This commit enables use of range-based `for` loop for iterating over
all the entries in a `LinkedList`. It adds private implementations of
`Iterator` and `ConstIterator` which inherit from `ItemPtrIterator`
and use the `GetNext()` to go to the next entry. The range-based
`for` loop practically acts as a syntactic sugar helping simplify the
code and does not add any code size (or any expected run-time)
overhead.
This commit renames and moves the related types in `Netif` module like
`UnicastAddress`, `MulticastAddress`, etc. under `Netif` class (as a
nested type). It also moves iterator types under the related type
(for example, `ExternalMulticastAddressIteratorBuilder` becomes
`Iterator::Builder` under `ExternalMulticastAddress` class. These
changes help simplify the code (allow us to use shorter names in the
`Netif` implementation).
This commit updates `VerifyOrQuit()` and `SuccessOrQuit()` macros to
include the failed condition in the error message that is printed on
a failure (in addition to function name and line number where the
error happened). This commit also changes the second parameter
(`aMessage`) to in these macros to be optional.
This commit also updates unit tests to remove the second `aMessage`
string in cases where the failure can be inferred from the condition
itself.
This commit adds a new core header files `common/error.hpp` which
defines `ot::Error` (mirroring `otError`) and `kError{Name}` constants
(mirroring the public `OT_ERROR_{NAME}` definitions). The new (C++
style) definitions are used by core modules. This commit also moves
`otThreadErrorToString()` (from `logging.hpp` to `error.hpp`) and
renames it to `ErrorToString()` which is used as the internal (to
core) function to covert an `Error` to a string.
Jonathan Hui