feat: Add HookData class.

[NeaguGeorgiana23]

This PR

• Adds HookData, the foundational state-management container required for the OpenFeature Hooks lifecycle specification (Section 4.6).
• Implements a type-safe key-value store backed by std::unordered_map<std::string, std::any> (Set, Get, and GetAs<T>) to allow individual hook instances to persist arbitrary runtime state (e.g., execution timers, OpenTelemetry span pointers, transaction IDs) across Before ,After / Error , FinallyAfter stages during a single flag evaluation.
• Adds comprehensive unit tests covering value setting, retrieving, type-safe casting, and edge cases for missing keys or type mismatches.

Related Issues

Fixes #111

Follow-up Tasks

• implement HookContext

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Review details

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro Plus

Run ID: 6bc4876e-91e7-4a08-8aa9-81c3e75d2295

📥 Commits

Reviewing files that changed from the base of the PR and between c8fc92d and e9e8852.

📒 Files selected for processing (3)

• openfeature/hook_data.cpp
• openfeature/hook_data.h
• test/hook_data_test.cpp

📝 Walkthrough

Walkthrough

Adds public flag and hook data types, implements HookData storage with typed access, registers Bazel targets, and introduces comprehensive GoogleTest coverage.

Changes

Hook data structures

Layer / File(s)	Summary
Hook type contracts openfeature/flag_type_value.h, openfeature/hook_hints.h, openfeature/BUILD	Adds FlagValueType, the HookHints alias, and Bazel library targets for the new public types.
HookData storage implementation openfeature/hook_data.h, openfeature/hook_data.cpp, openfeature/BUILD	Implements HookData with std::any values, replacement semantics, missing-key handling, and typed retrieval.
HookData validation test/hook_data_test.cpp, test/BUILD	Adds tests for primitive and custom values, type mismatches, overwrites, mutation, missing keys, and shared pointers.

Estimated code review effort: 3 (Moderate) | ~20 minutes

Possibly related issues

• open-feature/swift-sdk#99: Covers per-evaluation hook data storage for sharing arbitrary values across hook stages, corresponding to the new HookData APIs here.

🚥 Pre-merge checks | ✅ 2 | ❌ 3

❌ Failed checks (3 warnings)

Check name	Status	Explanation	Resolution
Linked Issues check	⚠️ Warning	The PR covers Hook data and Hook hints, but #111 also requires Evaluation option, which is not implemented.	Add the missing Evaluation option implementation or narrow the linked issue scope before merging.
Out of Scope Changes check	⚠️ Warning	The new flag_type_value public enum is not requested by #111 and appears unrelated to Hook data structures.	Remove the unrelated flag_type_value addition or explain how it is required by the linked issue.
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (2 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly matches the main change: adding the HookData class.
Description check	✅ Passed	The description matches the code changes and accurately describes HookData, tests, and the linked issue.

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🧹 Nitpick comments (1)

openfeature/hook_data.h (1)

21-28: 📐 Maintainability & Code Quality | 🔵 Trivial | 💤 Low value

Consider adding a const overload of GetAs for read-only contexts.

Currently GetAs is non-const only, which prevents typed retrieval from a const HookData&. A const overload returning const T* would improve API ergonomics for callers that only need read access.

♻️ Optional: add const GetAs overload

   template <typename T>
   T* GetAs(const std::string& key) {
     auto it_key = data_.find(key);
     if (it_key != data_.end()) {
       return std::any_cast<T>(&it_key->second);
     }
     return nullptr;
   }
+
+  template <typename T>
+  const T* GetAs(const std::string& key) const {
+    auto it_key = data_.find(key);
+    if (it_key != data_.end()) {
+      return std::any_cast<T>(&it_key->second);
+    }
+    return nullptr;
+  }

🤖 Prompt for AI Agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@openfeature/hook_data.h` around lines 21 - 28, Add a const overload of
HookData::GetAs(const std::string& key) returning const T* so typed values can
be retrieved from const HookData instances; preserve the existing non-const
overload and use const access to data_ in the new implementation.

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Nitpick comments:
In `@openfeature/hook_data.h`:
- Around line 21-28: Add a const overload of HookData::GetAs(const std::string&
key) returning const T* so typed values can be retrieved from const HookData
instances; preserve the existing non-const overload and use const access to
data_ in the new implementation.

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ℹ️ Review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro Plus

Run ID: b29e6623-cfa0-4781-ad37-8282518e3158

📥 Commits

Reviewing files that changed from the base of the PR and between 8254496 and c8fc92d.

📒 Files selected for processing (7)

• openfeature/BUILD
• openfeature/flag_type_value.h
• openfeature/hook_data.cpp
• openfeature/hook_data.h
• openfeature/hook_hints.h
• test/BUILD
• test/hook_data_test.cpp