[WIP] Add ANTLR4 support

CHANGES.md

@@ -7,6 +7,8 @@ You might be looking for:
 
 ### Version 1.18.0-SNAPSHOT - TBD (javadoc [lib](https://diffplug.github.io/spotless/javadoc/spotless-lib/snapshot/) [lib-extra](https://diffplug.github.io/spotless/javadoc/spotless-lib-extra/snapshot/), [snapshot repo](https://oss.sonatype.org/content/repositories/snapshots/com/diffplug/spotless/))
 
+* Added Antlr4 support ([#326](https://github.com/diffplug/spotless/issues/326))
+
 ### Version 1.17.0 - October 30th 2018 (javadoc [lib](https://diffplug.github.io/spotless/javadoc/spotless-lib/1.17.0/) [lib-extra](https://diffplug.github.io/spotless/javadoc/spotless-lib-extra/1.17.0/), artifact [lib]([jcenter](https://bintray.com/diffplug/opensource/spotless-lib), [lib-extra]([jcenter](https://bintray.com/diffplug/opensource/spotless-lib-extra)))
 
 * Updated default eclipse-jdt from 4.7.3a to 4.9.0 ([#316](https://github.com/diffplug/spotless/pull/316)). New version addresses enum-tab formatting bug in 4.8 ([#314](https://github.com/diffplug/spotless/issues/314)).

README.md

@@ -51,6 +51,7 @@ lib('npm.TsFmtFormatterStep')                    +'{{yes}}       | {{no}}
 lib('scala.ScalaFmtStep')                        +'{{yes}}       | {{yes}}       | {{no}}  |',
 lib('sql.DBeaverSQLFormatterStep')               +'{{yes}}       | {{no}}       | {{no}}  |',
 extra('wtp.EclipseWtpFormatterStep')             +'{{yes}}       | {{yes}}      | {{no}}  |',
+lib('antlr4.Antlr4FormatterStep')                +'{{yes}}       | {{yes}}       | {{no}}  |',
 '| [(Your FormatterStep here)](CONTRIBUTING.md#how-to-add-a-new-formatterstep) | {{no}}        | {{no}}       | {{no}}  |',
 '| Fast up-to-date checking                      | {{yes}}       | {{no}}       | {{no}}  |',
 '| Automatic idempotency safeguard               | {{yes}}       | {{no}}       | {{no}}  |',
@@ -78,6 +79,7 @@ extra('wtp.EclipseWtpFormatterStep')             +'{{yes}}       | {{yes}}
 | [`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:  |
 | [`wtp.EclipseWtpFormatterStep`](lib-extra/src/main/java/com/diffplug/spotless/extra/wtp/EclipseWtpFormatterStep.java) | :+1:       | :+1:      | :white_large_square:  |
+| [`antlr4.Antlr4FormatterStep`](lib/src/main/java/com/diffplug/spotless/antlr4/Antlr4FormatterStep.java) | :+1:       | :+1:       | :white_large_square:  |
 | [(Your FormatterStep here)](CONTRIBUTING.md#how-to-add-a-new-formatterstep) | :white_large_square:        | :white_large_square:       | :white_large_square:  |
 | Fast up-to-date checking                      | :+1:       | :white_large_square:       | :white_large_square:  |
 | Automatic idempotency safeguard               | :+1:       | :white_large_square:       | :white_large_square:  |

lib/src/main/java/com/diffplug/spotless/antlr4/Antlr4Defaults.java

@@ -0,0 +1,36 @@
+/*
+ * 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.antlr4;
+
+import java.util.Arrays;
+import java.util.List;
+
+public class Antlr4Defaults {
+
+	private static final String LICENSE_HEADER_DELIMITER = "(grammar|lexer grammar|parser grammar)";
+
+	private static final List<String> defaultIncludes = Arrays.asList("src/main/antlr4/**/*.g4", "src/test/antlr4/**/*.g4");
+
+	private Antlr4Defaults() {}
+
+	public static String licenseHeaderDelimiter() {
+		return LICENSE_HEADER_DELIMITER;
+	}
+
+	public static List<String> defaultIncludes() {
+		return defaultIncludes;
+	}
+}

lib/src/main/java/com/diffplug/spotless/antlr4/Antlr4FormatterStep.java

@@ -0,0 +1,74 @@
+/*
+ * 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.antlr4;
+
+import java.io.IOException;
+import java.io.Serializable;
+import java.lang.reflect.InvocationTargetException;
+import java.lang.reflect.Method;
+
+import com.diffplug.spotless.*;
+
+public class Antlr4FormatterStep {
+
+	public static final String NAME = "antlr4Formatter";
+
+	private Antlr4FormatterStep() {}
+
+	private static final String MAVEN_COORDINATE = "com.khubla.antlr4formatter:antlr4-formatter:";
+	private static final String DEFAULT_VERSION = "1.1.0";
+
+	public static FormatterStep create(Provisioner provisioner) {
+		return create(defaultVersion(), provisioner);
+	}
+
+	public static FormatterStep create(String version, Provisioner provisioner) {
+		return FormatterStep.createLazy(NAME, () -> new State(version, provisioner), State::createFormat);
+	}
+
+	public static String defaultVersion() {
+		return DEFAULT_VERSION;
+	}
+
+	static final class State implements Serializable {
+		private static final long serialVersionUID = 1L;
+
+		/**
+		 * The jar that contains the formatter.
+		 */
+		final JarState jarState;
+
+		State(String version, Provisioner provisioner) throws IOException {
+			this.jarState = JarState.from(MAVEN_COORDINATE + version, provisioner);
+		}
+
+		FormatterFunc createFormat() throws ClassNotFoundException, NoSuchMethodException {
+			ClassLoader classLoader = jarState.getClassLoader();
+
+			// String Antlr4Formatter::format(String input)
+			Class<?> formatter = classLoader.loadClass("com.khubla.antlr4formatter.Antlr4Formatter");
+			Method formatterMethod = formatter.getMethod("format", String.class);
+
+			return input -> {
+				try {
+					return (String) formatterMethod.invoke(null, input);
+				} catch (InvocationTargetException e) {
+					throw ThrowingEx.unwrapCause(e);
+				}
+			};
+		}
+	}
+}

plugin-gradle/CHANGES.md

@@ -2,6 +2,8 @@
 
 ### Version 3.18.0-SNAPSHOT - TBD ([javadoc](https://diffplug.github.io/spotless/javadoc/snapshot/), [snapshot](https://oss.sonatype.org/content/repositories/snapshots/com/diffplug/spotless/spotless-plugin-gradle/))
 
+* Added Antlr4 support ([#326](https://github.com/diffplug/spotless/issues/326))
+
 ### Version 3.17.0 - December 13th 2018 ([javadoc](https://diffplug.github.io/spotless/javadoc/spotless-plugin-gradle/3.17.0/), [jcenter](https://bintray.com/diffplug/opensource/spotless-plugin-gradle/3.17.0))
 
 * Updated default eclipse-jdt from 4.7.3a to 4.9.0 ([#316](https://github.com/diffplug/spotless/pull/316)). New version addresses enum-tab formatting bug in 4.8 ([#314](https://github.com/diffplug/spotless/issues/314)).

plugin-gradle/README.md

@@ -89,6 +89,7 @@ Spotless can check and apply formatting to any plain-text file, using simple rul
 * [DBeaver sql format](https://dbeaver.jkiss.org/)
 * [Prettier: An opinionated code formatter](https://prettier.io)
 * [TypeScript Formatter (tsfmt)](https://github.com/vvakame/typescript-formatter)
+* [Antlr4Formatter](https://github.com/antlr/Antlr4Formatter)
 * Any user-defined function which takes an unformatted string and outputs a formatted version.
 
 Contributions are welcome, see [the contributing guide](../CONTRIBUTING.md) for development info.
@@ -510,6 +511,26 @@ spotless {
 
 Spotless uses npm to install necessary packages locally. It runs prettier using [J2V8](https://github.com/eclipsesource/J2V8) internally after that.
 
+
+<a name="antlr4"></a>
+
+## Applying to ANTLR4 source
+
+By default, all ANTLR4 sources matching `src/main/antlr4/**/*.g4` or `src/test/antlr4/**/*.g4` will be formatted. To change this,
+set the `target` parameter as described in the [Custom rules](#custom) section.
+
+```gradle
+spotless {
+  antlr4 {
+    // use default Antlr4Formatter version
+    antlr4Formatter()
+
+    // specify a custom Antlr4Formatter version
+    antlr4Formatter('1.1.0')
+  }
+}
+```
+
 <a name="license-header"></a>
 
 ## License header options

plugin-gradle/src/main/java/com/diffplug/gradle/spotless/Antlr4Extension.java

@@ -0,0 +1,70 @@
+/*
+ * 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.util.Objects;
+
+import com.diffplug.spotless.FormatterStep;
+import com.diffplug.spotless.antlr4.Antlr4Defaults;
+import com.diffplug.spotless.antlr4.Antlr4FormatterStep;
+
+public class Antlr4Extension extends FormatExtension implements HasBuiltinDelimiterForLicense {
+	static final String NAME = "antlr4";
+
+	public Antlr4Extension(SpotlessExtension rootExtension) {
+		super(rootExtension);
+	}
+
+	public Antlr4FormatterConfig antlr4Formatter() {
+		return antlr4Formatter(Antlr4FormatterStep.defaultVersion());
+	}
+
+	public Antlr4FormatterConfig antlr4Formatter(String version) {
+		return new Antlr4FormatterConfig(version);
+	}
+
+	public class Antlr4FormatterConfig {
+
+		private final String version;
+
+		Antlr4FormatterConfig(String version) {
+			this.version = Objects.requireNonNull(version);
+			addStep(createStep());
+		}
+
+		private FormatterStep createStep() {
+			return Antlr4FormatterStep.create(this.version, GradleProvisioner.fromProject(getProject()));
+		}
+	}
+
+	@Override
+	protected void setupTask(SpotlessTask task) {
+		if (target == null) {
+			target = parseTarget(Antlr4Defaults.defaultIncludes());
+		}
+		super.setupTask(task);
+	}
+
+	@Override
+	public LicenseHeaderConfig licenseHeader(String licenseHeader) {
+		return licenseHeader(licenseHeader, Antlr4Defaults.licenseHeaderDelimiter());
+	}
+
+	@Override
+	public LicenseHeaderConfig licenseHeaderFile(Object licenseHeaderFile) {
+		return licenseHeaderFile(licenseHeaderFile, Antlr4Defaults.licenseHeaderDelimiter());
+	}
+}

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

@@ -138,6 +138,11 @@ public void typescript(Action<TypescriptExtension> closure) {
 		configure(TypescriptExtension.NAME, TypescriptExtension.class, closure);
 	}
 
+	/** Configures the special antlr4-specific extension for antlr4 files. */
+	public void antlr4(Action<Antlr4Extension> closure) {
+		configure(Antlr4Extension.NAME, Antlr4Extension.class, closure);
+	}
+
 	/** Configures a custom extension. */
 	public void format(String name, Action<FormatExtension> closure) {
 		requireNonNull(name, "name");

plugin-gradle/src/test/java/com/diffplug/gradle/spotless/Antlr4ExtensionTest.java

@@ -0,0 +1,79 @@
+/*
+ * 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 Antlr4ExtensionTest extends GradleIntegrationTest {
+
+	@Test
+	public void applyUsingDefaultVersion() throws IOException {
+		String[] buildScript = {
+				"buildscript {",
+				"    repositories {",
+				"        mavenCentral()",
+				"    }",
+				"}",
+				"plugins {",
+				"    id 'com.diffplug.gradle.spotless'",
+				"}",
+				"spotless {",
+				"    antlr4 {",
+				"        target 'src/main/antlr4/**/*.g4'",
+				"        antlr4Formatter()",
+				"    }",
+				"}"};
+
+		assertAppliedFormat(buildScript);
+	}
+
+	@Test
+	public void applyUsingCustomVersion() throws IOException {
+		String[] buildScript = {
+				"buildscript {",
+				"    repositories {",
+				"        mavenCentral()",
+				"    }",
+				"}",
+				"plugins {",
+				"    id 'com.diffplug.gradle.spotless'",
+				"}",
+				"spotless {",
+				"    antlr4 {",
+				"        target 'src/main/antlr4/**/*.g4'",
+				"        antlr4Formatter('1.1.0')",
+				"    }",
+				"}"};
+
+		assertAppliedFormat(buildScript);
+	}
+
+	private void assertAppliedFormat(String... buildScript) throws IOException {
+		String testFile = "src/main/antlr4/Hello.g4";
+
+		setFile("build.gradle").toLines(buildScript);
+
+		String unformatted = "antlr4/Hello.unformatted.g4";
+		String formatted = "antlr4/Hello.formatted.g4";
+		setFile(testFile).toResource(unformatted);
+
+		gradleRunner().withArguments("spotlessApply").build();
+
+		assertFile(testFile).sameAsResource(formatted);
+	}
+}