Add generation context interface

Add `GenerationContext` interface and `DefaultGenerationContext`
implementation as the central entry point for AOT processing.

See gh-28414

spring-core/src/main/java/org/springframework/aot/generate/DefaultGenerationContext.java

@@ -0,0 +1,102 @@
+/*
+ * Copyright 2002-2022 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.aot.generate;
+
+import java.io.IOException;
+
+import org.springframework.aot.hint.RuntimeHints;
+import org.springframework.util.Assert;
+
+/**
+ * Default implementation of {@link GenerationContext}.
+ *
+ * @author Phillip Webb
+ * @author Stephane Nicoll
+ * @since 6.0
+ */
+public class DefaultGenerationContext implements GenerationContext {
+
+	private final ClassNameGenerator classNameGenerator;
+
+	private final GeneratedClasses generatedClasses;
+
+	private final GeneratedFiles generatedFiles;
+
+	private final RuntimeHints runtimeHints;
+
+
+	/**
+	 * Create a new {@link DefaultGenerationContext} instance backed by the
+	 * specified {@code generatedFiles}.
+	 * @param generatedFiles the generated files
+	 */
+	public DefaultGenerationContext(GeneratedFiles generatedFiles) {
+		this(new ClassNameGenerator(), generatedFiles, new RuntimeHints());
+	}
+
+	/**
+	 * Create a new {@link DefaultGenerationContext} instance backed by the
+	 * specified items.
+	 * @param classNameGenerator the class name generator
+	 * @param generatedFiles the generated files
+	 * @param runtimeHints the runtime hints
+	 */
+	public DefaultGenerationContext(ClassNameGenerator classNameGenerator,
+			GeneratedFiles generatedFiles, RuntimeHints runtimeHints) {
+		Assert.notNull(classNameGenerator, "'classNameGenerator' must not be null");
+		Assert.notNull(generatedFiles, "'generatedFiles' must not be null");
+		Assert.notNull(runtimeHints, "'runtimeHints' must not be null");
+		this.classNameGenerator = classNameGenerator;
+		this.generatedClasses = new GeneratedClasses(classNameGenerator);
+		this.generatedFiles = generatedFiles;
+		this.runtimeHints = runtimeHints;
+	}
+
+
+	@Override
+	public ClassNameGenerator getClassNameGenerator() {
+		return this.classNameGenerator;
+	}
+
+	@Override
+	public GeneratedClasses getClassGenerator() {
+		return this.generatedClasses;
+	}
+
+	@Override
+	public GeneratedFiles getGeneratedFiles() {
+		return this.generatedFiles;
+	}
+
+	@Override
+	public RuntimeHints getRuntimeHints() {
+		return this.runtimeHints;
+	}
+
+	/**
+	 * Write any generated content out to the generated files.
+	 */
+	public void writeGeneratedContent() {
+		try {
+			this.generatedClasses.writeTo(this.generatedFiles);
+		}
+		catch (IOException ex) {
+			throw new IllegalStateException(ex);
+		}
+	}
+
+}

spring-core/src/main/java/org/springframework/aot/generate/GenerationContext.java

@@ -0,0 +1,76 @@
+/*
+ * Copyright 2002-2022 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.aot.generate;
+
+import org.springframework.aot.hint.JavaSerializationHints;
+import org.springframework.aot.hint.ProxyHints;
+import org.springframework.aot.hint.ReflectionHints;
+import org.springframework.aot.hint.ResourceHints;
+import org.springframework.aot.hint.RuntimeHints;
+
+/**
+ * Central interface used for code generation.
+ * <p>
+ * A generation context provides:
+ * <ul>
+ * <li>Support for {@link #getClassNameGenerator() class name generation}.</li>
+ * <li>Central management of all {@link #getGeneratedFiles() generated
+ * files}.</li>
+ * <li>Support for the recording of {@link #getRuntimeHints() runtime
+ * hints}.</li>
+ * </ul>
+ *
+ * @author Phillip Webb
+ * @author Stephane Nicoll
+ * @since 6.0
+ */
+public interface GenerationContext {
+
+	/**
+	 * Return the {@link ClassNameGenerator} being used by the context. Allows
+	 * new class names to be generated before they are added to the
+	 * {@link #getGeneratedFiles() generated files}.
+	 * @return the class name generator
+	 * @see #getGeneratedFiles()
+	 */
+	ClassNameGenerator getClassNameGenerator();
+
+	/**
+	 * Return the {@link GeneratedClasses} being used by the context. Allows a
+	 * single generated class to be shared across multiple AOT processors. All
+	 * generated classes are written at the end of AOT processing.
+	 * @return the generated classes
+	 */
+	ClassGenerator getClassGenerator();
+
+	/**
+	 * Return the {@link GeneratedFiles} being used by the context. Used to
+	 * write resource, java source or class bytecode files.
+	 * @return the generated files
+	 */
+	GeneratedFiles getGeneratedFiles();
+
+	/**
+	 * Return the {@link RuntimeHints} being used by the context. Used to record
+	 * {@link ReflectionHints reflection}, {@link ResourceHints resource},
+	 * {@link JavaSerializationHints serialization} and {@link ProxyHints proxy}
+	 * hints so that the application can run as a native image.
+	 * @return the runtime hints
+	 */
+	RuntimeHints getRuntimeHints();
+
+}

spring-core/src/test/java/org/springframework/aot/generate/DefaultGenerationContextTests.java

@@ -0,0 +1,105 @@
+/*
+ * Copyright 2002-2022 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.aot.generate;
+
+import org.junit.jupiter.api.Test;
+
+import org.springframework.aot.hint.RuntimeHints;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatIllegalArgumentException;
+
+/**
+ * Tests for {@link DefaultGenerationContext}.
+ *
+ * @author Phillip Webb
+ * @author Stephane Nicoll
+ */
+class DefaultGenerationContextTests {
+
+	private final ClassNameGenerator classNameGenerator = new ClassNameGenerator();
+
+	private final GeneratedFiles generatedFiles = new InMemoryGeneratedFiles();
+
+	private final RuntimeHints runtimeHints = new RuntimeHints();
+
+
+	@Test
+	void createWithOnlyGeneratedFilesCreatesContext() {
+		DefaultGenerationContext context = new DefaultGenerationContext(
+				this.generatedFiles);
+		assertThat(context.getClassNameGenerator())
+				.isInstanceOf(ClassNameGenerator.class);
+		assertThat(context.getGeneratedFiles()).isSameAs(this.generatedFiles);
+		assertThat(context.getRuntimeHints()).isInstanceOf(RuntimeHints.class);
+	}
+
+	@Test
+	void createCreatesContext() {
+		DefaultGenerationContext context = new DefaultGenerationContext(
+				this.classNameGenerator, this.generatedFiles, this.runtimeHints);
+		assertThat(context.getClassNameGenerator()).isNotNull();
+		assertThat(context.getGeneratedFiles()).isNotNull();
+		assertThat(context.getRuntimeHints()).isNotNull();
+	}
+
+	@Test
+	void createWhenClassNameGeneratorIsNullThrowsException() {
+		assertThatIllegalArgumentException()
+				.isThrownBy(() -> new DefaultGenerationContext(null, this.generatedFiles,
+						this.runtimeHints))
+				.withMessage("'classNameGenerator' must not be null");
+	}
+
+	@Test
+	void createWhenGeneratedFilesIsNullThrowsException() {
+		assertThatIllegalArgumentException()
+				.isThrownBy(() -> new DefaultGenerationContext(this.classNameGenerator,
+						null, this.runtimeHints))
+				.withMessage("'generatedFiles' must not be null");
+	}
+
+	@Test
+	void createWhenRuntimeHintsIsNullThrowsException() {
+		assertThatIllegalArgumentException()
+				.isThrownBy(() -> new DefaultGenerationContext(this.classNameGenerator,
+						this.generatedFiles, null))
+				.withMessage("'runtimeHints' must not be null");
+	}
+
+	@Test
+	void getClassNameGeneratorReturnsClassNameGenerator() {
+		DefaultGenerationContext context = new DefaultGenerationContext(
+				this.classNameGenerator, this.generatedFiles, this.runtimeHints);
+		assertThat(context.getClassNameGenerator()).isSameAs(this.classNameGenerator);
+	}
+
+	@Test
+	void getGeneratedFilesReturnsGeneratedFiles() {
+		DefaultGenerationContext context = new DefaultGenerationContext(
+				this.classNameGenerator, this.generatedFiles, this.runtimeHints);
+		assertThat(context.getGeneratedFiles()).isSameAs(this.generatedFiles);
+	}
+
+	@Test
+	void getRuntimeHintsReturnsRuntimeHints() {
+		DefaultGenerationContext context = new DefaultGenerationContext(
+				this.classNameGenerator, this.generatedFiles, this.runtimeHints);
+		assertThat(context.getRuntimeHints()).isSameAs(this.runtimeHints);
+	}
+
+}