feat(ktfmt): add ktfmt a new Kotlin formatter from Facebook Incubator

CHANGES.md

@@ -13,6 +13,7 @@ We adhere to the [keepachangelog](https://keepachangelog.com/en/1.0.0/) format (
 ### Added
 * Support for google-java-format 1.8 (including test infrastructure for Java 11). ([#562](https://github.com/diffplug/spotless/issues/562))
 * Improved PaddedCell such that it is as performant as non-padded cell - no reason not to have it always enabled.  Deprecated all of `PaddedCellBulk`. ([#561](https://github.com/diffplug/spotless/pull/561))
+* Support for ktfmt 0.13 ([#569](https://github.com/diffplug/spotless/pull/569))
 ### Changed
 * Updated a bunch of dependencies, most notably: ([#564](https://github.com/diffplug/spotless/pull/564))
   * jgit `5.5.0.201909110433-r` -> `5.7.0.202003110725-r`

README.md

@@ -46,6 +46,7 @@ lib('java.ImportOrderStep')                      +'{{yes}}       | {{yes}}
 lib('java.RemoveUnusedImportsStep')              +'{{yes}}       | {{yes}}      | {{no}}  |',
 extra('java.EclipseFormatterStep')               +'{{yes}}       | {{yes}}      | {{no}}  |',
 lib('kotlin.KtLintStep')                         +'{{yes}}       | {{yes}}      | {{no}}  |',
+lib('kotlin.KtfmtStep')                          +'{{yes}}       | {{yes}}      | {{no}}  |',
 lib('markdown.FreshMarkStep')                    +'{{yes}}       | {{no}}       | {{no}}  |',
 lib('npm.PrettierFormatterStep')                 +'{{yes}}       | {{yes}}       | {{no}}  |',
 lib('npm.TsFmtFormatterStep')                    +'{{yes}}       | {{yes}}       | {{no}}  |',
@@ -73,6 +74,7 @@ extra('wtp.EclipseWtpFormatterStep')             +'{{yes}}       | {{yes}}
 | [`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:       | :+1:      | :white_large_square:  |
+| [`kotlin.KtfmtStep`](lib/src/main/java/com/diffplug/spotless/kotlin/KtfmtStep.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:  |
 | [`npm.PrettierFormatterStep`](lib/src/main/java/com/diffplug/spotless/npm/PrettierFormatterStep.java) | :+1:       | :+1:       | :white_large_square:  |
 | [`npm.TsFmtFormatterStep`](lib/src/main/java/com/diffplug/spotless/npm/TsFmtFormatterStep.java) | :+1:       | :+1:       | :white_large_square:  |

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

@@ -0,0 +1,88 @@
+/*
+ * 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;
+
+import java.io.IOException;
+import java.io.Serializable;
+import java.lang.reflect.InvocationTargetException;
+import java.lang.reflect.Method;
+import java.util.Objects;
+
+import com.diffplug.spotless.*;
+
+/** Wraps up [ktfmt](https://github.com/facebookincubator/ktfmt) as a FormatterStep. */
+public class KtfmtStep {
+	// prevent direct instantiation
+	private KtfmtStep() {}
+
+	private static final String DEFAULT_VERSION = "0.13";
+	static final String NAME = "ktfmt";
+	static final String PACKAGE = "com.facebook";
+	static final String MAVEN_COORDINATE = PACKAGE + ":ktfmt:";
+
+	/**
+	 * The <code>format</code> method is available in the link below.
+	 *
+	 * @see:
+	 *     https://github.com/facebookincubator/ktfmt/blob/master/core/src/main/java/com/facebook/ktfmt/Formatter.kt#L61-L65
+	 */
+	static final String FORMATTER_METHOD = "format";
+
+	/** Creates a step which formats everything - code, import order, and unused imports. */
+	public static FormatterStep create(Provisioner provisioner) {
+		return create(defaultVersion(), provisioner);
+	}
+
+	/** Creates a step which formats everything - code, import order, and unused imports. */
+	public static FormatterStep create(String version, Provisioner provisioner) {
+		Objects.requireNonNull(version, "version");
+		Objects.requireNonNull(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;
+
+		private final String pkg;
+		/** The jar that contains the eclipse formatter. */
+		final JarState jarState;
+
+		State(String version, Provisioner provisioner) throws IOException {
+			this.pkg = PACKAGE;
+			this.jarState = JarState.from(MAVEN_COORDINATE + version, provisioner);
+		}
+
+		FormatterFunc createFormat() throws Exception {
+			ClassLoader classLoader = jarState.getClassLoader();
+
+			Class<?> formatterClazz = classLoader.loadClass(pkg + ".ktfmt.FormatterKt");
+			Method formatterMethod = formatterClazz.getMethod(FORMATTER_METHOD, String.class);
+
+			return input -> {
+				try {
+					return (String) formatterMethod.invoke(formatterClazz, input);
+				} catch (InvocationTargetException e) {
+					throw ThrowingEx.unwrapCause(e);
+				}
+			};
+		}
+	}
+}

plugin-gradle/CHANGES.md

@@ -5,7 +5,8 @@ We adhere to the [keepachangelog](https://keepachangelog.com/en/1.0.0/) format (
 ## [Unreleased]
 ### Added
 * [**VS Code Extension**](https://marketplace.visualstudio.com/items?itemName=richardwillis.vscode-spotless-gradle) thanks to [@badsyntax](https://github.com/badsyntax)
-* Support for google-java-format 1.8 (requires you to run build on Java 11) ([#562](https://github.com/diffplug/spotless/issues/562))
+* Support for google-java-format 1.8 (requires build to run on Java 11+) ([#562](https://github.com/diffplug/spotless/issues/562))
+* Support for ktfmt 0.13 (requires build to run on Java 11+) ([#569](https://github.com/diffplug/spotless/pull/569))
 ### Changed
 * PaddedCell is now always enabled.  It is strictly better than non-padded cell, and there is no performance penalty.  [See here](https://github.com/diffplug/spotless/pull/560#issuecomment-621752798) for detailed explanation. ([#561](https://github.com/diffplug/spotless/pull/561))
 * Updated a bunch of dependencies, most notably jgit `5.5.0.201909110433-r` -> `5.7.0.202003110725-r`. ([#564](https://github.com/diffplug/spotless/pull/564))

plugin-gradle/README.md

@@ -84,6 +84,7 @@ Spotless can check and apply formatting to any plain-text file, using simple rul
 * [Groovy Eclipse](#groovy-eclipse)'s groovy code formatter
 * [FreshMark](https://github.com/diffplug/freshmark) (markdown with variables)
 * [ktlint](https://github.com/pinterest/ktlint)
+* [ktfmt](https://github.com/facebookincubator/ktfmt)
 * [scalafmt](https://github.com/olafurpg/scalafmt)
 * [DBeaver sql format](https://dbeaver.jkiss.org/)
 * [Prettier: An opinionated code formatter](https://prettier.io)
@@ -278,6 +279,23 @@ spotless {
 }
 ```
 
+<a name="ktfmt"></a>
+
+## Applying [ktfmt](https://github.com/facebookincubator/ktfmt) to Kotlin files
+
+```gradle
+spotless {
+  kotlin {
+    // optionally takes a version
+    ktfmt()
+
+    // also supports license headers
+    licenseHeader '/* Licensed under Apache-2.0 */'	// License header
+    licenseHeaderFile 'path-to-license-file'		// License header file
+  }
+}
+```
+
 <a name="sql-dbeaver"></a>
 
 ## Applying [DBeaver](https://dbeaver.jkiss.org/) to SQL scripts

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

@@ -28,6 +28,7 @@
 
 import com.diffplug.spotless.FormatterStep;
 import com.diffplug.spotless.kotlin.KtLintStep;
+import com.diffplug.spotless.kotlin.KtfmtStep;
 
 public class KotlinExtension extends FormatExtension implements HasBuiltinDelimiterForLicense {
 	static final String NAME = "kotlin";
@@ -79,6 +80,33 @@ private FormatterStep createStep() {
 		}
 	}
 
+	/** Uses the [ktfmt](https://github.com/facebookincubator/ktfmt) jar to format source code. */
+	public KtfmtConfig ktfmt() {
+		return ktfmt(KtfmtStep.defaultVersion());
+	}
+
+	/**
+	 * Uses the given version of [ktfmt](https://github.com/facebookincubator/ktfmt) to format source
+	 * code.
+	 */
+	public KtfmtConfig ktfmt(String version) {
+		Objects.requireNonNull(version);
+		return new KtfmtConfig(version);
+	}
+
+	public class KtfmtConfig {
+		final String version;
+
+		KtfmtConfig(String version) {
+			this.version = Objects.requireNonNull(version);
+			addStep(createStep());
+		}
+
+		private FormatterStep createStep() {
+			return KtfmtStep.create(version, GradleProvisioner.fromProject(getProject()));
+		}
+	}
+
 	/** If the user hasn't specified the files yet, we'll assume he/she means all of the kotlin files. */
 	@Override
 	protected void setupTask(SpotlessTask task) {

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

@@ -23,6 +23,8 @@
 import org.gradle.testkit.runner.BuildResult;
 import org.junit.Test;
 
+import com.diffplug.spotless.JreVersion;
+
 public class KotlinExtensionTest extends GradleIntegrationTest {
 	private static final String HEADER = "// License Header";
 	private static final String HEADER_WITH_YEAR = "// License Header $YEAR";
@@ -45,6 +47,28 @@ public void integration() throws IOException {
 		assertFile("src/main/kotlin/basic.kt").sameAsResource("kotlin/ktlint/basic.clean");
 	}
 
+	@Test
+	public void integrationKtfmt() throws IOException {
+		if (JreVersion.thisVm() == JreVersion._8) {
+			// ktfmt's dependency, google-java-format 1.8 requires a minimum of JRE 11+.
+			return;
+		}
+		setFile("build.gradle").toLines(
+				"plugins {",
+				"    id 'nebula.kotlin' version '1.0.6'",
+				"    id 'com.diffplug.gradle.spotless'",
+				"}",
+				"repositories { mavenCentral() }",
+				"spotless {",
+				"    kotlin {",
+				"        ktfmt()",
+				"    }",
+				"}");
+		setFile("src/main/kotlin/basic.kt").toResource("kotlin/ktfmt/basic.dirty");
+		gradleRunner().withArguments("spotlessApply").build();
+		assertFile("src/main/kotlin/basic.kt").sameAsResource("kotlin/ktfmt/basic.clean");
+	}
+
 	@Test
 	public void testWithIndentation() throws IOException {
 		setFile("build.gradle").toLines(
@@ -82,6 +106,29 @@ public void testWithHeader() throws IOException {
 		assertFile("src/main/kotlin/test.kt").hasContent(HEADER + "\n" + getTestResource("kotlin/licenseheader/KotlinCodeWithoutHeader.test"));
 	}
 
+	@Test
+	public void testWithHeaderKtfmt() throws IOException {
+		if (JreVersion.thisVm() == JreVersion._8) {
+			// ktfmt's dependency, google-java-format 1.8 requires a minimum of JRE 11+.
+			return;
+		}
+		setFile("build.gradle").toLines(
+				"plugins {",
+				"    id 'nebula.kotlin' version '1.0.6'",
+				"    id 'com.diffplug.gradle.spotless'",
+				"}",
+				"repositories { mavenCentral() }",
+				"spotless {",
+				"    kotlin {",
+				"        licenseHeader('" + HEADER + "')",
+				"        ktfmt()",
+				"    }",
+				"}");
+		setFile("src/main/kotlin/test.kt").toResource("kotlin/licenseheader/KotlinCodeWithoutHeader.test");
+		gradleRunner().withArguments("spotlessApply").build();
+		assertFile("src/main/kotlin/test.kt").hasContent(HEADER + "\n" + getTestResource("kotlin/licenseheader/KotlinCodeWithoutHeaderKtfmt.test"));
+	}
+
 	@Test
 	public void testWithCustomHeaderSeparator() throws IOException {
 		setFile("build.gradle").toLines(
@@ -101,6 +148,29 @@ public void testWithCustomHeaderSeparator() throws IOException {
 		assertFile("src/main/kotlin/test.kt").hasContent(HEADER + "\n" + getTestResource("kotlin/licenseheader/KotlinCodeWithoutHeader.test"));
 	}
 
+	@Test
+	public void testWithCustomHeaderSeparatorKtfmt() throws IOException {
+		if (JreVersion.thisVm() == JreVersion._8) {
+			// ktfmt's dependency, google-java-format 1.8 requires a minimum of JRE 11+.
+			return;
+		}
+		setFile("build.gradle").toLines(
+				"plugins {",
+				"    id 'nebula.kotlin' version '1.0.6'",
+				"    id 'com.diffplug.gradle.spotless'",
+				"}",
+				"repositories { mavenCentral() }",
+				"spotless {",
+				"    kotlin {",
+				"        licenseHeader ('" + HEADER + "', '@file')",
+				"        ktfmt()",
+				"    }",
+				"}");
+		setFile("src/main/kotlin/test.kt").toResource("kotlin/licenseheader/KotlinCodeWithoutHeader.test");
+		gradleRunner().withArguments("spotlessApply").build();
+		assertFile("src/main/kotlin/test.kt").hasContent(HEADER + "\n" + getTestResource("kotlin/licenseheader/KotlinCodeWithoutHeaderKtfmt.test"));
+	}
+
 	@Test
 	public void testWithNonStandardYearSeparator() throws IOException {
 		setFile("build.gradle").toLines(
@@ -126,4 +196,34 @@ public void testWithNonStandardYearSeparator() throws IOException {
 			matcher.startsWith(HEADER_WITH_YEAR.replace("$YEAR", String.valueOf(YearMonth.now().getYear())));
 		});
 	}
+
+	@Test
+	public void testWithNonStandardYearSeparatorKtfmt() throws IOException {
+		if (JreVersion.thisVm() == JreVersion._8) {
+			// ktfmt's dependency, google-java-format 1.8 requires a minimum of JRE 11+.
+			return;
+		}
+		setFile("build.gradle").toLines(
+				"plugins {",
+				"    id 'nebula.kotlin' version '1.0.6'",
+				"    id 'com.diffplug.gradle.spotless'",
+				"}",
+				"repositories { mavenCentral() }",
+				"spotless {",
+				"    kotlin {",
+				"        licenseHeader('" + HEADER_WITH_YEAR + "').yearSeparator(', ')",
+				"        ktfmt()",
+				"    }",
+				"}");
+
+		setFile("src/main/kotlin/test.kt").toResource("kotlin/licenseheader/KotlinCodeWithMultiYearHeader.test");
+		setFile("src/main/kotlin/test2.kt").toResource("kotlin/licenseheader/KotlinCodeWithMultiYearHeader2.test");
+		gradleRunner().withArguments("spotlessApply").build();
+		assertFile("src/main/kotlin/test.kt").matches(matcher -> {
+			matcher.startsWith("// License Header 2012, 2014");
+		});
+		assertFile("src/main/kotlin/test2.kt").matches(matcher -> {
+			matcher.startsWith(HEADER_WITH_YEAR.replace("$YEAR", String.valueOf(YearMonth.now().getYear())));
+		});
+	}
 }

plugin-maven/CHANGES.md

@@ -4,7 +4,8 @@ We adhere to the [keepachangelog](https://keepachangelog.com/en/1.0.0/) format (
 
 ## [Unreleased]
 ### Added
-* Support for google-java-format 1.8 (requires you to run build on Java 11) ([#562](https://github.com/diffplug/spotless/issues/562))
+* Support for google-java-format 1.8 (requires build to run on Java 11+) ([#562](https://github.com/diffplug/spotless/issues/562))
+* Support for ktfmt 0.13 (requires build to run on Java 11+) ([#569](https://github.com/diffplug/spotless/pull/569))
 * `mvn spotless:apply` is now guaranteed to be idempotent, even if some of the formatters are not.  See [`PADDEDCELL.md` for details](https://github.com/diffplug/spotless/blob/master/PADDEDCELL.md) if you're curious. ([#565](https://github.com/diffplug/spotless/pull/565))
 * Updated a bunch of dependencies, most notably jgit `5.5.0.201909110433-r` -> `5.7.0.202003110725-r`. ([#564](https://github.com/diffplug/spotless/pull/564))
 

plugin-maven/README.md

@@ -153,6 +153,8 @@ By default, all files matching `src/main/scala/**/*.scala`, `src/test/scala/**/*
 
 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.
 
+### Applying [ktlint](https://github.com/pinterest/ktlint) to Kotlin files
+
 ```xml
 <configuration>
   <kotlin>
@@ -171,6 +173,26 @@ By default, all files matching `src/main/kotlin/**/*.kt` and `src/test/kotlin/**
 </configuration>
 ```
 
+### Applying [ktfmt](https://github.com/facebookincubator/ktfmt) to Kotlin files
+
+```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/>
+     <ktfmt>
+       <!-- Optional, available versions: https://github.com/facebookincubator/ktfmt/releases -->
+       <version>0.11</version>
+     </ktfmt>
+  </kotlin>
+</configuration>
+```
+
 <a name="cpp"></a>
 
 ## Applying to C/C++ source

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

@@ -39,4 +39,8 @@ public String licenseHeaderDelimiter() {
 	public void addKtlint(Ktlint ktlint) {
 		addStepFactory(ktlint);
 	}
+
+	public void addKtfmt(Ktfmt ktfmt) {
+		addStepFactory(ktfmt);
+	}
 }