labath marked an inline comment as done.
labath added inline comments.
================
Comment at: include/lldb/Core/UniqueCStringMap.h:87
T Find(ConstString unique_cstr, T fail_value) const {
- Entry search_entry(unique_cstr);
- const_iterator end = m_map.end();
- const_iterator pos = std::lower_bound(m_map.begin(), end, search_entry);
- if (pos != end) {
- if (pos->cstring == unique_cstr)
- return pos->value;
- }
+ auto pos = llvm::lower_bound(m_map, unique_cstr, Compare());
+ if (pos != m_map.end() && pos->cstring == unique_cstr)
----------------
clayborg wrote:
> What benefits does llvm::lower_bound offer here? With std::lower_bound and
> std::upper_bound you can write a comparison static functions that take a
> "const T &" on one side and a ConstString on the other. Lower bound will use
> one flavor ("static bool operator <(const T&, ConstString);") and upper_bound
> will use the other ("static bool operator <(ConstString, const T&);"). No
> need to specify a Compare() object. So the code would be:
> ```
> T Find(ConstString unique_cstr, T fail_value) const {
> const_iterator end = m_map.end();
> const_iterator pos = std::lower_bound(m_map.begin(), end, unique_cstr);
> if (pos != end && pos->cstring == unique_cstr)
> return pos->value;
> return fail_value;
> }
> ```
The only benefit of using llvm lower/upper bound is that operates on ranges --
you don't need to pass the begin/end iterator pairs, you can just pass the
container. Under the hood, it just delegates to the `std` version.
The issue of using the compare object is completely orthogonal to that. I could
define appropriate `operator<`s on the Entry class directly, and thereby avoid
the need for comparison objects. The reason I did not do that is because the
Entry class is public (and other parts of the code use and manipulate it), and
having a (ConstString, Entry) operator< on the Entry class would mean exposing
it to the outside world.. It's not a strong reason, it seemed to me like this
is the kind of thing that users outside of this class should not be able to do
implicitly/accidentally, so I tried to hide it a bit.
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D63268/new/
https://reviews.llvm.org/D63268
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