Add inspection to move the variable declaration into when

#KT-29001 Fixed
2019-02-14 13:25:27 +03:00
parent 7abe9333c8
commit 33954c7632
15 changed files with 220 additions and 0 deletions
@@ -2932,6 +2932,15 @@
                     language="kotlin"
    />

+    <localInspection implementationClass="org.jetbrains.kotlin.idea.inspections.MoveVariableDeclarationIntoWhenInspection"
+                     displayName="Variable declaration could be moved inside `when`"
+                     groupPath="Kotlin"
+                     groupName="Style issues"
+                     enabledByDefault="true"
+                     level="WEAK WARNING"
+                     language="kotlin"
+    />
+
    <localInspection implementationClass="org.jetbrains.kotlin.idea.inspections.MainFunctionReturnUnitInspection"
                     displayName="Entry point function should return Unit"
                     groupPath="Kotlin"
@@ -0,0 +1,5 @@
+<html>
+<body>
+This inspection reports the variable declaration that can be moved inside <code>when</code> expression.
+</body>
+</html>
@@ -0,0 +1,55 @@
+/*
+ * Copyright 2010-2019 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.inspections
+
+import com.intellij.codeInspection.CleanupLocalInspectionTool
+import com.intellij.codeInspection.LocalQuickFix
+import com.intellij.codeInspection.ProblemDescriptor
+import com.intellij.codeInspection.ProblemsHolder
+import com.intellij.openapi.project.Project
+import com.intellij.openapi.util.TextRange
+import com.intellij.psi.PsiElementVisitor
+import com.intellij.psi.SmartPsiElementPointer
+import org.jetbrains.kotlin.idea.intentions.loopToCallChain.countUsages
+import org.jetbrains.kotlin.idea.intentions.loopToCallChain.previousStatement
+import org.jetbrains.kotlin.psi.*
+import org.jetbrains.kotlin.psi.psiUtil.createSmartPointer
+
+class MoveVariableDeclarationIntoWhenInspection : AbstractKotlinInspection(), CleanupLocalInspectionTool {
+    override fun buildVisitor(holder: ProblemsHolder, isOnTheFly: Boolean): PsiElementVisitor =
+        whenExpressionVisitor(fun(expression: KtWhenExpression) {
+            val subjectExpression = expression.subjectExpression ?: return
+            val property = expression.findDeclarationNear() ?: return
+            if (!property.isUsedOnlyIn(expression)) return
+            val identifier = property.nameIdentifier ?: return
+            holder.registerProblem(
+                property,
+                TextRange.from(identifier.startOffsetInParent, identifier.textLength),
+                "Variable declaration could be moved inside `when`",
+                MoveVariableDeclarationIntoWhenFix(subjectExpression.createSmartPointer())
+            )
+        })
+}
+
+private fun KtProperty.isUsedOnlyIn(element: KtElement): Boolean = countUsages() == countUsages(element)
+
+private fun KtWhenExpression.findDeclarationNear(): KtProperty? {
+    val previousProperty = previousStatement() as? KtProperty ?: return null
+    return previousProperty.takeIf { !it.isVar && it.hasInitializer() && it.nameIdentifier?.text == subjectExpression?.text }
+}
+
+private class MoveVariableDeclarationIntoWhenFix(val subjectExpressionPointer: SmartPsiElementPointer<KtExpression>) : LocalQuickFix {
+    override fun getName() = "Move the variable into `when`"
+
+    override fun getFamilyName() = name
+
+    override fun applyFix(project: Project, descriptor: ProblemDescriptor) {
+        val property = descriptor.psiElement as? KtProperty ?: return
+        val subjectExpression = subjectExpressionPointer.element ?: return
+        subjectExpression.replace(property.copy())
+        property.delete()
+    }
+}
@@ -0,0 +1 @@
+org.jetbrains.kotlin.idea.inspections.MoveVariableDeclarationIntoWhenInspection
@@ -0,0 +1,11 @@
+// PROBLEM: none
+fun foo() {
+    val a = 1
+    val b<caret> = 1
+    when (a) {
+        1 -> {
+        }
+        else -> {
+        }
+    }
+}
@@ -0,0 +1,11 @@
+// PROBLEM: none
+fun foo() {
+    val a<caret> = 1
+    val b = 42
+    when (a) {
+        1 -> {
+        }
+        else -> {
+        }
+    }
+}
@@ -0,0 +1,11 @@
+// PROBLEM: none
+fun foo() {
+    val a<caret> = 1
+    when (a) {
+        1 -> {
+        }
+        else -> {
+        }
+    }
+    val b = a
+}
@@ -0,0 +1,10 @@
+// PROBLEM: none
+fun foo() {
+    var a<caret> = 1
+    when (a) {
+        1 -> {
+        }
+        else -> {
+        }
+    }
+}
@@ -0,0 +1,9 @@
+fun test() = 42
+
+fun foo() {
+    val a<caret> = test()
+    when (a) {
+        1 -> a
+        else -> 24
+    }
+}
@@ -0,0 +1,8 @@
+fun test() = 42
+
+fun foo() {
+    when (val a = test()) {
+        1 -> a
+        else -> 24
+    }
+}
@@ -0,0 +1,11 @@
+fun foo() {
+    val a<caret> = 1
+
+    // comment
+    when (a) {
+        1 -> {
+        }
+        else -> {
+        }
+    }
+}
@@ -0,0 +1,10 @@
+fun foo() {
+
+    // comment
+    when (val a = 1) {
+        1 -> {
+        }
+        else -> {
+        }
+    }
+}
@@ -0,0 +1,11 @@
+fun foo() {
+    val a<caret> = 1
+
+
+    when (a) {
+        1 -> {
+        }
+        else -> {
+        }
+    }
+}
@@ -0,0 +1,10 @@
+fun foo() {
+
+
+    when (val a = 1) {
+        1 -> {
+        }
+        else -> {
+        }
+    }
+}
@@ -4277,6 +4277,54 @@ public class LocalInspectionTestGenerated extends AbstractLocalInspectionTest {
        }
    }

+    @TestMetadata("idea/testData/inspectionsLocal/moveVariableDeclarationIntoWhen")
+    @TestDataPath("$PROJECT_ROOT")
+    @RunWith(JUnit3RunnerWithInners.class)
+    public static class MoveVariableDeclarationIntoWhen extends AbstractLocalInspectionTest {
+        private void runTest(String testDataFilePath) throws Exception {
+            KotlinTestUtils.runTest(this::doTest, TargetBackend.ANY, testDataFilePath);
+        }
+
+        public void testAllFilesPresentInMoveVariableDeclarationIntoWhen() throws Exception {
+            KotlinTestUtils.assertAllTestsPresentByMetadata(this.getClass(), new File("idea/testData/inspectionsLocal/moveVariableDeclarationIntoWhen"), Pattern.compile("^([\\w\\-_]+)\\.(kt|kts)$"), TargetBackend.ANY, true);
+        }
+
+        @TestMetadata("notApplicableOtherName.kt")
+        public void testNotApplicableOtherName() throws Exception {
+            runTest("idea/testData/inspectionsLocal/moveVariableDeclarationIntoWhen/notApplicableOtherName.kt");
+        }
+
+        @TestMetadata("notApplicableSideEffect.kt")
+        public void testNotApplicableSideEffect() throws Exception {
+            runTest("idea/testData/inspectionsLocal/moveVariableDeclarationIntoWhen/notApplicableSideEffect.kt");
+        }
+
+        @TestMetadata("notApplicableUsedInOtherScope.kt")
+        public void testNotApplicableUsedInOtherScope() throws Exception {
+            runTest("idea/testData/inspectionsLocal/moveVariableDeclarationIntoWhen/notApplicableUsedInOtherScope.kt");
+        }
+
+        @TestMetadata("notApplicableVar.kt")
+        public void testNotApplicableVar() throws Exception {
+            runTest("idea/testData/inspectionsLocal/moveVariableDeclarationIntoWhen/notApplicableVar.kt");
+        }
+
+        @TestMetadata("simple.kt")
+        public void testSimple() throws Exception {
+            runTest("idea/testData/inspectionsLocal/moveVariableDeclarationIntoWhen/simple.kt");
+        }
+
+        @TestMetadata("withComment.kt")
+        public void testWithComment() throws Exception {
+            runTest("idea/testData/inspectionsLocal/moveVariableDeclarationIntoWhen/withComment.kt");
+        }
+
+        @TestMetadata("withNewLine.kt")
+        public void testWithNewLine() throws Exception {
+            runTest("idea/testData/inspectionsLocal/moveVariableDeclarationIntoWhen/withNewLine.kt");
+        }
+    }
+
    @TestMetadata("idea/testData/inspectionsLocal/nestedLambdaShadowedImplicitParameter")
    @TestDataPath("$PROJECT_ROOT")
    @RunWith(JUnit3RunnerWithInners.class)
				`@@ -0,0 +1 @@`
				`org.jetbrains.kotlin.idea.inspections.MoveVariableDeclarationIntoWhenInspection`