Convert ktlint integration to use a compile-only sourceset. (#1012, example of #524)

Author: nedtwigg

CHANGES.md

@@ -10,9 +10,10 @@ This document is intended for Spotless developers.
 We adhere to the [keepachangelog](https://keepachangelog.com/en/1.0.0/) format (starting after version `1.27.0`).
 
 ## [Unreleased]
+### Changed
+* Converted `ktlint` integration to use a compile-only source set. ([#524](https://github.com/diffplug/spotless/issues/524))
 
 ## [2.20.1] - 2021-12-01
-
 ### Changed
 * Added `named` option to `licenseHeader` to support alternate license header within same format (like java) ([872](https://github.com/diffplug/spotless/issues/872)).
 * Added `onlyIfContentMatches` option to `licenseHeader` to skip license header application  based on source file content pattern ([#650](https://github.com/diffplug/spotless/issues/650)).

lib/build.gradle

@@ -7,7 +7,8 @@ apply from: rootProject.file('gradle/java-setup.gradle')
 apply from: rootProject.file('gradle/java-publish.gradle')
 
 def NEEDS_GLUE = [
-	'sortPom'
+	'sortPom',
+	'ktlint'
 ]
 for (glue in NEEDS_GLUE) {
 	sourceSets.register(glue) {
@@ -20,12 +21,17 @@ for (glue in NEEDS_GLUE) {
 dependencies {
 	// zero runtime reqs is a hard requirements for spotless-lib
 	// if you need a dep, put it in lib-extra
-	testImplementation "org.junit.jupiter:junit-jupiter:${VER_JUNIT}"
-	testImplementation "org.assertj:assertj-core:${VER_ASSERTJ}"
-	testImplementation "com.diffplug.durian:durian-testlib:${VER_DURIAN}"
+	testImplementation "org.junit.jupiter:junit-jupiter:$VER_JUNIT"
+	testImplementation "org.assertj:assertj-core:$VER_ASSERTJ"
+	testImplementation "com.diffplug.durian:durian-testlib:$VER_DURIAN"
 
 	// used for pom sorting
 	sortPomCompileOnly 'com.github.ekryd.sortpom:sortpom-sorter:3.0.0'
+
+	String VER_KTLINT='0.43.1'
+	ktlintCompileOnly "com.pinterest:ktlint:$VER_KTLINT"
+	ktlintCompileOnly "com.pinterest.ktlint:ktlint-core:$VER_KTLINT"
+	ktlintCompileOnly "com.pinterest.ktlint:ktlint-ruleset-standard:$VER_KTLINT"
 }
 
 // we'll hold the core lib to a high standard

lib/src/ktlint/java/com/diffplug/spotless/glue/ktlint/KtlintFormatterFunc.java

@@ -0,0 +1,72 @@
+/*
+ * Copyright 2021 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.glue.ktlint;
+
+import java.io.File;
+import java.util.Collections;
+import java.util.List;
+import java.util.Map;
+import java.util.logging.Logger;
+
+import com.pinterest.ktlint.core.KtLint;
+import com.pinterest.ktlint.core.KtLint.Params;
+import com.pinterest.ktlint.core.LintError;
+import com.pinterest.ktlint.core.RuleSet;
+import com.pinterest.ktlint.ruleset.standard.StandardRuleSetProvider;
+
+import com.diffplug.spotless.FormatterFunc;
+
+import kotlin.Unit;
+import kotlin.jvm.functions.Function2;
+
+public class KtlintFormatterFunc implements FormatterFunc.NeedsFile {
+	private static final Logger logger = Logger.getLogger(KtlintFormatterFunc.class.getName());
+
+	private final List<RuleSet> rulesets;
+	private final Map<String, String> userData;
+	private final Function2<? super LintError, ? super Boolean, Unit> formatterCallback;
+	private final boolean isScript;
+
+	public KtlintFormatterFunc(boolean isScript, Map<String, String> userData) {
+		rulesets = Collections.singletonList(new StandardRuleSetProvider().get());
+		this.userData = userData;
+		formatterCallback = new FormatterCallback();
+		this.isScript = isScript;
+	}
+
+	static class FormatterCallback implements Function2<LintError, Boolean, Unit> {
+		@Override
+		public Unit invoke(LintError lint, Boolean corrected) {
+			if (!corrected) {
+				throw new AssertionError("Error on line: " + lint.getLine() + ", column: " + lint.getCol() + "\n" + lint.getDetail());
+			}
+			return null;
+		}
+	}
+
+	@Override
+	public String applyWithFile(String unix, File file) throws Exception {
+		return KtLint.INSTANCE.format(new Params(
+				file.getName(),
+				unix,
+				rulesets,
+				userData,
+				formatterCallback,
+				isScript,
+				null,
+				false));
+	}
+}

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

@@ -103,8 +103,13 @@ static final class State implements Serializable {
 		}
 
 		FormatterFunc createFormat() throws Exception {
-			ClassLoader classLoader = jarState.getClassLoader();
+			if (useParams) {
+				Class<?> formatterFunc = jarState.getClassLoader().loadClass("com.diffplug.spotless.glue.ktlint.KtlintFormatterFunc");
+				Constructor<?> constructor = formatterFunc.getConstructor(boolean.class, Map.class);
+				return (FormatterFunc.NeedsFile) constructor.newInstance(isScript, userData);
+			}
 
+			ClassLoader classLoader = jarState.getClassLoader();
 			// String KtLint::format(String input, Iterable<RuleSet> rules, Function2 errorCallback)
 
 			// first, we get the standard rules
@@ -134,57 +139,17 @@ FormatterFunc createFormat() throws Exception {
 			// grab the KtLint singleton
 			Class<?> ktlintClass = classLoader.loadClass(pkg + ".ktlint.core.KtLint");
 			Object ktlint = ktlintClass.getDeclaredField("INSTANCE").get(null);
-			FormatterFunc formatterFunc;
-			if (useParams) {
-				//
-				// In KtLint 0.34+ there is a new "format(params: Params)" function. We create an
-				// instance of the Params class with our configuration and invoke it here.
-				//
-
-				// grab the Params class
-				Class<?> paramsClass = classLoader.loadClass(pkg + ".ktlint.core.KtLint$Params");
-				// and its constructor
-				Constructor<?> constructor = paramsClass.getConstructor(
-						/* fileName, nullable */ String.class,
-						/* text */ String.class,
-						/* ruleSets */ Iterable.class,
-						/* userData */ Map.class,
-						/* callback */ function2Interface,
-						/* script */ boolean.class,
-						/* editorConfigPath, nullable */ String.class,
-						/* debug */ boolean.class);
-				Method formatterMethod = ktlintClass.getMethod("format", paramsClass);
-				FormatterFunc.NeedsFile needsFile = (input, file) -> {
-					try {
-						Object params = constructor.newInstance(
-								/* fileName, nullable */ file.getName(),
-								/* text */ input,
-								/* ruleSets */ ruleSets,
-								/* userData */ userData,
-								/* callback */ formatterCallback,
-								/* script */ isScript,
-								/* editorConfigPath, nullable */ null,
-								/* debug */ false);
-						return (String) formatterMethod.invoke(ktlint, params);
-					} catch (InvocationTargetException e) {
-						throw ThrowingEx.unwrapCause(e);
-					}
-				};
-				formatterFunc = FormatterFunc.needsFile(needsFile);
-			} else {
-				// and its format method
-				String formatterMethodName = isScript ? "formatScript" : "format";
-				Method formatterMethod = ktlintClass.getMethod(formatterMethodName, String.class, Iterable.class, Map.class, function2Interface);
-				formatterFunc = input -> {
-					try {
-						return (String) formatterMethod.invoke(ktlint, input, ruleSets, userData, formatterCallback);
-					} catch (InvocationTargetException e) {
-						throw ThrowingEx.unwrapCause(e);
-					}
-				};
-			}
 
-			return formatterFunc;
+			// and its format method
+			String formatterMethodName = isScript ? "formatScript" : "format";
+			Method formatterMethod = ktlintClass.getMethod(formatterMethodName, String.class, Iterable.class, Map.class, function2Interface);
+			return input -> {
+				try {
+					return (String) formatterMethod.invoke(ktlint, input, ruleSets, userData, formatterCallback);
+				} catch (InvocationTargetException e) {
+					throw ThrowingEx.unwrapCause(e);
+				}
+			};
 		}
 	}
 }