1480: add npmInstallCache to api

Author: simschla

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

@@ -528,6 +528,9 @@ public abstract static class NpmStepConfig<T extends NpmStepConfig<?>> {
 		@Nullable
 		protected Object nodeFile;
 
+		@Nullable
+		protected Object npmInstallCache;
+
 		@Nullable
 		protected Object npmrcFile;
 
@@ -560,6 +563,18 @@ public T npmrc(final Object npmrcFile) {
 			return (T) this;
 		}
 
+		public T npmInstallCache(final Object npmInstallCache) {
+			this.npmInstallCache = npmInstallCache;
+			replaceStep();
+			return (T) this;
+		}
+
+		public T npmInstallCache() {
+			this.npmInstallCache = new File(project.getBuildDir(), "spotless-npm-install-cache");
+			replaceStep();
+			return (T) this;
+		}
+
 		File npmFileOrNull() {
 			return fileOrNull(npmFile);
 		}
@@ -572,6 +587,10 @@ File npmrcFileOrNull() {
 			return fileOrNull(npmrcFile);
 		}
 
+		File npmModulesCacheOrNull() {
+			return fileOrNull(npmInstallCache);
+		}
+
 		private File fileOrNull(Object npmFile) {
 			return npmFile != null ? project.file(npmFile) : null;
 		}
@@ -619,6 +638,7 @@ protected FormatterStep createStep() {
 					provisioner(),
 					project.getProjectDir(),
 					project.getBuildDir(),
+					npmModulesCacheOrNull(),
 					new NpmPathResolver(npmFileOrNull(), nodeFileOrNull(), npmrcFileOrNull(), Arrays.asList(project.getProjectDir(), project.getRootDir())),
 					new com.diffplug.spotless.npm.PrettierConfig(
 							this.prettierConfigFile != null ? project.file(this.prettierConfigFile) : null,

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

@@ -108,6 +108,7 @@ public FormatterStep createStep() {
 					provisioner(),
 					project.getProjectDir(),
 					project.getBuildDir(),
+					npmModulesCacheOrNull(),
 					new NpmPathResolver(npmFileOrNull(), nodeFileOrNull(), npmrcFileOrNull(), Arrays.asList(project.getProjectDir(), project.getRootDir())),
 					eslintConfig());
 		}

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

@@ -117,6 +117,7 @@ public FormatterStep createStep() {
 					provisioner(),
 					project.getProjectDir(),
 					project.getBuildDir(),
+					npmModulesCacheOrNull(),
 					new NpmPathResolver(npmFileOrNull(), nodeFileOrNull(), npmrcFileOrNull(), Arrays.asList(project.getProjectDir(), project.getRootDir())),
 					typedConfigFile(),
 					config);
@@ -213,6 +214,7 @@ public FormatterStep createStep() {
 					provisioner(),
 					project.getProjectDir(),
 					project.getBuildDir(),
+					npmModulesCacheOrNull(),
 					new NpmPathResolver(npmFileOrNull(), nodeFileOrNull(), npmrcFileOrNull(), Arrays.asList(project.getProjectDir(), project.getRootDir())),
 					eslintConfig());
 		}

plugin-maven/src/main/java/com/diffplug/spotless/maven/generic/Prettier.java

@@ -95,9 +95,10 @@ public FormatterStep newFormatterStep(FormatterStepConfig stepConfig) {
 		// create the format step
 		File baseDir = baseDir(stepConfig);
 		File buildDir = buildDir(stepConfig);
+		File cacheDir = cacheDir(stepConfig);
 		PrettierConfig prettierConfig = new PrettierConfig(configFileHandler, configInline);
 		NpmPathResolver npmPathResolver = npmPathResolver(stepConfig);
-		return PrettierFormatterStep.create(devDependencies, stepConfig.getProvisioner(), baseDir, buildDir, npmPathResolver, prettierConfig);
+		return PrettierFormatterStep.create(devDependencies, stepConfig.getProvisioner(), baseDir, buildDir, cacheDir, npmPathResolver, prettierConfig);
 	}
 
 	private static IllegalArgumentException onlyOneConfig() {

plugin-maven/src/main/java/com/diffplug/spotless/maven/javascript/AbstractEslint.java

@@ -67,8 +67,9 @@ public FormatterStep newFormatterStep(FormatterStepConfig stepConfig) {
 
 		File buildDir = buildDir(stepConfig);
 		File baseDir = baseDir(stepConfig);
+		File cacheDir = cacheDir(stepConfig);
 		NpmPathResolver npmPathResolver = npmPathResolver(stepConfig);
-		return EslintFormatterStep.create(devDependencies, stepConfig.getProvisioner(), baseDir, buildDir, npmPathResolver, eslintConfig(stepConfig));
+		return EslintFormatterStep.create(devDependencies, stepConfig.getProvisioner(), baseDir, buildDir, cacheDir, npmPathResolver, eslintConfig(stepConfig));
 	}
 
 	private static IllegalArgumentException onlyOneConfig() {

plugin-maven/src/main/java/com/diffplug/spotless/maven/npm/AbstractNpmFormatterStepFactory.java

@@ -19,6 +19,7 @@
 import java.util.AbstractMap;
 import java.util.Arrays;
 import java.util.Collections;
+import java.util.Locale;
 import java.util.Map;
 import java.util.Objects;
 import java.util.Properties;
@@ -41,6 +42,9 @@ public abstract class AbstractNpmFormatterStepFactory implements FormatterStepFa
 	@Parameter
 	private String npmrc;
 
+	@Parameter
+	private String npmInstallCache;
+
 	protected File npm(FormatterStepConfig stepConfig) {
 		File npm = npmExecutable != null ? stepConfig.getFileLocator().locateFile(npmExecutable) : null;
 		return npm;
@@ -60,6 +64,16 @@ protected File buildDir(FormatterStepConfig stepConfig) {
 		return stepConfig.getFileLocator().getBuildDir();
 	}
 
+	protected File cacheDir(FormatterStepConfig stepConfig) {
+		if (this.npmInstallCache == null) {
+			return null;
+		}
+		if ("true".equals(this.npmInstallCache.toLowerCase(Locale.ROOT))) {
+			return new File(buildDir(stepConfig), "spotless-npm-install-cache");
+		}
+		return stepConfig.getFileLocator().locateFile(this.npmInstallCache);
+	}
+
 	protected File baseDir(FormatterStepConfig stepConfig) {
 		return stepConfig.getFileLocator().getBaseDir();
 	}

plugin-maven/src/main/java/com/diffplug/spotless/maven/typescript/Tsfmt.java

@@ -111,8 +111,9 @@ public FormatterStep newFormatterStep(FormatterStepConfig stepConfig) {
 
 		File buildDir = buildDir(stepConfig);
 		File baseDir = baseDir(stepConfig);
+		File cacheDir = cacheDir(stepConfig);
 		NpmPathResolver npmPathResolver = npmPathResolver(stepConfig);
-		return TsFmtFormatterStep.create(devDependencies, stepConfig.getProvisioner(), baseDir, buildDir, npmPathResolver, configFile, configInline);
+		return TsFmtFormatterStep.create(devDependencies, stepConfig.getProvisioner(), baseDir, buildDir, cacheDir, npmPathResolver, configFile, configInline);
 	}
 
 	private static IllegalArgumentException onlyOneConfig() {