[WIP] Add traits and validators to express polymorphic responses

modules/core/resources/META-INF/services/software.amazon.smithy.model.traits.TraitService

@@ -26,3 +26,5 @@ alloy.UrlFormNameTrait$Provider
 alloy.UncheckedExamplesTrait$Provider
 alloy.UntaggedUnionTrait$Provider
 alloy.UuidFormatTrait$Provider
+alloy.HttpPolymorphicResponseTrait$Provider
+alloy.HttpSuccessTrait$Provider

modules/core/resources/META-INF/services/software.amazon.smithy.model.validation.Validator

@@ -11,3 +11,4 @@ alloy.validation.DiscriminatedUnionValidator
 alloy.validation.SimpleRestJsonHttpHeaderValidator
 alloy.validation.SimpleRestJsonValidator
 alloy.validation.StructurePatternTraitValidator
+alloy.validation.HttpPolymorphicResponseValidator

modules/core/resources/META-INF/smithy/http.smithy

@@ -0,0 +1,12 @@
+$version: "2"
+
+namespace alloy
+
+@trait(
+    selector: "structure > member[trait|required] :test(> :test(union))",
+    structurallyExclusive: "member"
+)
+structure httpPolymorphicResponse {}
+
+@trait(selector: "structure")
+integer httpSuccess

modules/core/resources/META-INF/smithy/manifest

@@ -12,3 +12,4 @@ unions.smithy
 urlform.smithy
 uuid.smithy
 metadata.smithy
+http.smithy

modules/core/resources/META-INF/smithy/uuid.smithy

@@ -8,3 +8,4 @@ structure uuidFormat {}
 
 @uuidFormat
 string UUID
+

modules/core/src/alloy/HttpPolymorphicResponseTrait.java

@@ -0,0 +1,46 @@
+/* Copyright 2022 Disney Streaming
+ *
+ * Licensed under the Tomorrow Open Source Technology License, Version 1.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    https://disneystreaming.github.io/TOST-1.0.txt
+ *
+ * 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 alloy;
+
+import software.amazon.smithy.model.node.Node;
+import software.amazon.smithy.model.node.ObjectNode;
+import software.amazon.smithy.model.shapes.ShapeId;
+import software.amazon.smithy.model.traits.AnnotationTrait;
+import software.amazon.smithy.model.traits.AbstractTrait;
+
+public class HttpPolymorphicResponseTrait extends AnnotationTrait {
+
+	public static ShapeId ID = ShapeId.from("alloy#httpPolymorphicResponse");
+
+	public HttpPolymorphicResponseTrait(ObjectNode node) {
+		super(ID, node);
+	}
+
+	public HttpPolymorphicResponseTrait() {
+		super(ID, Node.objectNode());
+	}
+
+	public static final class Provider extends AbstractTrait.Provider {
+		public Provider() {
+			super(ID);
+		}
+
+		@Override
+		public HttpPolymorphicResponseTrait createTrait(ShapeId target, Node node) {
+			return new HttpPolymorphicResponseTrait(node.expectObjectNode());
+		}
+	}
+}

modules/core/src/alloy/HttpSuccessTrait.java

@@ -0,0 +1,59 @@
+/* Copyright 2022 Disney Streaming
+ *
+ * Licensed under the Tomorrow Open Source Technology License, Version 1.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    https://disneystreaming.github.io/TOST-1.0.txt
+ *
+ * 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 alloy;
+
+import software.amazon.smithy.model.FromSourceLocation;
+import software.amazon.smithy.model.SourceLocation;
+import software.amazon.smithy.model.node.Node;
+import software.amazon.smithy.model.node.NumberNode;
+import software.amazon.smithy.model.traits.AbstractTrait;
+import software.amazon.smithy.model.traits.Trait;
+import software.amazon.smithy.model.shapes.ShapeId;
+
+public final class HttpSuccessTrait extends AbstractTrait {
+	public static final ShapeId ID = ShapeId.from("alloy#httpSuccess");
+
+	private final int code;
+
+	public HttpSuccessTrait(int code, FromSourceLocation sourceLocation) {
+		super(ID, sourceLocation);
+		this.code = code;
+	}
+
+	public HttpSuccessTrait(int code) {
+		this(code, SourceLocation.NONE);
+	}
+
+	public static final class Provider extends AbstractTrait.Provider {
+		public Provider() {
+			super(ID);
+		}
+
+		@Override
+		public Trait createTrait(ShapeId target, Node value) {
+			return new HttpSuccessTrait(value.expectNumberNode().getValue().intValue(), value.getSourceLocation());
+		}
+	}
+
+	public int getCode() {
+		return code;
+	}
+
+	@Override
+	protected Node createNode() {
+		return new NumberNode(code, getSourceLocation());
+	}
+}

modules/core/src/alloy/validation/HttpPolymorphicResponseValidator.java

@@ -0,0 +1,64 @@
+/* Copyright 2022 Disney Streaming
+ *
+ * Licensed under the Tomorrow Open Source Technology License, Version 1.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    https://disneystreaming.github.io/TOST-1.0.txt
+ *
+ * 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 alloy.validation;
+
+import alloy.HttpPolymorphicResponseTrait;
+import alloy.HttpSuccessTrait;
+import software.amazon.smithy.model.Model;
+import software.amazon.smithy.model.shapes.*;
+import software.amazon.smithy.model.traits.HttpTrait;
+import software.amazon.smithy.model.validation.AbstractValidator;
+import software.amazon.smithy.model.validation.ValidationEvent;
+
+import java.util.List;
+import java.util.Map;
+import java.util.Optional;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+
+public final class HttpPolymorphicResponseValidator extends AbstractValidator {
+
+	protected static String EXPECTED_SINGLE_MEMBER = "The httpPolymorphicResponse trait can only be used in a structure that has a single required member, and this member must target a union";
+	protected static String EXPECTED_HTTP_SUCCESS_ON_ALL_MEMBER_TARGETS = "The members of a union targeted by httpPolymorphicResponse trait must all target a structure annotated with @alloy.httpSuccess";
+	protected static String EXPECTED_DISTINCT_HTTP_SUCCESS = "The targets of the members of this union must have distinct httpSuccess values";
+
+	@Override
+	public List<ValidationEvent> validate(Model model) {
+		return model.getMemberShapesWithTrait(HttpPolymorphicResponseTrait.class).stream().flatMap(structureMember -> {
+			StructureShape container = model.expectShape(structureMember.getContainer(), StructureShape.class);
+			List<ValidationEvent> errors = new ArrayList<ValidationEvent>();
+			if (container.getAllMembers().size() != 1) {
+				errors.add(error(container, EXPECTED_SINGLE_MEMBER));
+			}
+			UnionShape union = model.expectShape(structureMember.getTarget(), UnionShape.class);
+			union.members().stream().collect(Collectors.groupingBy(member -> {
+				return model.expectShape(member.getTarget()).getTrait(HttpSuccessTrait.class)
+						.map(httpSuccess -> httpSuccess.getCode());
+			})).entrySet().stream().forEach(entry -> {
+				if (!entry.getKey().isPresent()) {
+					errors.add(error(structureMember, EXPECTED_HTTP_SUCCESS_ON_ALL_MEMBER_TARGETS));
+				} else if (entry.getValue().size() > 1) {
+					Optional<Integer> statusCode = entry.getKey();
+					errors.add(error(union, EXPECTED_DISTINCT_HTTP_SUCCESS));
+				}
+			});
+
+			return errors.stream();
+		}).collect(Collectors.toList());
+	}
+}

modules/core/test/resources/META-INF/smithy/traits.smithy

@@ -15,6 +15,8 @@ use alloy#untagged
 use alloy#urlFormFlattened
 use alloy#urlFormName
 use alloy#uuidFormat
+use alloy#httpSuccess
+use alloy#httpPolymorphicResponse
 use alloy.common#countryCodeFormat
 use alloy.common#emailFormat
 use alloy.common#hexColorCodeFormat
@@ -211,3 +213,24 @@ structure TestUrlFormName {
     @urlFormName("Test")
     test: String
 }
+
+operation TestHttpPolymporhicResponse  {
+    input:= {
+        @httpPolymorphicResponse
+        @required
+        response: PolymporhicResponseUnion
+    }
+}
+
+union PolymporhicResponseUnion{
+    created: TestCreated
+    okay: TestOkay
+}
+
+@httpSuccess(201)
+structure TestCreated {
+}
+
+@httpSuccess(200)
+structure TestOkay {
+}