Smithy generator for paginator #3690

kai-ion · 2026-01-13T19:49:52Z

Issue #, if available:

Description of changes:
Smithy-based code generator for paginators

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Did a review by yourself.
Added proper tests to cover this PR. (If tests are not applicable, explain.)
Checked if this PR is a breaking (APIs have been changed) change.
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...-codegen/src/main/java/com/amazonaws/util/awsclientsmithygenerator/generators/CppWriter.java

agicquelamz · 2026-01-23T19:22:41Z

tools/code-generation/smithy/codegen/cpp-pagination-codegen/build.gradle.kts

+    implementation("software.amazon.smithy:smithy-aws-traits:1.51.0")
+    implementation("software.amazon.smithy:smithy-waiters:1.51.0")
+    implementation("software.amazon.smithy:smithy-rules-engine:1.51.0")
+    implementation("software.amazon.smithy:smithy-aws-endpoints:1.51.0")


Why do we need this? It's not like we're going to be using smithy based endpoints rule traits right?

Ah, this was from copying the pattern used in our codegen-workshop.
I will refactor the build script to use our existing pattern from smoke-test gen

Smithy actually needs all the above dependencies, in the current set up we are not accepting any unknown traits

.../util/awsclientsmithygenerator/generators/pagination/PaginationCompilationTestGenerator.java

generated/src/aws-cpp-sdk-s3/include/aws/s3/S3ClientPagination.h

generated/src/aws-cpp-sdk-dynamodb/include/aws/dynamodb/DynamoDBClientPagination.h

sbiscigl · 2026-02-05T20:48:51Z

generated/src/aws-cpp-sdk-dynamodb/include/aws/dynamodb/model/ScanPaginationTraits.h

+
+namespace Aws {
+namespace DynamoDB {
+class DynamoDBClient;


instead of forward declaring DynamoDB why not have ScanPaginationTraits take a template parameter template <typename Client = ClientType> like you have on Invoke then the entire class is tempalted. You already pass DynamoDBClient as a template parameter in DynamoDBClientPagination.h

Gotcha, changed the traits to template files instead

generated/src/aws-cpp-sdk-dynamodb/include/aws/dynamodb/DynamoDBClient.h

sbiscigl · 2026-02-05T21:37:23Z

generated/src/aws-cpp-sdk-dynamodb/include/aws/dynamodb/DynamoDBPaginationBase.h

+  ListContributorInsightsPaginator(const Model::ListContributorInsightsRequest& request) {
+    return Aws::Utils::Pagination::PagePaginator<DerivedClient, Model::ListContributorInsightsRequest,
+                                                 Pagination::ListContributorInsightsPaginationTraits>{
+        std::shared_ptr<DerivedClient>(static_cast<DerivedClient*>(this), [](DerivedClient*) {}), request};


std::shared_ptr(static_cast<DerivedClient*>(this), {})

likely isnt what we want to be doing, you are creating a shared point from this then have a custom deleter [](DerivedClient*) {} that does nothing when delete is called. you are essentially trying to fit this into a shared pointer without using the actual properties of shared.

consider

#include <iostream> #include <thread> template<typename crtp_t> class thing { public: thing(crtp_t& ref) : ptr_(ref) {}; void do_something() { ptr_.work(); } private: crtp_t& ptr_; }; template <typename crtp_t> class mixin { public: void operation() { thing<crtp_t> operation_thing{*static_cast<crtp_t*>(this)}; operation_thing.do_something(); } }; class widget : public mixin<widget> { public: void work() { std::cout << "hello from class\n"; } }; auto main() -> int { widget w{}; w.operation(); return 0; }

which is long way of saying on PagePaginator make client a reference not a pointer

Changed paginator.h to make client a reference instead

generated/tests/dynamodb-gen-tests/DynamoDBPaginationCompilationTests.cpp

tests/aws-cpp-sdk-dynamodb-integration-tests/ScanPaginationIntegrationTest.cpp

sbiscigl · 2026-02-05T21:41:05Z

tools/scripts/codegen/legacy_c2j_cpp_gen.py

        print(f"Code generation done, (re)generated {len(done)} packages.")  # Including defaults and partitions

-        # Format generated client code
-        generated_clients = [service for service in self.c2j_models.keys()]


is this not needed in this code path anymore?

Yup, we moved the clang formatting to tools/scripts/run_code_generation.py so it can run after all files have been generated instead of just c2j generated codes

sbiscigl · 2026-02-05T21:41:37Z

tools/code-generation/smithy/codegen/smithy2c2j_service_map.json

    "cloudwatch-logs":"logs",
    "directory-service":"ds",
-    "elasticsearch-service ":"es",
+    "elasticsearch-service":"es",


nit: whitespace change

Original code had an inconsistency that made my custom parsing logic failed. I already fixed my custom parsing logic and went ahead to fix the inconsistency as well

sbiscigl · 2026-02-05T21:45:38Z

...m/amazonaws/util/awsclientsmithygenerator/generators/pagination/PaginationCodegenPlugin.java

+        var model = context.getModel();
+
+        // Handle legacy services without Smithy models
+        if (context.getProjectionName().endsWith(".mock")) {


how is ".mock" generated in the projection name?

We have a small logic in tools/code-generation/smithy/cpp-codegen/build.gradle.kts that generates these projections that do not exist in smithy but does exist in coral so we can maintain backwards compatibility.

// Legacy services without full Smithy models - generate mock projections for base classes val legacyServices = mapOf("importexport" to "ImportExport", "sdb" to "SimpleDB", "s3-crt" to "S3Crt") legacyServices.forEach { (c2jName, serviceName) -> if (filteredServiceList.isEmpty() || c2jName in filteredServiceList) { val mockProjectionContents = Node.objectNodeBuilder() .withMember("plugins", Node.objectNode() .withMember("smithy-cpp-codegen", Node.objectNodeBuilder() .withMember("c2jMap", Node.from(c2jMapStr)) .build())) .build() projectionsBuilder.withMember("$c2jName.mock", mockProjectionContents) }

...m/amazonaws/util/awsclientsmithygenerator/generators/pagination/PaginationCodegenPlugin.java

.../main/java/com/amazonaws/util/awsclientsmithygenerator/generators/ClientCodegenSettings.java

...-codegen/src/main/java/com/amazonaws/util/awsclientsmithygenerator/generators/ShapeUtil.java

...amazonaws/util/awsclientsmithygenerator/generators/pagination/PaginationTraitsGenerator.java

… clients, service-specific patches, and integration tests for S3, EC2, and DynamoDB

…dessed some nits change codegen to create templated pagination traits instead of forward declaring addressed comment on making paginators with references instead of pointers change pagepaginator to paginator

sbaluja reviewed Jan 15, 2026

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...-codegen/src/main/java/com/amazonaws/util/awsclientsmithygenerator/generators/CppWriter.java Show resolved Hide resolved

kai-ion force-pushed the paginatorModel branch 6 times, most recently from 0fd0691 to 661e748 Compare January 23, 2026 15:24

agicquelamz reviewed Jan 23, 2026

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sbiscigl reviewed Jan 23, 2026

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generated/src/aws-cpp-sdk-s3/include/aws/s3/S3ClientPagination.h Show resolved Hide resolved

kai-ion force-pushed the paginatorModel branch 6 times, most recently from 20097ca to 7433789 Compare February 3, 2026 18:26

kai-ion force-pushed the paginatorModel branch 5 times, most recently from a426d02 to 03ae46d Compare February 5, 2026 19:49

sbiscigl reviewed Feb 5, 2026

View reviewed changes

kai-ion force-pushed the paginatorModel branch 2 times, most recently from 239688c to fe3fc77 Compare February 6, 2026 15:36

sbiscigl reviewed Feb 6, 2026

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kai-ion force-pushed the paginatorModel branch 3 times, most recently from e95e912 to b68b5bb Compare February 10, 2026 19:46

kai-ion added 3 commits February 10, 2026 14:52

Added pagination codegen to new Smithy codegen project with CRTP base…

209e3e0

… clients, service-specific patches, and integration tests for S3, EC2, and DynamoDB

added a new codegen project for cpp-codegen

11c6a37

adding back removed dependencies and fixed integration test

75609a1

fixed some comments on PR. Resolved unused mehtods and classes and ad…

36e8b9b

…dessed some nits change codegen to create templated pagination traits instead of forward declaring addressed comment on making paginators with references instead of pointers change pagepaginator to paginator

kai-ion force-pushed the paginatorModel branch from b68b5bb to ac53a13 Compare February 10, 2026 19:53

Refactor generateHasMoreResultsLogic

3616995

kai-ion force-pushed the paginatorModel branch from ac53a13 to 3616995 Compare February 10, 2026 21:15

Smithy generator for paginator #3690

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Smithy generator for paginator #3690

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kai-ion commented Jan 13, 2026

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