Note: according to cppreference it is necessary to convert char to unsigned char when using std::tolower and std::toupper, otherwise the behaviour would be undefined.
There's no need to perform the resize separately here, since the
constructor allows presizing the buffer.
Also move the empty string check before the construction of the string
to make the early out more straightforward.
This is equivalent to doing:
push_back(std::string(""));
which is likely not to cause issues, assuming a decent std::string
implementation with small-string optimizations implemented in its
design, however it's still a little unnecessary to copy that buffer
regardless. Instead, we can use emplace_back() to directly construct the
empty string within the std::vector instance, eliminating any possible
overhead from the copy.
We can just use the variant of std::string's replace() function that can
replace an occurrence with N copies of the same character, eliminating
the need to allocate a std::string containing a buffer of spaces.
We can just leverage std::unique_ptr to automatically close these for us
in error cases instead of jumping to the end of the function to call
fclose on them.
Instead of using an unsigned int as a parameter and expecting a user to
always pass in the correct values, we can just convert the enum into an
enum class and use that type as the parameter type instead, which makes
the interface more type safe.
We also get rid of the bookkeeping "NUM_" element in the enum by just
using an unordered map. This function is generally low-frequency in
terms of calls (and I'd hope so, considering otherwise would mean we're
slamming the disk with IO all the time) so I'd consider this acceptable
in this case.
This avoids a redundant std::string construction if a key doesn't exist
in the map already.
e.g.
data[key] requires constructing a new default instance of the value in
the map (but this is wasteful, since we're already setting something
into the map over top of it).
Allows avoiding constructing std::string instances, since this only
reads an arbitrary sequence of characters.
We can also make ParseFilterRule() internal, since it doesn't depend on
any private instance state of Filter
These can just use a view to a string since its only comparing against
two names in both cases for matches. This avoids constructing
std::string instances where they aren't necessary.
These are unused and essentially don't provide much benefit either. If
we ever need rotation functions, these can be introduced in a way that
they don't sit in a common_* header and require a bunch of ifdefing to
simply be available
Android and macOS have supported thread_local for quite a while, but
most importantly is that we don't even really need it. Instead of using
a thread-local buffer, we can just return a non-static buffer as a
std::string, avoiding the need for that quality entirely.
