left = binaryExpression.getLeft() as? JetSimpleNameExpression ?: return null
+        val value = binaryExpression.expressionComparedToNull() as? JetSimpleNameExpression ?: return null
 
         if (ifExpression.getParent() !is JetBlockExpression) return null
         val prevStatement = ifExpression.siblings(forward = false, withItself = false)
                                     .firstIsInstanceOrNull<JetExpression>() ?: return null
         if (prevStatement !is JetVariableDeclaration) return null
-        if (prevStatement.getNameAsName() != left.getReferencedNameAsName()) return null
+        if (prevStatement.getNameAsName() != value.getReferencedNameAsName()) return null
         val initializer = prevStatement.getInitializer() ?: return null
         val then = ifExpression.getThen() ?: return null
 

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

@@ -16,34 +16,37 @@
 
 package org.jetbrains.kotlin.idea.intentions.branchedTransformations
 
-import org.jetbrains.kotlin.lexer.JetTokens
 import com.intellij.openapi.editor.Editor
-import org.jetbrains.kotlin.idea.refactoring.introduce.introduceVariable.KotlinIntroduceVariableHandler
-import org.jetbrains.kotlin.resolve.BindingContext
 import com.intellij.psi.PsiElement
-import org.jetbrains.kotlin.idea.refactoring.inline.KotlinInlineValHandler
-import org.jetbrains.kotlin.resolve.calls.smartcasts.DataFlowValueFactory
-import org.jetbrains.kotlin.resolve.BindingContextUtils
-import org.jetbrains.kotlin.descriptors.VariableDescriptor
-import com.intellij.psi.search.searches.ReferencesSearch
 import com.intellij.psi.search.LocalSearchScope
+import com.intellij.psi.search.searches.ReferencesSearch
+import org.jetbrains.kotlin.JetNodeTypes
+import org.jetbrains.kotlin.descriptors.VariableDescriptor
+import org.jetbrains.kotlin.idea.caches.resolve.analyze
+import org.jetbrains.kotlin.idea.refactoring.inline.KotlinInlineValHandler
+import org.jetbrains.kotlin.idea.refactoring.introduce.introduceVariable.KotlinIntroduceVariableHandler
+import org.jetbrains.kotlin.lexer.JetTokens
+import org.jetbrains.kotlin.psi.*
+import org.jetbrains.kotlin.resolve.BindingContext
+import org.jetbrains.kotlin.resolve.BindingContextUtils
 import org.jetbrains.kotlin.resolve.DescriptorUtils
 import org.jetbrains.kotlin.resolve.bindingContextUtil.isUsedAsStatement
-import org.jetbrains.kotlin.idea.caches.resolve.analyze
-import org.jetbrains.kotlin.psi.*
+import org.jetbrains.kotlin.resolve.calls.smartcasts.DataFlowValueFactory
 
 val NULL_PTR_EXCEPTION_FQ = "java.lang.NullPointerException"
 val KOTLIN_NULL_PTR_EXCEPTION_FQ = "kotlin.KotlinNullPointerException"
 
-fun JetBinaryExpression.comparesNonNullToNull(): Boolean {
+fun JetBinaryExpression.expressionComparedToNull(): JetExpression? {
     val operationToken = this.getOperationToken()
-    val rhs = this.getRight()
-    val lhs = this.getLeft()
-    if (rhs == null || lhs == null) return false
+    if (operationToken != JetTokens.EQEQ && operationToken != JetTokens.EXCLEQ) return null
 
-    val rightIsNull = rhs.isNullExpression()
-    val leftIsNull = lhs.isNullExpression()
-    return leftIsNull != rightIsNull && (operationToken == JetTokens.EQEQ || operationToken == JetTokens.EXCLEQ)
+    val right = this.getRight() ?: return null
+    val left = this.getLeft() ?: return null
+
+    val rightIsNull = right.isNullExpression()
+    val leftIsNull = left.isNullExpression()
+    if (leftIsNull == rightIsNull) return null
+    return if (leftIsNull) right else left
 }
 
 fun JetExpression.unwrapBlock(): JetExpression {
@@ -57,18 +60,9 @@ fun JetExpression.unwrapBlock(): JetExpression {
 
 fun JetExpression.isStatement(): Boolean = isUsedAsStatement(this.analyze())
 
-fun JetBinaryExpression.getNonNullExpression(): JetExpression? = when {
-    this.getLeft()?.isNullExpression() == false ->
-        this.getLeft()
-    this.getRight()?.isNullExpression() == false ->
-        this.getRight()
-    else ->
-        null
-}
+fun JetExpression?.isNullExpression(): Boolean = this?.unwrapBlock()?.getNode()?.getElementType() == JetNodeTypes.NULL
 
-fun JetExpression.isNullExpression(): Boolean = this.unwrapBlock().getText() == "null"
-
-fun JetExpression.isNullExpressionOrEmptyBlock(): Boolean = this.isNullExpression() || this is JetBlockExpression && this.getStatements().isEmpty()
+fun JetExpression?.isNullExpressionOrEmptyBlock(): Boolean = this.isNullExpression() || this is JetBlockExpression && this.getStatements().isEmpty()
 
 fun JetThrowExpression.throwsNullPointerExceptionWithNoArguments(): Boolean {
     val thrownExpression = this.getThrownExpression()
@@ -76,8 +70,7 @@ fun JetThrowExpression.throwsNullPointerExceptionWithNoArguments(): Boolean {
 
     val context = this.analyze()
     val descriptor = context.get(BindingContext.REFERENCE_TARGET, thrownExpression.getCalleeExpression() as JetSimpleNameExpression)
-    val declDescriptor = descriptor?.getContainingDeclaration()
-    if (declDescriptor == null) return false
+    val declDescriptor = descriptor?.getContainingDeclaration() ?: return false
 
     val exceptionName = DescriptorUtils.getFqName(declDescriptor).asString()
     return (exceptionName == NULL_PTR_EXCEPTION_FQ || exceptionName == KOTLIN_NULL_PTR_EXCEPTION_FQ) && thrownExpression.getValueArguments().isEmpty()

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

@@ -29,18 +29,13 @@ import org.jetbrains.kotlin.psi.JetThrowExpression
 public class IfThenToDoubleBangIntention : JetSelfTargetingOffsetIndependentIntention<JetIfExpression>("if.then.to.double.bang", javaClass()) {
 
     override fun isApplicableTo(element: JetIfExpression): Boolean {
-        val condition = element.getCondition()
+        val condition = element.getCondition() as? JetBinaryExpression ?: return false
         val thenClause = element.getThen()
         val elseClause = element.getElse()
 
-        if (condition !is JetBinaryExpression || !condition.comparesNonNullToNull()) return false
-
-        val expression = condition.getNonNullExpression()
-
-        if (expression == null) return false
+        val expression = condition.expressionComparedToNull() ?: return false
 
         val token = condition.getOperationToken()
-        if (token != JetTokens.EQEQ && token != JetTokens.EXCLEQ) return false
 
         val throwExpression =
                 when (token) {
@@ -80,7 +75,7 @@ public class IfThenToDoubleBangIntention : JetSelfTargetingOffsetIndependentInte
     override fun applyTo(element: JetIfExpression, editor: Editor) {
         val condition = element.getCondition() as JetBinaryExpression
 
-        val expression = checkNotNull(condition.getNonNullExpression(), "condition must contain non null expression")
+        val expression = condition.expressionComparedToNull()!!
         val resultingExprString = expression.getText() + "!!"
         val result = element.replace(resultingExprString) as JetPostfixExpression
 

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

@@ -17,21 +17,22 @@
 package org.jetbrains.kotlin.idea.intentions.branchedTransformations.intentions
 
 import com.intellij.openapi.editor.Editor
+import org.jetbrains.kotlin.JetNodeTypes
 import org.jetbrains.kotlin.idea.intentions.JetSelfTargetingOffsetIndependentIntention
 import org.jetbrains.kotlin.idea.intentions.branchedTransformations.*
 import org.jetbrains.kotlin.lexer.JetTokens
 import org.jetbrains.kotlin.psi.*
+import org.jetbrains.kotlin.psi.psiUtil.replaced
 
-public class IfThenToElvisIntention : JetSelfTargetingOffsetIndependentIntention<JetIfExpression>("if.then.to.elvis", javaClass()) {
+public class IfThenToElvisIntention : JetSelfTargetingOffsetIndependentIntention<JetIfExpression>(javaClass(), "Replace 'if' expression with elvis expression") {
 
     override fun isApplicableTo(element: JetIfExpression): Boolean {
-        val condition = element.getCondition()
-        val thenClause = element.getThen()
-        val elseClause = element.getElse()
-        if (thenClause == null || elseClause == null || condition !is JetBinaryExpression || !condition.comparesNonNullToNull()) return false
+        val condition = element.getCondition() as? JetBinaryExpression ?: return false
+        val thenClause = element.getThen() ?: return false
+        val elseClause = element.getElse() ?: return false
 
-        val expression = condition.getNonNullExpression()
-        if (expression == null || !expression.isStableVariable()) return false
+        val expression = condition.expressionComparedToNull() ?: return false
+        if (!expression.isStableVariable()) return false
 
         return when (condition.getOperationToken()) {
             JetTokens.EQEQ ->
@@ -49,7 +50,7 @@ public class IfThenToElvisIntention : JetSelfTargetingOffsetIndependentIntention
 
     private fun JetExpression.isNotNullExpression(): Boolean {
         val innerExpression = this.unwrapBlock()
-        return innerExpression !is JetBlockExpression && innerExpression.getText() != "null"
+        return innerExpression !is JetBlockExpression && innerExpression.getNode().getElementType() != JetNodeTypes.NULL
     }
 
     override fun applyTo(element: JetIfExpression, editor: Editor) {
@@ -60,8 +61,8 @@ public class IfThenToElvisIntention : JetSelfTargetingOffsetIndependentIntention
     public fun applyTo(element: JetIfExpression): JetBinaryExpression {
         val condition = element.getCondition() as JetBinaryExpression
 
-        val thenClause = checkNotNull(element.getThen(), "The then clause cannot be null")
-        val elseClause = checkNotNull(element.getElse(), "The else clause cannot be null")
+        val thenClause = element.getThen()!!
+        val elseClause = element.getElse()!!
         val thenExpression = thenClause.unwrapBlock()
         val elseExpression = elseClause.unwrapBlock()
 
@@ -69,16 +70,10 @@ public class IfThenToElvisIntention : JetSelfTargetingOffsetIndependentIntention
                 when(condition.getOperationToken()) {
                     JetTokens.EQEQ -> Pair(elseExpression, thenExpression)
                     JetTokens.EXCLEQ -> Pair(thenExpression, elseExpression)
-                    else -> throw IllegalStateException("Operation token must be either null or not null")
+                    else -> throw IllegalArgumentException()
                 }
 
-        val resultingExprString = "${left.getText()} ?: ${right.getText()}"
-        val resultingExpression = JetPsiUtil.deparenthesize(element.replace(resultingExprString) as? JetExpression)
-
-        assert(resultingExpression is JetBinaryExpression) {
-               "Unexpected expression type: ${resultingExpression?.javaClass}, expected JetBinaryExpression, element = '${element.getText()}'"
-        }
-
-        return resultingExpression as JetBinaryExpression
+        val newExpr = element.replaced(JetPsiFactory(element).createExpressionByPattern("$0 ?: $1", left, right))
+        return JetPsiUtil.deparenthesize(newExpr) as JetBinaryExpression
     }
 }

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

@@ -25,13 +25,12 @@ import org.jetbrains.kotlin.psi.*
 public class IfThenToSafeAccessIntention : JetSelfTargetingOffsetIndependentIntention<JetIfExpression>("if.then.to.safe.access", javaClass()) {
 
     override fun isApplicableTo(element: JetIfExpression): Boolean {
-        val condition = element.getCondition()
+        val condition = element.getCondition() as? JetBinaryExpression ?: return false
         val thenClause = element.getThen()
         val elseClause = element.getElse()
-        if (condition !is JetBinaryExpression || !condition.comparesNonNullToNull()) return false
 
-        val receiverExpression = condition.getNonNullExpression()
-        if (receiverExpression == null || !receiverExpression.isStableVariable()) return false
+        val receiverExpression = condition.expressionComparedToNull() ?: return false
+        if (!receiverExpression.isStableVariable()) return false
 
         return when (condition.getOperationToken()) {
             JetTokens.EQEQ ->
@@ -54,7 +53,7 @@ public class IfThenToSafeAccessIntention : JetSelfTargetingOffsetIndependentInte
 
     public fun applyTo(element: JetIfExpression): JetSafeQualifiedExpression {
         val condition = element.getCondition() as JetBinaryExpression
-        val receiverExpression = checkNotNull(condition.getNonNullExpression(), "The receiver expression cannot be null")
+        val receiverExpression = condition.expressionComparedToNull()!!
 
         val selectorExpression =
                 when(condition.getOperationToken()) {