Add rule to check that a single top level class name matches the file name

ktlint-ruleset-standard/src/main/kotlin/com/github/shyiko/ktlint/ruleset/standard/ClassNameMatchesFileNameRule.kt

@@ -0,0 +1,39 @@
+package com.github.shyiko.ktlint.ruleset.standard
+
+import com.github.shyiko.ktlint.core.KtLint
+import com.github.shyiko.ktlint.core.Rule
+import org.jetbrains.kotlin.com.intellij.lang.ASTNode
+import org.jetbrains.kotlin.lexer.KtTokens
+import org.jetbrains.kotlin.psi.stubs.elements.KtStubElementTypes
+import java.nio.file.Paths
+
+/**
+ * If there is only one top level class in a given file, then its name should match the file's name
+ */
+class ClassNameMatchesFileNameRule : Rule("class-name-matches-file-name"), Rule.Modifier.RestrictToRoot {
+
+ override fun visit(
+ node: ASTNode,
+ autoCorrect: Boolean,
+ emit: (offset: Int, errorMessage: String, canBeAutoCorrected: Boolean) -> Unit
+ ) {
+ val filePath = node.getUserData(KtLint.FILE_PATH_USER_DATA_KEY)
+
+ // Ignore all non ".kt" files (including ".kts")
+ if (filePath?.endsWith(".kt") != true) {
+ return
+ }
+
+ val topLevelClassNames = node.getChildren(null)
+ .filter { it.elementType == KtStubElementTypes.CLASS }
+ .mapNotNull { it.findChildByType(KtTokens.IDENTIFIER)?.text }
+
+ val name = Paths.get(filePath).fileName.toString().substringBefore(".")
+ if (topLevelClassNames.size == 1 && name != topLevelClassNames.first()) {
+ val className = topLevelClassNames.first()
+ emit(0,
+ "Class $className should be declared in a file named $className.kt",
+ false)
+ }
+ }
+}

ktlint-ruleset-standard/src/main/kotlin/com/github/shyiko/ktlint/ruleset/standard/NoMultipleSpacesRule.kt

@@ -78,9 +78,4 @@ class NoMultipleSpacesRule : Rule("no-multi-spaces") {
  }
  }
  }
-
- private fun ASTNode.visit(cb: (node: ASTNode) -> Unit) {
- cb(this)
- this.getChildren(null).forEach { it.visit(cb) }
- }
 }

ktlint-ruleset-standard/src/main/kotlin/com/github/shyiko/ktlint/ruleset/standard/NoUnusedImportsRule.kt

@@ -84,9 +84,4 @@ class NoUnusedImportsRule : Rule("no-unused-imports") {
  }
 
  private fun String.isComponentN() = componentNRegex.matches(this)
-
- private fun ASTNode.visit(cb: (node: ASTNode) -> Unit) {
- cb(this)
- this.getChildren(null).forEach { it.visit(cb) }
- }
 }

ktlint-ruleset-standard/src/main/kotlin/com/github/shyiko/ktlint/ruleset/standard/ParameterListWrappingRule.kt

@@ -115,11 +115,6 @@ class ParameterListWrappingRule : Rule("parameter-list-wrapping") {
  return offsetToTheLeft + 1
  }
 
- private fun ASTNode.visit(cb: (node: ASTNode) -> Unit) {
- cb(this)
- this.getChildren(null).forEach { it.visit(cb) }
- }
-
  private fun errorMessage(node: ASTNode) =
  when (node.elementType) {
  KtStubElementTypes.VALUE_PARAMETER ->

ktlint-ruleset-standard/src/main/kotlin/com/github/shyiko/ktlint/ruleset/standard/StandardRuleSetProvider.kt

@@ -7,6 +7,7 @@ class StandardRuleSetProvider : RuleSetProvider {
 
  override fun get(): RuleSet = RuleSet("standard",
  ChainWrappingRule(),
+ ClassNameMatchesFileNameRule(),
  FinalNewlineRule(),
  // disabled until it's clear how to reconcile difference in Intellij & Android Studio import layout
  // ImportOrderingRule(),

ktlint-ruleset-standard/src/main/kotlin/com/github/shyiko/ktlint/ruleset/standard/package.kt

@@ -1,5 +1,6 @@
 package com.github.shyiko.ktlint.ruleset.standard
 
+import org.jetbrains.kotlin.com.intellij.lang.ASTNode
 import org.jetbrains.kotlin.com.intellij.psi.PsiElement
 import org.jetbrains.kotlin.com.intellij.psi.impl.source.tree.LeafPsiElement
 import org.jetbrains.kotlin.com.intellij.psi.util.PsiTreeUtil
@@ -11,6 +12,10 @@ internal fun PsiElement.isPartOf(clazz: KClass<out PsiElement>) = getNonStrictPa
 internal fun PsiElement.isPartOfString() = isPartOf(KtStringTemplateEntry::class)
 internal fun PsiElement.prevLeaf(): LeafPsiElement? = PsiTreeUtil.prevLeaf(this) as LeafPsiElement?
 internal fun PsiElement.nextLeaf(): LeafPsiElement? = PsiTreeUtil.nextLeaf(this) as LeafPsiElement?
+internal fun ASTNode.visit(cb: (node: ASTNode) -> Unit) {
+ cb(this)
+ this.getChildren(null).forEach { it.visit(cb) }
+}
 
 internal fun <T> List<T>.head() = this.subList(0, this.size - 1)
 internal fun <T> List<T>.tail() = this.subList(1, this.size)

ktlint-ruleset-standard/src/test/kotlin/com/github/shyiko/ktlint/ruleset/standard/ClassNameMatchesFileNameRuleTest.kt

@@ -0,0 +1,81 @@
+package com.github.shyiko.ktlint.ruleset.standard
+
+import com.github.shyiko.ktlint.core.LintError
+import com.github.shyiko.ktlint.test.lint
+import org.assertj.core.api.Assertions.assertThat
+import org.testng.annotations.Test
+
+class ClassNameMatchesFileNameRuleTest {
+
+ @Test
+ fun testMatchingSingleClassName() {
+ assertThat(ClassNameMatchesFileNameRule().lint(
+ """
+ class A
+ """.trimIndent(),
+ fileName("/some/path/A.kt")
+ )).isEmpty()
+ }
+
+ @Test
+ fun testNonMatchingSingleClassName() {
+ assertThat(ClassNameMatchesFileNameRule().lint(
+ """
+ class B
+ """.trimIndent(),
+ fileName("A.kt")
+ )).isEqualTo(listOf(
+ LintError(1, 1, "class-name-matches-file-name", "Class B should be declared in a file named B.kt")
+ ))
+ }
+
+ @Test
+ fun testMultipleTopLevelClasses() {
+ assertThat(ClassNameMatchesFileNameRule().lint(
+ """
+ class B
+ class C
+ """.trimIndent(),
+ fileName("A.kt")
+ )).isEmpty()
+ }
+
+ @Test
+ fun testMultipleNonTopLevelClasses() {
+ assertThat(ClassNameMatchesFileNameRule().lint(
+ """
+ class B {
+ class C
+ class D
+ }
+ """.trimIndent(),
+ fileName("A.kt")
+ )).isEqualTo(listOf(
+ LintError(1, 1, "class-name-matches-file-name", "Class B should be declared in a file named B.kt")
+ ))
+ }
+
+ @Test
+ fun testCaseSensitiveMatching() {
+ assertThat(ClassNameMatchesFileNameRule().lint(
+ """
+ interface Woohoo
+ """.trimIndent(),
+ fileName("woohoo.kt")
+ )).isEqualTo(listOf(
+ LintError(1, 1, "class-name-matches-file-name", "Class Woohoo should be declared in a file named Woohoo.kt")
+ ))
+ }
+
+ @Test
+ fun testIgnoreKotlinScriptFiles() {
+ assertThat(ClassNameMatchesFileNameRule().lint(
+ """
+ class B
+ """.trimIndent(),
+ fileName("A.kts")
+ )).isEmpty()
+ }
+
+ private fun fileName(fileName: String) = mapOf("file_path" to fileName)
+}