Introduce FluxMapNotNull{,Transformation}OrElse Refaster rules (#1493)

PicnicSupermarket · Jan 2, 2025 · e67800e · e67800e
1 parent 7f90f26
commit e67800e
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diff --git a/error-prone-contrib/src/main/java/tech/picnic/errorprone/refasterrules/ReactorRules.java b/error-prone-contrib/src/main/java/tech/picnic/errorprone/refasterrules/ReactorRules.java
@@ -889,6 +889,38 @@ Flux<S> after(Flux<T> flux) {
     }
   }
 
+  /**
+   * Prefer immediately unwrapping {@link Optional} transformation results inside {@link
+   * Flux#mapNotNull(Function)} over more contrived alternatives.
+   */
+  abstract static class FluxMapNotNullTransformationOrElse<T, S> {
+    @Placeholder(allowsIdentity = true)
+    abstract Optional<S> transformation(@MayOptionallyUse T value);
+
+    @BeforeTemplate
+    Flux<S> before(Flux<T> flux) {
+      return flux.map(v -> transformation(v)).mapNotNull(o -> o.orElse(null));
+    }
+
+    @AfterTemplate
+    Flux<S> after(Flux<T> flux) {
+      return flux.mapNotNull(x -> transformation(x).orElse(null));
+    }
+  }
+
+  /** Prefer {@link Flux#mapNotNull(Function)} over more contrived alternatives. */
+  static final class FluxMapNotNullOrElse<T> {
+    @BeforeTemplate
+    Flux<T> before(Flux<Optional<T>> flux) {
+      return flux.filter(Optional::isPresent).map(Optional::orElseThrow);
+    }
+
+    @AfterTemplate
+    Flux<T> after(Flux<Optional<T>> flux) {
+      return flux.mapNotNull(x -> x.orElse(null));
+    }
+  }
+
   /** Prefer {@link Mono#flux()}} over more contrived alternatives. */
   static final class MonoFlux<T> {
     @BeforeTemplate

diff --git a/...ontrib/src/test/resources/tech/picnic/errorprone/refasterrules/ReactorRulesTestInput.java b/...ontrib/src/test/resources/tech/picnic/errorprone/refasterrules/ReactorRulesTestInput.java
@@ -325,6 +325,14 @@ ImmutableSet<Flux<Integer>> testFluxMapNotNull() {
         Flux.just(1).switchMap(n -> Mono.fromSupplier(() -> n * 2)));
   }
 
+  Flux<String> testFluxMapNotNullTransformationOrElse() {
+    return Flux.just(1).map(x -> Optional.of(x.toString())).mapNotNull(x -> x.orElse(null));
+  }
+
+  Flux<Integer> testFluxMapNotNullOrElse() {
+    return Flux.just(Optional.of(1)).filter(Optional::isPresent).map(Optional::orElseThrow);
+  }
+
   ImmutableSet<Flux<String>> testMonoFlux() {
     return ImmutableSet.of(
         Mono.just("foo").flatMapMany(Mono::just),

diff --git a/...ntrib/src/test/resources/tech/picnic/errorprone/refasterrules/ReactorRulesTestOutput.java b/...ntrib/src/test/resources/tech/picnic/errorprone/refasterrules/ReactorRulesTestOutput.java
@@ -325,6 +325,14 @@ ImmutableSet<Flux<Integer>> testFluxMapNotNull() {
         Flux.just(1).mapNotNull(n -> n * 2));
   }
 
+  Flux<String> testFluxMapNotNullTransformationOrElse() {
+    return Flux.just(1).mapNotNull(x -> Optional.of(x.toString()).orElse(null));
+  }
+
+  Flux<Integer> testFluxMapNotNullOrElse() {
+    return Flux.just(Optional.of(1)).mapNotNull(x -> x.orElse(null));
+  }
+
   ImmutableSet<Flux<String>> testMonoFlux() {
     return ImmutableSet.of(
         Mono.just("foo").flux(), Mono.just("bar").flux(), Mono.just("baz").flux());