As a performance optimization, mb_detect_encoding tries to stop
processing the input string early when there is only one 'candidate'
encoding which the input string is valid in. However, the code which
keeps count of how many candidate encodings have already been rejected
was buggy. This caused mb_detect_encoding to prematurely stop
processing the input when it should have continued.
As a result, it did not notice that in the test case provided by Alec,
the input string was not valid in UTF-16.
mbstring had an 'identify filter' for almost every supported text encoding
which was used when auto-detecting the most likely encoding for a string.
It would run over the string and set a 'flag' if it saw anything which
did not appear likely to be the encoding in question.
One problem with this scheme was that encodings which merely appeared
less likely to be the correct one were completely rejected, even if there
was no better candidate. Another problem was that the 'identify filters'
had a huge amount of code duplication with the 'conversion filters'.
Eliminate the identify filters. Instead, when auto-detecting text
encoding, use conversion filters to see whether the input string is valid
in candidate encodings or not. At the same type, watch the type of
codepoints which the string decodes to and mark it as less likely if
non-printable characters (ESC, form feed, bell, etc.) or 'private use
area' codepoints are seen.
Interestingly, one old test case in which JIS text was misidentified
as UTF-8 (and this wrong behavior was enshrined in the test) was 'fixed'
and the JIS string is now auto-detected as JIS.
Man, I can be pedantic sometimes. Tiny little things like misspelled words just
hurt me inside. So while it's not really a big deal, I couldn't leave these typos
alone...
This patch adds missing newlines, trims multiple redundant final
newlines into a single one, and trims redundant leading newlines in all
*.phpt sections.
According to POSIX, a line is a sequence of zero or more non-' <newline>'
characters plus a terminating '<newline>' character. [1] Files should
normally have at least one final newline character.
C89 [2] and later standards [3] mention a final newline:
"A source file that is not empty shall end in a new-line character,
which shall not be immediately preceded by a backslash character."
Although it is not mandatory for all files to have a final newline
fixed, a more consistent and homogeneous approach brings less of commit
differences issues and a better development experience in certain text
editors and IDEs.
[1] http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap03.html#tag_03_206
[2] https://port70.net/~nsz/c/c89/c89-draft.html#2.1.1.2
[3] https://port70.net/~nsz/c/c99/n1256.html#5.1.1.2
