Add rule class-signature

CHANGELOG.md

@@ -6,6 +6,8 @@ This project adheres to [Semantic Versioning](https://semver.org/).
 
 ### Added
 
+* Add rule `class-signature`. This rule rewrites the class header to a consistent format. In code style `ktlint_official`, super types are always wrapped to a separate line. In other code styles, super types are only wrapped in classes having multiple super types. Especially for code style `ktlint_official` the class headers are rewritten in a more consistent format. See [examples in documentation](https://pinterest.github.io/ktlint/latest/rules/experimental/#class-signature). `class-signature` [#875](https://github.com/pinterest/ktlint/issues/1349), [#1349](https://github.com/pinterest/ktlint/issues/875)
+
 ### Removed
 
 ### Fixed

documentation/snapshot/docs/rules/experimental.md

@@ -90,6 +90,183 @@ Rule id: `blank-line-before-declaration` (`standard` rule set)
 !!! Note
     This rule is only run when `ktlint_code_style` is set to `ktlint_official` or when the rule is enabled explicitly.
 
+## Class signature
+
+Rewrites the class signature to a consistent format respecting the `.editorconfig` property `max_line_length` if set. In the `ktlint_official` code style all class parameters are wrapped by default. Set `.editorconfig` property `ktlint_class_signature_wrapping_rule_always_with_minimum_parameters` to a value greater than 1 to allow class with a few parameters to be placed on a single line.
+The other code styles allow an infinite amount of parameters on the same line (as long as the `max_line_length` is not exceeded) unless `.editorconfig` property `ktlint_class_signature_wrapping_rule_always_with_minimum_parameters` is set explicitly.
+
+=== "[:material-heart:](#) Ktlint (ktlint_official)"
+
+    ```kotlin
+    // Assume that max_line_length is not exceeded when written as single line
+    class Foo0
+    class Foo1(
+        a: Any
+    )
+    class Foo2(
+        a: Any,
+        b: Any
+    )
+    class Foo3(
+        @Foo a: Any,
+        b: Any,
+        c: Any
+    )
+    class Foo4(
+        a: Any,
+        b: Any,
+        c: Any
+    ) : FooBar(a, c)
+    class Foo5 :
+        FooBar(
+            "bar1",
+            "bar2",
+        ) {
+        // body
+    }
+    class Foo6(
+        val bar1: Bar,
+        val bar2: Bar
+    ) : FooBar(
+            bar1,
+            bar2
+        ) {
+        // body
+    }
+    class Foo7(
+        val bar1: Bar,
+        val bar2: Bar
+    ) : FooBar(
+            bar1,
+            bar2
+        ),
+        BarFoo1,
+        BarFoo2 {
+        // body
+    }
+    class Foo8
+        constructor(
+            val bar1: Bar,
+            val bar2: Bar,
+        ) : FooBar(bar1, bar2),
+            BarFoo1,
+            BarFoo2 {
+        // body
+    }
+    ```
+
+=== "[:material-heart-off-outline:](#) Disallowed (ktlint_official)"
+
+    ```kotlin
+    // Assume that max_line_length is not exceeded when written as single line
+    class Foo0()
+    class Foo1(a: Any)
+    class Foo2(a: Any, b: Any)
+    class Foo3(@Foo a: Any, b: Any, c: Any)
+    class Foo4(a: Any, b: Any, c: Any) : FooBar(a, c)
+    class Foo5 : FooBar(
+        "bar1",
+        "bar2",
+    ) {
+        // body
+    }
+    class Foo6(
+        val bar1: Bar,
+        val bar2: Bar
+    ) : FooBar(
+        bar1,
+        bar2
+    ) {
+        // body
+    }
+    class Foo7(
+        val bar1: Bar,
+        val bar2: Bar
+    ) : FooBar(
+        bar1,
+        bar2
+    ),
+        BarFoo1,
+        BarFoo2 {
+        // body
+    }
+    class Foo8
+    constructor(
+        val bar1: Bar,
+        val bar2: Bar,
+    ) : FooBar(bar1, bar2),
+        BarFoo1,
+        BarFoo2 {
+        // body
+    }
+    ```
+
+=== "[:material-heart:](#) Ktlint (non ktlint_official)"
+
+    ```kotlin
+    // Assume that the last allowed character is
+    // at the X character on the right           X
+    class Foo0
+    class Foo1(
+        a: Any
+    )
+    class Foo2(a: Any)
+    class Foo3(
+        a: Any,
+        b: Any
+    )
+    class Foo4(a: Any, b: Any)
+    class Foo5(@Foo a: Any, b: Any, c: Any)
+    class Foo6(a: Any, b: Any, c: Any) :
+        FooBar(a, c)
+    class Foo7 : FooBar(
+        "bar1",
+        "bar2",
+    ) {
+        // body
+    }
+    class Foo8(
+        val bar1: Bar,
+        val bar2: Bar
+    ) : FooBar(
+        bar1,
+        bar2
+    ) {
+        // body
+    }
+    class Foo9(
+        val bar1: Bar,
+        val bar2: Bar
+    ) : FooBar(
+        bar1,
+        bar2
+    ),
+        BarFoo1,
+        BarFoo2 {
+        // body
+    }
+    class Foo10
+    constructor(
+        val bar1: Bar,
+        val bar2: Bar,
+    ) : FooBar(bar1, bar2),
+        BarFoo1,
+        BarFoo2 {
+        // body
+    }
+    ```
+
+=== "[:material-heart-off-outline:](#) Disallowed (non ktlint_official)"
+
+    ```kotlin
+    // Assume that the last allowed character is
+    // at the X character on the right           X
+    class Foo0()
+    class Foo6(a: Any, b: Any, c: Any) : FooBar(a, c)
+    ```
+
+Rule id: `class-signature` (`standard` rule set)
+
 ## Discouraged comment location
 
 Detect discouraged comment locations (no autocorrect).

ktlint-api-consumer/src/main/kotlin/com/example/ktlint/api/consumer/rules/NoVarRule.kt

@@ -5,10 +5,11 @@ import com.pinterest.ktlint.rule.engine.core.api.Rule
 import com.pinterest.ktlint.rule.engine.core.api.RuleId
 import org.jetbrains.kotlin.com.intellij.lang.ASTNode
 
-public class NoVarRule : Rule(
-    ruleId = RuleId("$CUSTOM_RULE_SET_ID:no-var"),
-    about = About(),
-) {
+public class NoVarRule :
+    Rule(
+        ruleId = RuleId("$CUSTOM_RULE_SET_ID:no-var"),
+        about = About(),
+    ) {
     override fun beforeVisitChildNodes(
         node: ASTNode,
         autoCorrect: Boolean,

ktlint-api-consumer/src/test/kotlin/com/pinterest/ktlint/api/consumer/ApiTestRunner.kt

@@ -14,7 +14,9 @@ import kotlin.io.path.relativeToOrSelf
 
 private val LOGGER = KotlinLogging.logger {}.initKtLintKLogger()
 
-class ApiTestRunner(private val tempDir: Path) {
+class ApiTestRunner(
+    private val tempDir: Path,
+) {
     fun prepareTestProject(testProjectName: String): Path {
         val testProjectPath = TEST_PROJECTS_PATHS.resolve(testProjectName)
         assert(Files.exists(testProjectPath)) {

ktlint-cli-reporter-baseline/src/main/kotlin/com/pinterest/ktlint/cli/reporter/baseline/Baseline.kt

@@ -63,7 +63,9 @@ public class Baseline(
  */
 public fun loadBaseline(path: String): Baseline = BaselineLoader(path).load()
 
-private class BaselineLoader(private val path: String) {
+private class BaselineLoader(
+    private val path: String,
+) {
     var ruleReferenceWithoutRuleSetIdPrefix = 0
 
     fun load(): Baseline {
@@ -165,7 +167,8 @@ private class BaselineLoader(private val path: String) {
                                 }
                             }
                     },
-            detail = "", // Not available in the baseline
+            // Detail is not available in the baseline
+            detail = "",
             status = BASELINE_IGNORED,
         )
 }

ktlint-cli-reporter-baseline/src/main/kotlin/com/pinterest/ktlint/cli/reporter/baseline/BaselineReporter.kt

@@ -6,7 +6,9 @@ import com.pinterest.ktlint.cli.reporter.core.api.ReporterV2
 import java.io.PrintStream
 import java.util.concurrent.ConcurrentHashMap
 
-public class BaselineReporter(private val out: PrintStream) : ReporterV2 {
+public class BaselineReporter(
+    private val out: PrintStream,
+) : ReporterV2 {
     private val acc = ConcurrentHashMap<String, MutableList<KtlintCliError>>()
 
     override fun onLintError(

ktlint-cli-reporter-checkstyle/src/main/kotlin/com/pinterest/ktlint/cli/reporter/checkstyle/CheckStyleReporter.kt

@@ -7,7 +7,9 @@ import java.io.PrintStream
 import java.util.ArrayList
 import java.util.concurrent.ConcurrentHashMap
 
-public class CheckStyleReporter(private val out: PrintStream) : ReporterV2 {
+public class CheckStyleReporter(
+    private val out: PrintStream,
+) : ReporterV2 {
     private val acc = ConcurrentHashMap<String, MutableList<KtlintCliError>>()
 
     override fun onLintError(

ktlint-cli-reporter-format/src/main/kotlin/com/pinterest/ktlint/cli/reporter/format/Color.kt

@@ -3,7 +3,9 @@ package com.pinterest.ktlint.cli.reporter.format
 /**
  * Stripped down version of https://github.com/ziggy42/kolor (ziggy42/kolor#6).
  */
-public enum class Color(public val code: Int) {
+public enum class Color(
+    public val code: Int,
+) {
     BLACK(30),
     RED(31),
     GREEN(32),

ktlint-cli-reporter-html/src/main/kotlin/com/pinterest/ktlint/cli/reporter/html/HtmlReporter.kt

@@ -30,7 +30,9 @@ import com.pinterest.ktlint.cli.reporter.core.api.ReporterV2
 import java.io.PrintStream
 import java.util.concurrent.ConcurrentHashMap
 
-public class HtmlReporter(private val out: PrintStream) : ReporterV2 {
+public class HtmlReporter(
+    private val out: PrintStream,
+) : ReporterV2 {
     private val acc = ConcurrentHashMap<String, MutableList<KtlintCliError>>()
     private var issueCount = 0
     private var correctedCount = 0

ktlint-cli-reporter-json/src/main/kotlin/com/pinterest/ktlint/cli/reporter/json/JsonReporter.kt

@@ -7,7 +7,9 @@ import java.io.PrintStream
 import java.util.ArrayList
 import java.util.concurrent.ConcurrentHashMap
 
-public class JsonReporter(private val out: PrintStream) : ReporterV2 {
+public class JsonReporter(
+    private val out: PrintStream,
+) : ReporterV2 {
     private val acc = ConcurrentHashMap<String, MutableList<KtlintCliError>>()
 
     override fun onLintError(

ktlint-cli-reporter-plain/src/main/kotlin/com/pinterest/ktlint/cli/reporter/plain/Color.kt

@@ -3,7 +3,9 @@ package com.pinterest.ktlint.cli.reporter.plain
 /**
  * Stripped down version of https://github.com/ziggy42/kolor (ziggy42/kolor#6).
  */
-public enum class Color(public val code: Int) {
+public enum class Color(
+    public val code: Int,
+) {
     BLACK(30),
     RED(31),
     GREEN(32),

ktlint-cli-reporter-sarif/src/main/kotlin/com/pinterest/ktlint/cli/reporter/sarif/SarifReporter.kt

@@ -30,7 +30,9 @@ internal fun String.sanitize(): String =
             if (it.endsWith('/')) it else "$it/"
         }
 
-public class SarifReporter(private val out: PrintStream) : ReporterV2 {
+public class SarifReporter(
+    private val out: PrintStream,
+) : ReporterV2 {
     private val results: MutableList<Result> = mutableListOf()
     private var workingDirectory: File? = null
 

ktlint-cli-ruleset-core/src/main/kotlin/com/pinterest/ktlint/cli/ruleset/core/api/RuleSetProviderV3.kt

@@ -10,7 +10,9 @@ import java.io.Serializable
  * `META-INF/services/com.pinterest.ktlint.cli.ruleset.core.api.RuleSetProviderV3` (see `ktlint-ruleset-standard/src/main/resources`
  * for an example).
  */
-public abstract class RuleSetProviderV3(public val id: RuleSetId) : Serializable {
+public abstract class RuleSetProviderV3(
+    public val id: RuleSetId,
+) : Serializable {
     /**
      * Gets a group of related [RuleProvider]s. A provided rule is not guaranteed to be run as rules can be disabled,
      * for example via ".editorconfig" properties.

ktlint-cli/src/main/kotlin/com/pinterest/ktlint/cli/internal/ReporterAggregator.kt

@@ -184,7 +184,9 @@ internal class ReporterAggregator(
         val output: String?,
     )
 
-    private class AggregatedReporter(val reporters: List<ReporterV2>) : ReporterV2 {
+    private class AggregatedReporter(
+        val reporters: List<ReporterV2>,
+    ) : ReporterV2 {
         override fun beforeAll() = reporters.forEach(ReporterV2::beforeAll)
 
         override fun before(file: String) = reporters.forEach { it.before(file) }

ktlint-cli/src/test/kotlin/com/pinterest/ktlint/cli/CommandLineTestRunner.kt

@@ -24,7 +24,9 @@ import kotlin.io.path.relativeToOrSelf
 
 private val LOGGER = KotlinLogging.logger {}.initKtLintKLogger()
 
-class CommandLineTestRunner(private val tempDir: Path) {
+class CommandLineTestRunner(
+    private val tempDir: Path,
+) {
     private val ktlintCli: String = System.getProperty("ktlint-cli")
 
     /**

ktlint-cli/src/test/kotlin/com/pinterest/ktlint/cli/environment/OsEnvironment.kt

@@ -41,4 +41,5 @@ internal class OsEnvironment private constructor(
 }
 
 private class CaseInsensitiveMap<V : Any> :
-    TreeMap<String, V>(java.lang.String.CASE_INSENSITIVE_ORDER), MutableMap<String, V>
+    TreeMap<String, V>(java.lang.String.CASE_INSENSITIVE_ORDER),
+    MutableMap<String, V>

ktlint-cli/src/test/kotlin/com/pinterest/ktlint/cli/internal/FileUtilsTest.kt

@@ -344,7 +344,8 @@ internal class FileUtilsTest {
                 patterns =
                     listOf(
                         pattern,
-                        "/some/non/existing/file", // This prevents the default patterns to be added
+                        // Prevents the default patterns to be added by specifying a file
+                        "/some/non/existing/file",
                     ),
                 rootDir = ktlintTestFileSystem.resolve("project1"),
             )
@@ -386,7 +387,8 @@ internal class FileUtilsTest {
                 patterns =
                     listOf(
                         pattern,
-                        "/some/non/existing/file", // This prevents the default patterns to be added
+                        // Prevents the default patterns to be added by specifying a file
+                        "/some/non/existing/file",
                     ),
                 rootDir = ktlintTestFileSystem.resolve("project1"),
             )

ktlint-rule-engine-core/src/main/kotlin/com/pinterest/ktlint/rule/engine/core/api/Rule.kt

@@ -5,7 +5,9 @@ import com.pinterest.ktlint.rule.engine.core.api.editorconfig.EditorConfigProper
 import com.pinterest.ktlint.rule.engine.core.internal.IdNamingPolicy
 import org.jetbrains.kotlin.com.intellij.lang.ASTNode
 
-public data class RuleId(public val value: String) {
+public data class RuleId(
+    public val value: String,
+) {
     init {
         IdNamingPolicy.enforceRuleIdNaming(value)
     }
@@ -26,7 +28,9 @@ public data class RuleId(public val value: String) {
     }
 }
 
-public data class RuleSetId(public val value: String) {
+public data class RuleSetId(
+    public val value: String,
+) {
     init {
         IdNamingPolicy.enforceRuleSetIdNaming(value)
     }