After rebasing on master and incorporating more 32-bit support,
perform a bunch of cleanup, documentation updates, comments, move code
back to String declaration, etc.
This is a giant squashing of a lot of individual changes prototyping a
switch of String in Swift 5 to be natively encoded as UTF-8. It
includes what's necessary for a functional prototype, dropping some
history, but still leaves plenty of history available for future
commits.
My apologies to anyone trying to do code archeology between this
commit and the one prior. This was the lesser of evils.
The functions in LibcShims are used externally, some directly and some through @inlineable functions. These are changed to SWIFT_RUNTIME_STDLIB_SPI to better match their actual usage. Their names are also changed to add "_swift" to the front to match our naming conventions.
Three functions from SwiftObject.mm are changed to SPI and get a _swift prefix.
A few other support functions are also changed to SPI. They already had a prefix and look like they were meant to be SPI anyway. It was just hard to notice any mixup when they were #defined to the same thing.
rdar://problem/35863717
Add some fast paths to String.init(decoding:as:) for inputs of
contiguously stored UTF-8 code units. Dramatically speeds up creation
when the String happens to be ASCII and we can form more small
strings.
Streamline internal String creation. Previously, everything funneled
into a single generic function, however, every single call of the
generic funnel had relevant specific information that could be used
for a more efficient algorithm.
In preparation for efficiently forming small strings, refactor this
logic into a handful of more specialized subroutines to preserve more
specific information from the callers.
As proposed by SE-0107: UnsafeRawPointer:
https://github.com/apple/swift-evolution/blob/master/proposals/0107-unsaferawpointer.md#cstring-conversion
Adds String.init(cString: UnsafePointer<UInt8>)
Adds String.nulTerminatedUTF8CString: ContiguousArray<CChar>
This is necessary for eliminating UnsafePointer conversion. Such
conversion is extremely common for interoperability between Swift
strings and C strings to bridge the difference between CChar and
UTF8.CodeUnit. The standard library does not provide any convenient
utilities for converting between the differently typed
buffers. These APIs will handle the simplest cases involving C
interoperability. More convenience can be added later.
[stdlib] Fix the `String.decodeCString` for UTF16 and UTF32
Resolves [SR-1578](https://bugs.swift.org/browse/SR-1578]
Essentially the problem was that `strlen` is not the right way of
obtaining a length of anything but null-terminated UTF-8 sequence of
characters. Other encodings require alternative mechanisms.
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.
Implements SE-0055: https://github.com/apple/swift-evolution/blob/master/proposals/0055-optional-unsafe-pointers.md
- Add NULL as an extra inhabitant of Builtin.RawPointer (currently
hardcoded to 0 rather than being target-dependent).
- Import non-object pointers as Optional/IUO when nullable/null_unspecified
(like everything else).
- Change the type checker's *-to-pointer conversions to handle a layer of
optional.
- Use 'AutoreleasingUnsafeMutablePointer<NSError?>?' as the type of error
parameters exported to Objective-C.
- Drop NilLiteralConvertible conformance for all pointer types.
- Update the standard library and then all the tests.
I've decided to leave this commit only updating existing tests; any new
tests will come in the following commits. (That may mean some additional
implementation work to follow.)
The other major piece that's missing here is migration. I'm hoping we get
a lot of that with Swift 1.1's work for optional object references, but
I still need to investigate.
This commit is the result of auditing the following files:
* StringBuffer.swift
* StringCharacterView.swift
* StringCore.swift
* StringInterpolation.swift.gyb
* StringLegacy.swift
