feat(codegen): generate paginators and waiters with default parameters for all optional inputs

.changes/4602d073-9393-4496-b63d-85535a2f631a.json

@@ -0,0 +1,5 @@
+{
+    "id": "4602d073-9393-4496-b63d-85535a2f631a",
+    "type": "feature",
+    "description": "Generate paginators and waiters with a default parameter when input shape has all optional members"
+}

codegen/smithy-kotlin-codegen-testutils/src/main/kotlin/software/amazon/smithy/kotlin/codegen/test/MiscTestUtils.kt

@@ -59,7 +59,7 @@ fun String.shouldContain(expectedStart: String, expectedEnd: String) {
 }
 
 fun <T> List<T>.indexOfSublistOrNull(sublist: List<T>, startFrom: Int = 0): Int? =
-    drop(startFrom).windowed(sublist.size).indexOf(sublist)
+    drop(startFrom).windowed(sublist.size).indexOf(sublist).takeIf { it >= 0 }
 
 /** Format a multi-line string suitable for comparison with codegen, defaults to one level of indention. */
 fun String.formatForTest(indent: String = "    ") =

codegen/smithy-kotlin-codegen/src/main/kotlin/software/amazon/smithy/kotlin/codegen/model/ShapeExt.kt

@@ -130,7 +130,7 @@ fun OperationIndex.operationSignature(
 
     val hasOutputStream = outputShape.map { it.hasStreamingMember(model) }.orElse(false)
     val inputParam = input.map {
-        if (includeOptionalDefault && inputShape.get().isOptional()) "input: $it = $it {}" else "input: $it"
+        if (includeOptionalDefault && inputShape.get().hasAllOptionalMembers) "input: $it = $it { }" else "input: $it"
     }.orElse("")
     val outputParam = output.map { ": $it" }.orElse("")
 
@@ -245,9 +245,10 @@ fun UnionShape.filterEventStreamErrors(model: Model): Collection<MemberShape> {
 }
 
 /**
- * Test if a shape is optional.
+ * Test if a shape has all optional members (no member marked `@required`)
  */
-fun Shape.isOptional(): Boolean = members().none { it.isRequired }
+val Shape.hasAllOptionalMembers: Boolean
+    get() = members().none { it.isRequired }
 
 /**
  * Derive the input and output symbols for an operation.

codegen/smithy-kotlin-codegen/src/main/kotlin/software/amazon/smithy/kotlin/codegen/rendering/PaginatorGenerator.kt

@@ -18,6 +18,7 @@ import software.amazon.smithy.kotlin.codegen.integration.KotlinIntegration
 import software.amazon.smithy.kotlin.codegen.lang.KotlinTypes
 import software.amazon.smithy.kotlin.codegen.model.SymbolProperty
 import software.amazon.smithy.kotlin.codegen.model.expectShape
+import software.amazon.smithy.kotlin.codegen.model.hasAllOptionalMembers
 import software.amazon.smithy.kotlin.codegen.model.hasTrait
 import software.amazon.smithy.kotlin.codegen.model.traits.PaginationTruncationMember
 import software.amazon.smithy.kotlin.codegen.utils.getOrNull
@@ -29,7 +30,6 @@ import software.amazon.smithy.model.shapes.MapShape
 import software.amazon.smithy.model.shapes.OperationShape
 import software.amazon.smithy.model.shapes.ServiceShape
 import software.amazon.smithy.model.shapes.Shape
-import software.amazon.smithy.model.shapes.StructureShape
 import software.amazon.smithy.model.traits.PaginatedTrait
 
 /**
@@ -54,60 +54,52 @@ class PaginatorGenerator : KotlinIntegration {
                     ?: throw CodegenException("Unexpectedly unable to get PaginationInfo from $service $paginatedOperation")
                 val paginationItemInfo = getItemDescriptorOrNull(paginationInfo, ctx)
 
-                renderPaginatorForOperation(writer, ctx, service, paginatedOperation, paginationInfo, paginationItemInfo)
+                renderPaginatorForOperation(ctx, writer, paginatedOperation, paginationInfo, paginationItemInfo)
             }
         }
     }
 
     // Render paginator(s) for operation
     private fun renderPaginatorForOperation(
-        writer: KotlinWriter,
         ctx: CodegenContext,
-        service: ServiceShape,
+        writer: KotlinWriter,
         paginatedOperation: OperationShape,
         paginationInfo: PaginationInfo,
         itemDesc: ItemDescriptor?,
     ) {
-        val serviceSymbol = ctx.symbolProvider.toSymbol(service)
-        val outputSymbol = ctx.symbolProvider.toSymbol(paginationInfo.output)
-        val inputSymbol = ctx.symbolProvider.toSymbol(paginationInfo.input)
-        val cursorMember = ctx.model.getShape(paginationInfo.inputTokenMember.target).get()
-        val cursorSymbol = ctx.symbolProvider.toSymbol(cursorMember)
-
         renderResponsePaginator(
+            ctx,
             writer,
-            serviceSymbol,
             paginatedOperation,
-            inputSymbol,
-            paginationInfo.output,
-            outputSymbol,
             paginationInfo,
-            cursorSymbol,
         )
 
         // Optionally generate paginator when nested item is specified on the trait.
         if (itemDesc != null) {
             renderItemPaginator(
+                ctx,
                 writer,
-                service,
                 paginatedOperation,
                 itemDesc,
-                outputSymbol,
             )
         }
     }
 
     // Generate the paginator that iterates over responses
     private fun renderResponsePaginator(
+        ctx: CodegenContext,
         writer: KotlinWriter,
-        serviceSymbol: Symbol,
         operationShape: OperationShape,
-        inputSymbol: Symbol,
-        outputShape: StructureShape,
-        outputSymbol: Symbol,
         paginationInfo: PaginationInfo,
-        cursorSymbol: Symbol,
     ) {
+        val service = ctx.model.expectShape<ServiceShape>(ctx.settings.service)
+        val serviceSymbol = ctx.symbolProvider.toSymbol(service)
+        val outputShape = paginationInfo.output
+        val outputSymbol = ctx.symbolProvider.toSymbol(outputShape)
+        val inputSymbol = ctx.symbolProvider.toSymbol(paginationInfo.input)
+        val cursorMember = ctx.model.getShape(paginationInfo.inputTokenMember.target).get()
+        val cursorSymbol = ctx.symbolProvider.toSymbol(cursorMember)
+
         val nextMarkerLiteral = paginationInfo.outputTokenMemberPath.joinToString(separator = "?.") {
             it.defaultName()
         }
@@ -124,6 +116,12 @@ class PaginatorGenerator : KotlinIntegration {
         """.trimIndent()
         val docReturn = "@return A [kotlinx.coroutines.flow.Flow] that can collect [${outputSymbol.name}]"
 
+        val inputParameter = if (paginationInfo.input.hasAllOptionalMembers) {
+            writer.format("initialRequest: #1T = #1T { }", inputSymbol)
+        } else {
+            writer.format("initialRequest: #T", inputSymbol)
+        }
+
         writer.write("")
         writer
             .dokka(
@@ -135,11 +133,12 @@ class PaginatorGenerator : KotlinIntegration {
             )
             .addImportReferences(cursorSymbol, SymbolReference.ContextOption.DECLARE)
             .withBlock(
-                "public fun #T.#LPaginated(initialRequest: #T): #T<#T> =",
+                "#L fun #T.#LPaginated(#L): #T<#T> =",
                 "",
+                ctx.settings.api.visibility,
                 serviceSymbol,
                 operationShape.defaultName(),
-                inputSymbol,
+                inputParameter,
                 ExternalTypes.KotlinxCoroutines.Flow,
                 outputSymbol,
             ) {
@@ -180,8 +179,9 @@ class PaginatorGenerator : KotlinIntegration {
                 """.trimMargin(),
             )
             .withBlock(
-                "public fun #T.#LPaginated(block: #T.Builder.() -> #T): #T<#T> =",
+                "#L fun #T.#LPaginated(block: #T.Builder.() -> #T): #T<#T> =",
                 "",
+                ctx.settings.api.visibility,
                 serviceSymbol,
                 operationShape.defaultName(),
                 inputSymbol,
@@ -195,12 +195,15 @@ class PaginatorGenerator : KotlinIntegration {
 
     // Generate a paginator that iterates over the model-specified item
     private fun renderItemPaginator(
+        ctx: CodegenContext,
         writer: KotlinWriter,
-        serviceShape: ServiceShape,
         operationShape: OperationShape,
         itemDesc: ItemDescriptor,
-        outputSymbol: Symbol,
     ) {
+        val serviceShape = ctx.model.expectShape<ServiceShape>(ctx.settings.service)
+        val outputShape = ctx.model.expectShape(operationShape.outputShape)
+        val outputSymbol = ctx.symbolProvider.toSymbol(outputShape)
+
         writer.write("")
         writer.dokka(
             """
@@ -223,8 +226,9 @@ class PaginatorGenerator : KotlinIntegration {
                 itemDesc.targetMember.defaultName(serviceShape),
             )
             .withBlock(
-                "public fun #T<#T>.#L(): #T<#L> =",
+                "#L fun #T<#T>.#L(): #T<#L> =",
                 "",
+                ctx.settings.api.visibility,
                 ExternalTypes.KotlinxCoroutines.Flow,
                 outputSymbol,
                 itemDesc.itemLiteral,

codegen/smithy-kotlin-codegen/src/main/kotlin/software/amazon/smithy/kotlin/codegen/rendering/waiters/WaiterGenerator.kt

@@ -9,6 +9,7 @@ import software.amazon.smithy.kotlin.codegen.core.KotlinWriter
 import software.amazon.smithy.kotlin.codegen.core.RuntimeTypes
 import software.amazon.smithy.kotlin.codegen.core.withBlock
 import software.amazon.smithy.kotlin.codegen.lang.KotlinTypes
+import software.amazon.smithy.kotlin.codegen.model.hasAllOptionalMembers
 import java.text.DecimalFormat
 import java.text.DecimalFormatSymbols
 
@@ -34,12 +35,18 @@ private fun KotlinWriter.renderRetryStrategy(wi: WaiterInfo, asValName: String)
 internal fun KotlinWriter.renderWaiter(wi: WaiterInfo) {
     write("")
     wi.waiter.documentation.ifPresent(::dokka)
+    val inputParameter = if (wi.input.hasAllOptionalMembers) {
+        format("request: #1T = #1T { }", wi.inputSymbol)
+    } else {
+        format("request: #T", wi.inputSymbol)
+    }
     withBlock(
-        "public suspend fun #T.#L(request: #T): #T<#T> {",
+        "#L suspend fun #T.#L(#L): #T<#T> {",
         "}",
+        wi.ctx.settings.api.visibility,
         wi.serviceSymbol,
         wi.methodName,
-        wi.inputSymbol,
+        inputParameter,
         RuntimeTypes.Core.Retries.Outcome,
         wi.outputSymbol,
     ) {
@@ -54,7 +61,8 @@ internal fun KotlinWriter.renderWaiter(wi: WaiterInfo) {
     write("")
     wi.waiter.documentation.ifPresent(this::dokka)
     write(
-        "public suspend fun #T.#L(block: #T.Builder.() -> Unit): #T<#T> =",
+        "#L suspend fun #T.#L(block: #T.Builder.() -> Unit): #T<#T> =",
+        wi.ctx.settings.api.visibility,
         wi.serviceSymbol,
         wi.methodName,
         wi.inputSymbol,

codegen/smithy-kotlin-codegen/src/test/kotlin/software/amazon/smithy/kotlin/codegen/rendering/PaginatorGeneratorTest.kt

@@ -93,7 +93,7 @@ class PaginatorGeneratorTest {
              * @param initialRequest A [ListFunctionsRequest] to start pagination
              * @return A [kotlinx.coroutines.flow.Flow] that can collect [ListFunctionsResponse]
              */
-            public fun TestClient.listFunctionsPaginated(initialRequest: ListFunctionsRequest): Flow<ListFunctionsResponse> =
+            public fun TestClient.listFunctionsPaginated(initialRequest: ListFunctionsRequest = ListFunctionsRequest { }): Flow<ListFunctionsResponse> =
                 flow {
                     var cursor: kotlin.String? = null
                     var hasNextPage: Boolean = true
@@ -204,7 +204,7 @@ class PaginatorGeneratorTest {
              * @param initialRequest A [ListFunctionsRequest] to start pagination
              * @return A [kotlinx.coroutines.flow.Flow] that can collect [ListFunctionsResponse]
              */
-            public fun TestClient.listFunctionsPaginated(initialRequest: ListFunctionsRequest): Flow<ListFunctionsResponse> =
+            public fun TestClient.listFunctionsPaginated(initialRequest: ListFunctionsRequest = ListFunctionsRequest { }): Flow<ListFunctionsResponse> =
                 flow {
                     var cursor: kotlin.String? = null
                     var hasNextPage: Boolean = true
@@ -333,7 +333,7 @@ class PaginatorGeneratorTest {
         val actual = testManifest.expectFileString("src/main/kotlin/smithy/kotlin/traits/paginators/Paginators.kt")
 
         val expectedCode = """
-            public fun TestClient.listFunctionsPaginated(initialRequest: ListFunctionsRequest): Flow<ListFunctionsResponse> =
+            public fun TestClient.listFunctionsPaginated(initialRequest: ListFunctionsRequest = ListFunctionsRequest { }): Flow<ListFunctionsResponse> =
                 flow {
                     var cursor: kotlin.String? = null
                     var hasNextPage: Boolean = true
@@ -352,4 +352,76 @@ class PaginatorGeneratorTest {
 
         actual.shouldContainOnlyOnceWithDiff(expectedCode)
     }
+
+    @Test
+    fun testRenderPaginatorWithRequiredInputMembers() {
+        val testModelNoItem = """
+            namespace com.test
+
+            use aws.protocols#restJson1
+
+            service Lambda {
+                operations: [ListFunctions]
+            }
+
+            @paginated(
+                inputToken: "Marker",
+                outputToken: "NextMarker",
+                pageSize: "MaxItems"
+            )
+            @readonly
+            @http(method: "GET", uri: "/functions", code: 200)
+            operation ListFunctions {
+                input: ListFunctionsRequest,
+                output: ListFunctionsResponse
+            }
+
+            structure ListFunctionsRequest {
+                @required
+                @httpQuery("FunctionVersion")
+                FunctionVersion: String,
+                @httpQuery("Marker")
+                Marker: String,
+                @httpQuery("MasterRegion")
+                MasterRegion: String,
+                @httpQuery("MaxItems")
+                MaxItems: Integer
+            }
+
+            structure ListFunctionsResponse {
+                Functions: FunctionConfigurationList,
+                NextMarker: String
+            }
+
+            list FunctionConfigurationList {
+                member: FunctionConfiguration
+            }
+
+            structure FunctionConfiguration {
+                FunctionName: String
+            }
+        """.toSmithyModel()
+        val testContextNoItem = testModelNoItem.newTestContext("Lambda", "com.test")
+
+        val codegenContextNoItem = object : CodegenContext {
+            override val model: Model = testContextNoItem.generationCtx.model
+            override val symbolProvider: SymbolProvider = testContextNoItem.generationCtx.symbolProvider
+            override val settings: KotlinSettings = testContextNoItem.generationCtx.settings
+            override val protocolGenerator: ProtocolGenerator = testContextNoItem.generator
+            override val integrations: List<KotlinIntegration> = testContextNoItem.generationCtx.integrations
+        }
+
+        val unit = PaginatorGenerator()
+        unit.writeAdditionalFiles(codegenContextNoItem, testContextNoItem.generationCtx.delegator)
+
+        testContextNoItem.generationCtx.delegator.flushWriters()
+        val testManifest = testContextNoItem.generationCtx.delegator.fileManifest as MockManifest
+        val actual = testManifest.expectFileString("src/main/kotlin/com/test/paginators/Paginators.kt")
+
+        val expected = """
+            public fun TestClient.listFunctionsPaginated(initialRequest: ListFunctionsRequest): Flow<ListFunctionsResponse> =
+        """.trimIndent()
+
+        actual.shouldContainOnlyOnceWithDiff(expected)
+    }
 }

codegen/smithy-kotlin-codegen/src/test/kotlin/software/amazon/smithy/kotlin/codegen/rendering/ServiceClientGeneratorTest.kt

@@ -38,13 +38,13 @@ class ServiceClientGeneratorTest {
     fun `it renders signatures correctly`() {
         val expectedSignatures = listOf(
             "public suspend fun getFoo(input: GetFooRequest): GetFooResponse",
-            "public suspend fun getFooNoRequired(input: GetFooNoRequiredRequest = GetFooNoRequiredRequest {}): GetFooNoRequiredResponse",
+            "public suspend fun getFooNoRequired(input: GetFooNoRequiredRequest = GetFooNoRequiredRequest { }): GetFooNoRequiredResponse",
             "public suspend fun getFooSomeRequired(input: GetFooSomeRequiredRequest): GetFooSomeRequiredResponse",
-            "public suspend fun getFooNoInput(input: GetFooNoInputRequest = GetFooNoInputRequest {}): GetFooNoInputResponse",
+            "public suspend fun getFooNoInput(input: GetFooNoInputRequest = GetFooNoInputRequest { }): GetFooNoInputResponse",
             "public suspend fun getFooNoOutput(input: GetFooNoOutputRequest): GetFooNoOutputResponse",
             "public suspend fun getFooStreamingInput(input: GetFooStreamingInputRequest): GetFooStreamingInputResponse",
             "public suspend fun <T> getFooStreamingOutput(input: GetFooStreamingOutputRequest, block: suspend (GetFooStreamingOutputResponse) -> T): T",
-            "public suspend fun <T> getFooStreamingOutputNoInput(input: GetFooStreamingOutputNoInputRequest = GetFooStreamingOutputNoInputRequest {}, block: suspend (GetFooStreamingOutputNoInputResponse) -> T): T",
+            "public suspend fun <T> getFooStreamingOutputNoInput(input: GetFooStreamingOutputNoInputRequest = GetFooStreamingOutputNoInputRequest { }, block: suspend (GetFooStreamingOutputNoInputResponse) -> T): T",
             "public suspend fun getFooStreamingInputNoOutput(input: GetFooStreamingInputNoOutputRequest): GetFooStreamingInputNoOutputResponse",
         )
         expectedSignatures.forEach {

codegen/smithy-kotlin-codegen/src/test/kotlin/software/amazon/smithy/kotlin/codegen/rendering/waiters/ServiceWaitersGeneratorTest.kt

@@ -5,6 +5,7 @@
 
 package software.amazon.smithy.kotlin.codegen.rendering.waiters
 
+import io.kotest.matchers.string.shouldContain
 import io.kotest.matchers.string.shouldContainOnlyOnce
 import software.amazon.smithy.build.MockManifest
 import software.amazon.smithy.codegen.core.SymbolProvider
@@ -42,7 +43,7 @@ class ServiceWaitersGeneratorTest {
             /**
              * Wait until a foo exists
              */
-            public suspend fun TestClient.waitUntilFooExists(request: DescribeFooRequest): Outcome<DescribeFooResponse> {
+            public suspend fun TestClient.waitUntilFooExists(request: DescribeFooRequest = DescribeFooRequest { }): Outcome<DescribeFooResponse> {
         """.trimIndent()
         val methodFooter = """
                 val policy = AcceptorRetryPolicy(request, acceptors)
@@ -52,6 +53,17 @@ class ServiceWaitersGeneratorTest {
         generated.shouldContain(methodHeader, methodFooter)
     }
 
+    @Test
+    fun testWaiterSignatureWithRequiredInput() {
+        val methodHeader = """
+            /**
+             * Wait until a foo exists with required input
+             */
+            public suspend fun TestClient.waitUntilFooRequiredExists(request: DescribeFooRequiredRequest): Outcome<DescribeFooRequiredResponse> {
+        """.trimIndent()
+        generated.shouldContainOnlyOnceWithDiff(methodHeader)
+    }
+
     @Test
     fun testConvenienceWaiterMethod() {
         val expected = """
@@ -89,7 +101,7 @@ class ServiceWaitersGeneratorTest {
                 }
             }
         """.formatForTest()
-        generated.shouldContainOnlyOnce(expected)
+        generated.shouldContain(expected)
     }
 
     private fun generateService(modelResourceName: String): String {