Replace mutable removeSuppressedLints with immutable withRemovedSuppressions.

Author: nedtwigg

lib/src/main/java/com/diffplug/spotless/LintState.java

@@ -18,16 +18,16 @@
 import java.io.File;
 import java.io.IOException;
 import java.nio.file.Files;
+import java.util.ArrayList;
 import java.util.Iterator;
 import java.util.LinkedHashMap;
 import java.util.List;
-import java.util.Objects;
 
 import javax.annotation.Nullable;
 
 public class LintState {
 	private final DirtyState dirtyState;
-	private @Nullable List<List<Lint>> lintsPerStep;
+	private final @Nullable List<List<Lint>> lintsPerStep;
 
 	LintState(DirtyState dirtyState, @Nullable List<List<Lint>> lintsPerStep) {
 		this.dirtyState = dirtyState;
@@ -64,36 +64,41 @@ public LinkedHashMap<String, List<Lint>> getLintsByStep(Formatter formatter) {
 		return result;
 	}
 
-	public void removeSuppressedLints(Formatter formatter, String relativePath, List<LintSuppression> suppressions) {
+	public LintState withRemovedSuppressions(Formatter formatter, String relativePath, List<LintSuppression> suppressions) {
 		if (lintsPerStep == null) {
-			return;
+			return this;
 		}
 		if (formatter.getSteps().size() != lintsPerStep.size()) {
 			throw new IllegalStateException("LintState was created with a different formatter!");
 		}
+		boolean changed = false;
+		ValuePerStep<List<Lint>> perStepFiltered = new ValuePerStep<>(formatter);
 		for (int i = 0; i < lintsPerStep.size(); i++) {
 			FormatterStep step = formatter.getSteps().get(i);
-			List<Lint> lints = lintsPerStep.get(i);
-			if (lints != null) {
+			List<Lint> lintsOriginal = lintsPerStep.get(i);
+			if (lintsOriginal != null) {
+				List<Lint> lints = new ArrayList<>(lintsOriginal);
 				Iterator<Lint> iter = lints.iterator();
 				while (iter.hasNext()) {
 					Lint lint = iter.next();
 					for (LintSuppression suppression : suppressions) {
 						if (suppression.suppresses(relativePath, step, lint)) {
+							changed = true;
 							iter.remove();
 							break;
 						}
 					}
 				}
-				if (lints.isEmpty()) {
-					lintsPerStep.set(i, null);
-					if (lintsPerStep.stream().allMatch(Objects::isNull)) {
-						lintsPerStep = null;
-						return;
-					}
+				if (!lints.isEmpty()) {
+					perStepFiltered.set(i, lints);
 				}
 			}
 		}
+		if (changed) {
+			return new LintState(dirtyState, perStepFiltered.indexOfFirstValue() == -1 ? null : perStepFiltered);
+		} else {
+			return this;
+		}
 	}
 
 	public String asStringDetailed(File file, Formatter formatter) {

lib/src/test/java/com/diffplug/spotless/LintSuppressionTest.java

@@ -46,8 +46,7 @@ private Formatter formatter() {
 
 	@Test
 	public void testMatchSingle() {
-		var noSuppressions = dummyLintState();
-		noSuppressions.removeSuppressedLints(formatter(), "file", List.of());
+		var noSuppressions = dummyLintState().withRemovedSuppressions(formatter(), "file", List.of());
 		assertThat(noSuppressions.isHasLints()).isTrue();
 		removesLint(s -> s.setStep("blah")).isFalse();
 		removesLint(s -> s.setStep("endWithNewline")).isTrue();
@@ -77,8 +76,7 @@ private AbstractBooleanAssert<?> removesLint(Consumer<LintSuppression> suppressi
 		var s = new LintSuppression();
 		suppression.accept(s);
 
-		var ls = dummyLintState();
-		ls.removeSuppressedLints(formatter(), "testFile", List.of(s));
+		var ls = dummyLintState().withRemovedSuppressions(formatter(), "testFile", List.of(s));
 		return assertThat(!ls.isHasLints());
 	}
 }

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

@@ -118,8 +118,7 @@ void processInputFile(@Nullable GitRatchet ratchet, Formatter formatter, File in
 			lintState = LintState.clean();
 		} else {
 			try {
-				lintState = LintState.of(formatter, input);
-				lintState.removeSuppressedLints(formatter, relativePath, getLintSuppressions());
+				lintState = LintState.of(formatter, input).withRemovedSuppressions(formatter, relativePath, getLintSuppressions());
 			} catch (Throwable e) {
 				throw new IllegalArgumentException("Issue processing file: " + input, e);
 			}