add string match --filter flag

Fixes #3957

tests/string.out

@@ -1,85 +1,247 @@
+# string match -r -v "c.*" dog can cat diz
 dog
 diz
 exit 0
+
+# string match -q -r -v "c.*" dog can cat diz
 exit 0
+
+# string match -v "c*" dog can cat diz
 dog
 diz
 exit 0
+
+# string match -q -v "c*" dog can cat diz
 exit 0
+
+# string match -v "d*" dog dan dat diz
 exit 1
+
+# string match -q -v "d*" dog dan dat diz
 exit 1
+
+# string match -r -v x y
 y
 exit 0
+
+# string match -r -v x x
 exit 1
+
+# string match -q -r -v x y
 exit 0
+
+# string match -q -r -v x x
 exit 1
+
+# string length "hello, world"
 12
+
+# string length -q ""
+zero length
+
+# string sub --length 2 abcde
 ab
+
+# string sub -s 2 -l 2 abcde
 bc
+
+# string sub --start=-2 abcde
 de
+
+# string split . example.com
 example
 com
+
+# string split -r -m1 / /usr/local/bin/fish
 /usr/local/bin
 fish
+
+# string split "" abc
 a
 b
 c
+
+# seq 3 | string join ...
 1...2...3
- abc 
+
+# string trim " abc  "
 abc
+
+# string trim --right --chars=yz xyzzy zany
 x
 zan
+
+# echo \x07 | string escape
 \cg
+
+# string match "?" a
 a
+
+# string match "a*b" axxb
 axxb
+
+# string match -i "a??B" Axxb
 Axxb
+
+# echo "ok?" | string match "*\?"
 ok?
+
+# string match -r "cat|dog|fish" "nice dog"
 dog
+
+# string match -r "(\d\d?):(\d\d):(\d\d)" 2:34:56
 2:34:56
 2
 34
 56
+
+# string match -r "^(\w{2,4})\g1\$" papa mud murmur
 papa
 pa
 murmur
 mur
+
+# string match -r -a -n at ratatat
 2 2
 4 2
 6 2
+
+# string match -r -i "0x[0-9a-f]{1,8}" "int magic = 0xBadC0de;"
 0xBadC0de
+
+# string replace is was "blue is my favorite"
 blue was my favorite
+
+# string replace 3rd last 1st 2nd 3rd
 1st
 2nd
 last
+
+# string replace -a " " _ "spaces to underscores"
 spaces_to_underscores
+
+# string replace -r -a "[^\d.]+" " " "0 one two 3.14 four 5x"
 0 3.14 5 
+
+# string replace -r "(\w+)\s+(\w+)" "\$2 \$1 \$\$" "left right"
 right left $
+
+# string replace -r "\s*newline\s*" "\n" "put a newline here"
 put a
 here
+
+# string replace -r -a "(\w)" "\$1\$1" ab
 aabb
-invalid expression error
-invalid argument error
-missing argument returns 0
+
+# string length
+missing argument returns 1
+
+# string match -r -v "[dcantg].*" dog can cat diz
 no regexp invert match
+
+# string match -v "???" dog can cat diz
 no glob invert match
+
+# string match -rvn a bbb
 1 3
+
+# string repeat -n 2 "foo"
 foofoo
+
+# string repeat --count 2 "foo"
 foofoo
+
+# echo foo | string repeat -n 2
 foofoo
+
+# string repeat -n2 -q "foo"
 exit 0
+
+# string repeat -n2 --quiet "foo"
 exit 0
+
+# string repeat -n0 "foo"
 exit 1
+
+# string repeat -n0
 exit 1
+
+# string repeat -m0
 exit 1
+
+# string repeat -n1 -N "there is "
 there is no newline
+
+# string repeat -n1 --no-newline "there is "
 there is no newline
+
+# string repeat -n10 -m4 "foo"
 foof
+
+# string repeat -n10 --max 5 "foo"
 foofo
+
+# string repeat -n3 -m20 "foo"
 foofoofoo
+
+# string repeat -m4 "foo"
 foof
-exit 2
-exit 2
-exit 2
-exit 2
-exit 2
-exit 2
+
+# string repeat ""
+string repeat empty string failed
+
+# string repeat -n3 ""
+string repeat empty string failed
+
+# string match -f x abc dxf xyz jkx x z
+dxf
+xyz
+jkx
+x
+
+# string match x abc dxf xyz jkx x z
+x
+
+# string match --filter -r "a*b[xy]+" abc abxc bye aaabyz kaabxz abbxy abcx caabxyxz
+abxc
+bye
+aaabyz
+kaabxz
+abbxy
+caabxyxz
+
+# string match -r "a*b[xy]+" abc abxc bye aaabyz kaabxz abbxy abcx caabxyxz
+abx
+by
+aaaby
+aabx
+bxy
+aabxyx
+
+# string match --filter -r "a*b([xy]+)" abc abxc bye aaabyz kaabxz abbxy abcx caabxyxz
+abxc
+x
+bye
+y
+aaabyz
+y
+kaabxz
+x
+abbxy
+xy
+caabxyxz
+xyx
+
+# string match -r "a*b([xy]+)" abc abxc bye aaabyz kaabxz abbxy abcx caabxyxz
+abx
+x
+by
+y
+aaaby
+y
+aabx
+x
+bxy
+xy
+aabxyx
+xyx