refactor XML deserialize

.changes/119ee420-38a5-4974-922e-29cb11de02d0.json

@@ -0,0 +1,8 @@
+{
+    "id": "119ee420-38a5-4974-922e-29cb11de02d0",
+    "type": "bugfix",
+    "description": "Refactor XML deserialization to handle flat collections",
+    "issues": [
+        "awslabs/aws-sdk-kotlin#1220"
+    ]
+}

codegen/aws-sdk-codegen/src/main/kotlin/aws/sdk/kotlin/codegen/customization/s3/UnwrappedXmlOutputIntegration.kt

@@ -11,31 +11,32 @@ import software.amazon.smithy.kotlin.codegen.model.expectShape
 import software.amazon.smithy.kotlin.codegen.model.hasTrait
 import software.amazon.smithy.kotlin.codegen.model.traits.UnwrappedXmlOutput
 import software.amazon.smithy.model.Model
+import software.amazon.smithy.model.shapes.OperationShape
 import software.amazon.smithy.model.shapes.ServiceShape
-import software.amazon.smithy.model.shapes.StructureShape
 import software.amazon.smithy.model.transform.ModelTransformer
 
 /**
- * Applies the [UnwrappedXmlOutput] custom-made [annotation trait](https://smithy.io/2.0/spec/model.html?highlight=annotation#annotation-traits) to structures
- * whose operation is annotated with `S3UnwrappedXmlOutput` trait to mark when special unwrapped xml output deserialization is required.
+ * Applies the custom [UnwrappedXmlOutput]
+ * [annotation trait](https://smithy.io/2.0/spec/model.html?highlight=annotation#annotation-traits) to operations
+ * annotated with `S3UnwrappedXmlOutput` trait to mark when special unwrapped xml output deserialization is required.
  */
 class UnwrappedXmlOutputIntegration : KotlinIntegration {
     override fun enabledForService(model: Model, settings: KotlinSettings): Boolean =
         model.expectShape<ServiceShape>(settings.service).isS3
 
     override fun preprocessModel(model: Model, settings: KotlinSettings): Model {
-        val unwrappedStructures = model
+        val unwrappedOperations = model
             .operationShapes
             .filter { it.hasTrait<S3UnwrappedXmlOutputTrait>() }
-            .map { it.outputShape }
+            .map { it.id }
             .toSet()
 
         return ModelTransformer
             .create()
             .mapShapes(model) { shape ->
                 when {
-                    shape.id in unwrappedStructures ->
-                        (shape as StructureShape).toBuilder().addTrait(UnwrappedXmlOutput()).build()
+                    shape.id in unwrappedOperations ->
+                        (shape as OperationShape).toBuilder().addTrait(UnwrappedXmlOutput()).build()
                     else -> shape
                 }
             }

codegen/smithy-aws-kotlin-codegen/src/main/kotlin/software/amazon/smithy/kotlin/codegen/aws/protocols/AwsQuery.kt

@@ -12,11 +12,10 @@ import software.amazon.smithy.kotlin.codegen.aws.protocols.core.AwsHttpBindingPr
 import software.amazon.smithy.kotlin.codegen.aws.protocols.core.QueryHttpBindingProtocolGenerator
 import software.amazon.smithy.kotlin.codegen.aws.protocols.formurl.QuerySerdeFormUrlDescriptorGenerator
 import software.amazon.smithy.kotlin.codegen.core.*
+import software.amazon.smithy.kotlin.codegen.lang.KotlinTypes
 import software.amazon.smithy.kotlin.codegen.model.*
-import software.amazon.smithy.kotlin.codegen.model.traits.OperationOutput
 import software.amazon.smithy.kotlin.codegen.rendering.protocol.*
 import software.amazon.smithy.kotlin.codegen.rendering.serde.*
-import software.amazon.smithy.kotlin.codegen.utils.dq
 import software.amazon.smithy.model.shapes.*
 import software.amazon.smithy.model.traits.*
 
@@ -68,24 +67,6 @@ private class AwsQuerySerdeFormUrlDescriptorGenerator(
         member.hasTrait<XmlFlattenedTrait>()
 }
 
-private class AwsQuerySerdeXmlDescriptorGenerator(
-    ctx: RenderingContext<Shape>,
-    memberShapes: List<MemberShape>? = null,
-) : XmlSerdeDescriptorGenerator(ctx, memberShapes) {
-
-    override fun getObjectDescriptorTraits(): List<SdkFieldDescriptorTrait> {
-        val traits = super.getObjectDescriptorTraits().toMutableList()
-
-        if (objectShape.hasTrait<OperationOutput>()) {
-            traits.removeIf { it.symbol == RuntimeTypes.Serde.SerdeXml.XmlSerialName }
-            val serialName = objectShape.changeNameSuffix("Response" to "Result")
-            traits.add(RuntimeTypes.Serde.SerdeXml.XmlSerialName, serialName.dq())
-        }
-
-        return traits
-    }
-}
-
 private class AwsQuerySerializerGenerator(
     private val protocolGenerator: AwsQuery,
 ) : AbstractQueryFormUrlSerializerGenerator(protocolGenerator, protocolGenerator.defaultTimestampFormat) {
@@ -98,50 +79,76 @@ private class AwsQuerySerializerGenerator(
 }
 
 private class AwsQueryXmlParserGenerator(
-    private val protocolGenerator: AwsQuery,
-) : XmlParserGenerator(protocolGenerator, protocolGenerator.defaultTimestampFormat) {
-
-    override fun descriptorGenerator(
-        ctx: ProtocolGenerator.GenerationContext,
-        shape: Shape,
-        members: List<MemberShape>,
-        writer: KotlinWriter,
-    ): XmlSerdeDescriptorGenerator = AwsQuerySerdeXmlDescriptorGenerator(ctx.toRenderingContext(protocolGenerator, shape, writer), members)
-
-    override fun renderDeserializeOperationBody(
-        ctx: ProtocolGenerator.GenerationContext,
-        op: OperationShape,
-        documentMembers: List<MemberShape>,
-        writer: KotlinWriter,
-    ) {
-        writer.write("val deserializer = #T(payload)", RuntimeTypes.Serde.SerdeXml.XmlDeserializer)
-        unwrapOperationResponseBody(op.id.name, writer)
-        val shape = ctx.model.expectShape(op.output.get())
-        renderDeserializerBody(ctx, shape, documentMembers, writer)
-    }
+    protocolGenerator: AwsQuery,
+) : XmlParserGenerator(protocolGenerator.defaultTimestampFormat) {
 
     /**
      * Unwraps the response body as specified by
      * https://awslabs.github.io/smithy/1.0/spec/aws/aws-query-protocol.html#response-serialization so that the
      * deserializer is in the correct state.
+     *
+     * ```
+     * <SomeOperationResponse>
+     *     <SomeOperationResult>
+     *          <-- SAME AS REST XML -->
+     *     </SomeOperationResult>
+     *</SomeOperationResponse>
+     * ```
      */
-    private fun unwrapOperationResponseBody(
-        operationName: String,
+    override fun unwrapOperationBody(
+        ctx: ProtocolGenerator.GenerationContext,
+        serdeCtx: SerdeCtx,
+        op: OperationShape,
         writer: KotlinWriter,
-    ) {
-        writer.write("// begin unwrap response wrapper")
-            .write("val resultDescriptor = #T(#T.Struct, #T(#S))", RuntimeTypes.Serde.SdkFieldDescriptor, RuntimeTypes.Serde.SerialKind, RuntimeTypes.Serde.SerdeXml.XmlSerialName, "${operationName}Result")
-            .withBlock("val wrapperDescriptor = #T.build {", "}", RuntimeTypes.Serde.SdkObjectDescriptor) {
-                write("trait(#T(#S))", RuntimeTypes.Serde.SerdeXml.XmlSerialName, "${operationName}Response")
-                write("#T(resultDescriptor)", RuntimeTypes.Serde.field)
+    ): SerdeCtx {
+        val operationName = op.id.getName(ctx.service)
+
+        val unwrapAwsQueryOperation = buildSymbol {
+            name = "unwrapAwsQueryResponse"
+            namespace = ctx.settings.pkg.serde
+            definitionFile = "AwsQueryUtil.kt"
+            renderBy = { writer ->
+
+                writer.withBlock(
+                    "internal fun $name(root: #1T, operationName: #2T): #1T {",
+                    "}",
+                    RuntimeTypes.Serde.SerdeXml.XmlTagReader,
+                    KotlinTypes.String,
+                ) {
+                    write("val responseWrapperName = \"\${operationName}Response\"")
+                    write("val resultWrapperName = \"\${operationName}Result\"")
+                    withBlock(
+                        "if (root.tagName != responseWrapperName) {",
+                        "}",
+                    ) {
+                        write("throw #T(#S)", RuntimeTypes.Serde.DeserializationException, "invalid root, expected \$responseWrapperName; found `\${root.tag}`")
+                    }
+
+                    write("val resultTag = ${serdeCtx.tagReader}.nextTag()")
+                    withBlock(
+                        "if (resultTag == null || resultTag.tagName != resultWrapperName) {",
+                        "}",
+                    ) {
+                        write("throw #T(#S)", RuntimeTypes.Serde.DeserializationException, "invalid result, expected \$resultWrapperName; found `\${resultTag?.tag}`")
+                    }
+
+                    write("return resultTag")
+                }
             }
-            .write("")
-            // abandon the iterator, this only occurs at the top level operational output
-            .write("val wrapper = deserializer.#T(wrapperDescriptor)", RuntimeTypes.Serde.deserializeStruct)
-            .withBlock("if (wrapper.findNextFieldIndex() != resultDescriptor.index) {", "}") {
-                write("throw #T(#S)", RuntimeTypes.Serde.DeserializationException, "failed to unwrap $operationName response")
-            }
-            .write("// end unwrap response wrapper")
-            .write("")
+        }
+
+        writer.write("val unwrapped = #T(#L, #S)", unwrapAwsQueryOperation, serdeCtx.tagReader, operationName)
+
+        return SerdeCtx("unwrapped")
+    }
+
+    override fun unwrapOperationError(
+        ctx: ProtocolGenerator.GenerationContext,
+        serdeCtx: SerdeCtx,
+        errorShape: StructureShape,
+        writer: KotlinWriter,
+    ): SerdeCtx {
+        writer.write("val errReader = #T(${serdeCtx.tagReader})", RestXmlErrors.wrappedErrorResponseDeserializer(ctx))
+        return SerdeCtx("errReader")
     }
 }

codegen/smithy-aws-kotlin-codegen/src/main/kotlin/software/amazon/smithy/kotlin/codegen/aws/protocols/Ec2Query.kt

@@ -6,20 +6,19 @@ package software.amazon.smithy.kotlin.codegen.aws.protocols
 
 import software.amazon.smithy.aws.traits.protocols.Ec2QueryNameTrait
 import software.amazon.smithy.aws.traits.protocols.Ec2QueryTrait
+import software.amazon.smithy.codegen.core.Symbol
 import software.amazon.smithy.kotlin.codegen.aws.protocols.core.AbstractQueryFormUrlSerializerGenerator
 import software.amazon.smithy.kotlin.codegen.aws.protocols.core.QueryHttpBindingProtocolGenerator
 import software.amazon.smithy.kotlin.codegen.aws.protocols.formurl.QuerySerdeFormUrlDescriptorGenerator
 import software.amazon.smithy.kotlin.codegen.core.KotlinWriter
 import software.amazon.smithy.kotlin.codegen.core.RenderingContext
 import software.amazon.smithy.kotlin.codegen.core.RuntimeTypes
-import software.amazon.smithy.kotlin.codegen.model.changeNameSuffix
+import software.amazon.smithy.kotlin.codegen.core.withBlock
+import software.amazon.smithy.kotlin.codegen.model.buildSymbol
 import software.amazon.smithy.kotlin.codegen.model.getTrait
-import software.amazon.smithy.kotlin.codegen.model.hasTrait
-import software.amazon.smithy.kotlin.codegen.model.traits.OperationOutput
 import software.amazon.smithy.kotlin.codegen.rendering.protocol.ProtocolGenerator
 import software.amazon.smithy.kotlin.codegen.rendering.protocol.toRenderingContext
 import software.amazon.smithy.kotlin.codegen.rendering.serde.*
-import software.amazon.smithy.kotlin.codegen.utils.dq
 import software.amazon.smithy.model.shapes.*
 import software.amazon.smithy.model.traits.XmlNameTrait
 
@@ -73,24 +72,6 @@ private class Ec2QuerySerdeFormUrlDescriptorGenerator(
         targetShape.type == ShapeType.LIST
 }
 
-private class Ec2QuerySerdeXmlDescriptorGenerator(
-    ctx: RenderingContext<Shape>,
-    memberShapes: List<MemberShape>? = null,
-) : XmlSerdeDescriptorGenerator(ctx, memberShapes) {
-
-    override fun getObjectDescriptorTraits(): List<SdkFieldDescriptorTrait> {
-        val traits = super.getObjectDescriptorTraits().toMutableList()
-
-        if (objectShape.hasTrait<OperationOutput>()) {
-            traits.removeIf { it.symbol == RuntimeTypes.Serde.SerdeXml.XmlSerialName }
-            val serialName = objectShape.changeNameSuffix("Response" to "Result")
-            traits.add(RuntimeTypes.Serde.SerdeXml.XmlSerialName, serialName.dq())
-        }
-
-        return traits
-    }
-}
-
 private class Ec2QuerySerializerGenerator(
     private val protocolGenerator: Ec2Query,
 ) : AbstractQueryFormUrlSerializerGenerator(protocolGenerator, protocolGenerator.defaultTimestampFormat) {
@@ -104,13 +85,73 @@ private class Ec2QuerySerializerGenerator(
 }
 
 private class Ec2QueryParserGenerator(
-    private val protocolGenerator: Ec2Query,
-) : XmlParserGenerator(protocolGenerator, protocolGenerator.defaultTimestampFormat) {
-
-    override fun descriptorGenerator(
+    protocolGenerator: Ec2Query,
+) : XmlParserGenerator(protocolGenerator.defaultTimestampFormat) {
+    override fun unwrapOperationError(
         ctx: ProtocolGenerator.GenerationContext,
-        shape: Shape,
-        members: List<MemberShape>,
+        serdeCtx: SerdeCtx,
+        errorShape: StructureShape,
         writer: KotlinWriter,
-    ): XmlSerdeDescriptorGenerator = Ec2QuerySerdeXmlDescriptorGenerator(ctx.toRenderingContext(protocolGenerator, shape, writer), members)
+    ): SerdeCtx {
+        val unwrapFn = unwrapErrorResponse(ctx)
+        writer.write("val errReader = #T(${serdeCtx.tagReader})", unwrapFn)
+        return SerdeCtx("errReader")
+    }
+
+    /**
+     * Error deserializer for a wrapped error response
+     *
+     * ```
+     * <Response>
+     *     <Errors>
+     *         <Error>
+     *             <-- DATA -->>
+     *         </Error>
+     *     </Errors>
+     * </Response>
+     * ```
+     *
+     * See https://smithy.io/2.0/aws/protocols/aws-ec2-query-protocol.html#operation-error-serialization
+     */
+    private fun unwrapErrorResponse(ctx: ProtocolGenerator.GenerationContext): Symbol = buildSymbol {
+        name = "unwrapXmlErrorResponse"
+        namespace = ctx.settings.pkg.serde
+        definitionFile = "XmlErrorUtils.kt"
+        renderBy = { writer ->
+            writer.dokka("Handle [wrapped](https://smithy.io/2.0/aws/protocols/aws-ec2-query-protocol.html#operation-error-serialization) error responses")
+            writer.withBlock(
+                "internal fun $name(root: #1T): #1T {",
+                "}",
+                RuntimeTypes.Serde.SerdeXml.XmlTagReader,
+            ) {
+                withBlock(
+                    "if (root.tagName != #S) {",
+                    "}",
+                    "Response",
+                ) {
+                    write("throw #T(#S)", RuntimeTypes.Serde.DeserializationException, "invalid root, expected <Response>; found `\${root.tag}`")
+                }
+
+                write("val errorsTag = root.nextTag()")
+                withBlock(
+                    "if (errorsTag == null || errorsTag.tagName != #S) {",
+                    "}",
+                    "Errors",
+                ) {
+                    write("throw #T(#S)", RuntimeTypes.Serde.DeserializationException, "invalid error, expected <Errors>; found `\${errorsTag?.tag}`")
+                }
+
+                write("val errTag = errorsTag.nextTag()")
+                withBlock(
+                    "if (errTag == null || errTag.tagName != #S) {",
+                    "}",
+                    "Error",
+                ) {
+                    write("throw #T(#S)", RuntimeTypes.Serde.DeserializationException, "invalid error, expected <Error>; found `\${errTag?.tag}`")
+                }
+
+                write("return errTag")
+            }
+        }
+    }
 }