Update codegen to support closure-based generation

This updates the code generators to support generating based on shape
closures. Shape closures are a new way to define a set of shapes to
generate in the model without rooting that set at a service shape.

This has implications that cause some chages throughout the generator.
Notably, a service might not exist. There are a number of places that
required a service shape to exist that had to be updated to tolerate
it being missing. Notably renames may now be driven through the
closure definition itself rather than a service shape, so renames
needed to be passed through in a lot of generator classes.

Previously types codegen was implemented by creating a synthetic
service shape and/or operation and attaching the shapes to it. The
generator would then skip those synthetic shapes so that no unwanted
scaffolding was generated. That whole system was removed.

Another important implication of shape closures is that a closure can
have multiple services. For now, smithy-java is keeping the
restriction to have exactly 0 or 1 services. Supporting multiple can
be done down the line if there's a need.

Author: JordonPhillips

codegen/codegen-core/src/internal/java/software/amazon/smithy/java/codegen/JavaTypesCodegenPlugin.java

@@ -5,17 +5,14 @@
 
 package software.amazon.smithy.java.codegen;
 
-import java.util.HashSet;
 import java.util.Set;
+import java.util.StringJoiner;
 import software.amazon.smithy.build.PluginContext;
 import software.amazon.smithy.build.SmithyBuildPlugin;
-import software.amazon.smithy.codegen.core.CodegenException;
 import software.amazon.smithy.codegen.core.directed.CodegenDirector;
 import software.amazon.smithy.java.codegen.writer.JavaWriter;
 import software.amazon.smithy.java.logging.InternalLogger;
-import software.amazon.smithy.model.Model;
-import software.amazon.smithy.model.loader.Prelude;
-import software.amazon.smithy.model.shapes.Shape;
+import software.amazon.smithy.model.metadata.ShapeClosure;
 import software.amazon.smithy.utils.SmithyInternalApi;
 
 /**
@@ -42,6 +39,10 @@
 public final class JavaTypesCodegenPlugin implements SmithyBuildPlugin {
     private static final InternalLogger LOGGER = InternalLogger.getLogger(JavaTypesCodegenPlugin.class);
 
+    // Id of the shape closure that drives types-only generation. Namespaced so it cannot collide
+    // with a model shape id or a model-authored closure.
+    private static final String CLOSURE_ID = "software.amazon.smithy.java.codegen#types";
+
     @Override
     public String getName() {
         return "internal-types-only";
@@ -60,35 +61,40 @@ public void execute(PluginContext context) {
         runner.settings(codegenSettings);
         runner.directedCodegen(new TypesDirectedJavaCodegen(modes));
         runner.fileManifest(context.getFileManifest());
-        runner.service(codegenSettings.service());
 
-        // Compute closure and create synthetic service
-        var closure = getClosure(context.getModel(), settings);
-        LOGGER.info("Found {} shapes in generation closure", closure.size());
-        var model = SyntheticServiceTransform.transform(context.getModel(), closure, settings.renames());
-        runner.model(model);
+        // Generate the data shapes selected by the settings as a shape closure, with no
+        // primary service. The director resolves the closure's transitive data shapes.
+        runner.shapeClosure(typesClosure(settings));
+        runner.generateDataShapesOnly();
+        runner.model(context.getModel());
         runner.integrationClass(JavaCodegenIntegration.class);
         DefaultTransforms.apply(runner, codegenSettings);
         runner.run();
         LOGGER.info("Successfully generated Java class files.");
     }
 
-    private static Set<Shape> getClosure(Model model, TypeCodegenSettings settings) {
-        Set<Shape> closure = new HashSet<>();
-        for (var shapeId : settings.shapes()) {
-            closure.add(model.expectShape(shapeId));
-        }
-        settings.selector()
-                .shapes(model)
-                .filter(s -> !s.isMemberShape())
-                .filter(s -> !Prelude.isPreludeShape(s))
-                .forEach(closure::add);
-
-        if (closure.isEmpty()) {
-            throw new CodegenException("Could not generate types. No shapes found in closure");
+    /**
+     * Builds the shape closure to generate from the configured selector, explicitly listed shapes,
+     * and renames. Explicit shapes are folded into the selector as id-equality clauses and trait
+     * definitions are excluded so only data shapes are generated.
+     */
+    private static ShapeClosure typesClosure(TypeCodegenSettings settings) {
+        // Fold the explicit shapes into the configured selector as id-equality alternatives,
+        // e.g. :is(<selector>, [id='ns#A'], [id='ns#B']).
+        String base = settings.selector().toString();
+        if (!settings.shapes().isEmpty()) {
+            var joiner = new StringJoiner(", ", ":is(", ")");
+            joiner.add(base);
+            for (var shape : settings.shapes()) {
+                joiner.add("[id='" + shape + "']");
+            }
+            base = joiner.toString();
         }
-        LOGGER.info("Found {} shapes in generation closure.", closure.size());
-
-        return closure;
+        return ShapeClosure.builder()
+                .id(CLOSURE_ID)
+                // Exclude trait definitions so only data shapes are generated.
+                .includeBySelector(base + " :not([trait|trait])")
+                .rename(settings.renames())
+                .build();
     }
 }

codegen/codegen-core/src/internal/java/software/amazon/smithy/java/codegen/TypesDirectedJavaCodegen.java

@@ -30,7 +30,6 @@
 import software.amazon.smithy.java.codegen.generators.SharedSerdeGenerator;
 import software.amazon.smithy.java.codegen.generators.StructureGenerator;
 import software.amazon.smithy.java.codegen.generators.UnionGenerator;
-import software.amazon.smithy.model.shapes.Shape;
 import software.amazon.smithy.utils.SmithyInternalApi;
 
 /**
@@ -53,7 +52,8 @@ public SymbolProvider createSymbolProvider(
     ) {
         return new JavaSymbolProvider(
                 directive.model(),
-                directive.service(),
+                directive.getService().orElse(null),
+                directive.getRenames(),
                 directive.settings().packageNamespace(),
                 directive.settings().name(),
                 modes);
@@ -68,9 +68,7 @@ public CodeGenerationContext createContext(
 
     @Override
     public void generateStructure(GenerateStructureDirective<CodeGenerationContext, JavaCodegenSettings> directive) {
-        if (!isSynthetic(directive.shape())) {
-            new StructureGenerator<>().accept(directive);
-        }
+        new StructureGenerator<>().accept(directive);
     }
 
     @Override
@@ -129,8 +127,4 @@ public void customizeBeforeIntegrations(CustomizeDirective<CodeGenerationContext
     public void customizeAfterIntegrations(CustomizeDirective<CodeGenerationContext, JavaCodegenSettings> directive) {
         // No-op for types-only mode
     }
-
-    private static boolean isSynthetic(Shape shape) {
-        return shape.getId().getNamespace().equals(SyntheticServiceTransform.SYNTHETIC_NAMESPACE);
-    }
 }

codegen/codegen-core/src/main/java/software/amazon/smithy/java/codegen/CodeGenerationContext.java

@@ -14,7 +14,6 @@
 import java.util.stream.Collectors;
 import software.amazon.smithy.build.FileManifest;
 import software.amazon.smithy.codegen.core.CodegenContext;
-import software.amazon.smithy.codegen.core.CodegenException;
 import software.amazon.smithy.codegen.core.SymbolProvider;
 import software.amazon.smithy.codegen.core.WriterDelegator;
 import software.amazon.smithy.codegen.core.directed.CreateContextDirective;
@@ -123,7 +122,7 @@ public CodeGenerationContext(
                 fileManifest,
                 this.symbolProvider,
                 new JavaWriter.Factory(settings));
-        this.runtimeTraits = collectRuntimeTraits();
+        this.runtimeTraits = collectRuntimeTraits(directive.getService().orElse(null));
         this.traitInitializers = collectTraitInitializers();
         this.plugin = plugin;
         this.schemaFieldOrder = new SchemaFieldOrder(directive, this);
@@ -186,32 +185,30 @@ public SchemaFieldOrder schemaFieldOrder() {
      *
      * @return Set of trait ShapeId's to include in generated Schemas.
      */
-    private Set<ShapeId> collectRuntimeTraits() {
-        ServiceShape shape = model.expectShape(settings.service())
-                .asServiceShape()
-                .orElseThrow(
-                        () -> new CodegenException(
-                                "Expected shapeId: "
-                                        + settings.service() + " to be a service shape."));
-
+    private Set<ShapeId> collectRuntimeTraits(ServiceShape service) {
         // Add all default runtime traits from the prelude
         Set<ShapeId> traits = new HashSet<>(PRELUDE_RUNTIME_TRAITS);
-        for (var entry : shape.getAllTraits().entrySet()) {
-            Optional<Shape> traitShapeOptional = model.getShape(entry.getKey());
-            if (traitShapeOptional.isEmpty()) {
-                LOGGER.debug("Skipping unknown trait: {}", entry.getKey());
-                continue;
-            }
-            var traitShape = traitShapeOptional.get();
-            // Add all traits supported by a protocol the service supports
-            if (traitShape.hasTrait(ProtocolDefinitionTrait.class)) {
-                var protocolDef = traitShape.expectTrait(ProtocolDefinitionTrait.class);
-                traits.addAll(protocolDef.getTraits());
-            }
-            // Add all traits supported by auth schemes the service supports
-            if (traitShape.hasTrait(AuthDefinitionTrait.class)) {
-                var authDef = traitShape.expectTrait(AuthDefinitionTrait.class);
-                traits.addAll(authDef.getTraits());
+
+        // Protocol- and auth-scheme-supported traits are rooted in the primary service. Pure types
+        // mode has no service, so only the prelude and customer-configured traits apply.
+        if (service != null) {
+            for (var entry : service.getAllTraits().entrySet()) {
+                Optional<Shape> traitShapeOptional = model.getShape(entry.getKey());
+                if (traitShapeOptional.isEmpty()) {
+                    LOGGER.debug("Skipping unknown trait: {}", entry.getKey());
+                    continue;
+                }
+                var traitShape = traitShapeOptional.get();
+                // Add all traits supported by a protocol the service supports
+                if (traitShape.hasTrait(ProtocolDefinitionTrait.class)) {
+                    var protocolDef = traitShape.expectTrait(ProtocolDefinitionTrait.class);
+                    traits.addAll(protocolDef.getTraits());
+                }
+                // Add all traits supported by auth schemes the service supports
+                if (traitShape.hasTrait(AuthDefinitionTrait.class)) {
+                    var authDef = traitShape.expectTrait(AuthDefinitionTrait.class);
+                    traits.addAll(authDef.getTraits());
+                }
             }
         }
 

codegen/codegen-core/src/main/java/software/amazon/smithy/java/codegen/CodegenUtils.java

@@ -9,6 +9,7 @@
 import java.net.URL;
 import java.util.List;
 import java.util.Locale;
+import java.util.Map;
 import java.util.Objects;
 import java.util.regex.Pattern;
 import java.util.stream.Collectors;
@@ -111,10 +112,24 @@ public static Symbol fromBoxedClass(Class<?> unboxed, Class<?> boxed) {
      * Gets the default class name to use for a given Smithy {@link Shape}.
      *
      * @param shape Shape to get name for.
+     * @param service Service whose renames provide contextual names, or null if none.
      * @return Default name.
      */
     public static String getDefaultName(Shape shape, ServiceShape service) {
-        String baseName = shape.getId().getName(service);
+        return getDefaultName(shape, service == null ? Map.of() : service.getRename());
+    }
+
+    /**
+     * Gets the default class name to use for a given Smithy {@link Shape}.
+     *
+     * @param shape Shape to get name for.
+     * @param renames Renames applied to the generated shapes (a shape id maps to its
+     *     contextual name). Used instead of a service so the closure-driven types path
+     *     can apply renames without a service.
+     * @return Default name.
+     */
+    public static String getDefaultName(Shape shape, Map<ShapeId, String> renames) {
+        String baseName = renames.getOrDefault(shape.getId(), shape.getId().getName());
 
         // If the name contains any problematic delimiters, use PascalCase converter,
         // otherwise, just capitalize first letter to avoid messing with user-defined
@@ -423,7 +438,7 @@ public static boolean isISO8601Date(String string) {
      * @return the property if found, or null.
      */
     public static <T> T tryGetServiceProperty(ShapeDirective<?, ?, ?> directive, Property<T> prop) {
-        var service = directive.service();
+        var service = directive.getService().orElse(null);
         if (service != null) {
             var symbol = directive.symbolProvider().toSymbol(service);
             if (symbol != null) {

codegen/codegen-core/src/main/java/software/amazon/smithy/java/codegen/JavaCodegenSettings.java

@@ -14,6 +14,7 @@
 import java.util.Locale;
 import java.util.Map;
 import java.util.Objects;
+import java.util.Optional;
 import java.util.Set;
 import software.amazon.smithy.codegen.core.CodegenException;
 import software.amazon.smithy.codegen.core.Symbol;
@@ -50,6 +51,13 @@ public final class JavaCodegenSettings {
     private static final String RUNTIME_TRAITS = "runtimeTraits";
     private static final String RUNTIME_TRAITS_SELECTOR = "runtimeTraitsSelector";
     private static final String MODES = "modes";
+    private static final String CLOSURE = "closure";
+
+    // Legacy default name for types-only generation. Before types generation was driven by a shape
+    // closure, it relied on a synthetic service named "TypesGenService", so the generated name
+    // defaulted to that when none was configured. The name is unused by types-only output, but this
+    // value is preserved so existing configs without a 'name' keep behaving as they did.
+    private static final String LEGACY_TYPES_NAME = "TypesGenService";
     private static final List<String> PROPERTIES = List.of(
             SERVICE,
             NAME,
@@ -66,9 +74,11 @@ public final class JavaCodegenSettings {
             EDITION,
             RUNTIME_TRAITS,
             RUNTIME_TRAITS_SELECTOR,
-            MODES);
+            MODES,
+            CLOSURE);
 
     private final ShapeId service;
+    private final String closure;
     private final String name;
     private final String packageNamespace;
     private final String header;
@@ -87,8 +97,9 @@ public final class JavaCodegenSettings {
     private final Map<String, Set<Symbol>> generatedSymbols = new HashMap<>();
 
     private JavaCodegenSettings(Builder builder) {
-        this.service = Objects.requireNonNull(builder.service);
-        this.name = StringUtils.capitalize(Objects.requireNonNullElse(builder.name, service.getName()));
+        this.service = builder.service;
+        this.closure = builder.closure;
+        this.name = StringUtils.capitalize(resolveName(builder.name, service));
         this.packageNamespace = Objects.requireNonNull(builder.packageNamespace);
         this.header = getHeader(builder.headerFilePath, builder.sourceLocation);
         this.addNullnessAnnotations = builder.addNullnessAnnotations;
@@ -105,6 +116,20 @@ private JavaCodegenSettings(Builder builder) {
         this.httpConfig = builder.httpConfig;
     }
 
+    // Resolves the generated name: an explicit name wins, otherwise the service name when a service
+    // is set, otherwise the legacy types-only default (with a warning nudging callers to set one).
+    private static String resolveName(String configuredName, ShapeId service) {
+        if (configuredName != null) {
+            return configuredName;
+        }
+        if (service != null) {
+            return service.getName();
+        }
+        LOGGER.warn("No 'name' configured for types-only generation; defaulting to '{}'. Set the "
+                + "'name' setting explicitly to silence this warning.", LEGACY_TYPES_NAME);
+        return LEGACY_TYPES_NAME;
+    }
+
     /**
      * Creates a settings object from a plugin settings node
      *
@@ -114,7 +139,8 @@ private JavaCodegenSettings(Builder builder) {
     public static JavaCodegenSettings fromNode(ObjectNode settingsNode) {
         var builder = new Builder();
         settingsNode.warnIfAdditionalProperties(PROPERTIES)
-                .expectStringMember(SERVICE, builder::service)
+                .getStringMember(SERVICE, builder::service)
+                .getStringMember(CLOSURE, builder::closure)
                 .getStringMember(NAME, builder::name)
                 .expectStringMember(NAMESPACE, builder::packageNamespace)
                 .getStringMember(HEADER_FILE, builder::headerFilePath)
@@ -135,10 +161,45 @@ public static JavaCodegenSettings fromNode(ObjectNode settingsNode) {
         return builder.build();
     }
 
+    /**
+     * Gets the primary service to generate.
+     *
+     * @return the configured service id.
+     * @see #getService() for a non-throwing variant.
+     */
     public ShapeId service() {
+        if (service == null) {
+            throw new CodegenException(
+                    "No service is configured for this code generation because types-only generation "
+                            + "has no primary service.");
+        }
         return service;
     }
 
+    /**
+     * Gets the primary service to generate, if one is configured.
+     *
+     * <p>Types-only generation is driven by a shape closure and has no primary service, so this
+     * returns an empty optional in that case.
+     *
+     * @return the configured service id, or empty if none is set.
+     */
+    public Optional<ShapeId> getService() {
+        return Optional.ofNullable(service);
+    }
+
+    /**
+     * Gets the id of a pre-authored shape closure to generate, if one was configured.
+     *
+     * <p>When set, generation is driven by the {@code shapeClosures} metadata entry with this id in
+     * the model, rather than by an inline {@code selector}/{@code shapes} configuration.
+     *
+     * @return the configured shape closure id, or empty if none is set.
+     */
+    public Optional<String> getClosure() {
+        return Optional.ofNullable(closure);
+    }
+
     public String name() {
         return name;
     }
@@ -232,6 +293,7 @@ public static Builder builder() {
 
     public static final class Builder {
         private ShapeId service;
+        private String closure;
         private String name;
         private String packageNamespace;
         private String headerFilePath;
@@ -254,6 +316,11 @@ public Builder service(String string) {
             return this;
         }
 
+        public Builder closure(String closure) {
+            this.closure = closure;
+            return this;
+        }
+
         public Builder name(String name) {
             this.name = name;
             return this;