[WIP] Add ANTLR4 support

CHANGES.md

@@ -15,6 +15,7 @@ We adhere to the [keepachangelog](https://keepachangelog.com/en/1.0.0/) format (
 ### Added
 * `prettier` will now autodetect the parser (and formatter) to use based on the filename, unless you override this using `config` or `configFile` with the option `parser` or `filepath`. ([#620](https://github.com/diffplug/spotless/pull/620))
 * `GitRatchet` now lives in `lib-extra`, and is shared across `plugin-gradle` and `plugin-maven` ([#626](https://github.com/diffplug/spotless/pull/626)).
+* Added ANTLR4 support ([#326](https://github.com/diffplug/spotless/issues/326)).
 ### Changed
 * **BREAKING** `FileSignature` can no longer sign folders, only files.  Signatures are now based only on filename (not path), size, and a content hash.  It throws an error if a signature is attempted on a folder or on multiple files with different paths but the same filename - it never breaks silently.  This change does not break any of Spotless' internal logic, so it is unlikely to affect any of Spotless' consumers either. ([#571](https://github.com/diffplug/spotless/pull/571))
   * This change allows the maven plugin to cache classloaders across subprojects when loading config resources from the classpath (fixes [#559](https://github.com/diffplug/spotless/issues/559)).

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

@@ -0,0 +1,31 @@
+/*
+ * Copyright 2016-2020 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;
+
+public class Antlr4Defaults {
+	private static final String LICENSE_HEADER_DELIMITER = "(grammar|lexer grammar|parser grammar)";
+	private static final String INCLUDES = "src/*/antlr4/**/*.g4";
+
+	private Antlr4Defaults() {}
+
+	public static String licenseHeaderDelimiter() {
+		return LICENSE_HEADER_DELIMITER;
+	}
+
+	public static String includes() {
+		return INCLUDES;
+	}
+}

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

@@ -0,0 +1,74 @@
+/*
+ * Copyright 2016-2020 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 = "1.2.1";
+
+	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

@@ -9,6 +9,7 @@ We adhere to the [keepachangelog](https://keepachangelog.com/en/1.0.0/) format (
 * Full support for the Gradle buildcache - previously only supported local, now supports remote too. Fixes [#566](https://github.com/diffplug/spotless/issues/566) and [#280](https://github.com/diffplug/spotless/issues/280), via changes in [#621](https://github.com/diffplug/spotless/pull/621) and [#571](https://github.com/diffplug/spotless/pull/571).
 * `prettier` will now autodetect the parser (and formatter) to use based on the filename, unless you override this using `config()` or `configFile()` with the option `parser` or `filepath`. ([#620](https://github.com/diffplug/spotless/pull/620))
 * (user-invisible) moved the deprecated lib code which was only being used in deprecated parts of `plugin-gradle` into the `.libdeprecated` package. ([#630](https://github.com/diffplug/spotless/pull/630))
+* Added ANTLR4 support ([#326](https://github.com/diffplug/spotless/issues/326)).
 ### Fixed
 * LineEndings.GIT_ATTRIBUTES is now a bit more efficient, and paves the way for remote build cache support in Gradle. ([#621](https://github.com/diffplug/spotless/pull/621))
 * `ratchetFrom` now ratchets from the merge base of `HEAD` and the specified branch.  This fixes the surprising behavior when a remote branch advanced ([#631](https://github.com/diffplug/spotless/pull/631) fixes [#627](https://github.com/diffplug/spotless/issues/627)).

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

@@ -0,0 +1,70 @@
+/*
+ * Copyright 2016-2020 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(SpotlessExtensionBase 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, provisioner());
+		}
+	}
+
+	@Override
+	protected void setupTask(SpotlessTask task) {
+		if (target == null) {
+			target = parseTarget(Antlr4Defaults.includes());
+		}
+		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/SpotlessExtensionBase.java

@@ -161,6 +161,11 @@ public void typescript(Action<TypescriptExtension> closure) {
 		format(TypescriptExtension.NAME, TypescriptExtension.class, closure);
 	}
 
+	/** Configures the special antlr4-specific extension for antlr4 files. */
+	public void antlr4(Action<Antlr4Extension> closure) {
+		format(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 2016-2020 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 GradleIntegrationHarness {
+
+	@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('1.2.1')",
+				"    }",
+				"}"};
+
+		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);
+	}
+}

plugin-maven/CHANGES.md

@@ -8,6 +8,7 @@ We adhere to the [keepachangelog](https://keepachangelog.com/en/1.0.0/) format (
 * Huge speed improvement for multi-module projects thanks to improved cross-project classloader caching ([#571](https://github.com/diffplug/spotless/pull/571), fixes [#559](https://github.com/diffplug/spotless/issues/559)).
 * If you specify `-DspotlessSetLicenseHeaderYearsFromGitHistory=true`, Spotless will perform an expensive search through git history to determine the oldest and newest commits for each file, and uses that to determine license header years. ([#626](https://github.com/diffplug/spotless/pull/626))
 * `prettier` will now autodetect the parser (and formatter) to use based on the filename, unless you override this using `config` or `configFile` with the option `parser` or `filepath` ([#620](https://github.com/diffplug/spotless/pull/620)).
+* Added ANTLR4 support ([#326](https://github.com/diffplug/spotless/issues/326)).
 ### Removed
 * **BREAKING** the long-deprecated `<xml>` and `<css>` formats have been removed, in favor of the long-available [`<eclipseWtp>`](https://github.com/diffplug/spotless/tree/main/plugin-maven#eclipse-wtp) step which is available in every generic format.
   * This probably doesn't affect you, but if it does, you just need to change `<xml>...` into `<formats><format><eclipseWtp><type>XML</type>...`

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

@@ -47,6 +47,7 @@
 import com.diffplug.spotless.LineEnding;
 import com.diffplug.spotless.Provisioner;
 import com.diffplug.spotless.generic.LicenseHeaderStep;
+import com.diffplug.spotless.maven.antlr4.Antlr4;
 import com.diffplug.spotless.maven.cpp.Cpp;
 import com.diffplug.spotless.maven.generic.Format;
 import com.diffplug.spotless.maven.generic.LicenseHeader;
@@ -108,6 +109,9 @@ public abstract class AbstractSpotlessMojo extends AbstractMojo {
 	@Parameter
 	private Typescript typescript;
 
+	@Parameter
+	private Antlr4 antlr4;
+
 	@Parameter(property = "spotlessFiles")
 	private String filePatterns;
 
@@ -194,7 +198,7 @@ private FileLocator getFileLocator() {
 	}
 
 	private List<FormatterFactory> getFormatterFactories() {
-		return Stream.concat(formats.stream(), Stream.of(java, scala, kotlin, cpp, typescript))
+		return Stream.concat(formats.stream(), Stream.of(java, scala, kotlin, cpp, typescript, antlr4))
 				.filter(Objects::nonNull)
 				.collect(toList());
 	}

plugin-maven/src/main/java/com/diffplug/spotless/maven/antlr4/Antlr4.java

@@ -0,0 +1,46 @@
+/*
+ * Copyright 2016-2020 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.antlr4;
+
+import java.util.Set;
+
+import com.diffplug.common.collect.ImmutableSet;
+import com.diffplug.spotless.antlr4.Antlr4Defaults;
+import com.diffplug.spotless.maven.FormatterFactory;
+import com.diffplug.spotless.maven.generic.LicenseHeader;
+
+/**
+ * A {@link FormatterFactory} implementation that corresponds to {@code <antlr4>...</antlr4>} configuration element.
+ * <p>
+ * It defines a formatter for ANTLR4 source files that can execute both language agnostic (e.g. {@link LicenseHeader})
+ * and anltr4-specific (e.g. {@link Antlr4Formatter}) steps.
+ */
+public class Antlr4 extends FormatterFactory {
+	@Override
+	public Set<String> defaultIncludes() {
+		return ImmutableSet.of(Antlr4Defaults.includes());
+	}
+
+	@Override
+	public String licenseHeaderDelimiter() {
+		return Antlr4Defaults.licenseHeaderDelimiter();
+	}
+
+	public void addAntlr4Formatter(Antlr4Formatter antlr4Formatter) {
+		addStepFactory(antlr4Formatter);
+	}
+
+}