Create a common interface for the license header

plugin-gradle/CHANGES.md

@@ -6,6 +6,7 @@
 * Fixed a bug in `LicenseHeaderStep` which caused an exception with some malformed date-aware licenses. ([#222](https://github.com/diffplug/spotless/pull/222))
 * Updated default ktlint from 0.14.0 to 0.21.0
 * Add ability to pass custom options to ktlint. See README for details.
+* Added interface `HasBuiltinDelimiterForLicense` to language extensions that have pre-defined licence header delimiter. ([#235](https://github.com/diffplug/spotless/pull/235))
 
 ### Version 3.10.0 - February 15th 2018 ([javadoc](https://diffplug.github.io/spotless/javadoc/spotless-plugin-gradle/3.10.0/), [jcenter](https://bintray.com/diffplug/opensource/spotless-plugin-gradle/3.10.0))
 

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

@@ -36,7 +36,7 @@
 import com.diffplug.spotless.generic.LicenseHeaderStep;
 import com.diffplug.spotless.java.ImportOrderStep;
 
-public class GroovyExtension extends FormatExtension {
+public class GroovyExtension extends FormatExtension implements HasBuiltinDelimiterForLicense {
 	static final String NAME = "groovy";
 
 	public GroovyExtension(SpotlessExtension rootExtension) {
@@ -55,10 +55,12 @@ public void excludeJava(boolean excludeJava) {
 		this.excludeJava = excludeJava;
 	}
 
+	@Override
 	public LicenseHeaderConfig licenseHeader(String licenseHeader) {
 		return licenseHeader(licenseHeader, JavaExtension.LICENSE_HEADER_DELIMITER);
 	}
 
+	@Override
 	public LicenseHeaderConfig licenseHeaderFile(Object licenseHeaderFile) {
 		return licenseHeaderFile(licenseHeaderFile, JavaExtension.LICENSE_HEADER_DELIMITER);
 	}

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

@@ -0,0 +1,41 @@
+/*
+ * 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.gradle.spotless;
+
+/**
+ * Every {@link FormatExtension} has a method
+ * {@link FormatExtension#licenseHeader(String, String) license(licenseContent, licenseDelimiter)},
+ * where licenseDelimiter is a regex that separates the license part of the code from the content.
+ * For some kinds of format -
+ * such as {@link JavaExtension java}, {@link KotlinExtension kotlin}, and {@link GroovyExtension groovy} -
+ * we already have a defined delimiter, so users don't have to provide it.
+ * By having the java, kotlin, and groovy formats implement this interface,
+ * you can write generic code for enforcing whitespace and licenses.
+ */
+public interface HasBuiltinDelimiterForLicense {
+
+	/**
+	 * @param licenseHeader
+	 *            Content that should be at the top of every file.
+	 */
+	FormatExtension.LicenseHeaderConfig licenseHeader(String licenseHeader);
+
+	/**
+	 * @param licenseHeaderFile
+	 *            Content that should be at the top of every file.
+	 */
+	FormatExtension.LicenseHeaderConfig licenseHeaderFile(Object licenseHeaderFile);
+}

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

@@ -35,7 +35,7 @@
 import com.diffplug.spotless.java.ImportOrderStep;
 import com.diffplug.spotless.java.RemoveUnusedImportsStep;
 
-public class JavaExtension extends FormatExtension {
+public class JavaExtension extends FormatExtension implements HasBuiltinDelimiterForLicense {
 	static final String NAME = "java";
 
 	public JavaExtension(SpotlessExtension rootExtension) {
@@ -46,10 +46,12 @@ public JavaExtension(SpotlessExtension rootExtension) {
 	// testlib/src/test/java/com/diffplug/spotless/generic/LicenseHeaderStepTest.java as well
 	static final String LICENSE_HEADER_DELIMITER = "package ";
 
+	@Override
 	public LicenseHeaderConfig licenseHeader(String licenseHeader) {
 		return licenseHeader(licenseHeader, LICENSE_HEADER_DELIMITER);
 	}
 
+	@Override
 	public LicenseHeaderConfig licenseHeaderFile(Object licenseHeaderFile) {
 		return licenseHeaderFile(licenseHeaderFile, LICENSE_HEADER_DELIMITER);
 	}

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

@@ -29,17 +29,19 @@
 import com.diffplug.spotless.FormatterStep;
 import com.diffplug.spotless.kotlin.KtLintStep;
 
-public class KotlinExtension extends FormatExtension {
+public class KotlinExtension extends FormatExtension implements HasBuiltinDelimiterForLicense {
 	static final String NAME = "kotlin";
 
 	public KotlinExtension(SpotlessExtension rootExtension) {
 		super(rootExtension);
 	}
 
+	@Override
 	public LicenseHeaderConfig licenseHeader(String licenseHeader) {
 		return licenseHeader(licenseHeader, LICENSE_HEADER_DELIMITER);
 	}
 
+	@Override
 	public LicenseHeaderConfig licenseHeaderFile(Object licenseHeaderFile) {
 		return licenseHeaderFile(licenseHeaderFile, LICENSE_HEADER_DELIMITER);
 	}

plugin-gradle/src/test/java/com/diffplug/gradle/spotless/HasBuiltinDelimiterForLicenseTest.java

@@ -0,0 +1,48 @@
+/*
+ * 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.gradle.spotless;
+
+import java.io.IOException;
+
+import org.junit.Test;
+
+public class HasBuiltinDelimiterForLicenseTest extends GradleIntegrationTest {
+
+	@Test
+	public void testWithCommonInterfaceForConfiguringLicences() throws IOException {
+		// TODO: JLL Convert this to a Kotlin example when supported: https://github.com/gradle/kotlin-dsl/issues/492
+		setFile("build.gradle").toLines(
+				"import com.diffplug.gradle.spotless.HasBuiltinDelimiterForLicense",
+				"plugins {",
+				"    id(\"org.jetbrains.kotlin.jvm\") version \"1.2.31\"",
+				"    id(\"com.diffplug.gradle.spotless\")",
+				"}",
+				"repositories { mavenCentral() }",
+				"spotless {",
+				"    kotlin {",
+				"        assert (it instanceof HasBuiltinDelimiterForLicense) : \"Was `$it`\"",
+				"    }",
+				"    java {",
+				"        assert (it instanceof HasBuiltinDelimiterForLicense) : \"Was `$it`\"",
+				"    }",
+				"}");
+		gradleRunner()
+				.withGradleVersion("4.6")
+				.withArguments("spotlessApply")
+				.forwardOutput()
+				.build();
+	}
+}