Kotlin support in Maven plugin

README.md

@@ -43,7 +43,7 @@ lib('java.GoogleJavaFormatStep')                 +'{{yes}}       | {{yes}}
 lib('java.ImportOrderStep')                      +'{{yes}}       | {{yes}}      | {{no}}  |',
 lib('java.RemoveUnusedImportsStep')              +'{{yes}}       | {{yes}}      | {{no}}  |',
 extra('java.EclipseFormatterStep')               +'{{yes}}       | {{yes}}      | {{no}}  |',
-lib('kotlin.KtLintStep')                         +'{{yes}}       | {{no}}       | {{no}}  |',
+lib('kotlin.KtLintStep')                         +'{{yes}}       | {{yes}}      | {{no}}  |',
 lib('markdown.FreshMarkStep')                    +'{{yes}}       | {{no}}       | {{no}}  |',
 lib('scala.ScalaFmtStep')                        +'{{yes}}       | {{yes}}       | {{no}}  |',
 lib('sql.DBeaverSQLFormatterStep')               +'{{yes}}       | {{no}}       | {{no}}  |',
@@ -66,7 +66,7 @@ lib('sql.DBeaverSQLFormatterStep')               +'{{yes}}       | {{no}}
 | [`java.ImportOrderStep`](lib/src/main/java/com/diffplug/spotless/java/ImportOrderStep.java) | :+1:       | :+1:      | :white_large_square:  |
 | [`java.RemoveUnusedImportsStep`](lib/src/main/java/com/diffplug/spotless/java/RemoveUnusedImportsStep.java) | :+1:       | :+1:      | :white_large_square:  |
 | [`java.EclipseFormatterStep`](lib-extra/src/main/java/com/diffplug/spotless/extra/java/EclipseFormatterStep.java) | :+1:       | :+1:      | :white_large_square:  |
-| [`kotlin.KtLintStep`](lib/src/main/java/com/diffplug/spotless/kotlin/KtLintStep.java) | :+1:       | :white_large_square:       | :white_large_square:  |
+| [`kotlin.KtLintStep`](lib/src/main/java/com/diffplug/spotless/kotlin/KtLintStep.java) | :+1:       | :+1:      | :white_large_square:  |
 | [`markdown.FreshMarkStep`](lib/src/main/java/com/diffplug/spotless/markdown/FreshMarkStep.java) | :+1:       | :white_large_square:       | :white_large_square:  |
 | [`scala.ScalaFmtStep`](lib/src/main/java/com/diffplug/spotless/scala/ScalaFmtStep.java) | :+1:       | :+1:       | :white_large_square:  |
 | [`sql.DBeaverSQLFormatterStep`](lib/src/main/java/com/diffplug/spotless/sql/DBeaverSQLFormatterStep.java) | :+1:       | :white_large_square:       | :white_large_square:  |

lib/src/main/java/com/diffplug/spotless/kotlin/KotlinConstants.java

@@ -0,0 +1,24 @@
+/*
+ * Copyright 2016 DiffPlug
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.diffplug.spotless.kotlin;
+
+public final class KotlinConstants {
+
+	// '^' is prepended to the regex in LICENSE_HEADER_DELIMITER later in FormatExtension.licenseHeader(String, String)
+	public static final String LICENSE_HEADER_DELIMITER = "(package |@file)";
+
+	private KotlinConstants() {}
+}

plugin-gradle/src/main/java/com/diffplug/gradle/spotless/KotlinExtension.java

@@ -15,6 +15,8 @@
  */
 package com.diffplug.gradle.spotless;
 
+import static com.diffplug.spotless.kotlin.KotlinConstants.LICENSE_HEADER_DELIMITER;
+
 import java.util.Objects;
 
 import org.gradle.api.GradleException;
@@ -25,8 +27,6 @@
 import com.diffplug.spotless.kotlin.KtLintStep;
 
 public class KotlinExtension extends FormatExtension {
-	// '^' is prepended to the regex in LICENSE_HEADER_DELIMITER later in FormatExtension.licenseHeader(String, String)
-	private static final String LICENSE_HEADER_DELIMITER = "(package |@file)";
 	static final String NAME = "kotlin";
 
 	public KotlinExtension(SpotlessExtension rootExtension) {

plugin-maven/CHANGES.md

@@ -3,6 +3,7 @@
 ### Version 1.10.0-SNAPSHOT - TBD ([javadoc](https://diffplug.github.io/spotless/javadoc/spotless-maven-plugin/snapshot/), [snapshot](https://oss.sonatype.org/content/repositories/snapshots/com/diffplug/spotless/spotless-maven-plugin/))
 
 * Fixed a bug in `LicenseHeaderStep` which caused an exception with some malformed date-aware licenses. ([#222](https://github.com/diffplug/spotless/pull/222))
+* Added support for Kotlin and Ktlint in Maven plugin ([#223](https://github.com/diffplug/spotless/pull/223)).
 
 ### Version 1.0.0.BETA4 - February 27th 2018 ([javadoc](https://diffplug.github.io/spotless/javadoc/spotless-maven-plugin/1.0.0.BETA4/), [jcenter](https://bintray.com/diffplug/opensource/spotless-maven-plugin/1.0.0.BETA4))
 

plugin-maven/README.md

@@ -115,6 +115,55 @@ By default, all files matching `src/main/java/**/*.java` and `src/test/java/**/*
 </configuration>
 ```
 
+<a name="scala"></a>
+
+## Applying to Scala source
+
+By default, all files matching `src/main/scala/**/*.scala`, `src/test/scala/**/*.scala`, `src/main/scala/**/*.sc` and `src/test/scala/**/*.sc` Ant style pattern will be formatted.  Each element under `<scala>` is a step, and they will be applied in the order specified.  Every step is optional.
+
+```xml
+<configuration>
+  <scala>
+     <licenseHeader>
+       <!-- Specify either content or file, but not both -->
+       <content>/* Licensed under Apache-2.0 */</content>
+       <file>${basedir}/license-header</file>
+     </licenseHeader>
+     <endWithNewLine/>
+     <trimTrailingWhitespace/>
+     <scalafmt>
+       <file>${basedir}/scalafmt.conf</file>
+       <!-- Optional, available versions: https://github.com/scalameta/scalafmt/releases -->
+       <version>1.1.0</version>
+     </scalafmt>
+  </scala>
+</configuration>
+```
+
+<a name="kotlin"></a>
+
+## Applying to Kotlin source
+
+By default, all files matching `src/main/kotlin/**/*.kt` and `src/test/kotlin/**/*.kt` Ant style pattern will be formatted.  Each element under `<kotlin>` is a step, and they will be applied in the order specified.  Every step is optional.
+
+```xml
+<configuration>
+  <kotlin>
+     <licenseHeader>
+       <!-- Specify either content or file, but not both -->
+       <content>/* Licensed under Apache-2.0 */</content>
+       <file>${basedir}/license-header</file>
+     </licenseHeader>
+     <endWithNewLine/>
+     <trimTrailingWhitespace/>
+     <ktlint>
+       <!-- Optional, available versions: https://github.com/shyiko/ktlint/releases -->
+       <version>0.14.0</version>
+     </ktlint>
+  </kotlin>
+</configuration>
+```
+
 <a name="format"></a>
 
 ## Applying to custom sources

plugin-maven/src/main/java/com/diffplug/spotless/maven/AbstractSpotlessMojo.java

@@ -42,6 +42,7 @@
 import com.diffplug.spotless.maven.generic.Format;
 import com.diffplug.spotless.maven.generic.LicenseHeader;
 import com.diffplug.spotless.maven.java.Java;
+import com.diffplug.spotless.maven.kotlin.Kotlin;
 import com.diffplug.spotless.maven.scala.Scala;
 
 public abstract class AbstractSpotlessMojo extends AbstractMojo {
@@ -85,6 +86,9 @@ public abstract class AbstractSpotlessMojo extends AbstractMojo {
 	@Parameter
 	private Scala scala;
 
+	@Parameter
+	private Kotlin kotlin;
+
 	protected abstract void process(List<File> files, Formatter formatter) throws MojoExecutionException;
 
 	@Override
@@ -142,7 +146,7 @@ private FileLocator getFileLocator() {
 	}
 
 	private List<FormatterFactory> getFormatterFactories() {
-		return Stream.of(format, java, scala)
+		return Stream.of(format, java, scala, kotlin)
 				.filter(Objects::nonNull)
 				.collect(toList());
 	}

plugin-maven/src/main/java/com/diffplug/spotless/maven/FormatterFactory.java

@@ -32,7 +32,7 @@
 import com.diffplug.spotless.Formatter;
 import com.diffplug.spotless.FormatterStep;
 import com.diffplug.spotless.LineEnding;
-import com.diffplug.spotless.maven.generic.LicenseHeader;
+import com.diffplug.spotless.maven.generic.*;
 
 public abstract class FormatterFactory {
 	@Parameter
@@ -87,7 +87,27 @@ public final void addLicenseHeader(LicenseHeader licenseHeader) {
 		addStepFactory(licenseHeader);
 	}
 
-	protected void addStepFactory(FormatterStepFactory stepFactory) {
+	public final void addEndWithNewline(EndWithNewline endWithNewline) {
+		addStepFactory(endWithNewline);
+	}
+
+	public final void addIndent(Indent indent) {
+		addStepFactory(indent);
+	}
+
+	public final void addTrimTrailingWhitespace(TrimTrailingWhitespace trimTrailingWhitespace) {
+		addStepFactory(trimTrailingWhitespace);
+	}
+
+	public final void addReplace(Replace replace) {
+		addStepFactory(replace);
+	}
+
+	public final void addReplaceRegex(ReplaceRegex replaceRegex) {
+		addStepFactory(replaceRegex);
+	}
+
+	protected final void addStepFactory(FormatterStepFactory stepFactory) {
 		Objects.requireNonNull(stepFactory);
 		stepFactories.add(stepFactory);
 	}

plugin-maven/src/main/java/com/diffplug/spotless/maven/generic/Format.java

@@ -20,6 +20,12 @@
 
 import com.diffplug.spotless.maven.FormatterFactory;
 
+/**
+ * A {@link FormatterFactory} implementation that corresponds to {@code <format>...</format>} configuration element.
+ * <p>
+ * It defines a formatter for custom includes/excludes that executes list of generic, language agnostic steps,
+ * like {@link LicenseHeader}.
+ */
 public class Format extends FormatterFactory {
 
 	@Override
@@ -32,24 +38,4 @@ public String licenseHeaderDelimiter() {
 		// do not specify a default delimiter
 		return null;
 	}
-
-	public void addEndWithNewline(EndWithNewline endWithNewline) {
-		addStepFactory(endWithNewline);
-	}
-
-	public void addIndent(Indent indent) {
-		addStepFactory(indent);
-	}
-
-	public void addTrimTrailingWhitespace(TrimTrailingWhitespace trimTrailingWhitespace) {
-		addStepFactory(trimTrailingWhitespace);
-	}
-
-	public void addReplace(Replace replace) {
-		addStepFactory(replace);
-	}
-
-	public void addReplaceRegex(ReplaceRegex replaceRegex) {
-		addStepFactory(replaceRegex);
-	}
 }

plugin-maven/src/main/java/com/diffplug/spotless/maven/java/Java.java

@@ -15,16 +15,21 @@
  */
 package com.diffplug.spotless.maven.java;
 
-import static com.diffplug.common.collect.Sets.newHashSet;
-import static java.util.Collections.unmodifiableSet;
-
 import java.util.Set;
 
-import com.diffplug.spotless.maven.generic.Format;
+import com.diffplug.common.collect.ImmutableSet;
+import com.diffplug.spotless.maven.FormatterFactory;
+import com.diffplug.spotless.maven.generic.LicenseHeader;
+
+/**
+ * A {@link FormatterFactory} implementation that corresponds to {@code <java>...</java>} configuration element.
+ * <p>
+ * It defines a formatter for java source files that can execute both language agnostic (e.g. {@link LicenseHeader})
+ * and java-specific (e.g. {@link Eclipse}) steps.
+ */
+public class Java extends FormatterFactory {
 
-public class Java extends Format {
-	private static final Set<String> DEFAULT_INCLUDES = unmodifiableSet(newHashSet("src/main/java/**/*.java",
-			"src/test/java/**/*.java"));
+	private static final Set<String> DEFAULT_INCLUDES = ImmutableSet.of("src/main/java/**/*.java", "src/test/java/**/*.java");
 	private static final String LICENSE_HEADER_DELIMITER = "package ";
 
 	@Override

plugin-maven/src/main/java/com/diffplug/spotless/maven/kotlin/Kotlin.java

@@ -0,0 +1,42 @@
+/*
+ * Copyright 2016 DiffPlug
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.diffplug.spotless.maven.kotlin;
+
+import static com.diffplug.spotless.kotlin.KotlinConstants.LICENSE_HEADER_DELIMITER;
+
+import java.util.Set;
+
+import com.diffplug.common.collect.ImmutableSet;
+import com.diffplug.spotless.maven.FormatterFactory;
+
+public class Kotlin extends FormatterFactory {
+
+	private static final Set<String> DEFAULT_INCLUDES = ImmutableSet.of("src/main/kotlin/**/*.kt", "src/test/kotlin/**/*.kt");
+
+	@Override
+	public Set<String> defaultIncludes() {
+		return DEFAULT_INCLUDES;
+	}
+
+	@Override
+	public String licenseHeaderDelimiter() {
+		return LICENSE_HEADER_DELIMITER;
+	}
+
+	public void addKtlint(Ktlint ktlint) {
+		addStepFactory(ktlint);
+	}
+}

plugin-maven/src/main/java/com/diffplug/spotless/maven/kotlin/Ktlint.java

@@ -0,0 +1,35 @@
+/*
+ * Copyright 2016 DiffPlug
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.diffplug.spotless.maven.kotlin;
+
+import org.apache.maven.plugins.annotations.Parameter;
+
+import com.diffplug.spotless.FormatterStep;
+import com.diffplug.spotless.kotlin.KtLintStep;
+import com.diffplug.spotless.maven.FormatterStepConfig;
+import com.diffplug.spotless.maven.FormatterStepFactory;
+
+public class Ktlint implements FormatterStepFactory {
+
+	@Parameter
+	private String version;
+
+	@Override
+	public FormatterStep newFormatterStep(FormatterStepConfig config) {
+		String ktlintVersion = version != null ? version : KtLintStep.defaultVersion();
+		return KtLintStep.create(ktlintVersion, config.getProvisioner());
+	}
+}

plugin-maven/src/main/java/com/diffplug/spotless/maven/scala/Scala.java

@@ -15,16 +15,22 @@
  */
 package com.diffplug.spotless.maven.scala;
 
-import static com.diffplug.common.collect.Sets.newHashSet;
-import static java.util.Collections.unmodifiableSet;
-
 import java.util.Set;
 
-import com.diffplug.spotless.maven.generic.Format;
+import com.diffplug.common.collect.ImmutableSet;
+import com.diffplug.spotless.maven.FormatterFactory;
+import com.diffplug.spotless.maven.generic.LicenseHeader;
+
+/**
+ * A {@link FormatterFactory} implementation that corresponds to {@code <scala>...</scala>} configuration element.
+ * <p>
+ * It defines a formatter for scala source files that can execute both language agnostic (e.g. {@link LicenseHeader})
+ * and scala-specific (e.g. {@link Scalafmt}) steps.
+ */
+public class Scala extends FormatterFactory {
 
-public class Scala extends Format {
-	private static final Set<String> DEFAULT_INCLUDES = unmodifiableSet(newHashSet("src/main/scala/**/*.scala",
-			"src/test/scala/**/*.scala", "src/main/scala/**/*.sc", "src/test/scala/**/*.sc"));
+	private static final Set<String> DEFAULT_INCLUDES = ImmutableSet.of("src/main/scala/**/*.scala",
+			"src/test/scala/**/*.scala", "src/main/scala/**/*.sc", "src/test/scala/**/*.sc");
 	private static final String LICENSE_HEADER_DELIMITER = "package ";
 
 	@Override

plugin-maven/src/test/java/com/diffplug/spotless/maven/MavenIntegrationTest.java

@@ -98,6 +98,10 @@ protected void writePomWithScalaSteps(String... steps) throws IOException {
 		writePom(groupWithSteps("scala", steps));
 	}
 
+	protected void writePomWithKotlinSteps(String... steps) throws IOException {
+		writePom(groupWithSteps("kotlin", steps));
+	}
+
 	protected void writePom(String... configuration) throws IOException {
 		writePom(null, configuration);
 	}