If underlying NSString contained isolated surrogates, then we were crashing in
following ways:
- subscripting by index could crash;
- index pointing to the second code unit sequence was not moved backwards
correctly. Instead of moving it to pointing to the beginning of the view it
could be moved to point to the code unit before the beginning of the view.
Swift SVN r19230
don't call into CoreFoundation to perform UTF-8 transcoding. CoreFoundation
can replace ill-formed sequences with a single byte, which is not good enough
to implement U+FFFD insertion. Instead, use the same transcoding routine as
for contiguous buffer.
Pulled out the transcoding routine into a generic function that should be
specialized and simplified for the case when input is UnsafeArray; we should
not be losing efficiency here.
Fixes <rdar://problem/17297055> [unicode] println crashes when given string
with unpaired surrogate
Swift SVN r19157
implementation:
- don't crash on NSStrings that contain isolated surrogates (partial fix, there
is a different code path that dispatches CoreFoundation and it still
crashes);
- insert U+FFFD according to Unicode recommendation;
- fix decoding of surrogate pairs when the internal buffer is almost full
(we used to drop characters in that case, rdar://16833733 + dups).
Swift SVN r19147
In UTF-8 decoder:
- implement U+FFFD insertion according to the recommendation given in the
Unicode spec. This required changing the decoder to become stateful, which
significantly increased complexity due to the need to maintain an internal
buffer.
- reject invalid code unit sequences properly instead of crashing rdar://16767868
- reject overlong sequences rdar://16767911
In stdlib:
- change APIs that assume that UTF decoding can never fail to account for
possibility of errors
- fix a bug in UnicodeScalarView that could cause a crash during backward
iteration if U+8000 is present in the string
- allow noncharacters in UnicodeScalar. They are explicitly allowed in the
definition of "Unicode scalar" in the specification. Disallowing noncharacters
in UnicodeScalar prevents actually using these scalar values as internal
special values during string processing, which is exactly the reason why they
are reserved in the first place.
- fix a crash in String.fromCString() that could happen if it was passed a null
pointer
In Lexer:
- allow noncharacters in string literals. These Unicode scalar values are not
allowed to be exchanged externally, but it is totally reasonable to have them
in literals as long as they don't escape the program. For example, using
U+FFFF as a delimiter and then calling str.split("\uffff") is completely
reasonable.
This is a lot of changes in a single commit; the primary reason why they are
lumped together is the need to change stdlib APIs to account for the
possibility of UTF decoding failure, and this has long-reaching effects
throughout stdlib where these APIs are used.
Swift SVN r19045
assert() and fatalError()
These functions are meant to be used in user code. They are enabled in debug
mode and disabled in release or fast mode.
_precondition() and _preconditionFailure()
These functions are meant to be used in library code to check preconditions at
the api boundry. They are enabled in debug mode (with a verbose message) and
release mode (trap). In fast mode they are disabled.
_debugPrecondition() and _debugPreconditionFailure()
These functions are meant to be used in library code to check preconditions that
are not neccesarily comprehensive for safety (UnsafePointer can be null or an
invalid pointer but we can't check both). They are enabled only in debug mode.
_sanityCheck() and _fatalError()
These are meant to be used for internal consistency checks. They are only
enabled when the library is build with -DSWIFT_STDLIB_INTERNAL_CHECKS=ON.
I modified the code in the standard library to the best of my judgement.
rdar://16477198
Swift SVN r18212
The old ones were:
- print/println
- printAny
- printf
- Console
The new printing story is just print/println. Every object can be printed.
You can customize the way it is printed by adopting Printable protocol. Full
details in comments inside stdlib/core/OutputStream.swift.
Printing is not completely finished yet. We still have ReplPrintable, which
should be removed, string interpolation still uses String constructors, and
printing objects that don't conform to Printable will result in printing
mangled names.
Swift SVN r18001
