Codechange: Improve LineCache queries #9417
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LordAro
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Jul 8, 2021
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| /** Comparator for std::map */ | ||
| struct LineCacheCompare { | ||
| using is_transparent = void; ///< Enable map queries with various key types |
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Don't understand why this is necessary?
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This is required to enable some overloads in std::map. Example, 3-4
Adds the support to query the linecache without copying the string. This uses a custom transparent comparator in conjunction with a query type using a std::string_view.
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@LordAro I implemented the changes. This PR is ready for review. |
LordAro
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LordAro
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Aug 16, 2021
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Motivation / Problem
After #9416, one major source of temporary allocations is
GetCachedParagraphLayout.The key of the
std::mapcontains astd::string, while the cache access uses aconst char* + size.The current version constructs the key to query the linecache, which needs to allocate and copy the string for each query.
With C++14, some queries of
std::mapallow to query using a different type than key using a transparent comparator.Description
This PR adds the support to query the linecache without copying the string.
Building pieces are:
std::string_viewAfter this PR and #9416, the allocations are dominated by the SpriteSorter.
Limitations
none
Checklist for review
Some things are not automated, and forgotten often. This list is a reminder for the reviewers.