[0.10] Apply streaming trait directly to shapes

docs/source/spec/core.rst

@@ -3353,10 +3353,7 @@ Summary
     not be stored in memory, or that the size of the data stored in the shape
     is unknown at the start of a request.
 Trait selector::
-    ``operation -[input, output]-> structure > :test(member > blob)``
-
-    This trait may only be applied to top level members of operation inputs and
-    outputs.
+    ``blob``
 Value type
     ``structure``
 
@@ -3377,6 +3374,10 @@ optional members:
         In an HTTP-based protocol, for instance, this indicates that the
         ``content-length`` header must be set.
 
+Shapes targeted by this trait MAY NOT be used outside of top level operation
+inputs and operation outputs. Additionally, only one member of a structure may
+target a shape with this trait.
+
 .. tabs::
 
     .. code-tab:: smithy
@@ -3386,10 +3387,12 @@ optional members:
         }
 
         structure StreamingOutputWrapper {
-            @streaming
-            output: Blob,
+            output: StreamingBlob,
         }
 
+        @streaming
+        blob StreamingBlob
+
 Constraint traits
 =================
 

smithy-model/src/main/java/software/amazon/smithy/model/validation/validators/StreamingTraitValidator.java

@@ -0,0 +1,73 @@
+/*
+ * Copyright 2020 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License").
+ * You may not use this file except in compliance with the License.
+ * A copy of the License is located at
+ *
+ *  http://aws.amazon.com/apache2.0
+ *
+ * or in the "license" file accompanying this file. This file 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 software.amazon.smithy.model.validation.validators;
+
+import java.util.List;
+import java.util.Set;
+import java.util.stream.Collectors;
+import software.amazon.smithy.model.Model;
+import software.amazon.smithy.model.shapes.MemberShape;
+import software.amazon.smithy.model.shapes.OperationShape;
+import software.amazon.smithy.model.shapes.ShapeId;
+import software.amazon.smithy.model.traits.StreamingTrait;
+import software.amazon.smithy.model.validation.AbstractValidator;
+import software.amazon.smithy.model.validation.ValidationEvent;
+import software.amazon.smithy.utils.OptionalUtils;
+import software.amazon.smithy.utils.SetUtils;
+
+public class StreamingTraitValidator extends AbstractValidator {
+    @Override
+    public List<ValidationEvent> validate(Model model) {
+        Set<MemberShape> streamingMembers = model.shapes(MemberShape.class)
+                .filter(member -> member.getMemberTrait(model, StreamingTrait.class).isPresent())
+                .collect(Collectors.toSet());
+
+        List<ValidationEvent> events = validateShapesOnlyUsedAtTopLevel(model, streamingMembers);
+        events.addAll(validateOnlyOneStreamPerStructure(model, streamingMembers));
+        return events;
+    }
+
+    private List<ValidationEvent> validateShapesOnlyUsedAtTopLevel(Model model, Set<MemberShape> streamingMembers) {
+        Set<ShapeId> topLevelIoShapes = model.shapes(OperationShape.class)
+                .flatMap(operation -> SetUtils.of(operation.getInput(), operation.getOutput()).stream())
+                .flatMap(OptionalUtils::stream)
+                .collect(Collectors.toSet());
+
+        return streamingMembers.stream()
+                .filter(member -> !topLevelIoShapes.contains(member.getContainer()))
+                .map(member -> error(member, String.format(
+                        "The shape %s has the smithy.api#streaming trait, and so may only be targeted by "
+                                + "top-level operation inputs and outputs.",
+                        member.getTarget())))
+                .collect(Collectors.toList());
+    }
+
+    private List<ValidationEvent> validateOnlyOneStreamPerStructure(Model model, Set<MemberShape> streamingMembers) {
+        return streamingMembers.stream()
+                .collect(Collectors.groupingBy(MemberShape::getContainer)).entrySet().stream()
+                .filter(entry -> entry.getValue().size() > 1)
+                .map(entry -> {
+                    String streamingTargets = entry.getValue().stream()
+                            .sorted()
+                            .map(member -> member.toShapeId().toString())
+                            .collect(Collectors.joining(", "));
+                    return error(model.expectShape(entry.getKey()), String.format(
+                            "Structures may only target one shape with the smithy.api#streaming trait, but found [%s]",
+                            streamingTargets));
+                })
+                .collect(Collectors.toList());
+    }
+}

smithy-model/src/main/resources/META-INF/services/software.amazon.smithy.model.validation.Validator

@@ -29,6 +29,7 @@ software.amazon.smithy.model.validation.validators.ShapeIdConflictValidator
 software.amazon.smithy.model.validation.validators.ShapeRecursionValidator
 software.amazon.smithy.model.validation.validators.SingleOperationBindingValidator
 software.amazon.smithy.model.validation.validators.SingleResourceBindingValidator
+software.amazon.smithy.model.validation.validators.StreamingTraitValidator
 software.amazon.smithy.model.validation.validators.TargetValidator
 software.amazon.smithy.model.validation.validators.TraitConflictValidator
 software.amazon.smithy.model.validation.validators.TraitTargetValidator

smithy-model/src/main/resources/software/amazon/smithy/model/loader/prelude-traits.smithy

@@ -293,8 +293,7 @@ string since
 /// Indicates that the the data stored in the shape is very large and should not
 /// be stored in memory, or that the size of the data stored in the shape is
 /// unknown at the start of a request
-@trait(selector: "operation -[input, output]-> structure > :test(member > blob)",
-       structurallyExclusive: true)
+@trait(selector: "blob")
 @tags(["diff.error.const"])
 structure streaming {
     /// Indicates that the stream must have a known size.

smithy-model/src/test/resources/software/amazon/smithy/model/errorfiles/validators/streaming-trait.errors

@@ -1 +1,3 @@
-[ERROR] ns.foo#InvalidStreamingStructure$Body: Trait `streaming` cannot be applied to `ns.foo#InvalidStreamingStructure$Body`. This trait may only be applied to shapes that match the following selector: operation -[input, output]-> structure > :test(member > blob) | TraitTarget
+[ERROR] ns.foo#InvalidStreamingStructure$Body: The shape ns.foo#StreamingBlob has the smithy.api#streaming trait, and so may only be targeted by top-level operation inputs and outputs. | StreamingTrait
+[ERROR] ns.foo#InvalidStreamingStructure2$Body: The shape ns.foo#StreamingBlob2 has the smithy.api#streaming trait, and so may only be targeted by top-level operation inputs and outputs. | StreamingTrait
+[ERROR] ns.foo#InvalidStreamingOutput: Structures may only target one shape with the smithy.api#streaming trait, but found [ns.foo#InvalidStreamingOutput$StreamingBlob1, ns.foo#InvalidStreamingOutput$StreamingBlob2] | StreamingTrait

smithy-model/src/test/resources/software/amazon/smithy/model/errorfiles/validators/streaming-trait.json

@@ -17,32 +17,60 @@
             "type": "structure",
             "members": {
                 "Body": {
-                    "target": "smithy.api#Blob",
-                    "traits": {
-                        "smithy.api#streaming": true
-                    }
+                    "target": "ns.foo#StreamingBlob"
                 }
             }
         },
         "ns.foo#StreamingOutput": {
             "type": "structure",
             "members": {
                 "Body": {
-                    "target": "smithy.api#Blob",
-                    "traits": {
-                        "smithy.api#streaming": true
-                    }
+                    "target": "ns.foo#StreamingBlob"
                 }
             }
         },
         "ns.foo#InvalidStreamingStructure": {
             "type": "structure",
             "members": {
                 "Body": {
-                    "target": "smithy.api#Blob",
-                    "traits": {
-                        "smithy.api#streaming": true
-                    }
+                    "target": "ns.foo#StreamingBlob"
+                }
+            }
+        },
+        "ns.foo#StreamingBlob": {
+            "type": "blob",
+            "traits": {
+                "smithy.api#streaming": true
+            }
+        },
+        "ns.foo#InvalidStreamingStructure2": {
+            "type": "structure",
+            "members": {
+                "Body": {
+                    "target": "ns.foo#StreamingBlob2"
+                }
+            }
+        },
+        "ns.foo#StreamingBlob2": {
+            "type": "blob",
+            "traits": {
+                "smithy.api#streaming": true
+            }
+        },
+        "ns.foo#InvalidStreamingOperation": {
+            "type": "operation",
+            "output": {
+                "target": "ns.foo#InvalidStreamingOutput"
+            }
+        },
+        "ns.foo#InvalidStreamingOutput": {
+            "type": "structure",
+            "members": {
+                "StreamingBlob1": {
+                    "target": "ns.foo#StreamingBlob"
+                },
+                "StreamingBlob2": {
+                    "target": "ns.foo#StreamingBlob2"
                 }
             }
         }

smithy-openapi/src/test/resources/software/amazon/smithy/openapi/fromsmithy/streaming-service.smithy

@@ -14,8 +14,8 @@ operation StreamingOperation {
 
 structure Output {
   @httpPayload
-  @streaming
   body: StreamingPayload,
 }
 
+@streaming
 blob StreamingPayload