Beside the general goal to remove inlinable functions, this reduces code size and also improves performance for several benchmarks.
The performance problem was that by inlining top-level String API functions into client code (like String.count) it ended up calling non-inlinable internal String functions eventually.
This is much slower than to make a single call at the top-level API boundary into the library. Inside the library all the internal String functions can be specialized and inlined.
rdar://problem/39921548
Include the initial implementation of _StringGuts, a 2-word
replacement for _LegacyStringCore. 64-bit Darwin supported, 32-bit and
Linux support in subsequent commits.
I failed to merge the upstream changes to swift-corelibs-foundation at the same
time as I merged that #9806, and it broke on linux. Going to get it right this
time.
This removes the `_core` property from UnicodeScalarView.Index
and moves any remaining index-moving logic from the index to
the view in UnicodeScalarView and CharacterView.
This documentation revision covers a large number of types & protocols:
String, its views and their indices, the Unicode codec types and protocol,
as well as Character, UnicodeScalar, and StaticString, among others.
This also includes a few small changes across the standard library for
consistency.
The RangeProtocol was a very weak and fragile abstraction because it
didn't specify the interpretation of the endpoints. To write a
non-trivial algorithm, one usually needed to consult that information.
The standard library code only actually worked correctly with half-open
and closed ranges (and didn't handle fully open ranges, for example).
The other two protocols, HalfOpenRangeProtocol and ClosedRangeProtocol,
were only used for code sharing, and present an ABI burden. We can use
gyb instead.
