Problem: regex: wrong match when searching multi-byte char
case-insensitive (diffsetter)
Solution: Apply proper case-folding for characters and search-string
This patch does the following 4 things:
1) When the regexp engine compares two utf-8 codepoints case
insensitive it may match an adjacent character, because it assumes
it can step over as many bytes as the pattern contains.
This however is not necessarily true because of case-folding, a
multi-byte UTF-8 character can be considered equal to some
single-byte value.
Let's consider the pattern 'ſ' and the string 's'. When comparing and
ignoring case, the single character 's' matches, and since it matches
Vim will try to step over the match (by the amount of bytes of the
pattern), assuming that since it matches, the length of both strings is
the same.
However in that case, it should only step over the single byte value
's' by 1 byte and try to start matching after it again. So for the
backtracking engine we need to ensure:
* we try to match the correct length for the pattern and the text
* in case of a match, we step over it correctly
There is one tricky thing for the backtracing engine. We also need to
calculate correctly the number of bytes to compare the 2 different
utf-8 strings s1 and s2. So we will count the number of characters in
s1 that the byte len specified. Then we count the number of bytes to
step over the same number of characters in string s2 and then we can
correctly compare the 2 utf-8 strings.
2) A similar thing can happen for the NFA engine, when skipping to the
next character to test for a match. We are skipping over the regstart
pointer, however we do not consider the case that because of
case-folding we may need to adjust the number of bytes to skip over.
So this needs to be adjusted in find_match_text() as well.
3) A related issue turned out, when prog->match_text is actually empty.
In that case we should try to find the next match and skip this
condition.
4) When comparing characters using collections, we must also apply case
folding to each character in the collection and not just to the
current character from the search string. This doesn't apply to the
NFA engine, because internally it converts collections to branches
[abc] -> a\|b\|c
fixes: #14294closes: #14756
Signed-off-by: Christian Brabandt <cb@256bit.org>
Problem: No test for highlight behavior with 'ambiwidth'.
Solution: Add a screendump test for 'ambiwidth' with 'cursorline'.
(zeertzjq)
closes: #14554
Signed-off-by: zeertzjq <zeertzjq@outlook.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
Problem: Patch 9.1.0296 causes too many issues
(Tony Mechelynck, @chdiza, CI)
Solution: Back out the change for now
Revert "patch 9.1.0296: regexp: engines do not handle case-folding well"
This reverts commit 7a27c108e0 it causes
issues with syntax highlighting and breaks the FreeBSD and MacOS CI. It
needs more work.
fixes: #14487
Signed-off-by: Christian Brabandt <cb@256bit.org>
Problem: Regex engines do not handle case-folding well
Solution: Correctly calculate byte length of characters to skip
When the regexp engine compares two utf-8 codepoints case insensitively
it may match an adjacent character, because it assumes it can step over
as many bytes as the pattern contains.
This however is not necessarily true because of case-folding, a
multi-byte UTF-8 character can be considered equal to some single-byte
value.
Let's consider the pattern 'ſ' and the string 's'. When comparing and
ignoring case, the single character 's' matches, and since it matches
Vim will try to step over the match (by the amount of bytes of the
pattern), assuming that since it matches, the length of both strings is
the same.
However in that case, it should only step over the single byte
value 's' so by 1 byte and try to start matching after it again. So for the
backtracking engine we need to ensure:
- we try to match the correct length for the pattern and the text
- in case of a match, we step over it correctly
The same thing can happen for the NFA engine, when skipping to the next
character to test for a match. We are skipping over the regstart
pointer, however we do not consider the case that because of
case-folding we may need to adjust the number of bytes to skip over. So
this needs to be adjusted in find_match_text() as well.
A related issue turned out, when prog->match_text is actually empty. In
that case we should try to find the next match and skip this condition.
fixes: #14294closes: #14433
Signed-off-by: Christian Brabandt <cb@256bit.org>
Problem: regexp cannot match combining chars in collection
Solution: Check for combining characters in regex collections for the
NFA and BT Regex Engine
Also, while at it, make debug mode work again.
fixes#10286closes: #12871
Signed-off-by: Christian Brabandt <cb@256bit.org>
Problem: regex: combining chars in collections not handled
Solution: Check for following combining characters for NFA and BT engine
closes: #10459closes: #10286
Signed-off-by: Christian Brabandt <cb@256bit.org>
Problem: There is no real need for a "big" build.
Solution: Move common features to "normal" build, less often used features
to the "huge" build. (Martin Tournoij, closes#11283)
Problem: Falling back to old regexp engine can some patterns.
Solution: Do not fall back once [[:lower:]] or [[:upper:]] is used.
(Christian Brabandt, closes#7572)
Problem: Pattern "^" does not match if the first character in the line is
combining. (Rene Kita)
Solution: Do accept a match at the start of the line. (closes#6963)
Problem: Line in test commented out.
Solution: Uncomment the lines for character classes that were failing before
8.0.0519. (Dominique Pelle, closes#1599)
Problem: Character classes are not well tested. They can differ between
platforms.
Solution: Add tests. In the documentation make clear which classes depend
on what library function. Only use :cntrl: and :graph: for ASCII.
(Kazunobu Kuriyama, Dominique Pelle, closes#1560)
Update the documentation.
Problem: Sourcing a script where a character has 0x80 as a second byte does
not work. (Filipe L B Correia)
Solution: Turn 0x80 into K_SPECIAL KS_SPECIAL KE_FILLER. (Christian
Brabandt, closes#728) Add a test case.
Problem: Using the system default encoding makes tests unpredictable.
Solution: Always use utf-8 or latin1 in the new style tests. Remove setting
encoding and scriptencoding where it is not needed.
