Fix possible exception with initializer body close to column limit

changelog/@unreleased/pr-257.v2.yml

@@ -0,0 +1,6 @@
+type: fix
+fix:
+  description: Fix edge case with empty levels causing formattings very close to the
+    column limit to throw.
+  links:
+  - https://github.com/palantir/palantir-java-format/pull/257

palantir-java-format/src/main/java/com/palantir/javaformat/doc/Level.java

@@ -42,6 +42,7 @@
 import java.util.OptionalInt;
 import java.util.stream.Collector;
 import java.util.stream.Collectors;
+import java.util.stream.Stream;
 import org.immutables.value.Value;
 
 /** A {@code Level} inside a {@link Doc}. */
@@ -262,10 +263,7 @@ private Optional<State> handle_breakOnlyIfInnerLevelsThenFitOnOneLine(
 
         // Note: we are not checking if the brokenState produced one extra line compared to state, as this can be
         // misleading if there is no level but a single comment that got reflowed onto multiple lines (see palantir-11).
-        boolean anyLevelWasBroken = docs.stream()
-                .filter(doc -> doc instanceof Level)
-                .map(doc -> ((Level) doc))
-                .anyMatch(level -> !brokenState.isOneLine(level));
+        boolean anyLevelWasBroken = getNonEmptyInnerLevels().anyMatch(level -> !brokenState.isOneLine(level));
 
         if (!anyLevelWasBroken) {
             return Optional.of(brokenState);
@@ -278,17 +276,21 @@ private Optional<State> handle_breakOnlyIfInnerLevelsThenFitOnOneLine(
         }
         State partiallyInlinedState = partiallyInlinedStateOpt.get();
 
-        boolean bodyIsComplex = this.docs.stream()
-                .filter(doc -> doc instanceof Level)
-                .map(doc -> ((Level) doc))
-                .anyMatch(il -> il.openOp.complexity() == Complexity.COMPLEX);
+        boolean bodyIsComplex = getNonEmptyInnerLevels().anyMatch(il -> il.openOp.complexity() == Complexity.COMPLEX);
 
         if (bodyIsComplex || partiallyInlinedState.numLines() < brokenState.numLines()) {
             return Optional.of(partiallyInlinedState);
         }
         return Optional.empty();
     }
 
+    private Stream<Level> getNonEmptyInnerLevels() {
+        return docs.stream()
+                .filter(doc -> doc instanceof Level)
+                .map(doc -> ((Level) doc))
+                .filter(doc -> StartsWithBreakVisitor.INSTANCE.visit(doc) != Result.EMPTY);
+    }
+
     private Optional<State> tryInlinePrefixOntoCurrentLine(
             CommentsHelper commentsHelper,
             int maxWidth,
@@ -297,15 +299,9 @@ private Optional<State> tryInlinePrefixOntoCurrentLine(
             Obs.ExplorationNode explorationNode) {
         // Find the last level, skipping empty levels (that contain nothing, or are made up
         // entirely of other empty levels).
-        List<Level> innerLevels = this.docs.stream()
-                .filter(doc -> doc instanceof Level)
-                .map(doc -> ((Level) doc))
-                .collect(Collectors.toList());
-
         // Last level because there might be other in-between levels after the initial break like `new
-        // int[]
-        // {`, and we want to skip those.
-        Level lastLevel = innerLevels.stream()
+        // int[] {`, and we want to skip those.
+        Level lastLevel = getNonEmptyInnerLevels()
                 .filter(doc -> StartsWithBreakVisitor.INSTANCE.visit(doc) != Result.EMPTY)
                 .collect(GET_LAST_COLLECTOR)
                 .orElseThrow(() ->

palantir-java-format/src/test/resources/com/palantir/javaformat/java/testdata/palantir-12.input

@@ -0,0 +1,25 @@
+public class Palantir12 {
+
+    @Override
+    public
+    void
+    foo() {
+        new DogWalker()
+                .walk(
+                        DogBreed.FOX_TERRIER,
+                        new RoadWalker<Void>() {
+                            @Override
+                            public Void call(Dog dog) {
+                                routes.forEach((route) -> route.getCoordinates()
+                                        .forEach((coordinate) -> {
+                                            coordinate.getOtherDogs().forEach(otherDog -> {
+                                                if (!dog.likes(otherDog)) {
+                                                    badEncounters.computeIfAbsent(coordinate, _x -> new HashSet<>())
+                                                            .add(dog).add(otherDog);
+                                                }
+                                            });
+                                        }));
+                            }
+                        });
+    }
+}

palantir-java-format/src/test/resources/com/palantir/javaformat/java/testdata/palantir-12.output

@@ -0,0 +1,21 @@
+public class Palantir12 {
+
+    @Override
+    public void foo() {
+        new DogWalker().walk(DogBreed.FOX_TERRIER, new RoadWalker<Void>() {
+            @Override
+            public Void call(Dog dog) {
+                routes.forEach((route) -> route.getCoordinates().forEach((coordinate) -> {
+                    coordinate.getOtherDogs().forEach(otherDog -> {
+                        if (!dog.likes(otherDog)) {
+                            badEncounters
+                                    .computeIfAbsent(coordinate, _x -> new HashSet<>())
+                                    .add(dog)
+                                    .add(otherDog);
+                        }
+                    });
+                }));
+            }
+        });
+    }
+}