Add custom code generation for bean definition property values

This commits allows ValueCodeGenerator$Delegate implementations to be
loaded from `META-INF/spring/aot.factories` and considered for code
generation of bean definition property values. This default behavior
in DefaultBeanRegistrationCodeFragments can be customized as usual.

Closes gh-31427

spring-beans/src/main/java/org/springframework/beans/factory/aot/BeanDefinitionPropertiesCodeGenerator.java

@@ -97,15 +97,17 @@ class BeanDefinitionPropertiesCodeGenerator {
 
 	BeanDefinitionPropertiesCodeGenerator(RuntimeHints hints,
 			Predicate<String> attributeFilter, GeneratedMethods generatedMethods,
+			List<Delegate> additionalDelegates,
 			BiFunction<String, Object, CodeBlock> customValueCodeGenerator) {
 
 		this.hints = hints;
 		this.attributeFilter = attributeFilter;
-		this.valueCodeGenerator = ValueCodeGenerator
-				.with(new ValueCodeGeneratorDelegateAdapter(customValueCodeGenerator))
-				.add(BeanDefinitionPropertyValueCodeGeneratorDelegates.INSTANCES)
-				.add(ValueCodeGeneratorDelegates.INSTANCES)
-				.scoped(generatedMethods);
+		List<Delegate> allDelegates = new ArrayList<>();
+		allDelegates.add((valueCodeGenerator, value) -> customValueCodeGenerator.apply(PropertyNamesStack.peek(), value));
+		allDelegates.addAll(additionalDelegates);
+		allDelegates.addAll(BeanDefinitionPropertyValueCodeGeneratorDelegates.INSTANCES);
+		allDelegates.addAll(ValueCodeGeneratorDelegates.INSTANCES);
+		this.valueCodeGenerator = ValueCodeGenerator.with(allDelegates).scoped(generatedMethods);
 	}
 
 
@@ -373,21 +375,6 @@ class BeanDefinitionPropertiesCodeGenerator {
 	}
 
 
-	static class ValueCodeGeneratorDelegateAdapter implements Delegate {
-
-		private final BiFunction<String, Object, CodeBlock> customValueCodeGenerator;
-
-		ValueCodeGeneratorDelegateAdapter(BiFunction<String, Object, CodeBlock> customValueCodeGenerator) {
-			this.customValueCodeGenerator = customValueCodeGenerator;
-		}
-
-		@Override
-		public CodeBlock generateCode(ValueCodeGenerator valueCodeGenerator, Object value) {
-			return this.customValueCodeGenerator.apply(PropertyNamesStack.peek(), value);
-		}
-	}
-
-
 	static class PropertyNamesStack {
 
 		private static final ThreadLocal<ArrayDeque<String>> threadLocal = ThreadLocal.withInitial(ArrayDeque::new);

spring-beans/src/main/java/org/springframework/beans/factory/aot/DefaultBeanRegistrationCodeFragments.java

@@ -28,7 +28,9 @@ import org.springframework.aot.generate.GenerationContext;
 import org.springframework.aot.generate.MethodReference;
 import org.springframework.aot.generate.MethodReference.ArgumentCodeGenerator;
 import org.springframework.aot.generate.ValueCodeGenerator;
+import org.springframework.aot.generate.ValueCodeGenerator.Delegate;
 import org.springframework.beans.factory.FactoryBean;
+import org.springframework.beans.factory.aot.AotServices.Loader;
 import org.springframework.beans.factory.config.BeanDefinition;
 import org.springframework.beans.factory.config.BeanDefinitionHolder;
 import org.springframework.beans.factory.support.InstanceSupplier;
@@ -171,12 +173,12 @@ class DefaultBeanRegistrationCodeFragments implements BeanRegistrationCodeFragme
 			GenerationContext generationContext,
 			BeanRegistrationCode beanRegistrationCode, RootBeanDefinition beanDefinition,
 			Predicate<String> attributeFilter) {
-
-		return new BeanDefinitionPropertiesCodeGenerator(
-				generationContext.getRuntimeHints(), attributeFilter,
-				beanRegistrationCode.getMethods(),
-				(name, value) -> generateValueCode(generationContext, name, value))
-				.generateCode(beanDefinition);
+		Loader loader = AotServices.factories(this.registeredBean.getBeanFactory().getBeanClassLoader());
+		List<Delegate> additionalDelegates = loader.load(Delegate.class).asList();
+		return new BeanDefinitionPropertiesCodeGenerator(generationContext.getRuntimeHints(),
+				attributeFilter, beanRegistrationCode.getMethods(),
+				additionalDelegates, (name, value) -> generateValueCode(generationContext, name, value)
+		).generateCode(beanDefinition);
 	}
 
 	@Nullable

spring-beans/src/test/java/org/springframework/beans/factory/aot/BeanDefinitionMethodGeneratorTests.java

@@ -45,6 +45,8 @@ import org.springframework.beans.factory.support.RootBeanDefinition;
 import org.springframework.beans.testfixture.beans.AnnotatedBean;
 import org.springframework.beans.testfixture.beans.GenericBean;
 import org.springframework.beans.testfixture.beans.TestBean;
+import org.springframework.beans.testfixture.beans.factory.aot.CustomBean;
+import org.springframework.beans.testfixture.beans.factory.aot.CustomPropertyValue;
 import org.springframework.beans.testfixture.beans.factory.aot.InnerBeanConfiguration;
 import org.springframework.beans.testfixture.beans.factory.aot.MockBeanRegistrationsCode;
 import org.springframework.beans.testfixture.beans.factory.aot.SimpleBean;
@@ -605,6 +607,23 @@ class BeanDefinitionMethodGeneratorTests {
 		});
 	}
 
+	@Test
+	void generateBeanDefinitionMethodWhenCustomPropertyValueUsesCustomDelegate() {
+		RootBeanDefinition beanDefinition = new RootBeanDefinition(CustomBean.class);
+		beanDefinition.getPropertyValues().addPropertyValue(
+				"customPropertyValue", new CustomPropertyValue("test"));
+		RegisteredBean bean = registerBean(beanDefinition);
+		BeanDefinitionMethodGenerator generator = new BeanDefinitionMethodGenerator(
+				this.methodGeneratorFactory, bean, "test",
+				Collections.emptyList());
+		MethodReference method = generator.generateBeanDefinitionMethod(
+				this.generationContext, this.beanRegistrationsCode);
+		compile(method, (actual, compiled) ->
+				assertThat(actual.getPropertyValues().get("customPropertyValue"))
+						.isInstanceOfSatisfying(CustomPropertyValue.class, customPropertyValue
+								-> assertThat(customPropertyValue.value()).isEqualTo("test")));
+	}
+
 	@Test
 	void generateBeanDefinitionMethodWhenHasAotContributionsAppliesContributions() {
 		RegisteredBean registeredBean = registerBean(

spring-beans/src/test/java/org/springframework/beans/factory/aot/BeanDefinitionPropertiesCodeGeneratorTests.java

@@ -18,6 +18,7 @@ package org.springframework.beans.factory.aot;
 
 import java.time.temporal.ChronoUnit;
 import java.util.ArrayList;
+import java.util.Collections;
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
@@ -33,6 +34,7 @@ import org.junit.jupiter.api.Test;
 import org.reactivestreams.Publisher;
 
 import org.springframework.aot.generate.GeneratedClass;
+import org.springframework.aot.generate.ValueCodeGenerator.Delegate;
 import org.springframework.aot.hint.MemberCategory;
 import org.springframework.aot.hint.predicate.RuntimeHintsPredicates;
 import org.springframework.aot.test.generate.TestGenerationContext;
@@ -49,6 +51,7 @@ import org.springframework.beans.factory.support.ManagedList;
 import org.springframework.beans.factory.support.ManagedMap;
 import org.springframework.beans.factory.support.ManagedSet;
 import org.springframework.beans.factory.support.RootBeanDefinition;
+import org.springframework.beans.testfixture.beans.factory.aot.CustomPropertyValue;
 import org.springframework.beans.testfixture.beans.factory.aot.DeferredTypeBuilder;
 import org.springframework.core.test.tools.Compiled;
 import org.springframework.core.test.tools.TestCompiler;
@@ -364,6 +367,21 @@ class BeanDefinitionPropertiesCodeGeneratorTests {
 		assertHasDeclaredFieldsHint(PropertyValuesFactoryBean.class);
 	}
 
+	@Test
+	void propertyValuesWhenCustomValuesUsingDelegate() {
+		this.beanDefinition.setTargetType(PropertyValuesBean.class);
+		this.beanDefinition.getPropertyValues().add("test", new CustomPropertyValue("test"));
+		this.beanDefinition.getPropertyValues().add("spring", new CustomPropertyValue("framework"));
+		compile(value -> true, List.of(new CustomPropertyValue.ValueCodeGeneratorDelegate()), (actual, compiled) -> {
+			assertThat(actual.getPropertyValues().get("test")).isInstanceOfSatisfying(CustomPropertyValue.class,
+					customPropertyValue -> assertThat(customPropertyValue.value()).isEqualTo("test"));
+			assertThat(actual.getPropertyValues().get("spring")).isInstanceOfSatisfying(CustomPropertyValue.class,
+					customPropertyValue -> assertThat(customPropertyValue.value()).isEqualTo("framework"));
+		});
+		assertHasMethodInvokeHints(PropertyValuesBean.class, "setTest", "setSpring");
+		assertHasDeclaredFieldsHint(PropertyValuesBean.class);
+	}
+
 	@Test
 	void attributesWhenAllFiltered() {
 		this.beanDefinition.setAttribute("a", "A");
@@ -548,12 +566,18 @@ class BeanDefinitionPropertiesCodeGeneratorTests {
 		compile(attribute -> true, result);
 	}
 
-	private void compile(Predicate<String> attributeFilter, BiConsumer<RootBeanDefinition, Compiled> result) {
+	private void compile(Predicate<String> attributeFilter,
+			BiConsumer<RootBeanDefinition, Compiled> result) {
+		compile(attributeFilter, Collections.emptyList(), result);
+	}
+
+	private void compile(Predicate<String> attributeFilter, List<Delegate> additionalDelegates,
+			BiConsumer<RootBeanDefinition, Compiled> result) {
 		DeferredTypeBuilder typeBuilder = new DeferredTypeBuilder();
 		GeneratedClass generatedClass = this.generationContext.getGeneratedClasses().addForFeature("TestCode", typeBuilder);
 		BeanDefinitionPropertiesCodeGenerator codeGenerator = new BeanDefinitionPropertiesCodeGenerator(
 				this.generationContext.getRuntimeHints(), attributeFilter,
-				generatedClass.getMethods(), (name, value) -> null);
+				generatedClass.getMethods(), additionalDelegates, (name, value) -> null);
 		CodeBlock generatedCode = codeGenerator.generateCode(this.beanDefinition);
 		typeBuilder.set(type -> {
 			type.addModifiers(Modifier.PUBLIC);

spring-beans/src/testFixtures/java/org/springframework/beans/testfixture/beans/factory/aot/CustomBean.java

@@ -0,0 +1,36 @@
+/*
+ * Copyright 2002-2023 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.beans.testfixture.beans.factory.aot;
+
+/**
+ * A bean that uses {@link CustomPropertyValue}.
+ *
+ * @author Stephane Nicoll
+ */
+public class CustomBean {
+
+	private CustomPropertyValue customPropertyValue;
+
+	public CustomPropertyValue getCustomPropertyValue() {
+		return this.customPropertyValue;
+	}
+
+	public void setCustomPropertyValue(CustomPropertyValue customPropertyValue) {
+		this.customPropertyValue = customPropertyValue;
+	}
+
+}

spring-beans/src/testFixtures/java/org/springframework/beans/testfixture/beans/factory/aot/CustomPropertyValue.java

@@ -0,0 +1,40 @@
+/*
+ * Copyright 2002-2023 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.beans.testfixture.beans.factory.aot;
+
+import org.springframework.aot.generate.ValueCodeGenerator;
+import org.springframework.aot.generate.ValueCodeGenerator.Delegate;
+import org.springframework.javapoet.CodeBlock;
+
+/**
+ * A custom value with its code generator {@link Delegate} implementation.
+ *
+ * @author Stephane Nicoll
+ */
+public record CustomPropertyValue(String value) {
+
+	public static class ValueCodeGeneratorDelegate implements Delegate {
+		@Override
+		public CodeBlock generateCode(ValueCodeGenerator valueCodeGenerator, Object value) {
+			if (value instanceof CustomPropertyValue data) {
+				return CodeBlock.of("new $T($S)", CustomPropertyValue.class, data.value);
+			}
+			return null;
+		}
+	}
+
+}

spring-beans/src/testFixtures/resources/META-INF/spring/aot.factories

@@ -0,0 +1,2 @@
+org.springframework.aot.generate.ValueCodeGenerator$Delegate=\
+org.springframework.beans.testfixture.beans.factory.aot.CustomPropertyValue$ValueCodeGeneratorDelegate