From 809fb4b0785803d96b2acde585db747f86e89c04 Mon Sep 17 00:00:00 2001
From: Ned Twigg <ned.twigg@diffplug.com>
Date: Thu, 28 Sep 2023 15:28:26 -0700
Subject: [PATCH] Make GIT_ATTRIBUTES_FAST_ALLSAME faster.

---
 .../extra/GitAttributesLineEndings.java       | 35 ++++++++++++
 .../com/diffplug/spotless/LineEnding.java     | 56 ++++---------------
 2 files changed, 47 insertions(+), 44 deletions(-)

diff --git a/lib-extra/src/main/java/com/diffplug/spotless/extra/GitAttributesLineEndings.java b/lib-extra/src/main/java/com/diffplug/spotless/extra/GitAttributesLineEndings.java
index fb54be4ba0..c53e9a3e92 100644
--- a/lib-extra/src/main/java/com/diffplug/spotless/extra/GitAttributesLineEndings.java
+++ b/lib-extra/src/main/java/com/diffplug/spotless/extra/GitAttributesLineEndings.java
@@ -68,6 +68,41 @@ public final class GitAttributesLineEndings {
 	// prevent direct instantiation
 	private GitAttributesLineEndings() {}
 
+	/**
+	 * Creates a line-endings policy which matches {@link #create(File, Supplier)},
+	 * which is much faster at the cost that every file under the policy
+	 * is assumed to have the same line endings as the first file.
+	 */
+	public static LineEnding.Policy createFastAllSame(File projectDir, Supplier<Iterable<File>> toFormat) {
+		return new LazyAllTheSame(projectDir, toFormat);
+	}
+
+	static class LazyAllTheSame extends LazyForwardingEquality<String> implements LineEnding.Policy {
+		transient File projectDir;
+		transient Supplier<Iterable<File>> toFormat;
+
+		public LazyAllTheSame(File projectDir, Supplier<Iterable<File>> toFormat) {
+			this.projectDir = projectDir;
+			this.toFormat = toFormat;
+		}
+
+		@Override
+		protected String calculateState() throws Exception {
+			var files = toFormat.get().iterator();
+			if (files.hasNext()) {
+				Runtime runtime = new RuntimeInit(projectDir).atRuntime();
+				return runtime.getEndingFor(files.next());
+			} else {
+				return LineEnding.UNIX.str();
+			}
+		}
+
+		@Override
+		public String getEndingFor(File file) {
+			return state();
+		}
+	}
+
 	/**
 	 * Creates a line-endings policy whose serialized state is relativized against projectDir,
 	 * at the cost of eagerly evaluating the line-ending state of every target file when the
diff --git a/lib/src/main/java/com/diffplug/spotless/LineEnding.java b/lib/src/main/java/com/diffplug/spotless/LineEnding.java
index fa487a03b7..708699904c 100644
--- a/lib/src/main/java/com/diffplug/spotless/LineEnding.java
+++ b/lib/src/main/java/com/diffplug/spotless/LineEnding.java
@@ -59,52 +59,20 @@ public Policy createPolicy() {
 	public Policy createPolicy(File projectDir, Supplier<Iterable<File>> toFormat) {
 		Objects.requireNonNull(projectDir, "projectDir");
 		Objects.requireNonNull(toFormat, "toFormat");
-		if (this != GIT_ATTRIBUTES && this != GIT_ATTRIBUTES_FAST_ALLSAME) {
-			return createPolicy();
+		String gitAttributesMethod;
+		if (this == GIT_ATTRIBUTES) {
+			gitAttributesMethod = "create";
+		} else if (this == GIT_ATTRIBUTES_FAST_ALLSAME) {
+			gitAttributesMethod = "createFastAllSame";
 		} else {
-			if (gitAttributesPolicyCreator == null) {
-				try {
-					Class<?> clazz = Class.forName("com.diffplug.spotless.extra.GitAttributesLineEndings");
-					Method method = clazz.getMethod("create", File.class, Supplier.class);
-					gitAttributesPolicyCreator = (proj, target) -> ThrowingEx.get(() -> (Policy) method.invoke(null, proj, target));
-				} catch (ClassNotFoundException | NoSuchMethodException | SecurityException e) {
-					throw new IllegalStateException("LineEnding.GIT_ATTRIBUTES requires the spotless-lib-extra library, but it is not on the classpath", e);
-				}
-			}
-			// gitAttributesPolicyCreator will always be nonnull at this point
-			Policy policy = gitAttributesPolicyCreator.apply(projectDir, toFormat);
-			if (this == GIT_ATTRIBUTES) {
-				return policy;
-			} else if (this == GIT_ATTRIBUTES_FAST_ALLSAME) {
-				return new LazyAllTheSame(policy, toFormat);
-			} else {
-				throw new IllegalArgumentException("Unknown " + this);
-			}
-		}
-	}
-
-	static class LazyAllTheSame extends LazyForwardingEquality<String> implements Policy {
-		private transient Policy policy;
-		private transient Supplier<Iterable<File>> toFormat;
-
-		public LazyAllTheSame(Policy policy, Supplier<Iterable<File>> toFormat) {
-			this.policy = policy;
-			this.toFormat = toFormat;
-		}
-
-		@Override
-		protected String calculateState() throws Exception {
-			var files = toFormat.get().iterator();
-			if (files.hasNext()) {
-				return policy.getEndingFor(files.next());
-			} else {
-				return LineEnding.UNIX.str();
-			}
+			return createPolicy();
 		}
-
-		@Override
-		public String getEndingFor(File file) {
-			return state();
+		try {
+			Class<?> clazz = Class.forName("com.diffplug.spotless.extra.GitAttributesLineEndings");
+			Method method = clazz.getMethod(gitAttributesMethod, File.class, Supplier.class);
+			return ThrowingEx.get(() -> (Policy) method.invoke(null, projectDir, toFormat));
+		} catch (ClassNotFoundException | NoSuchMethodException | SecurityException e) {
+			throw new IllegalStateException("LineEnding.GIT_ATTRIBUTES requires the spotless-lib-extra library, but it is not on the classpath", e);
 		}
 	}