LockedPtr::transform implemented

[sankurm]

Monadic interfaces help write functional code by supporting transform, and_then and or_else. This PR is to support transform.

This makes the following possible.

Synchronized<int> synced_int{42};
auto to_str = [](const LockedPtr<int>& lp) { return std::to_string(*lp); };

auto str = synced_int.lock()
                     .transform(to_str);
EXPECT_EQ(str, "42");

[github-actions]

The created documentation from the pull request is available at: docu-html

[Copilot]

Pull request overview

Adds monadic transformation support to LockedPtr.

Changes:

• Adds lvalue, const-lvalue, and rvalue transform overloads.
• Adds null and non-null transformation tests.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 5 comments.

File	Description
score/concurrency/locked_ptr.h	Implements transformation APIs.
score/concurrency/locked_ptr_test.cpp	Tests transformation behavior.

Suppressed comments (3)

score/concurrency/locked_ptr.h:239

• This overload also preserves top-level const, so its result type diverges from the linked transform contract and can reject const move-only return values. Strip top-level cv-qualification from the invocation result.

              typename FuncResult = std::invoke_result_t<Func, const LockedPtr&>,

score/concurrency/locked_ptr.h:260

• The rvalue overload must also remove top-level cv-qualification; otherwise a callable returning a const move-only value cannot be wrapped even though transform should store the unqualified value type.

              typename FuncResult = std::invoke_result_t<Func, LockedPtr>,

score/concurrency/locked_ptr_test.cpp:58

• These namespace-scope callable objects are also mutable globals, contrary to docs/cpp-style-guide.md:29 and MISRA 6.7.2. Use free functions or constexpr, k-prefixed lambda constants instead.

auto move_ptr = [](LPtr2IntW&& ptr) {
    return std::move(ptr);
};

auto get_obj = [](const LPtr2IntW& ptr) {

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