Smithy generator for paginator

[kai-ion]

Issue #, if available:

Description of changes:
Smithy-based code generator for paginators

Check all that applies:

• 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.
• Checked if this PR will not introduce cross-platform inconsistent behavior.
• Checked if this PR would require a ReadMe/Wiki update.

Check which platforms you have built SDK on to verify the correctness of this PR.

• Linux
• Windows
• Android
• MacOS
• IOS
• Other Platforms

By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.

[agicquelamz]

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

[kai-ion]

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

[kai-ion]

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

[sbiscigl]

lets change PagePaginator to Paginator, unless you feel strongly about the name

[sbiscigl]

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

[sbiscigl]

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

[sbiscigl]

nit: why shared pointer and not stack varable?

[kai-ion]

The other integration test had similar pattern tests/aws-cpp-sdk-dynamodb-integration-tests/TableOperationTest.cpp in using shared pointer,

I will go ahead and use a stack variable here

[sbiscigl]

is this not needed in this code path anymore?

[kai-ion]

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]

nit: whitespace change

[kai-ion]

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]

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

[kai-ion]

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)
            }