From c30a10fda2010e6632fd163e73ba045e0b8e541a Mon Sep 17 00:00:00 2001 From: Erik Date: Sat, 21 Mar 2026 10:49:14 +0100 Subject: [PATCH 01/17] Fix Fixes.fixTypeEverywhere() silently returning input unchanged (#117) Add DynamicOps parameter and implement encode-transform-decode logic so the rewrite function is actually applied. Document the breaking signature change in the v0.5-to-v1.0 migration guide. --- .../aether/datafixers/api/fix/Fixes.java | 46 ++++++++++++++----- docs/migration/v0.5-to-v1.0.md | 39 +++++++++++++--- 2 files changed, 68 insertions(+), 17 deletions(-) diff --git a/aether-datafixers-api/src/main/java/de/splatgames/aether/datafixers/api/fix/Fixes.java b/aether-datafixers-api/src/main/java/de/splatgames/aether/datafixers/api/fix/Fixes.java index f811ed3..b5b8f14 100644 --- a/aether-datafixers-api/src/main/java/de/splatgames/aether/datafixers/api/fix/Fixes.java +++ b/aether-datafixers-api/src/main/java/de/splatgames/aether/datafixers/api/fix/Fixes.java @@ -121,7 +121,7 @@ private Fixes() { * @param rewrite the function that transforms the typed value; must not be {@code null} * @return a type rewrite rule that applies the transformation to matching types; never {@code null} * @throws NullPointerException if any parameter is {@code null} - * @see #fixTypeEverywhere(String, Type, Function) + * @see #fixTypeEverywhere(String, DynamicOps, Type, Function) */ @NotNull public static TypeRewriteRule fixTypeEverywhereTyped(@NotNull final String name, @@ -156,22 +156,44 @@ public String toString() { /** * Creates a rule that transforms the dynamic representation of a type. * - * @param name the fix name - * @param type the type to transform - * @param rewrite the dynamic transformation function - * @return a type rewrite rule + *

This method creates a {@link TypeRewriteRule} that matches values of the specified + * type and transforms them by encoding to {@link Dynamic}, applying the rewrite function, and decoding back. The + * rule only matches types with the same {@link de.splatgames.aether.datafixers.api.TypeReference} as the target + * type.

+ * + *

Example

+ * 
{@code
+     * TypeRewriteRule rule = Fixes.fixTypeEverywhere(
+     *     "addTimestamp",
+     *     GsonOps.INSTANCE,
+     *     playerType,
+     *     dynamic -> dynamic.set("timestamp", dynamic.createLong(0L))
+     * );
+     * }
+ * + * @param the dynamic type + * @param name the fix name; must not be {@code null} + * @param ops the dynamic ops for encoding/decoding; must not be {@code null} + * @param type the type to transform; must not be {@code null} + * @param rewrite the dynamic transformation function; must not be {@code null} + * @return a type rewrite rule; never {@code null} + * @throws NullPointerException if any parameter is {@code null} + * @see #fixTypeEverywhereTyped(String, Type, Type, Function) */ @NotNull - public static TypeRewriteRule fixTypeEverywhere(@NotNull final String name, - @NotNull final Type type, - @NotNull final Function, Dynamic> rewrite) { + public static TypeRewriteRule fixTypeEverywhere(@NotNull final String name, + @NotNull final DynamicOps ops, + @NotNull final Type type, + @NotNull final Function, Dynamic> rewrite) { Preconditions.checkNotNull(name, "name must not be null"); + Preconditions.checkNotNull(ops, "ops must not be null"); Preconditions.checkNotNull(type, "type must not be null"); Preconditions.checkNotNull(rewrite, "rewrite must not be null"); return new TypeRewriteRule() { @NotNull @Override + @SuppressWarnings({"unchecked", "rawtypes"}) public Optional> rewrite(@NotNull final Type inputType, @NotNull final Typed input) { Preconditions.checkNotNull(inputType, "inputType must not be null"); @@ -180,9 +202,11 @@ public Optional> rewrite(@NotNull final Type inputType, return Optional.empty(); } - // We need to get DynamicOps from somewhere - this requires the caller to provide it - // For now, we'll use a simplified approach - return Optional.of(input); + final DataResult> encodeResult = input.encode(ops); + return encodeResult.flatMap(dynamic -> { + final Dynamic transformed = rewrite.apply(dynamic); + return ((Type) type).read(transformed); + }).map(newValue -> new Typed<>((Type) type, newValue)).result(); } @Override diff --git a/docs/migration/v0.5-to-v1.0.md b/docs/migration/v0.5-to-v1.0.md index c1199e3..71eb722 100644 --- a/docs/migration/v0.5-to-v1.0.md +++ b/docs/migration/v0.5-to-v1.0.md @@ -6,12 +6,13 @@ This guide helps you migrate your project from Aether Datafixers v0.5.x to v1.0. Version 1.0.0 introduces breaking changes to improve the codec package organization and API clarity. This guide will help you update your codebase with minimal effort. -| Change Type | Component | Impact | -|-----------------|-------------------------|---------------------------------------------------| -| **Breaking** | Codec package structure | Import statements must be updated | -| **Breaking** | `JacksonOps` rename | Class renamed to `JacksonJsonOps` | -| **Breaking** | `TestData.jackson()` | Method renamed to `TestData.jacksonJson()` | -| **Deprecation** | Rules traversal methods | Single-argument overloads deprecated (still work) | +| Change Type | Component | Impact | +|-----------------|-----------------------------|---------------------------------------------------| +| **Breaking** | Codec package structure | Import statements must be updated | +| **Breaking** | `JacksonOps` rename | Class renamed to `JacksonJsonOps` | +| **Breaking** | `TestData.jackson()` | Method renamed to `TestData.jacksonJson()` | +| **Breaking** | `Fixes.fixTypeEverywhere()` | Now requires a `DynamicOps` parameter | +| **Deprecation** | Rules traversal methods | Single-argument overloads deprecated (still work) | --- @@ -80,6 +81,31 @@ Dynamic testData = TestData.jacksonJson() **Rationale:** Consistency with `jacksonYaml()`, `jacksonToml()`, and `jacksonXml()` methods. +### 4. `Fixes.fixTypeEverywhere()` Signature Change + +The `Fixes.fixTypeEverywhere()` method now requires a `DynamicOps` parameter. In v0.5.x, this method was a **silent no-op** — it accepted a `Function, Dynamic>` but never applied it, returning the input unchanged. The fix adds the missing `DynamicOps` parameter needed to encode/decode the data during transformation. + +**Before (v0.5.x):** +```java +TypeRewriteRule rule = Fixes.fixTypeEverywhere( + "addTimestamp", + playerType, + dynamic -> dynamic.set("timestamp", dynamic.createLong(0L)) +); +``` + +**After (v1.0.0):** +```java +TypeRewriteRule rule = Fixes.fixTypeEverywhere( + "addTimestamp", + GsonOps.INSTANCE, + playerType, + dynamic -> dynamic.set("timestamp", dynamic.createLong(0L)) +); +``` + +**Rationale:** The previous implementation could not function without `DynamicOps` — it silently returned input unchanged, which is a data corruption risk. Adding the parameter fixes the method to actually apply the transformation. + --- ## Deprecations (Non-Breaking) @@ -332,6 +358,7 @@ The method was renamed. - [ ] Update `codec.jackson.JacksonOps` imports to `codec.json.jackson.JacksonJsonOps` - [ ] Replace `JacksonOps` class references with `JacksonJsonOps` - [ ] Replace `TestData.jackson()` with `TestData.jacksonJson()` +- [ ] Add `DynamicOps` parameter to `Fixes.fixTypeEverywhere()` calls - [ ] (Optional) Update deprecated `Rules` methods to include `DynamicOps` - [ ] Rebuild and verify no compilation errors - [ ] Run test suite From d6565fca25a4bcd7a557c0198b2035d0ff469058 Mon Sep 17 00:00:00 2001 From: Erik Date: Sat, 21 Mar 2026 10:51:46 +0100 Subject: [PATCH 02/17] Fix Schema.buildTypes() parent type inheritance and thread safety (#118, #119) Parent types were fetched but never copied into the child registry, requiring subclasses to re-register all types. Now iterates parent types and registers them before registerTypes() runs. Add double-checked locking with volatile for thread-safe lazy initialization of the type registry. Use a separate buildingTypes field during construction to avoid publishing an incomplete registry. --- .../aether/datafixers/api/schema/Schema.java | 40 +++++++++++++------ 1 file changed, 27 insertions(+), 13 deletions(-) diff --git a/aether-datafixers-api/src/main/java/de/splatgames/aether/datafixers/api/schema/Schema.java b/aether-datafixers-api/src/main/java/de/splatgames/aether/datafixers/api/schema/Schema.java index 1d1861d..596a7ad 100644 --- a/aether-datafixers-api/src/main/java/de/splatgames/aether/datafixers/api/schema/Schema.java +++ b/aether-datafixers-api/src/main/java/de/splatgames/aether/datafixers/api/schema/Schema.java @@ -94,7 +94,8 @@ public class Schema { private final DataVersion version; private final Schema parent; - private TypeRegistry types; + private volatile TypeRegistry types; + private TypeRegistry buildingTypes; /** * Creates a new schema for the specified version with the given types. @@ -161,10 +162,17 @@ public Schema parent() { */ @NotNull public TypeRegistry types() { - if (this.types == null) { - this.types = this.buildTypes(); + TypeRegistry result = this.types; + if (result == null) { + synchronized (this) { + result = this.types; + if (result == null) { + result = this.buildTypes(); + this.types = result; + } + } } - return this.types; + return result; } /** @@ -178,18 +186,22 @@ public TypeRegistry types() { @NotNull private TypeRegistry buildTypes() { final TypeRegistry registry = this.createTypeRegistry(); - this.types = registry; + this.buildingTypes = registry; // Inherit types from parent if present if (this.parent != null) { - // Copy types from parent - this.parent.types(); - // Parent types are already registered in parent's registry - // For now, we don't copy - subclass must re-register all types it needs + final TypeRegistry parentTypes = this.parent.types(); + for (final TypeReference ref : parentTypes.references()) { + final Type parentType = parentTypes.get(ref); + if (parentType != null) { + registry.register(parentType); + } + } } // Let subclass register types this.registerTypes(); + this.buildingTypes = null; return registry; } @@ -232,8 +244,9 @@ protected void registerTypes() { */ protected final void registerType(@NotNull final Type type) { Preconditions.checkNotNull(type, "type must not be null"); - Preconditions.checkState(this.types != null, "Cannot register types before types() is called"); - this.types.register(type); + final TypeRegistry registry = this.buildingTypes; + Preconditions.checkState(registry != null, "Cannot register types outside of registerTypes()"); + registry.register(type); } /** @@ -267,13 +280,14 @@ protected final void registerType(@NotNull final TypeReference reference, @NotNull final TypeTemplate template) { Preconditions.checkNotNull(reference, "reference must not be null"); Preconditions.checkNotNull(template, "template must not be null"); - Preconditions.checkState(this.types != null, "Cannot register types before types() is called"); + final TypeRegistry registry = this.buildingTypes; + Preconditions.checkState(registry != null, "Cannot register types outside of registerTypes()"); // Apply the template with an empty family to get the concrete type final Type templateType = template.apply(TypeFamily.empty()); // Wrap the template type with the reference - this.types.register(new TemplateBasedType<>(reference, templateType)); + registry.register(new TemplateBasedType<>(reference, templateType)); } /** From 74808e03bbeda3453bc76c0cc692112ca49343bb Mon Sep 17 00:00:00 2001 From: Erik Date: Sat, 21 Mar 2026 10:54:26 +0100 Subject: [PATCH 03/17] Implement `equals`, `hashCode`, and `toString` in `TaggedDynamic` class for improved object comparison, hashing, and debugging. (#120) --- .../datafixers/api/dynamic/TaggedDynamic.java | 64 +++++++++++++++++++ 1 file changed, 64 insertions(+) diff --git a/aether-datafixers-api/src/main/java/de/splatgames/aether/datafixers/api/dynamic/TaggedDynamic.java b/aether-datafixers-api/src/main/java/de/splatgames/aether/datafixers/api/dynamic/TaggedDynamic.java index fe308ed..49277a9 100644 --- a/aether-datafixers-api/src/main/java/de/splatgames/aether/datafixers/api/dynamic/TaggedDynamic.java +++ b/aether-datafixers-api/src/main/java/de/splatgames/aether/datafixers/api/dynamic/TaggedDynamic.java @@ -179,4 +179,68 @@ public TypeReference type() { public Dynamic value() { return this.value; } + + /** + * Indicates whether some other object is "equal to" this one. + * + *

Two {@code TaggedDynamic} instances are considered equal if they have the same type reference and the same + * dynamic value. + * This means that both the type and the data must match for two tagged dynamics to be considered equal.

+ * + *

Example

+ * 
{@code
+     * TaggedDynamic tagged1 = new TaggedDynamic(typeRef, dynamicValue);
+     * TaggedDynamic tagged2 = new TaggedDynamic(typeRef, dynamicValue);
+     *
+     * // tagged1 and tagged2 are equal because they have the same type and value
+     * boolean isEqual = tagged1.equals(tagged2); // true
+     * }
+ * + * @param obj the reference object with which to compare + * @return {@code true} if this object is the same as the obj argument; {@code false} otherwise + */ + @Override + public boolean equals(final Object obj) { + if (this == obj) { + return true; + } + if (obj == null || getClass() != obj.getClass()) { + return false; + } + + final TaggedDynamic that = (TaggedDynamic) obj; + return this.type.equals(that.type) && this.value.equals(that.value); + } + + /** + * Returns a hash code value for the object. + * + *

The hash code is computed based on both the type reference and the dynamic value. This ensures that equal + * {@code TaggedDynamic} instances will have the same hash code, which is important for correct behavior in + * hash-based collections.

+ * + * @return a hash code value for this object + */ + @Override + public int hashCode() { + int result = this.type.hashCode(); + result = 31 * result + this.value.hashCode(); + return result; + } + + /** + * Returns a string representation of the object. + * + *

The string representation includes the type reference and the dynamic value, providing a human-readable + * summary of the tagged dynamic's contents. This can be useful for debugging and logging purposes.

+ * + * @return a string representation of the object + */ + @Override + public String toString() { + return "TaggedDynamic{" + + "type=" + this.type + + ", value=" + this.value + + '}'; + } } From 8d772698738cc346089a2e847499fdfd34dd61bd Mon Sep 17 00:00:00 2001 From: Erik Date: Sat, 21 Mar 2026 10:57:57 +0100 Subject: [PATCH 04/17] Fix `Typed.encodeAndGet` to return `DataResult` and handle missing path errors gracefully (#121) --- .../de/splatgames/aether/datafixers/api/type/Typed.java | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/aether-datafixers-api/src/main/java/de/splatgames/aether/datafixers/api/type/Typed.java b/aether-datafixers-api/src/main/java/de/splatgames/aether/datafixers/api/type/Typed.java index 6215f4b..a85bef7 100644 --- a/aether-datafixers-api/src/main/java/de/splatgames/aether/datafixers/api/type/Typed.java +++ b/aether-datafixers-api/src/main/java/de/splatgames/aether/datafixers/api/type/Typed.java @@ -393,12 +393,12 @@ public DataResult> getAt(@NotNull final DynamicOps ops, @NotNull final Finder finder) { Preconditions.checkNotNull(ops, "ops must not be null"); Preconditions.checkNotNull(finder, "finder must not be null"); - return encode(ops).map(dynamic -> { + return encode(ops).flatMap(dynamic -> { final Dynamic found = finder.get(dynamic); if (found == null) { - return null; + return DataResult.error("Path not found: " + finder); } - return found.convert(ops); + return DataResult.success(found.convert(ops)); }); } From 479cc70f5bb6ec1e25eee5b7248fe068d1d84010 Mon Sep 17 00:00:00 2001 From: Erik Date: Sat, 21 Mar 2026 10:59:40 +0100 Subject: [PATCH 05/17] Validate non-negative index in `Finder.index` method (#122) --- .../java/de/splatgames/aether/datafixers/api/optic/Finder.java | 1 + 1 file changed, 1 insertion(+) diff --git a/aether-datafixers-api/src/main/java/de/splatgames/aether/datafixers/api/optic/Finder.java b/aether-datafixers-api/src/main/java/de/splatgames/aether/datafixers/api/optic/Finder.java index e212560..2b49d82 100644 --- a/aether-datafixers-api/src/main/java/de/splatgames/aether/datafixers/api/optic/Finder.java +++ b/aether-datafixers-api/src/main/java/de/splatgames/aether/datafixers/api/optic/Finder.java @@ -205,6 +205,7 @@ public Dynamic set(@NotNull final Dynamic root, */ @NotNull static Finder index(final int index) { + Preconditions.checkArgument(index >= 0, "index must not be negative, got: %s", index); return new Finder<>() { @NotNull @Override From c7c8362e46daae93f8f6aa793cd34cc3afa1c274 Mon Sep 17 00:00:00 2001 From: Erik Date: Sat, 21 Mar 2026 11:03:12 +0100 Subject: [PATCH 06/17] Remove unused `compose` method from reversed `Iso` implementation (#123) --- .../de/splatgames/aether/datafixers/api/optic/Iso.java | 7 ------- 1 file changed, 7 deletions(-) diff --git a/aether-datafixers-api/src/main/java/de/splatgames/aether/datafixers/api/optic/Iso.java b/aether-datafixers-api/src/main/java/de/splatgames/aether/datafixers/api/optic/Iso.java index 92b1b80..e314bab 100644 --- a/aether-datafixers-api/src/main/java/de/splatgames/aether/datafixers/api/optic/Iso.java +++ b/aether-datafixers-api/src/main/java/de/splatgames/aether/datafixers/api/optic/Iso.java @@ -384,13 +384,6 @@ public A modify(@NotNull final B source, Preconditions.checkNotNull(modifier, "modifier must not be null"); return from(modifier.apply(to(source))); } - - @NotNull - @Override - public Optic compose(@NotNull final Optic other) { - Preconditions.checkNotNull(other, "other must not be null"); - throw new UnsupportedOperationException("Compose on reversed iso"); - } }; } From 28e12b382f100a3cd6ecedc9e107618cda98dc92 Mon Sep 17 00:00:00 2001 From: Erik Date: Sat, 21 Mar 2026 14:57:47 +0100 Subject: [PATCH 07/17] Update `RandomFailuresChaosIT` to handle `FixException` instead of `ChaosException` Standardize exception handling by replacing direct `ChaosException` references with `FixException`, which encapsulates `ChaosException`. Update assertions and comments accordingly. --- .../chaos/RandomFailuresChaosIT.java | 19 +++++++++++-------- 1 file changed, 11 insertions(+), 8 deletions(-) diff --git a/aether-datafixers-functional-tests/src/test/java/de/splatgames/aether/datafixers/functional/chaos/RandomFailuresChaosIT.java b/aether-datafixers-functional-tests/src/test/java/de/splatgames/aether/datafixers/functional/chaos/RandomFailuresChaosIT.java index bf84494..49d84d2 100644 --- a/aether-datafixers-functional-tests/src/test/java/de/splatgames/aether/datafixers/functional/chaos/RandomFailuresChaosIT.java +++ b/aether-datafixers-functional-tests/src/test/java/de/splatgames/aether/datafixers/functional/chaos/RandomFailuresChaosIT.java @@ -29,6 +29,7 @@ import de.splatgames.aether.datafixers.api.dynamic.Dynamic; import de.splatgames.aether.datafixers.api.fix.DataFix; import de.splatgames.aether.datafixers.api.fix.DataFixer; +import de.splatgames.aether.datafixers.api.exception.FixException; import de.splatgames.aether.datafixers.api.fix.DataFixerContext; import de.splatgames.aether.datafixers.codec.json.gson.GsonOps; import de.splatgames.aether.datafixers.core.fix.DataFixerBuilder; @@ -104,8 +105,8 @@ void handlesSporadicFixFailures() { assertThat(result.get("processed").asBoolean().result()).contains(true); successCount.incrementAndGet(); - } catch (ChaosInjector.ChaosException e) { - // Expected chaos failure + } catch (FixException e) { + // Expected: DataFixerImpl wraps ChaosException in FixException failureCount.incrementAndGet(); } } @@ -142,8 +143,9 @@ void propagatesFixExceptionsCorrectly() { CHAOS_TYPE, input, new DataVersion(1), new DataVersion(2) )) - .isInstanceOf(ChaosInjector.ChaosException.class) - .hasMessageContaining("Chaos-injected failure"); + .isInstanceOf(FixException.class) + .hasMessageContaining("Chaos-injected failure") + .hasCauseInstanceOf(ChaosInjector.ChaosException.class); } @Test @@ -170,7 +172,8 @@ void failureInChainStopsSubsequentFixes() { assertThatThrownBy(() -> fixer.update( CHAOS_TYPE, input, new DataVersion(1), new DataVersion(4) - )).isInstanceOf(ChaosInjector.ChaosException.class); + )).isInstanceOf(FixException.class) + .hasCauseInstanceOf(ChaosInjector.ChaosException.class); // Fix 1 should have run assertThat(fix1Count.get()).isEqualTo(1); @@ -225,7 +228,7 @@ void isolatesFailuresBetweenThreads() throws Exception { totalSuccess.incrementAndGet(); threadsWithSuccess.add(threadId); - } catch (ChaosInjector.ChaosException e) { + } catch (FixException e) { totalFailure.incrementAndGet(); threadsWithFailure.add(threadId); } @@ -300,7 +303,7 @@ void fixerRemainsFunctionalAfterFailures() throws Exception { try { fixer.update(CHAOS_TYPE, input, new DataVersion(1), new DataVersion(2)); phase1Success.incrementAndGet(); - } catch (ChaosInjector.ChaosException e) { + } catch (FixException e) { phase1Failure.incrementAndGet(); } } @@ -336,7 +339,7 @@ void fixerRemainsFunctionalAfterFailures() throws Exception { try { fixer.update(CHAOS_TYPE, input, new DataVersion(1), new DataVersion(2)); phase3Success.incrementAndGet(); - } catch (ChaosInjector.ChaosException e) { + } catch (FixException e) { phase3Failure.incrementAndGet(); } } From 3d16a708c6966d513587b4a5c084aa67987542fe Mon Sep 17 00:00:00 2001 From: Erik Date: Sat, 21 Mar 2026 15:30:27 +0100 Subject: [PATCH 08/17] Add unit tests for negative index rejection in `Finder.index()` and `reverse()` composition in `Iso` --- .../datafixers/api/optic/FinderTest.java | 9 +++++++++ .../aether/datafixers/api/optic/IsoTest.java | 20 +++++++++++++++++++ 2 files changed, 29 insertions(+) diff --git a/aether-datafixers-api/src/test/java/de/splatgames/aether/datafixers/api/optic/FinderTest.java b/aether-datafixers-api/src/test/java/de/splatgames/aether/datafixers/api/optic/FinderTest.java index aa2ee0b..9e32dee 100644 --- a/aether-datafixers-api/src/test/java/de/splatgames/aether/datafixers/api/optic/FinderTest.java +++ b/aether-datafixers-api/src/test/java/de/splatgames/aether/datafixers/api/optic/FinderTest.java @@ -32,6 +32,7 @@ import java.util.Map; import static org.assertj.core.api.Assertions.assertThat; +import static org.assertj.core.api.Assertions.assertThatThrownBy; /** * Unit tests for {@link Finder}. @@ -167,6 +168,14 @@ void idReturnsDescriptiveIdentifier() { assertThat(finder.id()).isEqualTo("index[3]"); } + + @Test + @DisplayName("index() rejects negative index") + void indexRejectsNegativeIndex() { + assertThatThrownBy(() -> Finder.index(-1)) + .isInstanceOf(IllegalArgumentException.class) + .hasMessageContaining("must not be negative"); + } } @Nested diff --git a/aether-datafixers-api/src/test/java/de/splatgames/aether/datafixers/api/optic/IsoTest.java b/aether-datafixers-api/src/test/java/de/splatgames/aether/datafixers/api/optic/IsoTest.java index 55ef085..e89fe31 100644 --- a/aether-datafixers-api/src/test/java/de/splatgames/aether/datafixers/api/optic/IsoTest.java +++ b/aether-datafixers-api/src/test/java/de/splatgames/aether/datafixers/api/optic/IsoTest.java @@ -196,6 +196,26 @@ void reverseAddsReverseToId() { assertThat(unwrapIso.reverse().id()).isEqualTo("wrapper.unwrap.reverse"); } + @Test + @DisplayName("reverse() supports compose()") + void reverseSupportsCompose() { + // reversed: String -> Wrapper + final Iso, Wrapper> reversed = unwrapIso.reverse(); + + // another iso: Wrapper -> String (extract value and uppercase) + final Iso, Wrapper, String, String> extractUpper = Iso.of( + "wrapper.upper", + w -> w.value().toUpperCase(), + s -> new Wrapper<>(s.toLowerCase()) + ); + + // compose: String -> Wrapper -> String (uppercased) + final Iso composed = reversed.compose(extractUpper); + + assertThat(composed.to("hello")).isEqualTo("HELLO"); + assertThat(composed.from("HELLO")).isEqualTo("hello"); + } + @Test @DisplayName("double reverse returns to original") void doubleReverseReturnsToOriginal() { From d4dbc9e8cdb698d3ee3fc6a6ec1a8068a34a6b82 Mon Sep 17 00:00:00 2001 From: Erik Date: Sat, 21 Mar 2026 16:16:59 +0100 Subject: [PATCH 09/17] Improve robustness of dynamic key extraction in `Rules` by adding null checks and streamlining `asString` handling --- .../splatgames/aether/datafixers/api/rewrite/Rules.java | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/aether-datafixers-api/src/main/java/de/splatgames/aether/datafixers/api/rewrite/Rules.java b/aether-datafixers-api/src/main/java/de/splatgames/aether/datafixers/api/rewrite/Rules.java index dbc608e..1c47e68 100644 --- a/aether-datafixers-api/src/main/java/de/splatgames/aether/datafixers/api/rewrite/Rules.java +++ b/aether-datafixers-api/src/main/java/de/splatgames/aether/datafixers/api/rewrite/Rules.java @@ -1568,9 +1568,13 @@ public static TypeRewriteRule flattenField(@NotNull final DynamicOps ops, Dynamic result = typedDynamic.remove(fieldName); final var entries = entriesResult.result().orElse(java.util.stream.Stream.empty()).toList(); for (final var entry : entries) { - final String key = entry.first().asString().result().orElse(null); + final Dynamic keyDynamic = entry.first(); + final Dynamic value = entry.second(); + if (keyDynamic == null || value == null) { + continue; + } + final String key = keyDynamic.asString().result().orElse(null); if (key != null) { - final Dynamic value = entry.second(); result = result.set(key, value); } } From df9343a71ff854725d24f8d4463d12f8f51477dd Mon Sep 17 00:00:00 2001 From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com> Date: Sat, 21 Mar 2026 15:27:36 +0000 Subject: [PATCH 10/17] Initial plan From 214b5a989a4e1bd155d3d2ddf8df6db6e8c189cd Mon Sep 17 00:00:00 2001 From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com> Date: Sat, 21 Mar 2026 15:28:27 +0000 Subject: [PATCH 11/17] docs: update getAt @return Javadoc to reflect error-based behavior Co-authored-by: Splatcrafter <83497438+Splatcrafter@users.noreply.github.com> Agent-Logs-Url: https://github.com/aether-framework/aether-datafixers/sessions/f3b66d1c-d3d8-496d-a7b9-a4625bf96b66 --- .../java/de/splatgames/aether/datafixers/api/type/Typed.java | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/aether-datafixers-api/src/main/java/de/splatgames/aether/datafixers/api/type/Typed.java b/aether-datafixers-api/src/main/java/de/splatgames/aether/datafixers/api/type/Typed.java index a85bef7..a589532 100644 --- a/aether-datafixers-api/src/main/java/de/splatgames/aether/datafixers/api/type/Typed.java +++ b/aether-datafixers-api/src/main/java/de/splatgames/aether/datafixers/api/type/Typed.java @@ -384,7 +384,8 @@ public DataResult> updateDynamic(@NotNull final DynamicOps ops, * @param ops the dynamic operations for encoding, must not be {@code null} * @param finder the finder that locates the desired sub-value, must not be {@code null} * @param the underlying data format type - * @return a {@link DataResult} containing the found dynamic value or {@code null} if not found, never {@code null} + * @return a {@link DataResult} containing the found dynamic value on success, or an error result if the path + * was not found; never {@code null} * @throws NullPointerException if {@code ops} or {@code finder} is {@code null} * @see #updateAt(DynamicOps, Finder, Function) */ From 89883f042b0f84b41e1741ab9b3585429f97b2c0 Mon Sep 17 00:00:00 2001 From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com> Date: Sat, 21 Mar 2026 15:34:28 +0000 Subject: [PATCH 12/17] Initial plan From 734a3bd69be842c6196e7c260f5d8d73c4c5d8a5 Mon Sep 17 00:00:00 2001 From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com> Date: Sat, 21 Mar 2026 15:34:35 +0000 Subject: [PATCH 13/17] Initial plan From a66c154010bcc7594c6e733a4bde30f99d2f4918 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Erik=20Pf=C3=B6rtner?= Date: Sat, 21 Mar 2026 16:35:14 +0100 Subject: [PATCH 14/17] Update aether-datafixers-api/src/main/java/de/splatgames/aether/datafixers/api/fix/Fixes.java Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com> --- .../splatgames/aether/datafixers/api/fix/Fixes.java | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) diff --git a/aether-datafixers-api/src/main/java/de/splatgames/aether/datafixers/api/fix/Fixes.java b/aether-datafixers-api/src/main/java/de/splatgames/aether/datafixers/api/fix/Fixes.java index b5b8f14..a5c4841 100644 --- a/aether-datafixers-api/src/main/java/de/splatgames/aether/datafixers/api/fix/Fixes.java +++ b/aether-datafixers-api/src/main/java/de/splatgames/aether/datafixers/api/fix/Fixes.java @@ -203,10 +203,18 @@ public Optional> rewrite(@NotNull final Type inputType, } final DataResult> encodeResult = input.encode(ops); - return encodeResult.flatMap(dynamic -> { + final DataResult> result = encodeResult.flatMap(dynamic -> { final Dynamic transformed = rewrite.apply(dynamic); return ((Type) type).read(transformed); - }).map(newValue -> new Typed<>((Type) type, newValue)).result(); + }).map(newValue -> new Typed<>((Type) type, newValue)); + + final Typed value = result.getOrThrow(false, error -> { + throw new IllegalStateException( + "Error applying fixTypeEverywhere rule '" + name + "' to type " + type + ": " + error + ); + }); + + return Optional.of(value); } @Override From 4512c3dd0a8a144be3c3676ad0af2f7b654b0b94 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Erik=20Pf=C3=B6rtner?= Date: Sat, 21 Mar 2026 16:38:11 +0100 Subject: [PATCH 15/17] Revert "[WIP] [WIP] Address feedback on removing unused methods" From 7bf14cae745830673782f6d4fe1e73cd9fc3a456 Mon Sep 17 00:00:00 2001 From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com> Date: Sat, 21 Mar 2026 15:38:27 +0000 Subject: [PATCH 16/17] Fix Finder.index() Javadoc: negative index throws IAE at construction, not null from get() Co-authored-by: Splatcrafter <83497438+Splatcrafter@users.noreply.github.com> Agent-Logs-Url: https://github.com/aether-framework/aether-datafixers/sessions/2ba3dec6-7d25-47ab-b4b3-624a4c124efc --- .../aether/datafixers/api/optic/Finder.java | 16 +++++++++++----- 1 file changed, 11 insertions(+), 5 deletions(-) diff --git a/aether-datafixers-api/src/main/java/de/splatgames/aether/datafixers/api/optic/Finder.java b/aether-datafixers-api/src/main/java/de/splatgames/aether/datafixers/api/optic/Finder.java index 2b49d82..8d0f26b 100644 --- a/aether-datafixers-api/src/main/java/de/splatgames/aether/datafixers/api/optic/Finder.java +++ b/aether-datafixers-api/src/main/java/de/splatgames/aether/datafixers/api/optic/Finder.java @@ -179,8 +179,10 @@ public Dynamic set(@NotNull final Dynamic root, * Creates a finder that navigates to an element by index in a list/array structure. * *

The returned finder extracts and modifies the element at the specified - * index position. If the index is out of bounds (negative or beyond the list size), {@link #get} returns - * {@code null} and {@link #set} returns the root unchanged.

+ * index position. A negative {@code index} is rejected immediately by throwing + * {@link IllegalArgumentException} at construction time. If the index is non-negative + * but beyond the list size, {@link #get} returns {@code null} and {@link #set} returns + * the root unchanged.

* *

Example

* 
{@code
@@ -195,12 +197,16 @@ public Dynamic set(@NotNull final Dynamic root,
      * Dynamic updated = firstScoreFinder.set(data, data.createInt(100));
      * // updated: {"scores": [100, 92, 78]}
      *
-     * // Out of bounds access
+     * // Out-of-range (positive) index — get returns null, set returns root unchanged
      * Finder outOfBounds = scoresFinder.then(Finder.index(10));
      * Dynamic missing = outOfBounds.get(data);  // null
+     *
+     * // Negative index — throws IllegalArgumentException immediately
+     * Finder.index(-1);  // throws IllegalArgumentException
      * }
* - * @param index the zero-based index of the element to focus on + * @param index the zero-based index of the element to focus on; must not be negative + * @throws IllegalArgumentException if {@code index} is negative * @return a finder that navigates to the element at the specified index, never {@code null} */ @NotNull @@ -233,7 +239,7 @@ public String id() { return root; } final var list = listResult.result().orElseThrow().toList(); - if (index < 0 || index >= list.size()) { + if (index >= list.size()) { return root; } final List> newList = new ArrayList<>(); From 56f83524fbcab66ee727e556c4e65d67821ca843 Mon Sep 17 00:00:00 2001 From: Erik Date: Sat, 21 Mar 2026 16:50:27 +0100 Subject: [PATCH 17/17] Simplify `fixTypeEverywhere` by directly returning `Optional` from `DataResult#result` and removing redundant error handling. --- .../splatgames/aether/datafixers/api/fix/Fixes.java | 12 ++---------- 1 file changed, 2 insertions(+), 10 deletions(-) diff --git a/aether-datafixers-api/src/main/java/de/splatgames/aether/datafixers/api/fix/Fixes.java b/aether-datafixers-api/src/main/java/de/splatgames/aether/datafixers/api/fix/Fixes.java index a5c4841..b5b8f14 100644 --- a/aether-datafixers-api/src/main/java/de/splatgames/aether/datafixers/api/fix/Fixes.java +++ b/aether-datafixers-api/src/main/java/de/splatgames/aether/datafixers/api/fix/Fixes.java @@ -203,18 +203,10 @@ public Optional> rewrite(@NotNull final Type inputType, } final DataResult> encodeResult = input.encode(ops); - final DataResult> result = encodeResult.flatMap(dynamic -> { + return encodeResult.flatMap(dynamic -> { final Dynamic transformed = rewrite.apply(dynamic); return ((Type) type).read(transformed); - }).map(newValue -> new Typed<>((Type) type, newValue)); - - final Typed value = result.getOrThrow(false, error -> { - throw new IllegalStateException( - "Error applying fixTypeEverywhere rule '" + name + "' to type " + type + ": " + error - ); - }); - - return Optional.of(value); + }).map(newValue -> new Typed<>((Type) type, newValue)).result(); } @Override