Introduce a new type Result<T> to indicate if an operation succeeded or
not, and if it did, to hold the return value of the operation. This is
the same as how std::pair<bool, T> is already used in the codebase, so
replace all instances with Result<T> to improve clarity.
Result<T> is simply an alias for std::optional<T>. The difference is
semantic: use Result<T> as the return value for functions that can fail,
use std::optional<T> when values are truly optional. This is modelled
after Rust's std::result and std::option.
A future change may graduate Result<T> to a proper class which can hold
additional details on why an operation failed, such as a string or an
error code. As a special case, continue to use std::unique_ptr<T>
instead of Result<std::unique_ptr<T>> for now: the latter would increase
code complexity without added benefit.
Test: make idmap2_tests
Change-Id: I2a8355107ed2b6485409e5e655a84cf1e20b9911
idmap2 is a reboot of the idmap project. The project aims to
- use modern C++
- greatly improve test and debug support
- interface towards AssetManager2 (instead of AssetManager)
- provide a solid foundation to add support for new features
To make it easier to verify correctness, this first version of idmap2 is
feature equivalent to idmap. Later versions will add support for new
features such as <overlayable>.
Bug: 78815803
Test: make idmap2_tests
Change-Id: I1d806dc875a493e730ab55d2fdb027618e586d16
