testoutput1

/-- This set of tests is for features that are compatible with all versions of
    Perl >= 5.10, in non-UTF-8 mode. It should run clean for the 8-bit, 16-bit,
    and 32-bit PCRE libraries. --/
    
< forbid 89?=ABCDEFfGILMNPTUWXZ<

/the quick brown fox/
    the quick brown fox
 0: the quick brown fox
    The quick brown FOX
No match
    What do you know about the quick brown fox?
 0: the quick brown fox
    What do you know about THE QUICK BROWN FOX?
No match

/The quick brown fox/i
    the quick brown fox
 0: the quick brown fox
    The quick brown FOX
 0: The quick brown FOX
    What do you know about the quick brown fox?
 0: the quick brown fox
    What do you know about THE QUICK BROWN FOX?
 0: THE QUICK BROWN FOX

/abcd\t\n\r\f\a\e\071\x3b\$\\\?caxyz/
    abcd\t\n\r\f\a\e9;\$\\?caxyz
 0: abcd\x09\x0a\x0d\x0c\x07\x1b9;$\?caxyz

/a*abc?xyz+pqr{3}ab{2,}xy{4,5}pq{0,6}AB{0,}zz/
    abxyzpqrrrabbxyyyypqAzz
 0: abxyzpqrrrabbxyyyypqAzz
    abxyzpqrrrabbxyyyypqAzz
 0: abxyzpqrrrabbxyyyypqAzz
    aabxyzpqrrrabbxyyyypqAzz
 0: aabxyzpqrrrabbxyyyypqAzz
    aaabxyzpqrrrabbxyyyypqAzz
 0: aaabxyzpqrrrabbxyyyypqAzz
    aaaabxyzpqrrrabbxyyyypqAzz
 0: aaaabxyzpqrrrabbxyyyypqAzz
    abcxyzpqrrrabbxyyyypqAzz
 0: abcxyzpqrrrabbxyyyypqAzz
    aabcxyzpqrrrabbxyyyypqAzz
 0: aabcxyzpqrrrabbxyyyypqAzz
    aaabcxyzpqrrrabbxyyyypAzz
 0: aaabcxyzpqrrrabbxyyyypAzz
    aaabcxyzpqrrrabbxyyyypqAzz
 0: aaabcxyzpqrrrabbxyyyypqAzz
    aaabcxyzpqrrrabbxyyyypqqAzz
 0: aaabcxyzpqrrrabbxyyyypqqAzz
    aaabcxyzpqrrrabbxyyyypqqqAzz
 0: aaabcxyzpqrrrabbxyyyypqqqAzz
    aaabcxyzpqrrrabbxyyyypqqqqAzz
 0: aaabcxyzpqrrrabbxyyyypqqqqAzz
    aaabcxyzpqrrrabbxyyyypqqqqqAzz
 0: aaabcxyzpqrrrabbxyyyypqqqqqAzz
    aaabcxyzpqrrrabbxyyyypqqqqqqAzz
 0: aaabcxyzpqrrrabbxyyyypqqqqqqAzz
    aaaabcxyzpqrrrabbxyyyypqAzz
 0: aaaabcxyzpqrrrabbxyyyypqAzz
    abxyzzpqrrrabbxyyyypqAzz
 0: abxyzzpqrrrabbxyyyypqAzz
    aabxyzzzpqrrrabbxyyyypqAzz
 0: aabxyzzzpqrrrabbxyyyypqAzz
    aaabxyzzzzpqrrrabbxyyyypqAzz
 0: aaabxyzzzzpqrrrabbxyyyypqAzz
    aaaabxyzzzzpqrrrabbxyyyypqAzz
 0: aaaabxyzzzzpqrrrabbxyyyypqAzz
    abcxyzzpqrrrabbxyyyypqAzz
 0: abcxyzzpqrrrabbxyyyypqAzz
    aabcxyzzzpqrrrabbxyyyypqAzz
 0: aabcxyzzzpqrrrabbxyyyypqAzz
    aaabcxyzzzzpqrrrabbxyyyypqAzz
 0: aaabcxyzzzzpqrrrabbxyyyypqAzz
    aaaabcxyzzzzpqrrrabbxyyyypqAzz
 0: aaaabcxyzzzzpqrrrabbxyyyypqAzz
    aaaabcxyzzzzpqrrrabbbxyyyypqAzz
 0: aaaabcxyzzzzpqrrrabbbxyyyypqAzz
    aaaabcxyzzzzpqrrrabbbxyyyyypqAzz
 0: aaaabcxyzzzzpqrrrabbbxyyyyypqAzz
    aaabcxyzpqrrrabbxyyyypABzz
 0: aaabcxyzpqrrrabbxyyyypABzz
    aaabcxyzpqrrrabbxyyyypABBzz
 0: aaabcxyzpqrrrabbxyyyypABBzz
    >>>aaabxyzpqrrrabbxyyyypqAzz
 0: aaabxyzpqrrrabbxyyyypqAzz
    >aaaabxyzpqrrrabbxyyyypqAzz
 0: aaaabxyzpqrrrabbxyyyypqAzz
    >>>>abcxyzpqrrrabbxyyyypqAzz
 0: abcxyzpqrrrabbxyyyypqAzz
    *** Failers
No match
    abxyzpqrrabbxyyyypqAzz
No match
    abxyzpqrrrrabbxyyyypqAzz
No match
    abxyzpqrrrabxyyyypqAzz
No match
    aaaabcxyzzzzpqrrrabbbxyyyyyypqAzz
No match
    aaaabcxyzzzzpqrrrabbbxyyypqAzz
No match
    aaabcxyzpqrrrabbxyyyypqqqqqqqAzz
No match

/^(abc){1,2}zz/
    abczz
 0: abczz
 1: abc
    abcabczz
 0: abcabczz
 1: abc
    *** Failers
No match
    zz
No match
    abcabcabczz
No match
    >>abczz
No match

/^(b+?|a){1,2}?c/
    bc
 0: bc
 1: b
    bbc
 0: bbc
 1: b
    bbbc
 0: bbbc
 1: bb
    bac
 0: bac
 1: a
    bbac
 0: bbac
 1: a
    aac
 0: aac
 1: a
    abbbbbbbbbbbc
 0: abbbbbbbbbbbc
 1: bbbbbbbbbbb
    bbbbbbbbbbbac
 0: bbbbbbbbbbbac
 1: a
    *** Failers
No match
    aaac
No match
    abbbbbbbbbbbac
No match

/^(b+|a){1,2}c/
    bc
 0: bc
 1: b
    bbc
 0: bbc
 1: bb
    bbbc
 0: bbbc
 1: bbb
    bac
 0: bac
 1: a
    bbac
 0: bbac
 1: a
    aac
 0: aac
 1: a
    abbbbbbbbbbbc
 0: abbbbbbbbbbbc
 1: bbbbbbbbbbb
    bbbbbbbbbbbac
 0: bbbbbbbbbbbac
 1: a
    *** Failers
No match
    aaac
No match
    abbbbbbbbbbbac
No match

/^(b+|a){1,2}?bc/
    bbc
 0: bbc
 1: b

/^(b*|ba){1,2}?bc/
    babc
 0: babc
 1: ba
    bbabc
 0: bbabc
 1: ba
    bababc
 0: bababc
 1: ba
    *** Failers
No match
    bababbc
No match
    babababc
No match

/^(ba|b*){1,2}?bc/
    babc
 0: babc
 1: ba
    bbabc
 0: bbabc
 1: ba
    bababc
 0: bababc
 1: ba
    *** Failers
No match
    bababbc
No match
    babababc
No match

/^\ca\cA\c[;\c:/
    \x01\x01\e;z
 0: \x01\x01\x1b;z

/^[ab\]cde]/
    athing
 0: a
    bthing
 0: b
    ]thing
 0: ]
    cthing
 0: c
    dthing
 0: d
    ething
 0: e
    *** Failers
No match
    fthing
No match
    [thing
No match
    \\thing
No match

/^[]cde]/
    ]thing
 0: ]
    cthing
 0: c
    dthing
 0: d
    ething
 0: e
    *** Failers
No match
    athing
No match
    fthing
No match

/^[^ab\]cde]/
    fthing
 0: f
    [thing
 0: [
    \\thing
 0: \
    *** Failers
 0: *
    athing
No match
    bthing
No match
    ]thing
No match
    cthing
No match
    dthing
No match
    ething
No match

/^[^]cde]/
    athing
 0: a
    fthing
 0: f
    *** Failers
 0: *
    ]thing
No match
    cthing
No match
    dthing
No match
    ething
No match

/^\/
    
 0: \x81

/^ÿ/
    ÿ
 0: \xff

/^[0-9]+$/
    0
 0: 0
    1
 0: 1
    2
 0: 2
    3
 0: 3
    4
 0: 4
    5
 0: 5
    6
 0: 6
    7
 0: 7
    8
 0: 8
    9
 0: 9
    10
 0: 10
    100
 0: 100
    *** Failers
No match
    abc
No match

/^.*nter/
    enter
 0: enter
    inter
 0: inter
    uponter
 0: uponter

/^xxx[0-9]+$/
    xxx0
 0: xxx0
    xxx1234
 0: xxx1234
    *** Failers
No match
    xxx
No match

/^.+[0-9][0-9][0-9]$/
    x123
 0: x123
    xx123
 0: xx123
    123456
 0: 123456
    *** Failers
No match
    123
No match
    x1234
 0: x1234

/^.+?[0-9][0-9][0-9]$/
    x123
 0: x123
    xx123
 0: xx123
    123456
 0: 123456
    *** Failers
No match
    123
No match
    x1234
 0: x1234

/^([^!]+)!(.+)=apquxz\.ixr\.zzz\.ac\.uk$/
    abc!pqr=apquxz.ixr.zzz.ac.uk
 0: abc!pqr=apquxz.ixr.zzz.ac.uk
 1: abc
 2: pqr
    *** Failers
No match
    !pqr=apquxz.ixr.zzz.ac.uk
No match
    abc!=apquxz.ixr.zzz.ac.uk
No match
    abc!pqr=apquxz:ixr.zzz.ac.uk
No match
    abc!pqr=apquxz.ixr.zzz.ac.ukk
No match

/:/
    Well, we need a colon: somewhere
 0: :
    *** Fail if we don't
No match

/([\da-f:]+)$/i
    0abc
 0: 0abc
 1: 0abc
    abc
 0: abc
 1: abc
    fed
 0: fed
 1: fed
    E
 0: E
 1: E
    ::
 0: ::
 1: ::
    5f03:12C0::932e
 0: 5f03:12C0::932e
 1: 5f03:12C0::932e
    fed def
 0: def
 1: def
    Any old stuff
 0: ff
 1: ff
    *** Failers
No match
    0zzz
No match
    gzzz
No match
    fed\x20
No match
    Any old rubbish
No match

/^.*\.(\d{1,3})\.(\d{1,3})\.(\d{1,3})$/
    .1.2.3
 0: .1.2.3
 1: 1
 2: 2
 3: 3
    A.12.123.0
 0: A.12.123.0
 1: 12
 2: 123
 3: 0
    *** Failers
No match
    .1.2.3333
No match
    1.2.3
No match
    1234.2.3
No match

/^(\d+)\s+IN\s+SOA\s+(\S+)\s+(\S+)\s*\(\s*$/
    1 IN SOA non-sp1 non-sp2(
 0: 1 IN SOA non-sp1 non-sp2(
 1: 1
 2: non-sp1
 3: non-sp2
    1    IN    SOA    non-sp1    non-sp2   (
 0: 1    IN    SOA    non-sp1    non-sp2   (
 1: 1
 2: non-sp1
 3: non-sp2
    *** Failers
No match
    1IN SOA non-sp1 non-sp2(
No match

/^[a-zA-Z\d][a-zA-Z\d\-]*(\.[a-zA-Z\d][a-zA-z\d\-]*)*\.$/
    a.
 0: a.
    Z.
 0: Z.
    2.
 0: 2.
    ab-c.pq-r.
 0: ab-c.pq-r.
 1: .pq-r
    sxk.zzz.ac.uk.
 0: sxk.zzz.ac.uk.
 1: .uk
    x-.y-.
 0: x-.y-.
 1: .y-
    *** Failers
No match
    -abc.peq.
No match

/^\*\.[a-z]([a-z\-\d]*[a-z\d]+)?(\.[a-z]([a-z\-\d]*[a-z\d]+)?)*$/
    *.a
 0: *.a
    *.b0-a
 0: *.b0-a
 1: 0-a
    *.c3-b.c
 0: *.c3-b.c
 1: 3-b
 2: .c
    *.c-a.b-c
 0: *.c-a.b-c
 1: -a
 2: .b-c
 3: -c
    *** Failers
No match
    *.0
No match
    *.a-
No match
    *.a-b.c-
No match
    *.c-a.0-c
No match

/^(?=ab(de))(abd)(e)/
    abde
 0: abde
 1: de
 2: abd
 3: e

/^(?!(ab)de|x)(abd)(f)/
    abdf
 0: abdf
 1: <unset>
 2: abd
 3: f

/^(?=(ab(cd)))(ab)/
    abcd
 0: ab
 1: abcd
 2: cd
 3: ab

/^[\da-f](\.[\da-f])*$/i
    a.b.c.d
 0: a.b.c.d
 1: .d
    A.B.C.D
 0: A.B.C.D
 1: .D
    a.b.c.1.2.3.C
 0: a.b.c.1.2.3.C
 1: .C

/^\".*\"\s*(;.*)?$/
    \"1234\"
 0: "1234"
    \"abcd\" ;
 0: "abcd" ;
 1: ;
    \"\" ; rhubarb
 0: "" ; rhubarb
 1: ; rhubarb
    *** Failers
No match
    \"1234\" : things
No match

/^$/
    \
 0: 
    *** Failers
No match

/   ^    a   (?# begins with a)  b\sc (?# then b c) $ (?# then end)/x
    ab c
 0: ab c
    *** Failers
No match
    abc
No match
    ab cde
No match

/(?x)   ^    a   (?# begins with a)  b\sc (?# then b c) $ (?# then end)/
    ab c
 0: ab c
    *** Failers
No match
    abc
No match
    ab cde
No match

/^   a\ b[c ]d       $/x
    a bcd
 0: a bcd
    a b d
 0: a b d
    *** Failers
No match
    abcd
No match
    ab d
No match

/^(a(b(c)))(d(e(f)))(h(i(j)))(k(l(m)))$/
    abcdefhijklm
 0: abcdefhijklm
 1: abc
 2: bc
 3: c
 4: def
 5: ef
 6: f
 7: hij
 8: ij
 9: j
10: klm
11: lm
12: m

/^(?:a(b(c)))(?:d(e(f)))(?:h(i(j)))(?:k(l(m)))$/
    abcdefhijklm
 0: abcdefhijklm
 1: bc
 2: c
 3: ef
 4: f
 5: ij
 6: j
 7: lm
 8: m

/^[\w][\W][\s][\S][\d][\D][\b][\n][\c]][\022]/
    a+ Z0+\x08\n\x1d\x12
 0: a+ Z0+\x08\x0a\x1d\x12

/^[.^$|()*+?{,}]+/
    .^\$(*+)|{?,?}
 0: .^$(*+)|{?,?}

/^a*\w/
    z
 0: z
    az
 0: az
    aaaz
 0: aaaz
    a
 0: a
    aa
 0: aa
    aaaa
 0: aaaa
    a+
 0: a
    aa+
 0: aa

/^a*?\w/
    z
 0: z
    az
 0: a
    aaaz
 0: a
    a
 0: a
    aa
 0: a
    aaaa
 0: a
    a+
 0: a
    aa+
 0: a

/^a+\w/
    az
 0: az
    aaaz
 0: aaaz
    aa
 0: aa
    aaaa
 0: aaaa
    aa+
 0: aa

/^a+?\w/
    az
 0: az
    aaaz
 0: aa
    aa
 0: aa
    aaaa
 0: aa
    aa+
 0: aa

/^\d{8}\w{2,}/
    1234567890
 0: 1234567890
    12345678ab
 0: 12345678ab
    12345678__
 0: 12345678__
    *** Failers
No match
    1234567
No match

/^[aeiou\d]{4,5}$/
    uoie
 0: uoie
    1234
 0: 1234
    12345
 0: 12345
    aaaaa
 0: aaaaa
    *** Failers
No match
    123456
No match

/^[aeiou\d]{4,5}?/
    uoie
 0: uoie
    1234
 0: 1234
    12345
 0: 1234
    aaaaa
 0: aaaa
    123456
 0: 1234

/\A(abc|def)=(\1){2,3}\Z/
    abc=abcabc
 0: abc=abcabc
 1: abc
 2: abc
    def=defdefdef
 0: def=defdefdef
 1: def
 2: def
    *** Failers
No match
    abc=defdef
No match

/^(a)(b)(c)(d)(e)(f)(g)(h)(i)(j)(k)\11*(\3\4)\1(?#)2$/
    abcdefghijkcda2
 0: abcdefghijkcda2
 1: a
 2: b
 3: c
 4: d
 5: e
 6: f
 7: g
 8: h
 9: i
10: j
11: k
12: cd
    abcdefghijkkkkcda2
 0: abcdefghijkkkkcda2
 1: a
 2: b
 3: c
 4: d
 5: e
 6: f
 7: g
 8: h
 9: i
10: j
11: k
12: cd

/(cat(a(ract|tonic)|erpillar)) \1()2(3)/
    cataract cataract23
 0: cataract cataract23
 1: cataract
 2: aract
 3: ract
 4: 
 5: 3
    catatonic catatonic23
 0: catatonic catatonic23
 1: catatonic
 2: atonic
 3: tonic
 4: 
 5: 3
    caterpillar caterpillar23
 0: caterpillar caterpillar23
 1: caterpillar
 2: erpillar
 3: <unset>
 4: 
 5: 3


/^From +([^ ]+) +[a-zA-Z][a-zA-Z][a-zA-Z] +[a-zA-Z][a-zA-Z][a-zA-Z] +[0-9]?[0-9] +[0-9][0-9]:[0-9][0-9]/
    From abcd  Mon Sep 01 12:33:02 1997
 0: From abcd  Mon Sep 01 12:33
 1: abcd

/^From\s+\S+\s+([a-zA-Z]{3}\s+){2}\d{1,2}\s+\d\d:\d\d/
    From abcd  Mon Sep 01 12:33:02 1997
 0: From abcd  Mon Sep 01 12:33
 1: Sep 
    From abcd  Mon Sep  1 12:33:02 1997
 0: From abcd  Mon Sep  1 12:33
 1: Sep  
    *** Failers
No match
    From abcd  Sep 01 12:33:02 1997
No match

/^12.34/s
    12\n34
 0: 12\x0a34
    12\r34
 0: 12\x0d34

/\w+(?=\t)/
    the quick brown\t fox
 0: brown

/foo(?!bar)(.*)/
    foobar is foolish see?
 0: foolish see?
 1: lish see?

/(?:(?!foo)...|^.{0,2})bar(.*)/
    foobar crowbar etc
 0: rowbar etc
 1:  etc
    barrel
 0: barrel
 1: rel
    2barrel
 0: 2barrel
 1: rel
    A barrel
 0: A barrel
 1: rel

/^(\D*)(?=\d)(?!123)/
    abc456
 0: abc
 1: abc
    *** Failers
No match
    abc123
No match

/^1234(?# test newlines
  inside)/
    1234
 0: 1234

/^1234 #comment in extended re
  /x
    1234
 0: 1234

/#rhubarb
  abcd/x
    abcd
 0: abcd

/^abcd#rhubarb/x
    abcd
 0: abcd

/^(a)\1{2,3}(.)/
    aaab
 0: aaab
 1: a
 2: b
    aaaab
 0: aaaab
 1: a
 2: b
    aaaaab
 0: aaaaa
 1: a
 2: a
    aaaaaab
 0: aaaaa
 1: a
 2: a

/(?!^)abc/
    the abc
 0: abc
    *** Failers
No match
    abc
No match

/(?=^)abc/
    abc
 0: abc
    *** Failers
No match
    the abc
No match

/^[ab]{1,3}(ab*|b)/
    aabbbbb
 0: aabb
 1: b

/^[ab]{1,3}?(ab*|b)/
    aabbbbb
 0: aabbbbb
 1: abbbbb

/^[ab]{1,3}?(ab*?|b)/
    aabbbbb
 0: aa
 1: a

/^[ab]{1,3}(ab*?|b)/
    aabbbbb
 0: aabb
 1: b

/  (?: [\040\t] |  \(
(?:  [^\\\x80-\xff\n\015()]  |  \\ [^\x80-\xff]  |  \( (?:  [^\\\x80-\xff\n\015()]  |  \\ [^\x80-\xff]  )* \)  )*
\)  )*                          # optional leading comment
(?:    (?:
[^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]+    # some number of atom characters...
(?![^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]) # ..not followed by something that could be part of an atom
|
" (?:                      # opening quote...
[^\\\x80-\xff\n\015"]                #   Anything except backslash and quote
|                     #    or
\\ [^\x80-\xff]           #   Escaped something (something != CR)
)* "  # closing quote
)                    # initial word
(?:  (?: [\040\t] |  \(
(?:  [^\\\x80-\xff\n\015()]  |  \\ [^\x80-\xff]  |  \( (?:  [^\\\x80-\xff\n\015()]  |  \\ [^\x80-\xff]  )* \)  )*
\)  )*  \.  (?: [\040\t] |  \(
(?:  [^\\\x80-\xff\n\015()]  |  \\ [^\x80-\xff]  |  \( (?:  [^\\\x80-\xff\n\015()]  |  \\ [^\x80-\xff]  )* \)  )*
\)  )*   (?:
[^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]+    # some number of atom characters...
(?![^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]) # ..not followed by something that could be part of an atom
|
" (?:                      # opening quote...
[^\\\x80-\xff\n\015"]                #   Anything except backslash and quote
|                     #    or
\\ [^\x80-\xff]           #   Escaped something (something != CR)
)* "  # closing quote
)  )* # further okay, if led by a period
(?: [\040\t] |  \(
(?:  [^\\\x80-\xff\n\015()]  |  \\ [^\x80-\xff]  |  \( (?:  [^\\\x80-\xff\n\015()]  |  \\ [^\x80-\xff]  )* \)  )*
\)  )*  @  (?: [\040\t] |  \(
(?:  [^\\\x80-\xff\n\015()]  |  \\ [^\x80-\xff]  |  \( (?:  [^\\\x80-\xff\n\015()]  |  \\ [^\x80-\xff]  )* \)  )*
\)  )*    (?:
[^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]+    # some number of atom characters...
(?![^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]) # ..not followed by something that could be part of an atom
|   \[                         # [
(?: [^\\\x80-\xff\n\015\[\]] |  \\ [^\x80-\xff]  )*    #    stuff
\]                        #           ]
)                           # initial subdomain
(?:                                  #
(?: [\040\t] |  \(
(?:  [^\\\x80-\xff\n\015()]  |  \\ [^\x80-\xff]  |  \( (?:  [^\\\x80-\xff\n\015()]  |  \\ [^\x80-\xff]  )* \)  )*
\)  )*  \.                        # if led by a period...
(?: [\040\t] |  \(
(?:  [^\\\x80-\xff\n\015()]  |  \\ [^\x80-\xff]  |  \( (?:  [^\\\x80-\xff\n\015()]  |  \\ [^\x80-\xff]  )* \)  )*
\)  )*   (?:
[^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]+    # some number of atom characters...
(?![^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]) # ..not followed by something that could be part of an atom
|   \[                         # [
(?: [^\\\x80-\xff\n\015\[\]] |  \\ [^\x80-\xff]  )*    #    stuff
\]                        #           ]
)                     #   ...further okay
)*
# address
|                     #  or
(?:
[^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]+    # some number of atom characters...
(?![^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]) # ..not followed by something that could be part of an atom
|
" (?:                      # opening quote...
[^\\\x80-\xff\n\015"]                #   Anything except backslash and quote
|                     #    or
\\ [^\x80-\xff]           #   Escaped something (something != CR)
)* "  # closing quote
)             # one word, optionally followed by....
(?:
[^()<>@,;:".\\\[\]\x80-\xff\000-\010\012-\037]  |  # atom and space parts, or...
\(
(?:  [^\\\x80-\xff\n\015()]  |  \\ [^\x80-\xff]  |  \( (?:  [^\\\x80-\xff\n\015()]  |  \\ [^\x80-\xff]  )* \)  )*
\)       |  # comments, or...

" (?:                      # opening quote...
[^\\\x80-\xff\n\015"]                #   Anything except backslash and quote
|                     #    or
\\ [^\x80-\xff]           #   Escaped something (something != CR)
)* "  # closing quote
# quoted strings
)*
<  (?: [\040\t] |  \(
(?:  [^\\\x80-\xff\n\015()]  |  \\ [^\x80-\xff]  |  \( (?:  [^\\\x80-\xff\n\015()]  |  \\ [^\x80-\xff]  )* \)  )*
\)  )*                     # leading <
(?:  @  (?: [\040\t] |  \(
(?:  [^\\\x80-\xff\n\015()]  |  \\ [^\x80-\xff]  |  \( (?:  [^\\\x80-\xff\n\015()]  |  \\ [^\x80-\xff]  )* \)  )*
\)  )*    (?:
[^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]+    # some number of atom characters...
(?![^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]) # ..not followed by something that could be part of an atom
|   \[                         # [
(?: [^\\\x80-\xff\n\015\[\]] |  \\ [^\x80-\xff]  )*    #    stuff
\]                        #           ]
)                           # initial subdomain
(?:                                  #
(?: [\040\t] |  \(
(?:  [^\\\x80-\xff\n\015()]  |  \\ [^\x80-\xff]  |  \( (?:  [^\\\x80-\xff\n\015()]  |  \\ [^\x80-\xff]  )* \)  )*
\)  )*  \.                        # if led by a period...
(?: [\040\t] |  \(
(?:  [^\\\x80-\xff\n\015()]  |  \\ [^\x80-\xff]  |  \( (?:  [^\\\x80-\xff\n\015()]  |  \\ [^\x80-\xff]  )* \)  )*
\)  )*   (?:
[^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]+    # some number of atom characters...
(?![^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]) # ..not followed by something that could be part of an atom
|   \[                         # [
(?: [^\\\x80-\xff\n\015\[\]] |  \\ [^\x80-\xff]  )*    #    stuff
\]                        #           ]
)                     #   ...further okay
)*

(?:  (?: [\040\t] |  \(
(?:  [^\\\x80-\xff\n\015()]  |  \\ [^\x80-\xff]  |  \( (?:  [^\\\x80-\xff\n\015()]  |  \\ [^\x80-\xff]  )* \)  )*
\)  )*  ,  (?: [\040\t] |  \(
(?:  [^\\\x80-\xff\n\015()]  |  \\ [^\x80-\xff]  |  \( (?:  [^\\\x80-\xff\n\015()]  |  \\ [^\x80-\xff]  )* \)  )*
\)  )*  @  (?: [\040\t] |  \(
(?:  [^\\\x80-\xff\n\015()]  |  \\ [^\x80-\xff]  |  \( (?:  [^\\\x80-\xff\n\015()]  |  \\ [^\x80-\xff]  )* \)  )*
\)  )*    (?:
[^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]+    # some number of atom characters...
(?![^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]) # ..not followed by something that could be part of an atom
|   \[                         # [
(?: [^\\\x80-\xff\n\015\[\]] |  \\ [^\x80-\xff]  )*    #    stuff
\]                        #           ]
)                           # initial subdomain
(?:                                  #
(?: [\040\t] |  \(
(?:  [^\\\x80-\xff\n\015()]  |  \\ [^\x80-\xff]  |  \( (?:  [^\\\x80-\xff\n\015()]  |  \\ [^\x80-\xff]  )* \)  )*
\)  )*  \.                        # if led by a period...
(?: [\040\t] |  \(
(?:  [^\\\x80-\xff\n\015()]  |  \\ [^\x80-\xff]  |  \( (?:  [^\\\x80-\xff\n\015()]  |  \\ [^\x80-\xff]  )* \)  )*
\)  )*   (?:
[^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]+    # some number of atom characters...
(?![^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]) # ..not followed by something that could be part of an atom
|   \[                         # [
(?: [^\\\x80-\xff\n\015\[\]] |  \\ [^\x80-\xff]  )*    #    stuff
\]                        #           ]
)                     #   ...further okay
)*
)* # further okay, if led by comma
:                                # closing colon
(?: [\040\t] |  \(
(?:  [^\\\x80-\xff\n\015()]  |  \\ [^\x80-\xff]  |  \( (?:  [^\\\x80-\xff\n\015()]  |  \\ [^\x80-\xff]  )* \)  )*
\)  )*  )? #       optional route
(?:
[^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]+    # some number of atom characters...
(?![^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]) # ..not followed by something that could be part of an atom
|
" (?:                      # opening quote...
[^\\\x80-\xff\n\015"]                #   Anything except backslash and quote
|                     #    or
\\ [^\x80-\xff]           #   Escaped something (something != CR)
)* "  # closing quote
)                    # initial word
(?:  (?: [\040\t] |  \(
(?:  [^\\\x80-\xff\n\015()]  |  \\ [^\x80-\xff]  |  \( (?:  [^\\\x80-\xff\n\015()]  |  \\ [^\x80-\xff]  )* \)  )*
\)  )*  \.  (?: [\040\t] |  \(
(?:  [^\\\x80-\xff\n\015()]  |  \\ [^\x80-\xff]  |  \( (?:  [^\\\x80-\xff\n\015()]  |  \\ [^\x80-\xff]  )* \)  )*
\)  )*   (?:
[^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]+    # some number of atom characters...
(?![^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]) # ..not followed by something that could be part of an atom
|
" (?:                      # opening quote...
[^\\\x80-\xff\n\015"]                #   Anything except backslash and quote
|                     #    or
\\ [^\x80-\xff]           #   Escaped something (something != CR)
)* "  # closing quote
)  )* # further okay, if led by a period
(?: [\040\t] |  \(
(?:  [^\\\x80-\xff\n\015()]  |  \\ [^\x80-\xff]  |  \( (?:  [^\\\x80-\xff\n\015()]  |  \\ [^\x80-\xff]  )* \)  )*
\)  )*  @  (?: [\040\t] |  \(
(?:  [^\\\x80-\xff\n\015()]  |  \\ [^\x80-\xff]  |  \( (?:  [^\\\x80-\xff\n\015()]  |  \\ [^\x80-\xff]  )* \)  )*
\)  )*    (?:
[^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]+    # some number of atom characters...
(?![^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]) # ..not followed by something that could be part of an atom
|   \[                         # [
(?: [^\\\x80-\xff\n\015\[\]] |  \\ [^\x80-\xff]  )*    #    stuff
\]                        #           ]
)                           # initial subdomain
(?:                                  #
(?: [\040\t] |  \(
(?:  [^\\\x80-\xff\n\015()]  |  \\ [^\x80-\xff]  |  \( (?:  [^\\\x80-\xff\n\015()]  |  \\ [^\x80-\xff]  )* \)  )*
\)  )*  \.                        # if led by a period...
(?: [\040\t] |  \(
(?:  [^\\\x80-\xff\n\015()]  |  \\ [^\x80-\xff]  |  \( (?:  [^\\\x80-\xff\n\015()]  |  \\ [^\x80-\xff]  )* \)  )*
\)  )*   (?:
[^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]+    # some number of atom characters...
(?![^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]) # ..not followed by something that could be part of an atom
|   \[                         # [
(?: [^\\\x80-\xff\n\015\[\]] |  \\ [^\x80-\xff]  )*    #    stuff
\]                        #           ]
)                     #   ...further okay
)*
#       address spec
(?: [\040\t] |  \(
(?:  [^\\\x80-\xff\n\015()]  |  \\ [^\x80-\xff]  |  \( (?:  [^\\\x80-\xff\n\015()]  |  \\ [^\x80-\xff]  )* \)  )*
\)  )*  > #                  trailing >
# name and address
)  (?: [\040\t] |  \(
(?:  [^\\\x80-\xff\n\015()]  |  \\ [^\x80-\xff]  |  \( (?:  [^\\\x80-\xff\n\015()]  |  \\ [^\x80-\xff]  )* \)  )*
\)  )*                       # optional trailing comment
/x
    Alan Other <user\@dom.ain>
 0: Alan Other <user@dom.ain>
    <user\@dom.ain>
 0: user@dom.ain
    user\@dom.ain
 0: user@dom.ain
    \"A. Other\" <user.1234\@dom.ain> (a comment)
 0: "A. Other" <user.1234@dom.ain> (a comment)
    A. Other <user.1234\@dom.ain> (a comment)
 0:  Other <user.1234@dom.ain> (a comment)
    \"/s=user/ou=host/o=place/prmd=uu.yy/admd= /c=gb/\"\@x400-re.lay
 0: "/s=user/ou=host/o=place/prmd=uu.yy/admd= /c=gb/"@x400-re.lay
    A missing angle <user\@some.where
 0: user@some.where
    *** Failers
No match
    The quick brown fox
No match

/[\040\t]*                    # Nab whitespace.
(?:
\(                              #  (
[^\\\x80-\xff\n\015()] *                             #     normal*
(?:                                 #       (
(?:  \\ [^\x80-\xff]  |
\(                            #  (
[^\\\x80-\xff\n\015()] *                            #     normal*
(?:  \\ [^\x80-\xff]   [^\\\x80-\xff\n\015()] * )*        #     (special normal*)*
\)                           #                       )
)    #         special
[^\\\x80-\xff\n\015()] *                         #         normal*
)*                                  #            )*
\)                             #                )
[\040\t]* )*    # If comment found, allow more spaces.
# optional leading comment
(?:
(?:
[^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]+    # some number of atom characters...
(?![^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]) # ..not followed by something that could be part of an atom
# Atom
|                       #  or
"                                     # "
[^\\\x80-\xff\n\015"] *                            #   normal
(?:  \\ [^\x80-\xff]  [^\\\x80-\xff\n\015"] * )*        #   ( special normal* )*
"                                     #        "
# Quoted string
)
[\040\t]*                    # Nab whitespace.
(?:
\(                              #  (
[^\\\x80-\xff\n\015()] *                             #     normal*
(?:                                 #       (
(?:  \\ [^\x80-\xff]  |
\(                            #  (
[^\\\x80-\xff\n\015()] *                            #     normal*
(?:  \\ [^\x80-\xff]   [^\\\x80-\xff\n\015()] * )*        #     (special normal*)*
\)                           #                       )
)    #         special
[^\\\x80-\xff\n\015()] *                         #         normal*
)*                                  #            )*
\)                             #                )
[\040\t]* )*    # If comment found, allow more spaces.
(?:
\.
[\040\t]*                    # Nab whitespace.
(?:
\(                              #  (
[^\\\x80-\xff\n\015()] *                             #     normal*
(?:                                 #       (
(?:  \\ [^\x80-\xff]  |
\(                            #  (
[^\\\x80-\xff\n\015()] *                            #     normal*
(?:  \\ [^\x80-\xff]   [^\\\x80-\xff\n\015()] * )*        #     (special normal*)*
\)                           #                       )
)    #         special
[^\\\x80-\xff\n\015()] *                         #         normal*
)*                                  #            )*
\)                             #                )
[\040\t]* )*    # If comment found, allow more spaces.
(?:
[^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]+    # some number of atom characters...
(?![^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]) # ..not followed by something that could be part of an atom
# Atom
|                       #  or
"                                     # "
[^\\\x80-\xff\n\015"] *                            #   normal
(?:  \\ [^\x80-\xff]  [^\\\x80-\xff\n\015"] * )*        #   ( special normal* )*
"                                     #        "
# Quoted string
)
[\040\t]*                    # Nab whitespace.
(?:
\(                              #  (
[^\\\x80-\xff\n\015()] *                             #     normal*
(?:                                 #       (
(?:  \\ [^\x80-\xff]  |
\(                            #  (
[^\\\x80-\xff\n\015()] *                            #     normal*
(?:  \\ [^\x80-\xff]   [^\\\x80-\xff\n\015()] * )*        #     (special normal*)*
\)                           #                       )
)    #         special
[^\\\x80-\xff\n\015()] *                         #         normal*
)*                                  #            )*
\)                             #                )
[\040\t]* )*    # If comment found, allow more spaces.
# additional words
)*
@
[\040\t]*                    # Nab whitespace.
(?:
\(                              #  (
[^\\\x80-\xff\n\015()] *                             #     normal*
(?:                                 #       (
(?:  \\ [^\x80-\xff]  |
\(                            #  (
[^\\\x80-\xff\n\015()] *                            #     normal*
(?:  \\ [^\x80-\xff]   [^\\\x80-\xff\n\015()] * )*        #     (special normal*)*
\)                           #                       )
)    #         special
[^\\\x80-\xff\n\015()] *                         #         normal*
)*                                  #            )*
\)                             #                )
[\040\t]* )*    # If comment found, allow more spaces.
(?:
[^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]+    # some number of atom characters...
(?![^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]) # ..not followed by something that could be part of an atom
|
\[                            # [
(?: [^\\\x80-\xff\n\015\[\]] |  \\ [^\x80-\xff]  )*     #    stuff
\]                           #           ]
)
[\040\t]*                    # Nab whitespace.
(?:
\(                              #  (
[^\\\x80-\xff\n\015()] *                             #     normal*
(?:                                 #       (
(?:  \\ [^\x80-\xff]  |
\(                            #  (
[^\\\x80-\xff\n\015()] *                            #     normal*
(?:  \\ [^\x80-\xff]   [^\\\x80-\xff\n\015()] * )*        #     (special normal*)*
\)                           #                       )
)    #         special
[^\\\x80-\xff\n\015()] *                         #         normal*
)*                                  #            )*
\)                             #                )
[\040\t]* )*    # If comment found, allow more spaces.
# optional trailing comments
(?:
\.
[\040\t]*                    # Nab whitespace.
(?:
\(                              #  (
[^\\\x80-\xff\n\015()] *                             #     normal*
(?:                                 #       (
(?:  \\ [^\x80-\xff]  |
\(                            #  (
[^\\\x80-\xff\n\015()] *                            #     normal*
(?:  \\ [^\x80-\xff]   [^\\\x80-\xff\n\015()] * )*        #     (special normal*)*
\)                           #                       )
)    #         special
[^\\\x80-\xff\n\015()] *                         #         normal*
)*                                  #            )*
\)                             #                )
[\040\t]* )*    # If comment found, allow more spaces.
(?:
[^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]+    # some number of atom characters...
(?![^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]) # ..not followed by something that could be part of an atom
|
\[                            # [
(?: [^\\\x80-\xff\n\015\[\]] |  \\ [^\x80-\xff]  )*     #    stuff
\]                           #           ]
)
[\040\t]*                    # Nab whitespace.
(?:
\(                              #  (
[^\\\x80-\xff\n\015()] *                             #     normal*
(?:                                 #       (
(?:  \\ [^\x80-\xff]  |
\(                            #  (
[^\\\x80-\xff\n\015()] *                            #     normal*
(?:  \\ [^\x80-\xff]   [^\\\x80-\xff\n\015()] * )*        #     (special normal*)*
\)                           #                       )
)    #         special
[^\\\x80-\xff\n\015()] *                         #         normal*
)*                                  #            )*
\)                             #                )
[\040\t]* )*    # If comment found, allow more spaces.
# optional trailing comments
)*
# address
|                             #  or
(?:
[^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]+    # some number of atom characters...
(?![^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]) # ..not followed by something that could be part of an atom
# Atom
|                       #  or
"                                     # "
[^\\\x80-\xff\n\015"] *                            #   normal
(?:  \\ [^\x80-\xff]  [^\\\x80-\xff\n\015"] * )*        #   ( special normal* )*
"                                     #        "
# Quoted string
)
# leading word
[^()<>@,;:".\\\[\]\x80-\xff\000-\010\012-\037] *               # "normal" atoms and or spaces
(?:
(?:
\(                              #  (
[^\\\x80-\xff\n\015()] *                             #     normal*
(?:                                 #       (
(?:  \\ [^\x80-\xff]  |
\(                            #  (
[^\\\x80-\xff\n\015()] *                            #     normal*
(?:  \\ [^\x80-\xff]   [^\\\x80-\xff\n\015()] * )*        #     (special normal*)*
\)                           #                       )
)    #         special
[^\\\x80-\xff\n\015()] *                         #         normal*
)*                                  #            )*
\)                             #                )
|
"                                     # "
[^\\\x80-\xff\n\015"] *                            #   normal
(?:  \\ [^\x80-\xff]  [^\\\x80-\xff\n\015"] * )*        #   ( special normal* )*
"                                     #        "
) # "special" comment or quoted string
[^()<>@,;:".\\\[\]\x80-\xff\000-\010\012-\037] *            #  more "normal"
)*
<
[\040\t]*                    # Nab whitespace.
(?:
\(                              #  (
[^\\\x80-\xff\n\015()] *                             #     normal*
(?:                                 #       (
(?:  \\ [^\x80-\xff]  |
\(                            #  (
[^\\\x80-\xff\n\015()] *                            #     normal*
(?:  \\ [^\x80-\xff]   [^\\\x80-\xff\n\015()] * )*        #     (special normal*)*
\)                           #                       )
)    #         special
[^\\\x80-\xff\n\015()] *                         #         normal*
)*                                  #            )*
\)                             #                )
[\040\t]* )*    # If comment found, allow more spaces.
# <
(?:
@
[\040\t]*                    # Nab whitespace.
(?:
\(                              #  (
[^\\\x80-\xff\n\015()] *                             #     normal*
(?:                                 #       (
(?:  \\ [^\x80-\xff]  |
\(                            #  (
[^\\\x80-\xff\n\015()] *                            #     normal*
(?:  \\ [^\x80-\xff]   [^\\\x80-\xff\n\015()] * )*        #     (special normal*)*
\)                           #                       )
)    #         special
[^\\\x80-\xff\n\015()] *                         #         normal*
)*                                  #            )*
\)                             #                )
[\040\t]* )*    # If comment found, allow more spaces.
(?:
[^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]+    # some number of atom characters...
(?![^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]) # ..not followed by something that could be part of an atom
|
\[                            # [
(?: [^\\\x80-\xff\n\015\[\]] |  \\ [^\x80-\xff]  )*     #    stuff
\]                           #           ]
)
[\040\t]*                    # Nab whitespace.
(?:
\(                              #  (
[^\\\x80-\xff\n\015()] *                             #     normal*
(?:                                 #       (
(?:  \\ [^\x80-\xff]  |
\(                            #  (
[^\\\x80-\xff\n\015()] *                            #     normal*
(?:  \\ [^\x80-\xff]   [^\\\x80-\xff\n\015()] * )*        #     (special normal*)*
\)                           #                       )
)    #         special
[^\\\x80-\xff\n\015()] *                         #         normal*
)*                                  #            )*
\)                             #                )
[\040\t]* )*    # If comment found, allow more spaces.
# optional trailing comments
(?:
\.
[\040\t]*                    # Nab whitespace.
(?:
\(                              #  (
[^\\\x80-\xff\n\015()] *                             #     normal*
(?:                                 #       (
(?:  \\ [^\x80-\xff]  |
\(                            #  (
[^\\\x80-\xff\n\015()] *                            #     normal*
(?:  \\ [^\x80-\xff]   [^\\\x80-\xff\n\015()] * )*        #     (special normal*)*
\)                           #                       )
)    #         special
[^\\\x80-\xff\n\015()] *                         #         normal*
)*                                  #            )*
\)                             #                )
[\040\t]* )*    # If comment found, allow more spaces.
(?:
[^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]+    # some number of atom characters...
(?![^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]) # ..not followed by something that could be part of an atom
|
\[                            # [
(?: [^\\\x80-\xff\n\015\[\]] |  \\ [^\x80-\xff]  )*     #    stuff
\]                           #           ]
)
[\040\t]*                    # Nab whitespace.
(?:
\(                              #  (
[^\\\x80-\xff\n\015()] *                             #     normal*
(?:                                 #       (
(?:  \\ [^\x80-\xff]  |
\(                            #  (
[^\\\x80-\xff\n\015()] *                            #     normal*
(?:  \\ [^\x80-\xff]   [^\\\x80-\xff\n\015()] * )*        #     (special normal*)*
\)                           #                       )
)    #         special
[^\\\x80-\xff\n\015()] *                         #         normal*
)*                                  #            )*
\)                             #                )
[\040\t]* )*    # If comment found, allow more spaces.
# optional trailing comments
)*
(?: ,
[\040\t]*                    # Nab whitespace.
(?:
\(                              #  (
[^\\\x80-\xff\n\015()] *                             #     normal*
(?:                                 #       (
(?:  \\ [^\x80-\xff]  |
\(                            #  (
[^\\\x80-\xff\n\015()] *                            #     normal*
(?:  \\ [^\x80-\xff]   [^\\\x80-\xff\n\015()] * )*        #     (special normal*)*
\)                           #                       )
)    #         special
[^\\\x80-\xff\n\015()] *                         #         normal*
)*                                  #            )*
\)                             #                )
[\040\t]* )*    # If comment found, allow more spaces.
@
[\040\t]*                    # Nab whitespace.
(?:
\(                              #  (
[^\\\x80-\xff\n\015()] *                             #     normal*
(?:                                 #       (
(?:  \\ [^\x80-\xff]  |
\(                            #  (
[^\\\x80-\xff\n\015()] *                            #     normal*
(?:  \\ [^\x80-\xff]   [^\\\x80-\xff\n\015()] * )*        #     (special normal*)*
\)                           #                       )
)    #         special
[^\\\x80-\xff\n\015()] *                         #         normal*
)*                                  #            )*
\)                             #                )
[\040\t]* )*    # If comment found, allow more spaces.
(?:
[^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]+    # some number of atom characters...
(?![^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]) # ..not followed by something that could be part of an atom
|
\[                            # [
(?: [^\\\x80-\xff\n\015\[\]] |  \\ [^\x80-\xff]  )*     #    stuff
\]                           #           ]
)
[\040\t]*                    # Nab whitespace.
(?:
\(                              #  (
[^\\\x80-\xff\n\015()] *                             #     normal*
(?:                                 #       (
(?:  \\ [^\x80-\xff]  |
\(                            #  (
[^\\\x80-\xff\n\015()] *                            #     normal*
(?:  \\ [^\x80-\xff]   [^\\\x80-\xff\n\015()] * )*        #     (special normal*)*
\)                           #                       )
)    #         special
[^\\\x80-\xff\n\015()] *                         #         normal*
)*                                  #            )*
\)                             #                )
[\040\t]* )*    # If comment found, allow more spaces.
# optional trailing comments
(?:
\.
[\040\t]*                    # Nab whitespace.
(?:
\(                              #  (
[^\\\x80-\xff\n\015()] *                             #     normal*
(?:                                 #       (
(?:  \\ [^\x80-\xff]  |
\(                            #  (
[^\\\x80-\xff\n\015()] *                            #     normal*
(?:  \\ [^\x80-\xff]   [^\\\x80-\xff\n\015()] * )*        #     (special normal*)*
\)                           #                       )
)    #         special
[^\\\x80-\xff\n\015()] *                         #         normal*
)*                                  #            )*
\)                             #                )
[\040\t]* )*    # If comment found, allow more spaces.
(?:
[^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]+    # some number of atom characters...
(?![^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]) # ..not followed by something that could be part of an atom
|
\[                            # [
(?: [^\\\x80-\xff\n\015\[\]] |  \\ [^\x80-\xff]  )*     #    stuff
\]                           #           ]
)
[\040\t]*                    # Nab whitespace.
(?:
\(                              #  (
[^\\\x80-\xff\n\015()] *                             #     normal*
(?:                                 #       (
(?:  \\ [^\x80-\xff]  |
\(                            #  (
[^\\\x80-\xff\n\015()] *                            #     normal*
(?:  \\ [^\x80-\xff]   [^\\\x80-\xff\n\015()] * )*        #     (special normal*)*
\)                           #                       )
)    #         special
[^\\\x80-\xff\n\015()] *                         #         normal*
)*                                  #            )*
\)                             #                )
[\040\t]* )*    # If comment found, allow more spaces.
# optional trailing comments
)*
)*  # additional domains
:
[\040\t]*                    # Nab whitespace.
(?:
\(                              #  (
[^\\\x80-\xff\n\015()] *                             #     normal*
(?:                                 #       (
(?:  \\ [^\x80-\xff]  |
\(                            #  (
[^\\\x80-\xff\n\015()] *                            #     normal*
(?:  \\ [^\x80-\xff]   [^\\\x80-\xff\n\015()] * )*        #     (special normal*)*
\)                           #                       )
)    #         special
[^\\\x80-\xff\n\015()] *                         #         normal*
)*                                  #            )*
\)                             #                )
[\040\t]* )*    # If comment found, allow more spaces.
# optional trailing comments
)?     #       optional route
(?:
[^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]+    # some number of atom characters...
(?![^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]) # ..not followed by something that could be part of an atom
# Atom
|                       #  or
"                                     # "
[^\\\x80-\xff\n\015"] *                            #   normal
(?:  \\ [^\x80-\xff]  [^\\\x80-\xff\n\015"] * )*        #   ( special normal* )*
"                                     #        "
# Quoted string
)
[\040\t]*                    # Nab whitespace.
(?:
\(                              #  (
[^\\\x80-\xff\n\015()] *                             #     normal*
(?:                                 #       (
(?:  \\ [^\x80-\xff]  |
\(                            #  (
[^\\\x80-\xff\n\015()] *                            #     normal*
(?:  \\ [^\x80-\xff]   [^\\\x80-\xff\n\015()] * )*        #     (special normal*)*
\)                           #                       )
)    #         special
[^\\\x80-\xff\n\015()] *                         #         normal*
)*                                  #            )*
\)                             #                )
[\040\t]* )*    # If comment found, allow more spaces.
(?:
\.
[\040\t]*                    # Nab whitespace.
(?:
\(                              #  (
[^\\\x80-\xff\n\015()] *                             #     normal*
(?:                                 #       (
(?:  \\ [^\x80-\xff]  |
\(                            #  (
[^\\\x80-\xff\n\015()] *                            #     normal*
(?:  \\ [^\x80-\xff]   [^\\\x80-\xff\n\015()] * )*        #     (special normal*)*
\)                           #                       )
)    #         special
[^\\\x80-\xff\n\015()] *                         #         normal*
)*                                  #            )*
\)                             #                )
[\040\t]* )*    # If comment found, allow more spaces.
(?:
[^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]+    # some number of atom characters...
(?![^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]) # ..not followed by something that could be part of an atom
# Atom
|                       #  or
"                                     # "
[^\\\x80-\xff\n\015"] *                            #   normal
(?:  \\ [^\x80-\xff]  [^\\\x80-\xff\n\015"] * )*        #   ( special normal* )*
"                                     #        "
# Quoted string
)
[\040\t]*                    # Nab whitespace.
(?:
\(                              #  (
[^\\\x80-\xff\n\015()] *                             #     normal*
(?:                                 #       (
(?:  \\ [^\x80-\xff]  |
\(                            #  (
[^\\\x80-\xff\n\015()] *                            #     normal*
(?:  \\ [^\x80-\xff]   [^\\\x80-\xff\n\015()] * )*        #     (special normal*)*
\)                           #                       )
)    #         special
[^\\\x80-\xff\n\015()] *                         #         normal*
)*                                  #            )*
\)                             #                )
[\040\t]* )*    # If comment found, allow more spaces.
# additional words
)*
@
[\040\t]*                    # Nab whitespace.
(?:
\(                              #  (
[^\\\x80-\xff\n\015()] *                             #     normal*
(?:                                 #       (
(?:  \\ [^\x80-\xff]  |
\(                            #  (
[^\\\x80-\xff\n\015()] *                            #     normal*
(?:  \\ [^\x80-\xff]   [^\\\x80-\xff\n\015()] * )*        #     (special normal*)*
\)                           #                       )
)    #         special
[^\\\x80-\xff\n\015()] *                         #         normal*
)*                                  #            )*
\)                             #                )
[\040\t]* )*    # If comment found, allow more spaces.
(?:
[^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]+    # some number of atom characters...
(?![^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]) # ..not followed by something that could be part of an atom
|
\[                            # [
(?: [^\\\x80-\xff\n\015\[\]] |  \\ [^\x80-\xff]  )*     #    stuff
\]                           #           ]
)
[\040\t]*                    # Nab whitespace.
(?:
\(                              #  (
[^\\\x80-\xff\n\015()] *                             #     normal*
(?:                                 #       (
(?:  \\ [^\x80-\xff]  |
\(                            #  (
[^\\\x80-\xff\n\015()] *                            #     normal*
(?:  \\ [^\x80-\xff]   [^\\\x80-\xff\n\015()] * )*        #     (special normal*)*
\)                           #                       )
)    #         special
[^\\\x80-\xff\n\015()] *                         #         normal*
)*                                  #            )*
\)                             #                )
[\040\t]* )*    # If comment found, allow more spaces.
# optional trailing comments
(?:
\.
[\040\t]*                    # Nab whitespace.
(?:
\(                              #  (
[^\\\x80-\xff\n\015()] *                             #     normal*
(?:                                 #       (
(?:  \\ [^\x80-\xff]  |
\(                            #  (
[^\\\x80-\xff\n\015()] *                            #     normal*
(?:  \\ [^\x80-\xff]   [^\\\x80-\xff\n\015()] * )*        #     (special normal*)*
\)                           #                       )
)    #         special
[^\\\x80-\xff\n\015()] *                         #         normal*
)*                                  #            )*
\)                             #                )
[\040\t]* )*    # If comment found, allow more spaces.
(?:
[^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]+    # some number of atom characters...
(?![^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]) # ..not followed by something that could be part of an atom
|
\[                            # [
(?: [^\\\x80-\xff\n\015\[\]] |  \\ [^\x80-\xff]  )*     #    stuff
\]                           #           ]
)
[\040\t]*                    # Nab whitespace.
(?:
\(                              #  (
[^\\\x80-\xff\n\015()] *                             #     normal*
(?:                                 #       (
(?:  \\ [^\x80-\xff]  |
\(                            #  (
[^\\\x80-\xff\n\015()] *                            #     normal*
(?:  \\ [^\x80-\xff]   [^\\\x80-\xff\n\015()] * )*        #     (special normal*)*
\)                           #                       )
)    #         special
[^\\\x80-\xff\n\015()] *                         #         normal*
)*                                  #            )*
\)                             #                )
[\040\t]* )*    # If comment found, allow more spaces.
# optional trailing comments
)*
#       address spec
>                    #                 >
# name and address
)
/x
    Alan Other <user\@dom.ain>
 0: Alan Other <user@dom.ain>
    <user\@dom.ain>
 0: user@dom.ain
    user\@dom.ain
 0: user@dom.ain
    \"A. Other\" <user.1234\@dom.ain> (a comment)
 0: "A. Other" <user.1234@dom.ain>
    A. Other <user.1234\@dom.ain> (a comment)
 0:  Other <user.1234@dom.ain>
    \"/s=user/ou=host/o=place/prmd=uu.yy/admd= /c=gb/\"\@x400-re.lay
 0: "/s=user/ou=host/o=place/prmd=uu.yy/admd= /c=gb/"@x400-re.lay
    A missing angle <user\@some.where
 0: user@some.where
    *** Failers
No match
    The quick brown fox
No match

/abc\0def\00pqr\000xyz\0000AB/
    abc\0def\00pqr\000xyz\0000AB
 0: abc\x00def\x00pqr\x00xyz\x000AB
    abc456 abc\0def\00pqr\000xyz\0000ABCDE
 0: abc\x00def\x00pqr\x00xyz\x000AB

/abc\x0def\x00pqr\x000xyz\x0000AB/
    abc\x0def\x00pqr\x000xyz\x0000AB
 0: abc\x0def\x00pqr\x000xyz\x0000AB
    abc456 abc\x0def\x00pqr\x000xyz\x0000ABCDE
 0: abc\x0def\x00pqr\x000xyz\x0000AB

/^[\000-\037]/
    \0A
 0: \x00
    \01B
 0: \x01
    \037C
 0: \x1f

/\0*/
    \0\0\0\0
 0: \x00\x00\x00\x00

/A\x0{2,3}Z/
    The A\x0\x0Z
 0: A\x00\x00Z
    An A\0\x0\0Z
 0: A\x00\x00\x00Z
    *** Failers
No match
    A\0Z
No match
    A\0\x0\0\x0Z
No match

/^(cow|)\1(bell)/
    cowcowbell
 0: cowcowbell
 1: cow
 2: bell
    bell
 0: bell
 1: 
 2: bell
    *** Failers
No match
    cowbell
No match

/^\s/
    \040abc
 0:  
    \x0cabc
 0: \x0c
    \nabc
 0: \x0a
    \rabc
 0: \x0d
    \tabc
 0: \x09
    *** Failers
No match
    abc
No match

/^a	b
      c/x
    abc
 0: abc

/^(a|)\1*b/
    ab
 0: ab
 1: a
    aaaab
 0: aaaab
 1: a
    b
 0: b
 1: 
    *** Failers
No match
    acb
No match

/^(a|)\1+b/
    aab
 0: aab
 1: a
    aaaab
 0: aaaab
 1: a
    b
 0: b
 1: 
    *** Failers
No match
    ab
No match

/^(a|)\1?b/
    ab
 0: ab
 1: a
    aab
 0: aab
 1: a
    b
 0: b
 1: 
    *** Failers
No match
    acb
No match

/^(a|)\1{2}b/
    aaab
 0: aaab
 1: a
    b
 0: b
 1: 
    *** Failers
No match
    ab
No match
    aab
No match
    aaaab
No match

/^(a|)\1{2,3}b/
    aaab
 0: aaab
 1: a
    aaaab
 0: aaaab
 1: a
    b
 0: b
 1: 
    *** Failers
No match
    ab
No match
    aab
No match
    aaaaab
No match

/ab{1,3}bc/
    abbbbc
 0: abbbbc
    abbbc
 0: abbbc
    abbc
 0: abbc
    *** Failers
No match
    abc
No match
    abbbbbc
No match

/([^.]*)\.([^:]*):[T ]+(.*)/
    track1.title:TBlah blah blah
 0: track1.title:TBlah blah blah
 1: track1
 2: title
 3: Blah blah blah

/([^.]*)\.([^:]*):[T ]+(.*)/i
    track1.title:TBlah blah blah
 0: track1.title:TBlah blah blah
 1: track1
 2: title
 3: Blah blah blah

/([^.]*)\.([^:]*):[t ]+(.*)/i
    track1.title:TBlah blah blah
 0: track1.title:TBlah blah blah
 1: track1
 2: title
 3: Blah blah blah

/^[W-c]+$/
    WXY_^abc
 0: WXY_^abc
    *** Failers
No match
    wxy
No match

/^[W-c]+$/i
    WXY_^abc
 0: WXY_^abc
    wxy_^ABC
 0: wxy_^ABC

/^[\x3f-\x5F]+$/i
    WXY_^abc
 0: WXY_^abc
    wxy_^ABC
 0: wxy_^ABC

/^abc$/m
    abc
 0: abc
    qqq\nabc
 0: abc
    abc\nzzz
 0: abc
    qqq\nabc\nzzz
 0: abc

/^abc$/
    abc
 0: abc
    *** Failers
No match
    qqq\nabc
No match
    abc\nzzz
No match
    qqq\nabc\nzzz
No match

/\Aabc\Z/m
    abc
 0: abc
    abc\n 
 0: abc
    *** Failers
No match
    qqq\nabc
No match
    abc\nzzz
No match
    qqq\nabc\nzzz
No match
    
/\A(.)*\Z/s
    abc\ndef
 0: abc\x0adef
 1: f

/\A(.)*\Z/m
    *** Failers
 0: *** Failers
 1: s
    abc\ndef
No match

/(?:b)|(?::+)/
    b::c
 0: b
    c::b
 0: ::

/[-az]+/
    az-
 0: az-
    *** Failers
 0: a
    b
No match

/[az-]+/
    za-
 0: za-
    *** Failers
 0: a
    b
No match

/[a\-z]+/
    a-z
 0: a-z
    *** Failers
 0: a
    b
No match

/[a-z]+/
    abcdxyz
 0: abcdxyz

/[\d-]+/
    12-34
 0: 12-34
    *** Failers
No match
    aaa
No match

/[\d-z]+/
    12-34z
 0: 12-34z
    *** Failers
No match
    aaa
No match

/\x5c/
    \\
 0: \

/\x20Z/
    the Zoo
 0:  Z
    *** Failers
No match
    Zulu
No match

/(abc)\1/i
    abcabc
 0: abcabc
 1: abc
    ABCabc
 0: ABCabc
 1: ABC
    abcABC
 0: abcABC
 1: abc

/ab{3cd/
    ab{3cd
 0: ab{3cd

/ab{3,cd/
    ab{3,cd
 0: ab{3,cd

/ab{3,4a}cd/
    ab{3,4a}cd
 0: ab{3,4a}cd

/{4,5a}bc/
    {4,5a}bc
 0: {4,5a}bc

/abc$/
    abc
 0: abc
    abc\n
 0: abc
    *** Failers
No match
    abc\ndef
No match

/(abc)\123/
    abc\x53
 0: abcS
 1: abc

/(abc)\223/
    abc\x93
 0: abc\x93
 1: abc

/(abc)\323/
    abc\xd3
 0: abc\xd3
 1: abc

/(abc)\100/
    abc\x40
 0: abc@
 1: abc
    abc\100
 0: abc@
 1: abc

/(abc)\1000/
    abc\x400
 0: abc@0
 1: abc
    abc\x40\x30
 0: abc@0
 1: abc
    abc\1000
 0: abc@0
 1: abc
    abc\100\x30
 0: abc@0
 1: abc
    abc\100\060
 0: abc@0
 1: abc
    abc\100\60
 0: abc@0
 1: abc
    
/^A\8B\9C$/
    A8B9C
 0: A8B9C
    *** Failers
No match
    A\08B\09C  
No match
    
/^(A)(B)(C)(D)(E)(F)(G)(H)(I)\8\9$/
    ABCDEFGHIHI 
 0: ABCDEFGHIHI
 1: A
 2: B
 3: C
 4: D
 5: E
 6: F
 7: G
 8: H
 9: I

/^[A\8B\9C]+$/
    A8B9C
 0: A8B9C
    *** Failers 
No match
    A8B9C\x00
No match

/(a)(b)(c)(d)(e)(f)(g)(h)(i)(j)(k)(l)\12\123/
    abcdefghijkllS
 0: abcdefghijkllS
 1: a
 2: b
 3: c
 4: d
 5: e
 6: f
 7: g
 8: h
 9: i
10: j
11: k
12: l

/(a)(b)(c)(d)(e)(f)(g)(h)(i)(j)(k)\12\123/
    abcdefghijk\12S
 0: abcdefghijk\x0aS
 1: a
 2: b
 3: c
 4: d
 5: e
 6: f
 7: g
 8: h
 9: i
10: j
11: k

/ab\idef/
    abidef
 0: abidef

/a{0}bc/
    bc
 0: bc

/(a|(bc)){0,0}?xyz/
    xyz
 0: xyz

/abc[\10]de/
    abc\010de
 0: abc\x08de

/abc[\1]de/
    abc\1de
 0: abc\x01de

/(abc)[\1]de/
    abc\1de
 0: abc\x01de
 1: abc

/(?s)a.b/
    a\nb
 0: a\x0ab

/^([^a])([^\b])([^c]*)([^d]{3,4})/
    baNOTccccd
 0: baNOTcccc
 1: b
 2: a
 3: NOT
 4: cccc
    baNOTcccd
 0: baNOTccc
 1: b
 2: a
 3: NOT
 4: ccc
    baNOTccd
 0: baNOTcc
 1: b
 2: a
 3: NO
 4: Tcc
    bacccd
 0: baccc
 1: b
 2: a
 3: 
 4: ccc
    *** Failers
 0: *** Failers
 1: *
 2: *
 3: * Fail
 4: ers
    anything
No match
    b\bc   
No match
    baccd
No match

/[^a]/
    Abc
 0: A
  
/[^a]/i
    Abc 
 0: b

/[^a]+/
    AAAaAbc
 0: AAA
  
/[^a]+/i
    AAAaAbc 
 0: bc

/[^a]+/
    bbb\nccc
 0: bbb\x0accc
   
/[^k]$/
    abc
 0: c
    *** Failers
 0: s
    abk   
No match
   
/[^k]{2,3}$/
    abc
 0: abc
    kbc
 0: bc
    kabc 
 0: abc
    *** Failers
 0: ers
    abk
No match
    akb
No match
    akk 
No match

/^\d{8,}\@.+[^k]$/
    12345678\@a.b.c.d
 0: 12345678@a.b.c.d
    123456789\@x.y.z
 0: 123456789@x.y.z
    *** Failers
No match
    12345678\@x.y.uk
No match
    1234567\@a.b.c.d       
No match

/(a)\1{8,}/
    aaaaaaaaa
 0: aaaaaaaaa
 1: a
    aaaaaaaaaa
 0: aaaaaaaaaa
 1: a
    *** Failers
No match
    aaaaaaa   
No match

/[^a]/
    aaaabcd
 0: b
    aaAabcd 
 0: A

/[^a]/i
    aaaabcd
 0: b
    aaAabcd 
 0: b

/[^az]/
    aaaabcd
 0: b
    aaAabcd 
 0: A

/[^az]/i
    aaaabcd
 0: b
    aaAabcd 
 0: b

/\000\001\002\003\004\005\006\007\010\011\012\013\014\015\016\017\020\021\022\023\024\025\026\027\030\031\032\033\034\035\036\037\040\041\042\043\044\045\046\047\050\051\052\053\054\055\056\057\060\061\062\063\064\065\066\067\070\071\072\073\074\075\076\077\100\101\102\103\104\105\106\107\110\111\112\113\114\115\116\117\120\121\122\123\124\125\126\127\130\131\132\133\134\135\136\137\140\141\142\143\144\145\146\147\150\151\152\153\154\155\156\157\160\161\162\163\164\165\166\167\170\171\172\173\174\175\176\177\200\201\202\203\204\205\206\207\210\211\212\213\214\215\216\217\220\221\222\223\224\225\226\227\230\231\232\233\234\235\236\237\240\241\242\243\244\245\246\247\250\251\252\253\254\255\256\257\260\261\262\263\264\265\266\267\270\271\272\273\274\275\276\277\300\301\302\303\304\305\306\307\310\311\312\313\314\315\316\317\320\321\322\323\324\325\326\327\330\331\332\333\334\335\336\337\340\341\342\343\344\345\346\347\350\351\352\353\354\355\356\357\360\361\362\363\364\365\366\367\370\371\372\373\374\375\376\377/
 \000\001\002\003\004\005\006\007\010\011\012\013\014\015\016\017\020\021\022\023\024\025\026\027\030\031\032\033\034\035\036\037\040\041\042\043\044\045\046\047\050\051\052\053\054\055\056\057\060\061\062\063\064\065\066\067\070\071\072\073\074\075\076\077\100\101\102\103\104\105\106\107\110\111\112\113\114\115\116\117\120\121\122\123\124\125\126\127\130\131\132\133\134\135\136\137\140\141\142\143\144\145\146\147\150\151\152\153\154\155\156\157\160\161\162\163\164\165\166\167\170\171\172\173\174\175\176\177\200\201\202\203\204\205\206\207\210\211\212\213\214\215\216\217\220\221\222\223\224\225\226\227\230\231\232\233\234\235\236\237\240\241\242\243\244\245\246\247\250\251\252\253\254\255\256\257\260\261\262\263\264\265\266\267\270\271\272\273\274\275\276\277\300\301\302\303\304\305\306\307\310\311\312\313\314\315\316\317\320\321\322\323\324\325\326\327\330\331\332\333\334\335\336\337\340\341\342\343\344\345\346\347\350\351\352\353\354\355\356\357\360\361\362\363\364\365\366\367\370\371\372\373\374\375\376\377
 0: \x00\x01\x02\x03\x04\x05\x06\x07\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f\x10\x11\x12\x13\x14\x15\x16\x17\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f !"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_`abcdefghijklmnopqrstuvwxyz{|}~\x7f\x80\x81\x82\x83\x84\x85\x86\x87\x88\x89\x8a\x8b\x8c\x8d\x8e\x8f\x90\x91\x92\x93\x94\x95\x96\x97\x98\x99\x9a\x9b\x9c\x9d\x9e\x9f\xa0\xa1\xa2\xa3\xa4\xa5\xa6\xa7\xa8\xa9\xaa\xab\xac\xad\xae\xaf\xb0\xb1\xb2\xb3\xb4\xb5\xb6\xb7\xb8\xb9\xba\xbb\xbc\xbd\xbe\xbf\xc0\xc1\xc2\xc3\xc4\xc5\xc6\xc7\xc8\xc9\xca\xcb\xcc\xcd\xce\xcf\xd0\xd1\xd2\xd3\xd4\xd5\xd6\xd7\xd8\xd9\xda\xdb\xdc\xdd\xde\xdf\xe0\xe1\xe2\xe3\xe4\xe5\xe6\xe7\xe8\xe9\xea\xeb\xec\xed\xee\xef\xf0\xf1\xf2\xf3\xf4\xf5\xf6\xf7\xf8\xf9\xfa\xfb\xfc\xfd\xfe\xff

/P[^*]TAIRE[^*]{1,6}?LL/
    xxxxxxxxxxxPSTAIREISLLxxxxxxxxx
 0: PSTAIREISLL

/P[^*]TAIRE[^*]{1,}?LL/
    xxxxxxxxxxxPSTAIREISLLxxxxxxxxx
 0: PSTAIREISLL

/(\.\d\d[1-9]?)\d+/
    1.230003938
 0: .230003938
 1: .23
    1.875000282   
 0: .875000282
 1: .875
    1.235  
 0: .235
 1: .23
                  
/(\.\d\d((?=0)|\d(?=\d)))/
    1.230003938      
 0: .23
 1: .23
 2: 
    1.875000282
 0: .875
 1: .875
 2: 5
    *** Failers 
No match
    1.235 
No match
    
/a(?)b/
    ab 
 0: ab
 
/\b(foo)\s+(\w+)/i
    Food is on the foo table
 0: foo table
 1: foo
 2: table
    
/foo(.*)bar/
    The food is under the bar in the barn.
 0: food is under the bar in the bar
 1: d is under the bar in the 
    
/foo(.*?)bar/  
    The food is under the bar in the barn.
 0: food is under the bar
 1: d is under the 

/(.*)(\d*)/
    I have 2 numbers: 53147
 0: I have 2 numbers: 53147
 1: I have 2 numbers: 53147
 2: 
    
/(.*)(\d+)/
    I have 2 numbers: 53147
 0: I have 2 numbers: 53147
 1: I have 2 numbers: 5314
 2: 7
 
/(.*?)(\d*)/
    I have 2 numbers: 53147
 0: 
 1: 
 2: 

/(.*?)(\d+)/
    I have 2 numbers: 53147
 0: I have 2
 1: I have 
 2: 2

/(.*)(\d+)$/
    I have 2 numbers: 53147
 0: I have 2 numbers: 53147
 1: I have 2 numbers: 5314
 2: 7

/(.*?)(\d+)$/
    I have 2 numbers: 53147
 0: I have 2 numbers: 53147
 1: I have 2 numbers: 
 2: 53147

/(.*)\b(\d+)$/
    I have 2 numbers: 53147
 0: I have 2 numbers: 53147
 1: I have 2 numbers: 
 2: 53147

/(.*\D)(\d+)$/
    I have 2 numbers: 53147
 0: I have 2 numbers: 53147
 1: I have 2 numbers: 
 2: 53147

/^\D*(?!123)/
    ABC123
 0: AB
     
/^(\D*)(?=\d)(?!123)/
    ABC445
 0: ABC
 1: ABC
    *** Failers
No match
    ABC123
No match
    
/^[W-]46]/
    W46]789 
 0: W46]
    -46]789
 0: -46]
    *** Failers
No match
    Wall
No match
    Zebra
No match
    42
No match
    [abcd] 
No match
    ]abcd[
No match
       
/^[W-\]46]/
    W46]789 
 0: W
    Wall
 0: W
    Zebra
 0: Z
    Xylophone  
 0: X
    42
 0: 4
    [abcd] 
 0: [
    ]abcd[
 0: ]
    \\backslash 
 0: \
    *** Failers
No match
    -46]789
No match
    well
No match
    
/\d\d\/\d\d\/\d\d\d\d/
    01/01/2000
 0: 01/01/2000

/word (?:[a-zA-Z0-9]+ ){0,10}otherword/
  word cat dog elephant mussel cow horse canary baboon snake shark otherword
 0: word cat dog elephant mussel cow horse canary baboon snake shark otherword
  word cat dog elephant mussel cow horse canary baboon snake shark
No match

/word (?:[a-zA-Z0-9]+ ){0,300}otherword/
  word cat dog elephant mussel cow horse canary baboon snake shark the quick brown fox and the lazy dog and several other words getting close to thirty by now I hope
No match

/^(a){0,0}/
    bcd
 0: 
    abc
 0: 
    aab     
 0: 

/^(a){0,1}/
    bcd
 0: 
    abc
 0: a
 1: a
    aab  
 0: a
 1: a

/^(a){0,2}/
    bcd
 0: 
    abc
 0: a
 1: a
    aab  
 0: aa
 1: a

/^(a){0,3}/
    bcd
 0: 
    abc
 0: a
 1: a
    aab
 0: aa
 1: a
    aaa   
 0: aaa
 1: a

/^(a){0,}/
    bcd
 0: 
    abc
 0: a
 1: a
    aab
 0: aa
 1: a
    aaa
 0: aaa
 1: a
    aaaaaaaa    
 0: aaaaaaaa
 1: a

/^(a){1,1}/
    bcd
No match
    abc
 0: a
 1: a
    aab  
 0: a
 1: a

/^(a){1,2}/
    bcd
No match
    abc
 0: a
 1: a
    aab  
 0: aa
 1: a

/^(a){1,3}/
    bcd
No match
    abc
 0: a
 1: a
    aab
 0: aa
 1: a
    aaa   
 0: aaa
 1: a

/^(a){1,}/
    bcd
No match
    abc
 0: a
 1: a
    aab
 0: aa
 1: a
    aaa
 0: aaa
 1: a
    aaaaaaaa    
 0: aaaaaaaa
 1: a

/.*\.gif/
    borfle\nbib.gif\nno
 0: bib.gif

/.{0,}\.gif/
    borfle\nbib.gif\nno
 0: bib.gif

/.*\.gif/m
    borfle\nbib.gif\nno
 0: bib.gif

/.*\.gif/s
    borfle\nbib.gif\nno
 0: borfle\x0abib.gif

/.*\.gif/ms
    borfle\nbib.gif\nno
 0: borfle\x0abib.gif
    
/.*$/
    borfle\nbib.gif\nno
 0: no

/.*$/m
    borfle\nbib.gif\nno
 0: borfle

/.*$/s
    borfle\nbib.gif\nno
 0: borfle\x0abib.gif\x0ano

/.*$/ms
    borfle\nbib.gif\nno
 0: borfle\x0abib.gif\x0ano
    
/.*$/
    borfle\nbib.gif\nno\n
 0: no

/.*$/m
    borfle\nbib.gif\nno\n
 0: borfle

/.*$/s
    borfle\nbib.gif\nno\n
 0: borfle\x0abib.gif\x0ano\x0a

/.*$/ms
    borfle\nbib.gif\nno\n
 0: borfle\x0abib.gif\x0ano\x0a
    
/(.*X|^B)/
    abcde\n1234Xyz
 0: 1234X
 1: 1234X
    BarFoo 
 0: B
 1: B
    *** Failers
No match
    abcde\nBar  
No match

/(.*X|^B)/m
    abcde\n1234Xyz
 0: 1234X
 1: 1234X
    BarFoo 
 0: B
 1: B
    abcde\nBar  
 0: B
 1: B

/(.*X|^B)/s
    abcde\n1234Xyz
 0: abcde\x0a1234X
 1: abcde\x0a1234X
    BarFoo 
 0: B
 1: B
    *** Failers
No match
    abcde\nBar  
No match

/(.*X|^B)/ms
    abcde\n1234Xyz
 0: abcde\x0a1234X
 1: abcde\x0a1234X
    BarFoo 
 0: B
 1: B
    abcde\nBar  
 0: B
 1: B

/(?s)(.*X|^B)/
    abcde\n1234Xyz
 0: abcde\x0a1234X
 1: abcde\x0a1234X
    BarFoo 
 0: B
 1: B
    *** Failers 
No match
    abcde\nBar  
No match

/(?s:.*X|^B)/
    abcde\n1234Xyz
 0: abcde\x0a1234X
    BarFoo 
 0: B
    *** Failers 
No match
    abcde\nBar  
No match

/^.*B/
    **** Failers
No match
    abc\nB
No match
     
/(?s)^.*B/
    abc\nB
 0: abc\x0aB

/(?m)^.*B/
    abc\nB
 0: B
     
/(?ms)^.*B/
    abc\nB
 0: abc\x0aB

/(?ms)^B/
    abc\nB
 0: B

/(?s)B$/
    B\n
 0: B

/^[0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9]/
    123456654321
 0: 123456654321
  
/^\d\d\d\d\d\d\d\d\d\d\d\d/
    123456654321 
 0: 123456654321

/^[\d][\d][\d][\d][\d][\d][\d][\d][\d][\d][\d][\d]/
    123456654321
 0: 123456654321
  
/^[abc]{12}/
    abcabcabcabc
 0: abcabcabcabc
    
/^[a-c]{12}/
    abcabcabcabc
 0: abcabcabcabc
    
/^(a|b|c){12}/
    abcabcabcabc 
 0: abcabcabcabc
 1: c

/^[abcdefghijklmnopqrstuvwxy0123456789]/
    n
 0: n
    *** Failers 
No match
    z 
No match

/abcde{0,0}/
    abcd
 0: abcd
    *** Failers
No match
    abce  
No match

/ab[cd]{0,0}e/
    abe
 0: abe
    *** Failers
No match
    abcde 
No match
    
/ab(c){0,0}d/
    abd
 0: abd
    *** Failers
No match
    abcd   
No match

/a(b*)/
    a
 0: a
 1: 
    ab
 0: ab
 1: b
    abbbb
 0: abbbb
 1: bbbb
    *** Failers
 0: a
 1: 
    bbbbb    
No match
    
/ab\d{0}e/
    abe
 0: abe
    *** Failers
No match
    ab1e   
No match
    
/"([^\\"]+|\\.)*"/
    the \"quick\" brown fox
 0: "quick"
 1: quick
    \"the \\\"quick\\\" brown fox\" 
 0: "the \"quick\" brown fox"
 1:  brown fox

/.*?/g+
    abc
 0: 
 0+ abc
 0: a
 0+ bc
 0: 
 0+ bc
 0: b
 0+ c
 0: 
 0+ c
 0: c
 0+ 
 0: 
 0+ 
  
/\b/g+
    abc 
 0: 
 0+ abc
 0: 
 0+ 

/\b/+g
    abc 
 0: 
 0+ abc
 0: 
 0+ 

//g
    abc
 0: 
 0: 
 0: 
 0: 

/<tr([\w\W\s\d][^<>]{0,})><TD([\w\W\s\d][^<>]{0,})>([\d]{0,}\.)(.*)((<BR>([\w\W\s\d][^<>]{0,})|[\s]{0,}))<\/a><\/TD><TD([\w\W\s\d][^<>]{0,})>([\w\W\s\d][^<>]{0,})<\/TD><TD([\w\W\s\d][^<>]{0,})>([\w\W\s\d][^<>]{0,})<\/TD><\/TR>/is
  <TR BGCOLOR='#DBE9E9'><TD align=left valign=top>43.<a href='joblist.cfm?JobID=94 6735&Keyword='>Word Processor<BR>(N-1286)</a></TD><TD align=left valign=top>Lega lstaff.com</TD><TD align=left valign=top>CA - Statewide</TD></TR>
 0: <TR BGCOLOR='#DBE9E9'><TD align=left valign=top>43.<a href='joblist.cfm?JobID=94 6735&Keyword='>Word Processor<BR>(N-1286)</a></TD><TD align=left valign=top>Lega lstaff.com</TD><TD align=left valign=top>CA - Statewide</TD></TR>
 1:  BGCOLOR='#DBE9E9'
 2:  align=left valign=top
 3: 43.
 4: <a href='joblist.cfm?JobID=94 6735&Keyword='>Word Processor<BR>(N-1286)
 5: 
 6: 
 7: <unset>
 8:  align=left valign=top
 9: Lega lstaff.com
10:  align=left valign=top
11: CA - Statewide

/a[^a]b/
    acb
 0: acb
    a\nb
 0: a\x0ab
    
/a.b/
    acb
 0: acb
    *** Failers 
No match
    a\nb   
No match
    
/a[^a]b/s
    acb
 0: acb
    a\nb  
 0: a\x0ab
    
/a.b/s
    acb
 0: acb
    a\nb  
 0: a\x0ab

/^(b+?|a){1,2}?c/
    bac
 0: bac
 1: a
    bbac
 0: bbac
 1: a
    bbbac
 0: bbbac
 1: a
    bbbbac
 0: bbbbac
 1: a
    bbbbbac 
 0: bbbbbac
 1: a

/^(b+|a){1,2}?c/
    bac
 0: bac
 1: a
    bbac
 0: bbac
 1: a
    bbbac
 0: bbbac
 1: a
    bbbbac
 0: bbbbac
 1: a
    bbbbbac 
 0: bbbbbac
 1: a
    
/(?!\A)x/m
    x\nb\n
No match
    a\bx\n  
 0: x
    
/\x0{ab}/
    \0{ab} 
 0: \x00{ab}

/(A|B)*?CD/
    CD 
 0: CD
    
/(A|B)*CD/
    CD 
 0: CD

/(AB)*?\1/
    ABABAB
 0: ABAB
 1: AB

/(AB)*\1/
    ABABAB
 0: ABABAB
 1: AB
    
/(?<!bar)foo/
    foo
 0: foo
    catfood
 0: foo
    arfootle
 0: foo
    rfoosh
 0: foo
    *** Failers
No match
    barfoo
No match
    towbarfoo
No match

/\w{3}(?<!bar)foo/
    catfood
 0: catfoo
    *** Failers
No match
    foo
No match
    barfoo
No match
    towbarfoo
No match

/(?<=(foo)a)bar/
    fooabar
 0: bar
 1: foo
    *** Failers
No match
    bar
No match
    foobbar
No match
      
/\Aabc\z/m
    abc
 0: abc
    *** Failers
No match
    abc\n   
No match
    qqq\nabc
No match
    abc\nzzz
No match
    qqq\nabc\nzzz
No match

"(?>.*/)foo"
    /this/is/a/very/long/line/in/deed/with/very/many/slashes/in/it/you/see/
No match

"(?>.*/)foo"
    /this/is/a/very/long/line/in/deed/with/very/many/slashes/in/and/foo
 0: /this/is/a/very/long/line/in/deed/with/very/many/slashes/in/and/foo

/(?>(\.\d\d[1-9]?))\d+/
    1.230003938
 0: .230003938
 1: .23
    1.875000282
 0: .875000282
 1: .875
    *** Failers 
No match
    1.235 
No match

/^((?>\w+)|(?>\s+))*$/
    now is the time for all good men to come to the aid of the party
 0: now is the time for all good men to come to the aid of the party
 1: party
    *** Failers
No match
    this is not a line with only words and spaces!
No match
    
/(\d+)(\w)/
    12345a
 0: 12345a
 1: 12345
 2: a
    12345+ 
 0: 12345
 1: 1234
 2: 5

/((?>\d+))(\w)/
    12345a
 0: 12345a
 1: 12345
 2: a
    *** Failers
No match
    12345+ 
No match

/(?>a+)b/
    aaab
 0: aaab

/((?>a+)b)/
    aaab
 0: aaab
 1: aaab

/(?>(a+))b/
    aaab
 0: aaab
 1: aaa

/(?>b)+/
    aaabbbccc
 0: bbb

/(?>a+|b+|c+)*c/
    aaabbbbccccd
 0: aaabbbbc

/((?>[^()]+)|\([^()]*\))+/
    ((abc(ade)ufh()()x
 0: abc(ade)ufh()()x
 1: x
    
/\(((?>[^()]+)|\([^()]+\))+\)/ 
    (abc)
 0: (abc)
 1: abc
    (abc(def)xyz)
 0: (abc(def)xyz)
 1: xyz
    *** Failers
No match
    ((()aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa   
No match

/a(?-i)b/i
    ab
 0: ab
    Ab
 0: Ab
    *** Failers 
No match
    aB
No match
    AB
No match
        
/(a (?x)b c)d e/
    a bcd e
 0: a bcd e
 1: a bc
    *** Failers
No match
    a b cd e
No match
    abcd e   
No match
    a bcde 
No match
 
/(a b(?x)c d (?-x)e f)/
    a bcde f
 0: a bcde f
 1: a bcde f
    *** Failers
No match
    abcdef  
No match

/(a(?i)b)c/
    abc
 0: abc
 1: ab
    aBc
 0: aBc
 1: aB
    *** Failers
No match
    abC
No match
    aBC  
No match
    Abc
No match
    ABc
No match
    ABC
No match
    AbC
No match
    
/a(?i:b)c/
    abc
 0: abc
    aBc
 0: aBc
    *** Failers 
No match
    ABC
No match
    abC
No match
    aBC
No match
    
/a(?i:b)*c/
    aBc
 0: aBc
    aBBc
 0: aBBc
    *** Failers 
No match
    aBC
No match
    aBBC
No match
    
/a(?=b(?i)c)\w\wd/
    abcd
 0: abcd
    abCd
 0: abCd
    *** Failers
No match
    aBCd
No match
    abcD     
No match
    
/(?s-i:more.*than).*million/i
    more than million
 0: more than million
    more than MILLION
 0: more than MILLION
    more \n than Million 
 0: more \x0a than Million
    *** Failers
No match
    MORE THAN MILLION    
No match
    more \n than \n million 
No match

/(?:(?s-i)more.*than).*million/i
    more than million
 0: more than million
    more than MILLION
 0: more than MILLION
    more \n than Million 
 0: more \x0a than Million
    *** Failers
No match
    MORE THAN MILLION    
No match
    more \n than \n million 
No match
    
/(?>a(?i)b+)+c/ 
    abc
 0: abc
    aBbc
 0: aBbc
    aBBc 
 0: aBBc
    *** Failers
No match
    Abc
No match
    abAb    
No match
    abbC 
No match
    
/(?=a(?i)b)\w\wc/
    abc
 0: abc
    aBc
 0: aBc
    *** Failers
No match
    Ab 
No match
    abC
No match
    aBC     
No match
    
/(?<=a(?i)b)(\w\w)c/
    abxxc
 0: xxc
 1: xx
    aBxxc
 0: xxc
 1: xx
    *** Failers
No match
    Abxxc
No match
    ABxxc
No match
    abxxC      
No match

/(?:(a)|b)(?(1)A|B)/
    aA
 0: aA
 1: a
    bB
 0: bB
    *** Failers
No match
    aB
No match
    bA    
No match

/^(a)?(?(1)a|b)+$/
    aa
 0: aa
 1: a
    b
 0: b
    bb  
 0: bb
    *** Failers
No match
    ab   
No match

/^(?(?=abc)\w{3}:|\d\d)$/
    abc:
 0: abc:
    12
 0: 12
    *** Failers
No match
    123
No match
    xyz    
No match

/^(?(?!abc)\d\d|\w{3}:)$/
    abc:
 0: abc:
    12
 0: 12
    *** Failers
No match
    123
No match
    xyz    
No match
    
/(?(?<=foo)bar|cat)/
    foobar
 0: bar
    cat
 0: cat
    fcat
 0: cat
    focat   
 0: cat
    *** Failers
No match
    foocat  
No match

/(?(?<!foo)cat|bar)/
    foobar
 0: bar
    cat
 0: cat
    fcat
 0: cat
    focat   
 0: cat
    *** Failers
No match
    foocat  
No match

/( \( )? [^()]+ (?(1) \) |) /x
    abcd
 0: abcd
    (abcd)
 0: (abcd)
 1: (
    the quick (abcd) fox
 0: the quick 
    (abcd   
 0: abcd

/( \( )? [^()]+ (?(1) \) ) /x
    abcd
 0: abcd
    (abcd)
 0: (abcd)
 1: (
    the quick (abcd) fox
 0: the quick 
    (abcd   
 0: abcd

/^(?(2)a|(1)(2))+$/
    12
 0: 12
 1: 1
 2: 2
    12a
 0: 12a
 1: 1
 2: 2
    12aa
 0: 12aa
 1: 1
 2: 2
    *** Failers
No match
    1234    
No match

/((?i)blah)\s+\1/
    blah blah
 0: blah blah
 1: blah
    BLAH BLAH
 0: BLAH BLAH
 1: BLAH
    Blah Blah
 0: Blah Blah
 1: Blah
    blaH blaH
 0: blaH blaH
 1: blaH
    *** Failers
No match
    blah BLAH
No match
    Blah blah      
No match
    blaH blah 
No match

/((?i)blah)\s+(?i:\1)/
    blah blah
 0: blah blah
 1: blah
    BLAH BLAH
 0: BLAH BLAH
 1: BLAH
    Blah Blah
 0: Blah Blah
 1: Blah
    blaH blaH
 0: blaH blaH
 1: blaH
    blah BLAH
 0: blah BLAH
 1: blah
    Blah blah      
 0: Blah blah
 1: Blah
    blaH blah 
 0: blaH blah
 1: blaH

/(?>a*)*/
    a
 0: a
    aa
 0: aa
    aaaa
 0: aaaa
    
/(abc|)+/
    abc
 0: abc
 1: 
    abcabc
 0: abcabc
 1: 
    abcabcabc
 0: abcabcabc
 1: 
    xyz      
 0: 
 1: 

/([a]*)*/
    a
 0: a
 1: 
    aaaaa 
 0: aaaaa
 1: 
 
/([ab]*)*/
    a
 0: a
 1: 
    b
 0: b
 1: 
    ababab
 0: ababab
 1: 
    aaaabcde
 0: aaaab
 1: 
    bbbb    
 0: bbbb
 1: 
 
/([^a]*)*/
    b
 0: b
 1: 
    bbbb
 0: bbbb
 1: 
    aaa   
 0: 
 1: 
 
/([^ab]*)*/
    cccc
 0: cccc
 1: 
    abab  
 0: 
 1: 
 
/([a]*?)*/
    a
 0: 
 1: 
    aaaa 
 0: 
 1: 
 
/([ab]*?)*/
    a
 0: 
 1: 
    b
 0: 
 1: 
    abab
 0: 
 1: 
    baba   
 0: 
 1: 
 
/([^a]*?)*/
    b
 0: 
 1: 
    bbbb
 0: 
 1: 
    aaa   
 0: 
 1: 
 
/([^ab]*?)*/
    c
 0: 
 1: 
    cccc
 0: 
 1: 
    baba   
 0: 
 1: 
 
/(?>a*)*/
    a
 0: a
    aaabcde 
 0: aaa
 
/((?>a*))*/
    aaaaa
 0: aaaaa
 1: 
    aabbaa 
 0: aa
 1: 
 
/((?>a*?))*/
    aaaaa
 0: 
 1: 
    aabbaa 
 0: 
 1: 

/(?(?=[^a-z]+[a-z])  \d{2}-[a-z]{3}-\d{2}  |  \d{2}-\d{2}-\d{2} ) /x
    12-sep-98
 0: 12-sep-98
    12-09-98
 0: 12-09-98
    *** Failers
No match
    sep-12-98
No match
        
/(?<=(foo))bar\1/
    foobarfoo
 0: barfoo
 1: foo
    foobarfootling 
 0: barfoo
 1: foo
    *** Failers
No match
    foobar
No match
    barfoo   
No match

/(?i:saturday|sunday)/
    saturday
 0: saturday
    sunday
 0: sunday
    Saturday
 0: Saturday
    Sunday
 0: Sunday
    SATURDAY
 0: SATURDAY
    SUNDAY
 0: SUNDAY
    SunDay
 0: SunDay
    
/(a(?i)bc|BB)x/
    abcx
 0: abcx
 1: abc
    aBCx
 0: aBCx
 1: aBC
    bbx
 0: bbx
 1: bb
    BBx
 0: BBx
 1: BB
    *** Failers
No match
    abcX
No match
    aBCX
No match
    bbX
No match
    BBX               
No match

/^([ab](?i)[cd]|[ef])/
    ac
 0: ac
 1: ac
    aC
 0: aC
 1: aC
    bD
 0: bD
 1: bD
    elephant
 0: e
 1: e
    Europe 
 0: E
 1: E
    frog
 0: f
 1: f
    France
 0: F
 1: F
    *** Failers
No match
    Africa     
No match

/^(ab|a(?i)[b-c](?m-i)d|x(?i)y|z)/
    ab
 0: ab
 1: ab
    aBd
 0: aBd
 1: aBd
    xy
 0: xy
 1: xy
    xY
 0: xY
 1: xY
    zebra
 0: z
 1: z
    Zambesi
 0: Z
 1: Z
    *** Failers
No match
    aCD  
No match
    XY  
No match

/(?<=foo\n)^bar/m
    foo\nbar
 0: bar
    *** Failers
No match
    bar
No match
    baz\nbar   
No match

/(?<=(?<!foo)bar)baz/
    barbaz
 0: baz
    barbarbaz 
 0: baz
    koobarbaz 
 0: baz
    *** Failers
No match
    baz
No match
    foobarbaz 
No match

/The cases of aaaa and aaaaaa are missed out below because Perl does things/
/differently. We know that odd, and maybe incorrect, things happen with/
No match
/recursive references in Perl, as far as 5.11.3 - see some stuff in test #2./
No match

/^(a\1?){4}$/
    a
No match
    aa
No match
    aaa
No match
    aaaaa
 0: aaaaa
 1: a
    aaaaaaa
 0: aaaaaaa
 1: a
    aaaaaaaa
No match
    aaaaaaaaa
No match
    aaaaaaaaaa
 0: aaaaaaaaaa
 1: aaaa
    aaaaaaaaaaa
No match
    aaaaaaaaaaaa
No match
    aaaaaaaaaaaaa
No match
    aaaaaaaaaaaaaa
No match
    aaaaaaaaaaaaaaa
No match
    aaaaaaaaaaaaaaaa               
No match

/^(a\1?)(a\1?)(a\2?)(a\3?)$/
    a
No match
    aa
No match
    aaa
No match
    aaaa
 0: aaaa
 1: a
 2: a
 3: a
 4: a
    aaaaa
 0: aaaaa
 1: a
 2: aa
 3: a
 4: a
    aaaaaa
 0: aaaaaa
 1: a
 2: aa
 3: a
 4: aa
    aaaaaaa
 0: aaaaaaa
 1: a
 2: aa
 3: aaa
 4: a
    aaaaaaaa
No match
    aaaaaaaaa
No match
    aaaaaaaaaa
 0: aaaaaaaaaa
 1: a
 2: aa
 3: aaa
 4: aaaa
    aaaaaaaaaaa
No match
    aaaaaaaaaaaa
No match
    aaaaaaaaaaaaa
No match
    aaaaaaaaaaaaaa
No match
    aaaaaaaaaaaaaaa
No match
    aaaaaaaaaaaaaaaa               
No match

/The following tests are taken from the Perl 5.005 test suite; some of them/
/are compatible with 5.004, but I'd rather not have to sort them out./
No match

/abc/
    abc
 0: abc
    xabcy
 0: abc
    ababc
 0: abc
    *** Failers
No match
    xbc
No match
    axc
No match
    abx
No match

/ab*c/
    abc
 0: abc

/ab*bc/
    abc
 0: abc
    abbc
 0: abbc
    abbbbc
 0: abbbbc

/.{1}/
    abbbbc
 0: a

/.{3,4}/
    abbbbc
 0: abbb

/ab{0,}bc/
    abbbbc
 0: abbbbc

/ab+bc/
    abbc
 0: abbc
    *** Failers
No match
    abc
No match
    abq
No match

/ab{1,}bc/

/ab+bc/
    abbbbc
 0: abbbbc

/ab{1,}bc/
    abbbbc
 0: abbbbc

/ab{1,3}bc/
    abbbbc
 0: abbbbc

/ab{3,4}bc/
    abbbbc
 0: abbbbc

/ab{4,5}bc/
    *** Failers
No match
    abq
No match
    abbbbc
No match

/ab?bc/
    abbc
 0: abbc
    abc
 0: abc

/ab{0,1}bc/
    abc
 0: abc

/ab?bc/

/ab?c/
    abc
 0: abc

/ab{0,1}c/
    abc
 0: abc

/^abc$/
    abc
 0: abc
    *** Failers
No match
    abbbbc
No match
    abcc
No match

/^abc/
    abcc
 0: abc

/^abc$/

/abc$/
    aabc
 0: abc
    *** Failers
No match
    aabc
 0: abc
    aabcd
No match

/^/
    abc
 0: 

/$/
    abc
 0: 

/a.c/
    abc
 0: abc
    axc
 0: axc

/a.*c/
    axyzc
 0: axyzc

/a[bc]d/
    abd
 0: abd
    *** Failers
No match
    axyzd
No match
    abc
No match

/a[b-d]e/
    ace
 0: ace

/a[b-d]/
    aac
 0: ac

/a[-b]/
    a-
 0: a-

/a[b-]/
    a-
 0: a-

/a]/
    a]
 0: a]

/a[]]b/
    a]b
 0: a]b

/a[^bc]d/
    aed
 0: aed
    *** Failers
No match
    abd
No match
    abd
No match

/a[^-b]c/
    adc
 0: adc

/a[^]b]c/
    adc
 0: adc
    *** Failers
No match
    a-c
 0: a-c
    a]c
No match

/\ba\b/
    a-
 0: a
    -a
 0: a
    -a-
 0: a

/\by\b/
    *** Failers
No match
    xy
No match
    yz
No match
    xyz
No match

/\Ba\B/
    *** Failers
 0: a
    a-
No match
    -a
No match
    -a-
No match

/\By\b/
    xy
 0: y

/\by\B/
    yz
 0: y

/\By\B/
    xyz
 0: y

/\w/
    a
 0: a

/\W/
    -
 0: -
    *** Failers
 0: *
    -
 0: -
    a
No match

/a\sb/
    a b
 0: a b

/a\Sb/
    a-b
 0: a-b
    *** Failers
No match
    a-b
 0: a-b
    a b
No match

/\d/
    1
 0: 1

/\D/
    -
 0: -
    *** Failers
 0: *
    -
 0: -
    1
No match

/[\w]/
    a
 0: a

/[\W]/
    -
 0: -
    *** Failers
 0: *
    -
 0: -
    a
No match

/a[\s]b/
    a b
 0: a b

/a[\S]b/
    a-b
 0: a-b
    *** Failers
No match
    a-b
 0: a-b
    a b
No match

/[\d]/
    1
 0: 1

/[\D]/
    -
 0: -
    *** Failers
 0: *
    -
 0: -
    1
No match

/ab|cd/
    abc
 0: ab
    abcd
 0: ab

/()ef/
    def
 0: ef
 1: 

/$b/

/a\(b/
    a(b
 0: a(b

/a\(*b/
    ab
 0: ab
    a((b
 0: a((b

/a\\b/
    a\b
No match

/((a))/
    abc
 0: a
 1: a
 2: a

/(a)b(c)/
    abc
 0: abc
 1: a
 2: c

/a+b+c/
    aabbabc
 0: abc

/a{1,}b{1,}c/
    aabbabc
 0: abc

/a.+?c/
    abcabc
 0: abc

/(a+|b)*/
    ab
 0: ab
 1: b

/(a+|b){0,}/
    ab
 0: ab
 1: b

/(a+|b)+/
    ab
 0: ab
 1: b

/(a+|b){1,}/
    ab
 0: ab
 1: b

/(a+|b)?/
    ab
 0: a
 1: a

/(a+|b){0,1}/
    ab
 0: a
 1: a

/[^ab]*/
    cde
 0: cde

/abc/
    *** Failers
No match
    b
No match
    

/a*/
    

/([abc])*d/
    abbbcd
 0: abbbcd
 1: c

/([abc])*bcd/
    abcd
 0: abcd
 1: a

/a|b|c|d|e/
    e
 0: e

/(a|b|c|d|e)f/
    ef
 0: ef
 1: e

/abcd*efg/
    abcdefg
 0: abcdefg

/ab*/
    xabyabbbz
 0: ab
    xayabbbz
 0: a

/(ab|cd)e/
    abcde
 0: cde
 1: cd

/[abhgefdc]ij/
    hij
 0: hij

/^(ab|cd)e/

/(abc|)ef/
    abcdef
 0: ef
 1: 

/(a|b)c*d/
    abcd
 0: bcd
 1: b

/(ab|ab*)bc/
    abc
 0: abc
 1: a

/a([bc]*)c*/
    abc
 0: abc
 1: bc

/a([bc]*)(c*d)/
    abcd
 0: abcd
 1: bc
 2: d

/a([bc]+)(c*d)/
    abcd
 0: abcd
 1: bc
 2: d

/a([bc]*)(c+d)/
    abcd
 0: abcd
 1: b
 2: cd

/a[bcd]*dcdcde/
    adcdcde
 0: adcdcde

/a[bcd]+dcdcde/
    *** Failers
No match
    abcde
No match
    adcdcde
No match

/(ab|a)b*c/
    abc
 0: abc
 1: ab

/((a)(b)c)(d)/
    abcd
 0: abcd
 1: abc
 2: a
 3: b
 4: d

/[a-zA-Z_][a-zA-Z0-9_]*/
    alpha
 0: alpha

/^a(bc+|b[eh])g|.h$/
    abh
 0: bh

/(bc+d$|ef*g.|h?i(j|k))/
    effgz
 0: effgz
 1: effgz
    ij
 0: ij
 1: ij
 2: j
    reffgz
 0: effgz
 1: effgz
    *** Failers
No match
    effg
No match
    bcdd
No match

/((((((((((a))))))))))/
    a
 0: a
 1: a
 2: a
 3: a
 4: a
 5: a
 6: a
 7: a
 8: a
 9: a
10: a

/((((((((((a))))))))))\10/
    aa
 0: aa
 1: a
 2: a
 3: a
 4: a
 5: a
 6: a
 7: a
 8: a
 9: a
10: a

/(((((((((a)))))))))/
    a
 0: a
 1: a
 2: a
 3: a
 4: a
 5: a
 6: a
 7: a
 8: a
 9: a

/multiple words of text/
    *** Failers
No match
    aa
No match
    uh-uh
No match

/multiple words/
    multiple words, yeah
 0: multiple words

/(.*)c(.*)/
    abcde
 0: abcde
 1: ab
 2: de

/\((.*), (.*)\)/
    (a, b)
 0: (a, b)
 1: a
 2: b

/[k]/

/abcd/
    abcd
 0: abcd

/a(bc)d/
    abcd
 0: abcd
 1: bc

/a[-]?c/
    ac
 0: ac

/(abc)\1/
    abcabc
 0: abcabc
 1: abc

/([a-c]*)\1/
    abcabc
 0: abcabc
 1: abc

/(a)|\1/
    a
 0: a
 1: a
    *** Failers
 0: a
 1: a
    ab
 0: a
 1: a
    x
No match

/(([a-c])b*?\2)*/
    ababbbcbc
 0: ababb
 1: bb
 2: b

/(([a-c])b*?\2){3}/
    ababbbcbc
 0: ababbbcbc
 1: cbc
 2: c

/((\3|b)\2(a)x)+/
    aaaxabaxbaaxbbax
 0: bbax
 1: bbax
 2: b
 3: a

/((\3|b)\2(a)){2,}/
    bbaababbabaaaaabbaaaabba
 0: bbaaaabba
 1: bba
 2: b
 3: a

/abc/i
    ABC
 0: ABC
    XABCY
 0: ABC
    ABABC
 0: ABC
    *** Failers
No match
    aaxabxbaxbbx
No match
    XBC
No match
    AXC
No match
    ABX
No match

/ab*c/i
    ABC
 0: ABC

/ab*bc/i
    ABC
 0: ABC
    ABBC
 0: ABBC

/ab*?bc/i
    ABBBBC
 0: ABBBBC

/ab{0,}?bc/i
    ABBBBC
 0: ABBBBC

/ab+?bc/i
    ABBC
 0: ABBC

/ab+bc/i
    *** Failers
No match
    ABC
No match
    ABQ
No match

/ab{1,}bc/i

/ab+bc/i
    ABBBBC
 0: ABBBBC

/ab{1,}?bc/i
    ABBBBC
 0: ABBBBC

/ab{1,3}?bc/i
    ABBBBC
 0: ABBBBC

/ab{3,4}?bc/i
    ABBBBC
 0: ABBBBC

/ab{4,5}?bc/i
    *** Failers
No match
    ABQ
No match
    ABBBBC
No match

/ab??bc/i
    ABBC
 0: ABBC
    ABC
 0: ABC

/ab{0,1}?bc/i
    ABC
 0: ABC

/ab??bc/i

/ab??c/i
    ABC
 0: ABC

/ab{0,1}?c/i
    ABC
 0: ABC

/^abc$/i
    ABC
 0: ABC
    *** Failers
No match
    ABBBBC
No match
    ABCC
No match

/^abc/i
    ABCC
 0: ABC

/^abc$/i

/abc$/i
    AABC
 0: ABC

/^/i
    ABC
 0: 

/$/i
    ABC
 0: 

/a.c/i
    ABC
 0: ABC
    AXC
 0: AXC

/a.*?c/i
    AXYZC
 0: AXYZC

/a.*c/i
    *** Failers
No match
    AABC
 0: AABC
    AXYZD
No match

/a[bc]d/i
    ABD
 0: ABD

/a[b-d]e/i
    ACE
 0: ACE
    *** Failers
No match
    ABC
No match
    ABD
No match

/a[b-d]/i
    AAC
 0: AC

/a[-b]/i
    A-
 0: A-

/a[b-]/i
    A-
 0: A-

/a]/i
    A]
 0: A]

/a[]]b/i
    A]B
 0: A]B

/a[^bc]d/i
    AED
 0: AED

/a[^-b]c/i
    ADC
 0: ADC
    *** Failers
No match
    ABD
No match
    A-C
No match

/a[^]b]c/i
    ADC
 0: ADC

/ab|cd/i
    ABC
 0: AB
    ABCD
 0: AB

/()ef/i
    DEF
 0: EF
 1: 

/$b/i
    *** Failers
No match
    A]C
No match
    B
No match

/a\(b/i
    A(B
 0: A(B

/a\(*b/i
    AB
 0: AB
    A((B
 0: A((B

/a\\b/i
    A\B
No match

/((a))/i
    ABC
 0: A
 1: A
 2: A

/(a)b(c)/i
    ABC
 0: ABC
 1: A
 2: C

/a+b+c/i
    AABBABC
 0: ABC

/a{1,}b{1,}c/i
    AABBABC
 0: ABC

/a.+?c/i
    ABCABC
 0: ABC

/a.*?c/i
    ABCABC
 0: ABC

/a.{0,5}?c/i
    ABCABC
 0: ABC

/(a+|b)*/i
    AB
 0: AB
 1: B

/(a+|b){0,}/i
    AB
 0: AB
 1: B

/(a+|b)+/i
    AB
 0: AB
 1: B

/(a+|b){1,}/i
    AB
 0: AB
 1: B

/(a+|b)?/i
    AB
 0: A
 1: A

/(a+|b){0,1}/i
    AB
 0: A
 1: A

/(a+|b){0,1}?/i
    AB
 0: 

/[^ab]*/i
    CDE
 0: CDE

/abc/i

/a*/i
    

/([abc])*d/i
    ABBBCD
 0: ABBBCD
 1: C

/([abc])*bcd/i
    ABCD
 0: ABCD
 1: A

/a|b|c|d|e/i
    E
 0: E

/(a|b|c|d|e)f/i
    EF
 0: EF
 1: E

/abcd*efg/i
    ABCDEFG
 0: ABCDEFG

/ab*/i
    XABYABBBZ
 0: AB
    XAYABBBZ
 0: A

/(ab|cd)e/i
    ABCDE
 0: CDE
 1: CD

/[abhgefdc]ij/i
    HIJ
 0: HIJ

/^(ab|cd)e/i
    ABCDE
No match

/(abc|)ef/i
    ABCDEF
 0: EF
 1: 

/(a|b)c*d/i
    ABCD
 0: BCD
 1: B

/(ab|ab*)bc/i
    ABC
 0: ABC
 1: A

/a([bc]*)c*/i
    ABC
 0: ABC
 1: BC

/a([bc]*)(c*d)/i
    ABCD
 0: ABCD
 1: BC
 2: D

/a([bc]+)(c*d)/i
    ABCD
 0: ABCD
 1: BC
 2: D

/a([bc]*)(c+d)/i
    ABCD
 0: ABCD
 1: B
 2: CD

/a[bcd]*dcdcde/i
    ADCDCDE
 0: ADCDCDE

/a[bcd]+dcdcde/i

/(ab|a)b*c/i
    ABC
 0: ABC
 1: AB

/((a)(b)c)(d)/i
    ABCD
 0: ABCD
 1: ABC
 2: A
 3: B
 4: D

/[a-zA-Z_][a-zA-Z0-9_]*/i
    ALPHA
 0: ALPHA

/^a(bc+|b[eh])g|.h$/i
    ABH
 0: BH

/(bc+d$|ef*g.|h?i(j|k))/i
    EFFGZ
 0: EFFGZ
 1: EFFGZ
    IJ
 0: IJ
 1: IJ
 2: J
    REFFGZ
 0: EFFGZ
 1: EFFGZ
    *** Failers
No match
    ADCDCDE
No match
    EFFG
No match
    BCDD
No match

/((((((((((a))))))))))/i
    A
 0: A
 1: A
 2: A
 3: A
 4: A
 5: A
 6: A
 7: A
 8: A
 9: A
10: A

/((((((((((a))))))))))\10/i
    AA
 0: AA
 1: A
 2: A
 3: A
 4: A
 5: A
 6: A
 7: A
 8: A
 9: A
10: A

/(((((((((a)))))))))/i
    A
 0: A
 1: A
 2: A
 3: A
 4: A
 5: A
 6: A
 7: A
 8: A
 9: A

/(?:(?:(?:(?:(?:(?:(?:(?:(?:(a))))))))))/i
    A
 0: A
 1: A

/(?:(?:(?:(?:(?:(?:(?:(?:(?:(a|b|c))))))))))/i
    C
 0: C
 1: C

/multiple words of text/i
    *** Failers
No match
    AA
No match
    UH-UH
No match

/multiple words/i
    MULTIPLE WORDS, YEAH
 0: MULTIPLE WORDS

/(.*)c(.*)/i
    ABCDE
 0: ABCDE
 1: AB
 2: DE

/\((.*), (.*)\)/i
    (A, B)
 0: (A, B)
 1: A
 2: B

/[k]/i

/abcd/i
    ABCD
 0: ABCD

/a(bc)d/i
    ABCD
 0: ABCD
 1: BC

/a[-]?c/i
    AC
 0: AC

/(abc)\1/i
    ABCABC
 0: ABCABC
 1: ABC

/([a-c]*)\1/i
    ABCABC
 0: ABCABC
 1: ABC

/a(?!b)./
    abad
 0: ad

/a(?=d)./
    abad
 0: ad

/a(?=c|d)./
    abad
 0: ad

/a(?:b|c|d)(.)/
    ace
 0: ace
 1: e

/a(?:b|c|d)*(.)/
    ace
 0: ace
 1: e

/a(?:b|c|d)+?(.)/
    ace
 0: ace
 1: e
    acdbcdbe
 0: acd
 1: d

/a(?:b|c|d)+(.)/
    acdbcdbe
 0: acdbcdbe
 1: e

/a(?:b|c|d){2}(.)/
    acdbcdbe
 0: acdb
 1: b

/a(?:b|c|d){4,5}(.)/
    acdbcdbe
 0: acdbcdb
 1: b

/a(?:b|c|d){4,5}?(.)/
    acdbcdbe
 0: acdbcd
 1: d

/((foo)|(bar))*/
    foobar
 0: foobar
 1: bar
 2: foo
 3: bar

/a(?:b|c|d){6,7}(.)/
    acdbcdbe
 0: acdbcdbe
 1: e

/a(?:b|c|d){6,7}?(.)/
    acdbcdbe
 0: acdbcdbe
 1: e

/a(?:b|c|d){5,6}(.)/
    acdbcdbe
 0: acdbcdbe
 1: e

/a(?:b|c|d){5,6}?(.)/
    acdbcdbe
 0: acdbcdb
 1: b

/a(?:b|c|d){5,7}(.)/
    acdbcdbe
 0: acdbcdbe
 1: e

/a(?:b|c|d){5,7}?(.)/
    acdbcdbe
 0: acdbcdb
 1: b

/a(?:b|(c|e){1,2}?|d)+?(.)/
    ace
 0: ace
 1: c
 2: e

/^(.+)?B/
    AB
 0: AB
 1: A

/^([^a-z])|(\^)$/
    .
 0: .
 1: .

/^[<>]&/
    <&OUT
 0: <&

/^(a\1?){4}$/
    aaaaaaaaaa
 0: aaaaaaaaaa
 1: aaaa
    *** Failers
No match
    AB
No match
    aaaaaaaaa
No match
    aaaaaaaaaaa
No match

/^(a(?(1)\1)){4}$/
    aaaaaaaaaa
 0: aaaaaaaaaa
 1: aaaa
    *** Failers
No match
    aaaaaaaaa
No match
    aaaaaaaaaaa
No match

/(?:(f)(o)(o)|(b)(a)(r))*/
    foobar
 0: foobar
 1: f
 2: o
 3: o
 4: b
 5: a
 6: r

/(?<=a)b/
    ab
 0: b
    *** Failers
No match
    cb
No match
    b
No match

/(?<!c)b/
    ab
 0: b
    b
 0: b
    b
 0: b

/(?:..)*a/
    aba
 0: aba

/(?:..)*?a/
    aba
 0: a

/^(?:b|a(?=(.)))*\1/
    abc
 0: ab
 1: b

/^(){3,5}/
    abc
 0: 
 1: 

/^(a+)*ax/
    aax
 0: aax
 1: a

/^((a|b)+)*ax/
    aax
 0: aax
 1: a
 2: a

/^((a|bc)+)*ax/
    aax
 0: aax
 1: a
 2: a

/(a|x)*ab/
    cab
 0: ab

/(a)*ab/
    cab
 0: ab

/(?:(?i)a)b/
    ab
 0: ab

/((?i)a)b/
    ab
 0: ab
 1: a

/(?:(?i)a)b/
    Ab
 0: Ab

/((?i)a)b/
    Ab
 0: Ab
 1: A

/(?:(?i)a)b/
    *** Failers
No match
    cb
No match
    aB
No match

/((?i)a)b/

/(?i:a)b/
    ab
 0: ab

/((?i:a))b/
    ab
 0: ab
 1: a

/(?i:a)b/
    Ab
 0: Ab

/((?i:a))b/
    Ab
 0: Ab
 1: A

/(?i:a)b/
    *** Failers
No match
    aB
No match
    aB
No match

/((?i:a))b/

/(?:(?-i)a)b/i
    ab
 0: ab

/((?-i)a)b/i
    ab
 0: ab
 1: a

/(?:(?-i)a)b/i
    aB
 0: aB

/((?-i)a)b/i
    aB
 0: aB
 1: a

/(?:(?-i)a)b/i
    *** Failers
No match
    aB
 0: aB
    Ab
No match

/((?-i)a)b/i

/(?:(?-i)a)b/i
    aB
 0: aB

/((?-i)a)b/i
    aB
 0: aB
 1: a

/(?:(?-i)a)b/i
    *** Failers
No match
    Ab
No match
    AB
No match

/((?-i)a)b/i

/(?-i:a)b/i
    ab
 0: ab

/((?-i:a))b/i
    ab
 0: ab
 1: a

/(?-i:a)b/i
    aB
 0: aB

/((?-i:a))b/i
    aB
 0: aB
 1: a

/(?-i:a)b/i
    *** Failers
No match
    AB
No match
    Ab
No match

/((?-i:a))b/i

/(?-i:a)b/i
    aB
 0: aB

/((?-i:a))b/i
    aB
 0: aB
 1: a

/(?-i:a)b/i
    *** Failers
No match
    Ab
No match
    AB
No match

/((?-i:a))b/i

/((?-i:a.))b/i
    *** Failers
No match
    AB
No match
    a\nB
No match

/((?s-i:a.))b/i
    a\nB
 0: a\x0aB
 1: a\x0a

/(?:c|d)(?:)(?:a(?:)(?:b)(?:b(?:))(?:b(?:)(?:b)))/
    cabbbb
 0: cabbbb

/(?:c|d)(?:)(?:aaaaaaaa(?:)(?:bbbbbbbb)(?:bbbbbbbb(?:))(?:bbbbbbbb(?:)(?:bbbbbbbb)))/
    caaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb
 0: caaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb

/(ab)\d\1/i
    Ab4ab
 0: Ab4ab
 1: Ab
    ab4Ab
 0: ab4Ab
 1: ab

/foo\w*\d{4}baz/
    foobar1234baz
 0: foobar1234baz

/x(~~)*(?:(?:F)?)?/
    x~~
 0: x~~
 1: ~~

/^a(?#xxx){3}c/
    aaac
 0: aaac

/^a (?#xxx) (?#yyy) {3}c/x
    aaac
 0: aaac

/(?<![cd])b/
    *** Failers
No match
    B\nB
No match
    dbcb
No match

/(?<![cd])[ab]/
    dbaacb
 0: a

/(?<!(c|d))b/

/(?<!(c|d))[ab]/
    dbaacb
 0: a

/(?<!cd)[ab]/
    cdaccb
 0: b

/^(?:a?b?)*$/
    \
 0: 
    a
 0: a
    ab
 0: ab
    aaa   
 0: aaa
    *** Failers
No match
    dbcb
No match
    a--
No match
    aa-- 
No match

/((?s)^a(.))((?m)^b$)/
    a\nb\nc\n
 0: a\x0ab
 1: a\x0a
 2: \x0a
 3: b

/((?m)^b$)/
    a\nb\nc\n
 0: b
 1: b

/(?m)^b/
    a\nb\n
 0: b

/(?m)^(b)/
    a\nb\n
 0: b
 1: b

/((?m)^b)/
    a\nb\n
 0: b
 1: b

/\n((?m)^b)/
    a\nb\n
 0: \x0ab
 1: b

/((?s).)c(?!.)/
    a\nb\nc\n
 0: \x0ac
 1: \x0a
    a\nb\nc\n
 0: \x0ac
 1: \x0a

/((?s)b.)c(?!.)/
    a\nb\nc\n
 0: b\x0ac
 1: b\x0a
    a\nb\nc\n
 0: b\x0ac
 1: b\x0a

/^b/

/()^b/
    *** Failers
No match
    a\nb\nc\n
No match
    a\nb\nc\n
No match

/((?m)^b)/
    a\nb\nc\n
 0: b
 1: b

/(x)?(?(1)a|b)/
    *** Failers
No match
    a
No match
    a
No match

/(x)?(?(1)b|a)/
    a
 0: a

/()?(?(1)b|a)/
    a
 0: a

/()(?(1)b|a)/

/()?(?(1)a|b)/
    a
 0: a
 1: 

/^(\()?blah(?(1)(\)))$/
    (blah)
 0: (blah)
 1: (
 2: )
    blah
 0: blah
    *** Failers
No match
    a
No match
    blah)
No match
    (blah
No match

/^(\(+)?blah(?(1)(\)))$/
    (blah)
 0: (blah)
 1: (
 2: )
    blah
 0: blah
    *** Failers
No match
    blah)
No match
    (blah
No match

/(?(?!a)a|b)/

/(?(?!a)b|a)/
    a
 0: a

/(?(?=a)b|a)/
    *** Failers
No match
    a
No match
    a
No match

/(?(?=a)a|b)/
    a
 0: a

/(?=(a+?))(\1ab)/
    aaab
 0: aab
 1: a
 2: aab

/^(?=(a+?))\1ab/

/(\w+:)+/
    one:
 0: one:
 1: one:

/$(?<=^(a))/
    a
 0: 
 1: a

/(?=(a+?))(\1ab)/
    aaab
 0: aab
 1: a
 2: aab

/^(?=(a+?))\1ab/
    *** Failers
No match
    aaab
No match
    aaab
No match

/([\w:]+::)?(\w+)$/
    abcd
 0: abcd
 1: <unset>
 2: abcd
    xy:z:::abcd
 0: xy:z:::abcd
 1: xy:z:::
 2: abcd

/^[^bcd]*(c+)/
    aexycd
 0: aexyc
 1: c

/(a*)b+/
    caab
 0: aab
 1: aa

/([\w:]+::)?(\w+)$/
    abcd
 0: abcd
 1: <unset>
 2: abcd
    xy:z:::abcd
 0: xy:z:::abcd
 1: xy:z:::
 2: abcd
    *** Failers
 0: Failers
 1: <unset>
 2: Failers
    abcd:
No match
    abcd:
No match

/^[^bcd]*(c+)/
    aexycd
 0: aexyc
 1: c

/(>a+)ab/

/(?>a+)b/
    aaab
 0: aaab

/([[:]+)/
    a:[b]:
 0: :[
 1: :[

/([[=]+)/
    a=[b]=
 0: =[
 1: =[

/([[.]+)/
    a.[b].
 0: .[
 1: .[

/((?>a+)b)/
    aaab
 0: aaab
 1: aaab

/(?>(a+))b/
    aaab
 0: aaab
 1: aaa

/((?>[^()]+)|\([^()]*\))+/
    ((abc(ade)ufh()()x
 0: abc(ade)ufh()()x
 1: x

/a\Z/
    *** Failers
No match
    aaab
No match
    a\nb\n
No match

/b\Z/
    a\nb\n
 0: b

/b\z/

/b\Z/
    a\nb
 0: b

/b\z/
    a\nb
 0: b
    *** Failers
No match
    
/^(?>(?(1)\.|())[^\W_](?>[a-z0-9-]*[^\W_])?)+$/
    a
 0: a
 1: 
    abc
 0: abc
 1: 
    a-b
 0: a-b
 1: 
    0-9 
 0: 0-9
 1: 
    a.b
 0: a.b
 1: 
    5.6.7  
 0: 5.6.7
 1: 
    the.quick.brown.fox
 0: the.quick.brown.fox
 1: 
    a100.b200.300c  
 0: a100.b200.300c
 1: 
    12-ab.1245 
 0: 12-ab.1245
 1: 
    *** Failers
No match
    \
No match
    .a
No match
    -a
No match
    a-
No match
    a.  
No match
    a_b 
No match
    a.-
No match
    a..  
No match
    ab..bc 
No match
    the.quick.brown.fox-
No match
    the.quick.brown.fox.
No match
    the.quick.brown.fox_
No match
    the.quick.brown.fox+       
No match

/(?>.*)(?<=(abcd|wxyz))/
    alphabetabcd
 0: alphabetabcd
 1: abcd
    endingwxyz
 0: endingwxyz
 1: wxyz
    *** Failers
No match
    a rather long string that doesn't end with one of them
No match

/word (?>(?:(?!otherword)[a-zA-Z0-9]+ ){0,30})otherword/
    word cat dog elephant mussel cow horse canary baboon snake shark otherword
 0: word cat dog elephant mussel cow horse canary baboon snake shark otherword
    word cat dog elephant mussel cow horse canary baboon snake shark
No match
  
/word (?>[a-zA-Z0-9]+ ){0,30}otherword/
    word cat dog elephant mussel cow horse canary baboon snake shark the quick brown fox and the lazy dog and several other words getting close to thirty by now I hope
No match

/(?<=\d{3}(?!999))foo/
    999foo
 0: foo
    123999foo 
 0: foo
    *** Failers
No match
    123abcfoo
No match
    
/(?<=(?!...999)\d{3})foo/
    999foo
 0: foo
    123999foo 
 0: foo
    *** Failers
No match
    123abcfoo
No match

/(?<=\d{3}(?!999)...)foo/
    123abcfoo
 0: foo
    123456foo 
 0: foo
    *** Failers
No match
    123999foo  
No match
    
/(?<=\d{3}...)(?<!999)foo/
    123abcfoo   
 0: foo
    123456foo 
 0: foo
    *** Failers
No match
    123999foo  
No match

/<a[\s]+href[\s]*=[\s]*          # find <a href=
 ([\"\'])?                       # find single or double quote
 (?(1) (.*?)\1 | ([^\s]+))       # if quote found, match up to next matching
                                 # quote, otherwise match up to next space
/isx
    <a href=abcd xyz
 0: <a href=abcd
 1: <unset>
 2: <unset>
 3: abcd
    <a href=\"abcd xyz pqr\" cats
 0: <a href="abcd xyz pqr"
 1: "
 2: abcd xyz pqr
    <a href=\'abcd xyz pqr\' cats
 0: <a href='abcd xyz pqr'
 1: '
 2: abcd xyz pqr

/<a\s+href\s*=\s*                # find <a href=
 (["'])?                         # find single or double quote
 (?(1) (.*?)\1 | (\S+))          # if quote found, match up to next matching
                                 # quote, otherwise match up to next space
/isx
    <a href=abcd xyz
 0: <a href=abcd
 1: <unset>
 2: <unset>
 3: abcd
    <a href=\"abcd xyz pqr\" cats
 0: <a href="abcd xyz pqr"
 1: "
 2: abcd xyz pqr
    <a href       =       \'abcd xyz pqr\' cats
 0: <a href       =       'abcd xyz pqr'
 1: '
 2: abcd xyz pqr

/<a\s+href(?>\s*)=(?>\s*)        # find <a href=
 (["'])?                         # find single or double quote
 (?(1) (.*?)\1 | (\S+))          # if quote found, match up to next matching
                                 # quote, otherwise match up to next space
/isx
    <a href=abcd xyz
 0: <a href=abcd
 1: <unset>
 2: <unset>
 3: abcd
    <a href=\"abcd xyz pqr\" cats
 0: <a href="abcd xyz pqr"
 1: "
 2: abcd xyz pqr
    <a href       =       \'abcd xyz pqr\' cats
 0: <a href       =       'abcd xyz pqr'
 1: '
 2: abcd xyz pqr

/((Z)+|A)*/
    ZABCDEFG
 0: ZA
 1: A
 2: Z

/(Z()|A)*/
    ZABCDEFG
 0: ZA
 1: A
 2: 

/(Z(())|A)*/
    ZABCDEFG
 0: ZA
 1: A
 2: 
 3: 

/((?>Z)+|A)*/
    ZABCDEFG
 0: ZA
 1: A

/((?>)+|A)*/
    ZABCDEFG
 0: 
 1: 

/a*/g
    abbab
 0: a
 0: 
 0: 
 0: a
 0: 
 0: 

/^[\d-a]/
    abcde
 0: a
    -things
 0: -
    0digit
 0: 0
    *** Failers
No match
    bcdef    
No match
    
/[[:space:]]+/
    > \x09\x0a\x0c\x0d\x0b<
 0:  \x09\x0a\x0c\x0d\x0b
     
/[[:blank:]]+/
    > \x09\x0a\x0c\x0d\x0b<
 0:  \x09
     
/[\s]+/
    > \x09\x0a\x0c\x0d\x0b<
 0:  \x09\x0a\x0c\x0d\x0b
     
/\s+/
    > \x09\x0a\x0c\x0d\x0b<
 0:  \x09\x0a\x0c\x0d\x0b
     
/ab/x
    ab
 0: ab

/(?!\A)x/m
  a\nxb\n
 0: x

/(?!^)x/m
  a\nxb\n
No match

/abc\Qabc\Eabc/
    abcabcabc
 0: abcabcabc
    
/abc\Q(*+|\Eabc/
    abc(*+|abc 
 0: abc(*+|abc

/   abc\Q abc\Eabc/x
    abc abcabc
 0: abc abcabc
    *** Failers
No match
    abcabcabc  
No match
    
/abc#comment
    \Q#not comment
    literal\E/x
    abc#not comment\n    literal     
 0: abc#not comment\x0a    literal

/abc#comment
    \Q#not comment
    literal/x
    abc#not comment\n    literal     
 0: abc#not comment\x0a    literal

/abc#comment
    \Q#not comment
    literal\E #more comment
    /x
    abc#not comment\n    literal     
 0: abc#not comment\x0a    literal

/abc#comment
    \Q#not comment
    literal\E #more comment/x
    abc#not comment\n    literal     
 0: abc#not comment\x0a    literal

/\Qabc\$xyz\E/
    abc\\\$xyz
 0: abc\$xyz

/\Qabc\E\$\Qxyz\E/
    abc\$xyz
 0: abc$xyz

/\Gabc/
    abc
 0: abc
    *** Failers
No match
    xyzabc  
No match

/\Gabc./g
    abc1abc2xyzabc3
 0: abc1
 0: abc2

/abc./g
    abc1abc2xyzabc3 
 0: abc1
 0: abc2
 0: abc3

/a(?x: b c )d/
    XabcdY
 0: abcd
    *** Failers 
No match
    Xa b c d Y 
No match

/((?x)x y z | a b c)/
    XabcY
 0: abc
 1: abc
    AxyzB 
 0: xyz
 1: xyz

/(?i)AB(?-i)C/
    XabCY
 0: abC
    *** Failers
No match
    XabcY  
No match

/((?i)AB(?-i)C|D)E/
    abCE
 0: abCE
 1: abC
    DE
 0: DE
 1: D
    *** Failers
No match
    abcE
No match
    abCe  
No match
    dE
No match
    De    
No match

/(.*)\d+\1/
    abc123abc
 0: abc123abc
 1: abc
    abc123bc 
 0: bc123bc
 1: bc

/(.*)\d+\1/s
    abc123abc
 0: abc123abc
 1: abc
    abc123bc 
 0: bc123bc
 1: bc
    
/((.*))\d+\1/
    abc123abc
 0: abc123abc
 1: abc
 2: abc
    abc123bc  
 0: bc123bc
 1: bc
 2: bc

/-- This tests for an IPv6 address in the form where it can have up to
    eight components, one and only one of which is empty. This must be
    an internal component. --/

/^(?!:)                       # colon disallowed at start
  (?:                         # start of item
    (?: [0-9a-f]{1,4} |       # 1-4 hex digits or
    (?(1)0 | () ) )           # if null previously matched, fail; else null
    :                         # followed by colon
  ){1,7}                      # end item; 1-7 of them required               
  [0-9a-f]{1,4} $             # final hex number at end of string
  (?(1)|.)                    # check that there was an empty component
  /xi
    a123::a123
 0: a123::a123
 1: 
    a123:b342::abcd
 0: a123:b342::abcd
 1: 
    a123:b342::324e:abcd
 0: a123:b342::324e:abcd
 1: 
    a123:ddde:b342::324e:abcd
 0: a123:ddde:b342::324e:abcd
 1: 
    a123:ddde:b342::324e:dcba:abcd
 0: a123:ddde:b342::324e:dcba:abcd
 1: 
    a123:ddde:9999:b342::324e:dcba:abcd
 0: a123:ddde:9999:b342::324e:dcba:abcd
 1: 
    *** Failers
No match
    1:2:3:4:5:6:7:8
No match
    a123:bce:ddde:9999:b342::324e:dcba:abcd
No match
    a123::9999:b342::324e:dcba:abcd
No match
    abcde:2:3:4:5:6:7:8
No match
    ::1
No match
    abcd:fee0:123::   
No match
    :1
No match
    1:  
No match

/[z\Qa-d]\E]/
    z
 0: z
    a
 0: a
    -
 0: -
    d
 0: d
    ] 
 0: ]
    *** Failers
 0: a
    b     
No match

/[\z\C]/
    z
 0: z
    C 
 0: C
    
/\M/
    M 
 0: M
    
/(a+)*b/
    aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa 
No match
    
/(?i)reg(?:ul(?:[aä]|ae)r|ex)/
    REGular
 0: REGular
    regulaer
 0: regulaer
    Regex  
 0: Regex
    regulär 
 0: regul\xe4r

/Åæåä[à-ÿÀ-ß]+/
    Åæåäà
 0: \xc5\xe6\xe5\xe4\xe0
    Åæåäÿ
 0: \xc5\xe6\xe5\xe4\xff
    ÅæåäÀ
 0: \xc5\xe6\xe5\xe4\xc0
    Åæåäß
 0: \xc5\xe6\xe5\xe4\xdf

/(?<=Z)X./
  \x84XAZXB
 0: XB

/ab cd (?x) de fg/
    ab cd defg
 0: ab cd defg

/ab cd(?x) de fg/
    ab cddefg
 0: ab cddefg
    ** Failers 
No match
    abcddefg
No match

/(?<![^f]oo)(bar)/
    foobarX 
 0: bar
 1: bar
    ** Failers 
No match
    boobarX
No match

/(?<![^f])X/
    offX
 0: X
    ** Failers
No match
    onyX  
No match

/(?<=[^f])X/
    onyX
 0: X
    ** Failers
No match
    offX 
No match

/^/mg
    a\nb\nc\n
 0: 
 0: 
 0: 
    \ 
 0: 
    
/(?<=C\n)^/mg
    A\nC\nC\n 
 0: 

/(?:(?(1)a|b)(X))+/
    bXaX
 0: bXaX
 1: X

/(?:(?(1)\1a|b)(X|Y))+/
    bXXaYYaY
 0: bXXaYYaY
 1: Y
    bXYaXXaX  
 0: bX
 1: X

/()()()()()()()()()(?:(?(10)\10a|b)(X|Y))+/
    bXXaYYaY
 0: bX
 1: 
 2: 
 3: 
 4: 
 5: 
 6: 
 7: 
 8: 
 9: 
10: X

/[[,abc,]+]/
    abc]
 0: abc]
    a,b]
 0: a,b]
    [a,b,c]  
 0: [a,b,c]

/(?-x: )/x
    A\x20B
 0:  
    
"(?x)(?-x: \s*#\s*)"
    A # B
 0:  # 
    ** Failers
No match
    #  
No match

"(?x-is)(?:(?-ixs) \s*#\s*) include"
    A #include
 0:  #include
    ** Failers
No match
    A#include  
No match
    A #Include
No match

/a*b*\w/
    aaabbbb
 0: aaabbbb
    aaaa
 0: aaaa
    a
 0: a

/a*b?\w/
    aaabbbb
 0: aaabb
    aaaa
 0: aaaa
    a
 0: a

/a*b{0,4}\w/
    aaabbbb
 0: aaabbbb
    aaaa
 0: aaaa
    a
 0: a

/a*b{0,}\w/
    aaabbbb
 0: aaabbbb
    aaaa
 0: aaaa
    a
 0: a
    
/a*\d*\w/
    0a
 0: 0a
    a 
 0: a
    
/a*b *\w/x
    a 
 0: a

/a*b#comment
  *\w/x
    a 
 0: a

/a* b *\w/x
    a 
 0: a

/^\w+=.*(\\\n.*)*/
    abc=xyz\\\npqr
 0: abc=xyz\

/(?=(\w+))\1:/
    abcd:
 0: abcd:
 1: abcd

/^(?=(\w+))\1:/
    abcd:
 0: abcd:
 1: abcd

/^\Eabc/
    abc
 0: abc
    
/^[\Eabc]/
    a
 0: a
    ** Failers 
No match
    E 
No match
    
/^[a-\Ec]/
    b
 0: b
    ** Failers
No match
    -
No match
    E    
No match

/^[a\E\E-\Ec]/
    b
 0: b
    ** Failers
No match
    -
No match
    E    
No match

/^[\E\Qa\E-\Qz\E]+/
    b
 0: b
    ** Failers
No match
    -  
No match
    
/^[a\Q]bc\E]/
    a
 0: a
    ]
 0: ]
    c
 0: c
    
/^[a-\Q\E]/
    a
 0: a
    -     
 0: -

/^(a()*)*/
    aaaa
 0: aaaa
 1: a
 2: 

/^(?:a(?:(?:))*)*/
    aaaa
 0: aaaa

/^(a()+)+/
    aaaa
 0: aaaa
 1: a
 2: 

/^(?:a(?:(?:))+)+/
    aaaa
 0: aaaa

/(a){0,3}(?(1)b|(c|))*D/
    abbD
 0: abbD
 1: a
    ccccD
 0: ccccD
 1: <unset>
 2: 
    D  
 0: D
 1: <unset>
 2: 

/(a|)*\d/
  aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
No match
  aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa4
 0: aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa4
 1: 

/(?>a|)*\d/
  aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
No match
  aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa4
 0: aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa4

/(?:a|)*\d/
  aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
No match
  aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa4
 0: aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa4

/\Z/g
  abc\n
 0: 
 0: 
  
/^(?s)(?>.*)(?<!\n)/
  abc
 0: abc
  abc\n  
No match

/^(?![^\n]*\n\z)/
  abc
 0: 
  abc\n 
No match
  
/\z(?<!\n)/
  abc
 0: 
  abc\n  
No match

/(.*(.)?)*/
    abcd
 0: abcd
 1: 

/( (A | (?(1)0|) )*   )/x
    abcd
 0: 
 1: 
 2: 

/( ( (?(1)0|) )*   )/x
    abcd
 0: 
 1: 
 2: 

/(  (?(1)0|)*   )/x
    abcd
 0: 
 1: 

/[[:abcd:xyz]]/
    a]
 0: a]
    :] 
 0: :]
    
/[abc[:x\]pqr]/
    a
 0: a
    [
 0: [
    :
 0: :
    ]
 0: ]
    p    
 0: p

/.*[op][xyz]/
    fooabcfoo
No match

/(?(?=.*b)b|^)/
   adc
 0: 
   abc 
 0: b

/(?(?=^.*b)b|^)/
   adc
 0: 
   abc 
No match

/(?(?=.*b)b|^)*/
   adc
 0: 
   abc 
 0: 

/(?(?=.*b)b|^)+/
   adc
 0: 
   abc 
 0: b

/(?(?=b).*b|^d)/
    abc
 0: b

/(?(?=.*b).*b|^d)/
    abc
 0: ab

/^%((?(?=[a])[^%])|b)*%$/
    %ab%
 0: %ab%
 1: 

/(?i)a(?-i)b|c/
    XabX
 0: ab
    XAbX
 0: Ab
    CcC 
 0: c
    ** Failers
No match
    XABX   
No match

/[\x00-\xff\s]+/
    \x0a\x0b\x0c\x0d
 0: \x0a\x0b\x0c\x0d

/^\c/
    ?
 0: ?

/(abc)\1/i
   abc
No match

/(abc)\1/
   abc
No match

/[^a]*/i
    12abc
 0: 12
    12ABC
 0: 12

/[^a]*+/i
    12abc
 0: 12
    12ABC
 0: 12

/[^a]*?X/i
    ** Failers
No match
    12abc
No match
    12ABC
No match
    
/[^a]+?X/i   
    ** Failers
No match
    12abc
No match
    12ABC
No match

/[^a]?X/i
    12aXbcX
 0: X
    12AXBCX
 0: X
    BCX 
 0: CX

/[^a]??X/i
    12aXbcX
 0: X
    12AXBCX
 0: X
    BCX
 0: CX
    
/[^a]?+X/i
    12aXbcX
 0: cX
    12AXBCX
 0: CX
    BCX 
 0: CX

/[^a]{2,3}/i
    abcdef
 0: bcd
    ABCDEF  
 0: BCD

/[^a]{2,3}?/i
    abcdef
 0: bc
    ABCDEF  
 0: BC

/[^a]{2,3}+/i
    abcdef
 0: bcd
    ABCDEF  
 0: BCD

/((a|)+)+Z/
    Z
 0: Z
 1: 
 2: 

/(a)b|(a)c/
    ac
 0: ac
 1: <unset>
 2: a

/(?>(a))b|(a)c/
    ac
 0: ac
 1: <unset>
 2: a

/(?=(a))ab|(a)c/
    ac
 0: ac
 1: <unset>
 2: a

/((?>(a))b|(a)c)/
    ac
 0: ac
 1: ac
 2: <unset>
 3: a

/((?>(a))b|(a)c)++/
    ac
 0: ac
 1: ac
 2: <unset>
 3: a

/(?:(?>(a))b|(a)c)++/
    ac
 0: ac
 1: <unset>
 2: a

/(?=(?>(a))b|(a)c)(..)/
    ac
 0: ac
 1: <unset>
 2: a
 3: ac

/(?>(?>(a))b|(a)c)/
    ac
 0: ac
 1: <unset>
 2: a

/(?:(?>([ab])))+a=/+
    =ba=
 0: ba=
 0+ 
 1: b

/(?>([ab]))+a=/+
    =ba=
 0: ba=
 0+ 
 1: b

/((?>(a+)b)+(aabab))/
    aaaabaaabaabab
 0: aaaabaaabaabab
 1: aaaabaaabaabab
 2: aaa
 3: aabab

/(?>a+|ab)+?c/
    aabc
No match

/(?>a+|ab)+c/
    aabc
No match

/(?:a+|ab)+c/
    aabc
 0: aabc

/(?(?=(a))a)/
    a
 0: a
 1: a

/(?(?=(a))a)(b)/
    ab
 0: ab
 1: a
 2: b

/^(?:a|ab)++c/
    aaaabc
No match

/^(?>a|ab)++c/
    aaaabc
No match

/^(?:a|ab)+c/
    aaaabc
 0: aaaabc

/(?=abc){3}abc/+
    abcabcabc
 0: abc
 0+ abcabc
    ** Failers
No match
    xyz  
No match
    
/(?=abc)+abc/+
    abcabcabc
 0: abc
 0+ abcabc
    ** Failers
No match
    xyz  
No match
    
/(?=abc)++abc/+
    abcabcabc
 0: abc
 0+ abcabc
    ** Failers
No match
    xyz  
No match
    
/(?=abc){0}xyz/
    xyz 
 0: xyz

/(?=abc){1}xyz/
    ** Failers
No match
    xyz 
No match
    
/(?=(a))?./
    ab
 0: a
 1: a
    bc
 0: b
      
/(?=(a))??./
    ab
 0: a
    bc
 0: b

/^(?=(?1))?[az]([abc])d/
    abd 
 0: abd
 1: b
    zcdxx 
 0: zcd
 1: c

/^(?!a){0}\w+/
    aaaaa
 0: aaaaa

/(?<=(abc))?xyz/
    abcxyz
 0: xyz
 1: abc
    pqrxyz 
 0: xyz

/^[\g<a>]+/
    ggg<<<aaa>>>
 0: ggg<<<aaa>>>
    ** Failers
No match
    \\ga  
No match
    
/^[\ga]+/
    gggagagaxyz 
 0: gggagaga
    
/^[:a[:digit:]]+/
    aaaa444:::Z 
 0: aaaa444:::

/^[:a[:digit:]:b]+/
    aaaa444:::bbbZ 
 0: aaaa444:::bbb

/[:a]xxx[b:]/
     :xxx:
 0: :xxx:
     
/(?<=a{2})b/i
    xaabc
 0: b
    ** Failers
No match
    xabc  
No match

/(?<!a{2})b/i
    xabc
 0: b
    ** Failers
No match
    xaabc  
No match

/(?<=a\h)c/
    xa c
 0: c
    
/(?<=[^a]{2})b/
    axxbc
 0: b
    aAAbc 
 0: b
    ** Failers
No match
    xaabc    
No match

/(?<=[^a]{2})b/i
    axxbc  
 0: b
    ** Failers
No match
    aAAbc 
No match
    xaabc    
No match

/(?<=a\H)c/
    abc
 0: c

/(?<=a\V)c/
    abc
 0: c
    
/(?<=a\v)c/
    a\nc
 0: c

/(?(?=c)c|d)++Y/
    XcccddYX
 0: cccddY

/(?(?=c)c|d)*+Y/
    XcccddYX
 0: cccddY

/^(a{2,3}){2,}+a/
    aaaaaaa
 0: aaaaaaa
 1: aaa
    ** Failers
No match
    aaaaaa
No match
    aaaaaaaaa 
No match

/^(a{2,3})++a/
    ** Failers
No match
    aaaaaa
No match

/^(a{2,3})*+a/
    ** Failers
No match
    aaaaaa
No match

/ab\Cde/
    abXde
 0: abXde
    
/(?<=ab\Cde)X/
    abZdeX
 0: X

/a[\CD]b/
    aCb
 0: aCb
    aDb 
 0: aDb

/a[\C-X]b/
    aJb
 0: aJb

/\H\h\V\v/
    X X\x0a
 0: X X\x0a
    X\x09X\x0b
 0: X\x09X\x0b
    ** Failers
No match
    \xa0 X\x0a   
No match
    
/\H*\h+\V?\v{3,4}/ 
    \x09\x20\xa0X\x0a\x0b\x0c\x0d\x0a
 0: \x09 \xa0X\x0a\x0b\x0c\x0d
    \x09\x20\xa0\x0a\x0b\x0c\x0d\x0a
 0: \x09 \xa0\x0a\x0b\x0c\x0d
    \x09\x20\xa0\x0a\x0b\x0c
 0: \x09 \xa0\x0a\x0b\x0c
    ** Failers 
No match
    \x09\x20\xa0\x0a\x0b
No match
     
/\H{3,4}/
    XY  ABCDE
 0: ABCD
    XY  PQR ST 
 0: PQR
    
/.\h{3,4}./
    XY  AB    PQRS
 0: B    P

/\h*X\h?\H+Y\H?Z/
    >XNNNYZ
 0: XNNNYZ
    >  X NYQZ
 0:   X NYQZ
    ** Failers
No match
    >XYZ   
No match
    >  X NY Z
No match

/\v*X\v?Y\v+Z\V*\x0a\V+\x0b\V{2,3}\x0c/
    >XY\x0aZ\x0aA\x0bNN\x0c
 0: XY\x0aZ\x0aA\x0bNN\x0c
    >\x0a\x0dX\x0aY\x0a\x0bZZZ\x0aAAA\x0bNNN\x0c
 0: \x0a\x0dX\x0aY\x0a\x0bZZZ\x0aAAA\x0bNNN\x0c

/(foo)\Kbar/
    foobar
 0: bar
 1: foo
   
/(foo)(\Kbar|baz)/
    foobar
 0: bar
 1: foo
 2: bar
    foobaz 
 0: foobaz
 1: foo
 2: baz

/(foo\Kbar)baz/
    foobarbaz
 0: barbaz
 1: foobar

/abc\K|def\K/g+
    Xabcdefghi
 0: 
 0+ defghi
 0: 
 0+ ghi

/ab\Kc|de\Kf/g+
    Xabcdefghi
 0: c
 0+ defghi
 0: f
 0+ ghi
    
/(?=C)/g+
    ABCDECBA
 0: 
 0+ CDECBA
 0: 
 0+ CBA
    
/^abc\K/+
    abcdef
 0: 
 0+ def
    ** Failers
No match
    defabcxyz   
No match

/^(a(b))\1\g1\g{1}\g-1\g{-1}\g{-02}Z/
    ababababbbabZXXXX
 0: ababababbbabZ
 1: ab
 2: b

/(?<A>tom|bon)-\g{A}/
    tom-tom
 0: tom-tom
 1: tom
    bon-bon 
 0: bon-bon
 1: bon
    
/(^(a|b\g{-1}))/
    bacxxx
No match

/(?|(abc)|(xyz))\1/
    abcabc
 0: abcabc
 1: abc
    xyzxyz 
 0: xyzxyz
 1: xyz
    ** Failers
No match
    abcxyz
No match
    xyzabc   
No match
    
/(?|(abc)|(xyz))(?1)/
    abcabc
 0: abcabc
 1: abc
    xyzabc 
 0: xyzabc
 1: xyz
    ** Failers 
No match
    xyzxyz 
No match
 
/^X(?5)(a)(?|(b)|(q))(c)(d)(Y)/
    XYabcdY
 0: XYabcdY
 1: a
 2: b
 3: c
 4: d
 5: Y

/^X(?7)(a)(?|(b|(r)(s))|(q))(c)(d)(Y)/
    XYabcdY
 0: XYabcdY
 1: a
 2: b
 3: <unset>
 4: <unset>
 5: c
 6: d
 7: Y

/^X(?7)(a)(?|(b|(?|(r)|(t))(s))|(q))(c)(d)(Y)/
    XYabcdY
 0: XYabcdY
 1: a
 2: b
 3: <unset>
 4: <unset>
 5: c
 6: d
 7: Y

/(?'abc'\w+):\k<abc>{2}/
    a:aaxyz
 0: a:aa
 1: a
    ab:ababxyz
 0: ab:abab
 1: ab
    ** Failers
No match
    a:axyz
No match
    ab:abxyz
No match

/(?'abc'\w+):\g{abc}{2}/
    a:aaxyz
 0: a:aa
 1: a
    ab:ababxyz
 0: ab:abab
 1: ab
    ** Failers
No match
    a:axyz
No match
    ab:abxyz
No match

/^(?<ab>a)? (?(<ab>)b|c) (?('ab')d|e)/x
    abd
 0: abd
 1: a
    ce
 0: ce

/^(a.)\g-1Z/
    aXaXZ
 0: aXaXZ
 1: aX

/^(a.)\g{-1}Z/
    aXaXZ
 0: aXaXZ
 1: aX

/^(?(DEFINE) (?<A> a) (?<B> b) )  (?&A) (?&B) /x
    abcd
 0: ab

/(?<NAME>(?&NAME_PAT))\s+(?<ADDR>(?&ADDRESS_PAT))
  (?(DEFINE)
  (?<NAME_PAT>[a-z]+)
  (?<ADDRESS_PAT>\d+)
  )/x
    metcalfe 33
 0: metcalfe 33
 1: metcalfe
 2: 33

/(?(DEFINE)(?<byte>2[0-4]\d|25[0-5]|1\d\d|[1-9]?\d))\b(?&byte)(\.(?&byte)){3}/
    1.2.3.4
 0: 1.2.3.4
 1: <unset>
 2: .4
    131.111.10.206
 0: 131.111.10.206
 1: <unset>
 2: .206
    10.0.0.0
 0: 10.0.0.0
 1: <unset>
 2: .0
    ** Failers
No match
    10.6
No match
    455.3.4.5
No match

/\b(?&byte)(\.(?&byte)){3}(?(DEFINE)(?<byte>2[0-4]\d|25[0-5]|1\d\d|[1-9]?\d))/
    1.2.3.4
 0: 1.2.3.4
 1: .4
    131.111.10.206
 0: 131.111.10.206
 1: .206
    10.0.0.0
 0: 10.0.0.0
 1: .0
    ** Failers
No match
    10.6
No match
    455.3.4.5
No match

/^(\w++|\s++)*$/
    now is the time for all good men to come to the aid of the party
 0: now is the time for all good men to come to the aid of the party
 1: party
    *** Failers
No match
    this is not a line with only words and spaces!
No match

/(\d++)(\w)/
    12345a
 0: 12345a
 1: 12345
 2: a
    *** Failers
No match
    12345+
No match

/a++b/
    aaab
 0: aaab

/(a++b)/
    aaab
 0: aaab
 1: aaab

/(a++)b/
    aaab
 0: aaab
 1: aaa

/([^()]++|\([^()]*\))+/
    ((abc(ade)ufh()()x
 0: abc(ade)ufh()()x
 1: x

/\(([^()]++|\([^()]+\))+\)/
    (abc)
 0: (abc)
 1: abc
    (abc(def)xyz)
 0: (abc(def)xyz)
 1: xyz
    *** Failers
No match
    ((()aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
No match

/^([^()]|\((?1)*\))*$/
    abc
 0: abc
 1: c
    a(b)c
 0: a(b)c
 1: c
    a(b(c))d
 0: a(b(c))d
 1: d
    *** Failers)
No match
    a(b(c)d
No match

/^>abc>([^()]|\((?1)*\))*<xyz<$/
   >abc>123<xyz<
 0: >abc>123<xyz<
 1: 3
   >abc>1(2)3<xyz<
 0: >abc>1(2)3<xyz<
 1: 3
   >abc>(1(2)3)<xyz<
 0: >abc>(1(2)3)<xyz<
 1: (1(2)3)

/^(?:((.)(?1)\2|)|((.)(?3)\4|.))$/i
    1221
 0: 1221
 1: 1221
 2: 1
    Satanoscillatemymetallicsonatas
 0: Satanoscillatemymetallicsonatas
 1: <unset>
 2: <unset>
 3: Satanoscillatemymetallicsonatas
 4: S
    AmanaplanacanalPanama
 0: AmanaplanacanalPanama
 1: <unset>
 2: <unset>
 3: AmanaplanacanalPanama
 4: A
    AblewasIereIsawElba
 0: AblewasIereIsawElba
 1: <unset>
 2: <unset>
 3: AblewasIereIsawElba
 4: A
    *** Failers
No match
    Thequickbrownfox
No match

/^(\d+|\((?1)([+*-])(?1)\)|-(?1))$/
    12
 0: 12
 1: 12
    (((2+2)*-3)-7)
 0: (((2+2)*-3)-7)
 1: (((2+2)*-3)-7)
 2: -
    -12
 0: -12
 1: -12
    *** Failers
No match
    ((2+2)*-3)-7)
No match

/^(x(y|(?1){2})z)/
    xyz
 0: xyz
 1: xyz
 2: y
    xxyzxyzz
 0: xxyzxyzz
 1: xxyzxyzz
 2: xyzxyz
    *** Failers
No match
    xxyzz
No match
    xxyzxyzxyzz
No match

/((< (?: (?(R) \d++  | [^<>]*+) | (?2)) * >))/x
    <>
 0: <>
 1: <>
 2: <>
    <abcd>
 0: <abcd>
 1: <abcd>
 2: <abcd>
    <abc <123> hij>
 0: <abc <123> hij>
 1: <abc <123> hij>
 2: <abc <123> hij>
    <abc <def> hij>
 0: <def>
 1: <def>
 2: <def>
    <abc<>def>
 0: <abc<>def>
 1: <abc<>def>
 2: <abc<>def>
    <abc<>
 0: <>
 1: <>
 2: <>
    *** Failers
No match
    <abc
No match

/^a+(*FAIL)/
    aaaaaa
No match
    
/a+b?c+(*FAIL)/
    aaabccc
No match

/a+b?(*PRUNE)c+(*FAIL)/
    aaabccc
No match

/a+b?(*COMMIT)c+(*FAIL)/
    aaabccc
No match
    
/a+b?(*SKIP)c+(*FAIL)/
    aaabcccaaabccc
No match

/^(?:aaa(*THEN)\w{6}|bbb(*THEN)\w{5}|ccc(*THEN)\w{4}|\w{3})/
    aaaxxxxxx
 0: aaaxxxxxx
    aaa++++++ 
 0: aaa
    bbbxxxxx
 0: bbbxxxxx
    bbb+++++ 
 0: bbb
    cccxxxx
 0: cccxxxx
    ccc++++ 
 0: ccc
    dddddddd   
 0: ddd

/^(aaa(*THEN)\w{6}|bbb(*THEN)\w{5}|ccc(*THEN)\w{4}|\w{3})/
    aaaxxxxxx
 0: aaaxxxxxx
 1: aaaxxxxxx
    aaa++++++ 
 0: aaa
 1: aaa
    bbbxxxxx
 0: bbbxxxxx
 1: bbbxxxxx
    bbb+++++ 
 0: bbb
 1: bbb
    cccxxxx
 0: cccxxxx
 1: cccxxxx
    ccc++++ 
 0: ccc
 1: ccc
    dddddddd   
 0: ddd
 1: ddd

/a+b?(*THEN)c+(*FAIL)/
    aaabccc
No match

/(A (A|B(*ACCEPT)|C) D)(E)/x
    AB
 0: AB
 1: AB
 2: B
    ABX
 0: AB
 1: AB
 2: B
    AADE
 0: AADE
 1: AAD
 2: A
 3: E
    ACDE
 0: ACDE
 1: ACD
 2: C
 3: E
    ** Failers
No match
    AD 
No match
        
/^\W*+(?:((.)\W*+(?1)\W*+\2|)|((.)\W*+(?3)\W*+\4|\W*+.\W*+))\W*+$/i
    1221
 0: 1221
 1: 1221
 2: 1
    Satan, oscillate my metallic sonatas!
 0: Satan, oscillate my metallic sonatas!
 1: <unset>
 2: <unset>
 3: Satan, oscillate my metallic sonatas
 4: S
    A man, a plan, a canal: Panama!
 0: A man, a plan, a canal: Panama!
 1: <unset>
 2: <unset>
 3: A man, a plan, a canal: Panama
 4: A
    Able was I ere I saw Elba.
 0: Able was I ere I saw Elba.
 1: <unset>
 2: <unset>
 3: Able was I ere I saw Elba
 4: A
    *** Failers
No match
    The quick brown fox
No match

/^((.)(?1)\2|.)$/
    a
 0: a
 1: a
    aba
 0: aba
 1: aba
 2: a
    aabaa  
 0: aabaa
 1: aabaa
 2: a
    abcdcba 
 0: abcdcba
 1: abcdcba
 2: a
    pqaabaaqp  
 0: pqaabaaqp
 1: pqaabaaqp
 2: p
    ablewasiereisawelba
 0: ablewasiereisawelba
 1: ablewasiereisawelba
 2: a
    rhubarb
No match
    the quick brown fox  
No match

/(a)(?<=b(?1))/
    baz
 0: a
 1: a
    ** Failers
No match
    caz  
No match
    
/(?<=b(?1))(a)/
    zbaaz
 0: a
 1: a
    ** Failers
No match
    aaa  
No match
    
/(?<X>a)(?<=b(?&X))/
    baz
 0: a
 1: a

/^(?|(abc)|(def))\1/
    abcabc
 0: abcabc
 1: abc
    defdef 
 0: defdef
 1: def
    ** Failers
No match
    abcdef
No match
    defabc   
No match
    
/^(?|(abc)|(def))(?1)/
    abcabc
 0: abcabc
 1: abc
    defabc
 0: defabc
 1: def
    ** Failers
No match
    defdef
No match
    abcdef    
No match

/(?:a(?<quote> (?<apostrophe>')|(?<realquote>")) |b(?<quote> (?<apostrophe>')|(?<realquote>")) ) (?('quote')[a-z]+|[0-9]+)/xJ
    a\"aaaaa
 0: a"aaaaa
 1: "
 2: <unset>
 3: "
    b\"aaaaa 
 0: b"aaaaa
 1: <unset>
 2: <unset>
 3: <unset>
 4: "
 5: <unset>
 6: "
    ** Failers 
No match
    b\"11111
No match

/(?:(?1)|B)(A(*F)|C)/
    ABCD
 0: BC
 1: C
    CCD
 0: CC
 1: C
    ** Failers
No match
    CAD   
No match

/^(?:(?1)|B)(A(*F)|C)/
    CCD
 0: CC
 1: C
    BCD 
 0: BC
 1: C
    ** Failers
No match
    ABCD
No match
    CAD
No match
    BAD    
No match

/(?:(?1)|B)(A(*ACCEPT)XX|C)D/
    AAD
 0: AA
 1: A
    ACD
 0: ACD
 1: C
    BAD
 0: BA
 1: A
    BCD
 0: BCD
 1: C
    BAX  
 0: BA
 1: A
    ** Failers
No match
    ACX
No match
    ABC   
No match

/(?(DEFINE)(A))B(?1)C/
    BAC
 0: BAC

/(?(DEFINE)((A)\2))B(?1)C/
    BAAC
 0: BAAC

/(?<pn> \( ( [^()]++ | (?&pn) )* \) )/x
    (ab(cd)ef)
 0: (ab(cd)ef)
 1: (ab(cd)ef)
 2: ef

/^(?=a(*SKIP)b|ac)/
    ** Failers
No match
    ac
No match
    
/^(?=a(*PRUNE)b)/
    ab  
 0: 
    ** Failers 
No match
    ac
No match

/^(?=a(*ACCEPT)b)/
    ac
 0: 

/(?>a\Kb)/
    ab
 0: b

/((?>a\Kb))/
    ab
 0: b
 1: ab

/(a\Kb)/
    ab
 0: b
 1: ab
    
/^a\Kcz|ac/
    ac
 0: ac
    
/(?>a\Kbz|ab)/
    ab 
 0: ab

/^(?&t)(?(DEFINE)(?<t>a\Kb))$/
    ab
 0: b

/^([^()]|\((?1)*\))*$/
    a(b)c
 0: a(b)c
 1: c
    a(b(c)d)e 
 0: a(b(c)d)e
 1: e

/(?P<L1>(?P<L2>0)(?P>L1)|(?P>L2))/
    0
 0: 0
 1: 0
    00
 0: 00
 1: 00
 2: 0
    0000  
 0: 0000
 1: 0000
 2: 0

/(?P<L1>(?P<L2>0)|(?P>L2)(?P>L1))/
    0
 0: 0
 1: 0
 2: 0
    00
 0: 0
 1: 0
 2: 0
    0000  
 0: 0
 1: 0
 2: 0

/--- This one does fail, as expected, in Perl. It needs the complex item at the
     end of the pattern. A single letter instead of (B|D) makes it not fail,
     which I think is a Perl bug. --- /

/A(*COMMIT)(B|D)/
    ACABX
No match

/--- Check the use of names for failure ---/

/^(A(*PRUNE:A)B|C(*PRUNE:B)D)/K
    ** Failers
No match
    AC
No match, mark = A
    CB    
No match, mark = B
    
/--- Force no study, otherwise mark is not seen. The studied version is in
     test 2 because it isn't Perl-compatible. ---/

/(*MARK:A)(*SKIP:B)(C|X)/KSS
    C
 0: C
 1: C
MK: A
    D
No match, mark = A
     
/^(A(*THEN:A)B|C(*THEN:B)D)/K
    ** Failers
No match
    CB    
No match, mark = B

/^(?:A(*THEN:A)B|C(*THEN:B)D)/K
    CB    
No match, mark = B
    
/^(?>A(*THEN:A)B|C(*THEN:B)D)/K
    CB    
No match, mark = B
    
/--- This should succeed, as the skip causes bump to offset 1 (the mark). Note
that we have to have something complicated such as (B|Z) at the end because,
for Perl, a simple character somehow causes an unwanted optimization to mess
with the handling of backtracking verbs. ---/

/A(*MARK:A)A+(*SKIP:A)(B|Z) | AC/xK
    AAAC
 0: AC
    
/--- Test skipping over a non-matching mark. ---/

/A(*MARK:A)A+(*MARK:B)(*SKIP:A)(B|Z) | AC/xK
    AAAC
 0: AC
    
/--- Check shorthand for MARK ---/

/A(*:A)A+(*SKIP:A)(B|Z) | AC/xK
    AAAC
 0: AC

/--- Don't loop! Force no study, otherwise mark is not seen. ---/

/(*:A)A+(*SKIP:A)(B|Z)/KSS
    AAAC
No match, mark = A

/--- This should succeed, as a non-existent skip name disables the skip ---/ 

/A(*MARK:A)A+(*SKIP:B)(B|Z) | AC/xK
    AAAC
 0: AC

/A(*MARK:A)A+(*SKIP:B)(B|Z) | AC(*:B)/xK
    AAAC
 0: AC
MK: B

/--- COMMIT at the start of a pattern should act like an anchor. Again, 
however, we need the complication for Perl. ---/

/(*COMMIT)(A|P)(B|P)(C|P)/
    ABCDEFG
 0: ABC
 1: A
 2: B
 3: C
    ** Failers
No match
    DEFGABC  
No match

/--- COMMIT inside an atomic group can't stop backtracking over the group. ---/

/(\w+)(?>b(*COMMIT))\w{2}/
    abbb
 0: abbb
 1: a

/(\w+)b(*COMMIT)\w{2}/
    abbb
No match

/--- Check opening parens in comment when seeking forward reference. ---/ 

/(?&t)(?#()(?(DEFINE)(?<t>a))/
    bac
 0: a

/--- COMMIT should override THEN ---/

/(?>(*COMMIT)(?>yes|no)(*THEN)(*F))?/
  yes
No match

/(?>(*COMMIT)(yes|no)(*THEN)(*F))?/
  yes
No match

/b?(*SKIP)c/
    bc
 0: bc
    abc
 0: bc
   
/(*SKIP)bc/
    a
No match

/(*SKIP)b/
    a 
No match

/(?P<abn>(?P=abn)xxx|)+/
    xxx
 0: 
 1: 

/(?i:([^b]))(?1)/
    aa
 0: aa
 1: a
    aA     
 0: aA
 1: a
    ** Failers
 0: **
 1: *
    ab
No match
    aB
No match
    Ba
No match
    ba
No match

/^(?&t)*+(?(DEFINE)(?<t>a))\w$/
    aaaaaaX
 0: aaaaaaX
    ** Failers 
No match
    aaaaaa 
No match

/^(?&t)*(?(DEFINE)(?<t>a))\w$/
    aaaaaaX
 0: aaaaaaX
    aaaaaa 
 0: aaaaaa

/^(a)*+(\w)/
    aaaaX
 0: aaaaX
 1: a
 2: X
    YZ 
 0: Y
 1: <unset>
 2: Y
    ** Failers 
No match
    aaaa
No match

/^(?:a)*+(\w)/
    aaaaX
 0: aaaaX
 1: X
    YZ 
 0: Y
 1: Y
    ** Failers 
No match
    aaaa
No match

/^(a)++(\w)/
    aaaaX
 0: aaaaX
 1: a
 2: X
    ** Failers 
No match
    aaaa
No match
    YZ 
No match

/^(?:a)++(\w)/
    aaaaX
 0: aaaaX
 1: X
    ** Failers 
No match
    aaaa
No match
    YZ 
No match

/^(a)?+(\w)/
    aaaaX
 0: aa
 1: a
 2: a
    YZ 
 0: Y
 1: <unset>
 2: Y

/^(?:a)?+(\w)/
    aaaaX
 0: aa
 1: a
    YZ 
 0: Y
 1: Y

/^(a){2,}+(\w)/
    aaaaX
 0: aaaaX
 1: a
 2: X
    ** Failers
No match
    aaa
No match
    YZ 
No match

/^(?:a){2,}+(\w)/
    aaaaX
 0: aaaaX
 1: X
    ** Failers
No match
    aaa
No match
    YZ 
No match

/(a|)*(?1)b/
    b
 0: b
 1: 
    ab
 0: ab
 1: 
    aab  
 0: aab
 1: 

/(a)++(?1)b/
    ** Failers
No match
    ab 
No match
    aab
No match

/(a)*+(?1)b/
    ** Failers
No match
    ab
No match
    aab  
No match

/(?1)(?:(b)){0}/
    b
 0: b

/(foo ( \( ((?:(?> [^()]+ )|(?2))*) \) ) )/x
    foo(bar(baz)+baz(bop))
 0: foo(bar(baz)+baz(bop))
 1: foo(bar(baz)+baz(bop))
 2: (bar(baz)+baz(bop))
 3: bar(baz)+baz(bop)

/(A (A|B(*ACCEPT)|C) D)(E)/x
    AB
 0: AB
 1: AB
 2: B

/\A.*?(a|bc)/
    ba
 0: ba
 1: a

/\A.*?(?:a|bc)++/
    ba
 0: ba

/\A.*?(a|bc)++/
    ba
 0: ba
 1: a

/\A.*?(?:a|bc|d)/
    ba
 0: ba

/(?:(b))++/
    beetle
 0: b
 1: b

/(?(?=(a(*ACCEPT)z))a)/
    a
 0: a
 1: a

/^(a)(?1)+ab/
    aaaab
 0: aaaab
 1: a
    
/^(a)(?1)++ab/
    aaaab
No match

/^(?=a(*:M))aZ/K
    aZbc
 0: aZ
MK: M

/^(?!(*:M)b)aZ/K
    aZbc
 0: aZ

/(?(DEFINE)(a))?b(?1)/
    backgammon
 0: ba

/^\N+/
    abc\ndef
 0: abc
    
/^\N{1,}/
    abc\ndef 
 0: abc

/(?(R)a+|(?R)b)/
    aaaabcde
 0: aaaab

/(?(R)a+|((?R))b)/
    aaaabcde
 0: aaaab
 1: aaaa

/((?(R)a+|(?1)b))/
    aaaabcde
 0: aaaab
 1: aaaab

/((?(R1)a+|(?1)b))/
    aaaabcde
 0: aaaab
 1: aaaab
    
/((?(R)a|(?1)))*/
    aaa
 0: aaa
 1: a

/((?(R)a|(?1)))+/
    aaa
 0: aaa
 1: a

/a(*:any 
name)/K
    abc
 0: a
MK: any \x0aname
    
/(?>(?&t)c|(?&t))(?(DEFINE)(?<t>a|b(*PRUNE)c))/
    a
 0: a
    ba
 0: a
    bba 
 0: a
    
/--- Checking revised (*THEN) handling ---/ 

/--- Capture ---/

/^.*? (a(*THEN)b) c/x
    aabc
No match

/^.*? (a(*THEN)b|(*F)) c/x
    aabc
 0: aabc
 1: ab

/^.*? ( (a(*THEN)b) | (*F) ) c/x
    aabc
 0: aabc
 1: ab
 2: ab

/^.*? ( (a(*THEN)b) ) c/x
    aabc
No match

/--- Non-capture ---/

/^.*? (?:a(*THEN)b) c/x
    aabc
No match

/^.*? (?:a(*THEN)b|(*F)) c/x
    aabc
 0: aabc

/^.*? (?: (?:a(*THEN)b) | (*F) ) c/x
    aabc
 0: aabc

/^.*? (?: (?:a(*THEN)b) ) c/x
    aabc
No match

/--- Atomic ---/

/^.*? (?>a(*THEN)b) c/x
    aabc
No match

/^.*? (?>a(*THEN)b|(*F)) c/x
    aabc
 0: aabc

/^.*? (?> (?>a(*THEN)b) | (*F) ) c/x
    aabc
 0: aabc

/^.*? (?> (?>a(*THEN)b) ) c/x
    aabc
No match

/--- Possessive capture ---/

/^.*? (a(*THEN)b)++ c/x
    aabc
No match

/^.*? (a(*THEN)b|(*F))++ c/x
    aabc
 0: aabc
 1: ab

/^.*? ( (a(*THEN)b)++ | (*F) )++ c/x
    aabc
 0: aabc
 1: ab
 2: ab

/^.*? ( (a(*THEN)b)++ )++ c/x
    aabc
No match

/--- Possessive non-capture ---/

/^.*? (?:a(*THEN)b)++ c/x
    aabc
No match

/^.*? (?:a(*THEN)b|(*F))++ c/x
    aabc
 0: aabc

/^.*? (?: (?:a(*THEN)b)++ | (*F) )++ c/x
    aabc
 0: aabc

/^.*? (?: (?:a(*THEN)b)++ )++ c/x
    aabc
No match
    
/--- Condition assertion ---/

/^(?(?=a(*THEN)b)ab|ac)/
    ac
 0: ac
 
/--- Condition ---/

/^.*?(?(?=a)a|b(*THEN)c)/
    ba
No match

/^.*?(?:(?(?=a)a|b(*THEN)c)|d)/
    ba
 0: ba

/^.*?(?(?=a)a(*THEN)b|c)/
    ac
No match

/--- Assertion ---/

/^.*(?=a(*THEN)b)/ 
    aabc
 0: a

/------------------------------/

/(?>a(*:m))/imsxSK 
    a
 0: a
MK: m

/(?>(a)(*:m))/imsxSK 
    a
 0: a
 1: a
MK: m

/(?<=a(*ACCEPT)b)c/
    xacd
 0: c

/(?<=(a(*ACCEPT)b))c/
    xacd
 0: c
 1: a

/(?<=(a(*COMMIT)b))c/
    xabcd
 0: c
 1: ab
    ** Failers 
No match
    xacd
No match
    
/(?<!a(*FAIL)b)c/
    xcd
 0: c
    acd 
 0: c

/(?<=a(*:N)b)c/K
    xabcd
 0: c
MK: N
    
/(?<=a(*PRUNE)b)c/
    xabcd 
 0: c

/(?<=a(*SKIP)b)c/
    xabcd 
 0: c

/(?<=a(*THEN)b)c/
    xabcd 
 0: c

/(a)(?2){2}(.)/
    abcd
 0: abcd
 1: a
 2: d

/(*MARK:A)(*PRUNE:B)(C|X)/KS
    C
 0: C
 1: C
MK: B
    D 
No match, mark = B

/(*MARK:A)(*PRUNE:B)(C|X)/KSS
    C
 0: C
 1: C
MK: B
    D 
No match, mark = B

/(*MARK:A)(*THEN:B)(C|X)/KS
    C
 0: C
 1: C
MK: B
    D 
No match, mark = B

/(*MARK:A)(*THEN:B)(C|X)/KSY
    C
 0: C
 1: C
MK: B
    D 
No match, mark = B

/(*MARK:A)(*THEN:B)(C|X)/KSS
    C
 0: C
 1: C
MK: B
    D 
No match, mark = B

/--- This should fail, as the skip causes a bump to offset 3 (the skip) ---/

/A(*MARK:A)A+(*SKIP)(B|Z) | AC/xK
    AAAC
No match, mark = A

/--- Same --/

/A(*MARK:A)A+(*MARK:B)(*SKIP:B)(B|Z) | AC/xK
    AAAC
No match, mark = B

/A(*:A)A+(*SKIP)(B|Z) | AC/xK
    AAAC
No match, mark = A

/--- This should fail, as a null name is the same as no name ---/

/A(*MARK:A)A+(*SKIP:)(B|Z) | AC/xK
    AAAC
No match, mark = A

/--- A check on what happens after hitting a mark and them bumping along to
something that does not even start. Perl reports tags after the failures here, 
though it does not when the individual letters are made into something 
more complicated. ---/

/A(*:A)B|XX(*:B)Y/K
    AABC
 0: AB
MK: A
    XXYZ 
 0: XXY
MK: B
    ** Failers
No match
    XAQQ  
No match, mark = A
    XAQQXZZ  
No match, mark = A
    AXQQQ 
No match, mark = A
    AXXQQQ 
No match, mark = B
    
/^(A(*THEN:A)B|C(*THEN:B)D)/K
    AB
 0: AB
 1: AB
MK: A
    CD
 0: CD
 1: CD
MK: B
    ** Failers
No match
    AC
No match, mark = A
    CB    
No match, mark = B
    
/^(A(*PRUNE:A)B|C(*PRUNE:B)D)/K
    AB
 0: AB
 1: AB
MK: A
    CD
 0: CD
 1: CD
MK: B
    ** Failers
No match
    AC
No match, mark = A
    CB    
No match, mark = B
    
/--- An empty name does not pass back an empty string. It is the same as if no
name were given. ---/ 

/^(A(*PRUNE:)B|C(*PRUNE:B)D)/K
    AB
 0: AB
 1: AB
    CD 
 0: CD
 1: CD
MK: B

/--- PRUNE goes to next bumpalong; COMMIT does not. ---/
    
/A(*PRUNE:A)B/K
    ACAB
 0: AB
MK: A

/--- Mark names can be duplicated ---/

/A(*:A)B|X(*:A)Y/K
    AABC
 0: AB
MK: A
    XXYZ 
 0: XY
MK: A
    
/b(*:m)f|a(*:n)w/K
    aw 
 0: aw
MK: n
    ** Failers 
No match, mark = n
    abc
No match, mark = m

/b(*:m)f|aw/K
    abaw
 0: aw
    ** Failers 
No match
    abc
No match, mark = m
    abax 
No match, mark = m

/A(*MARK:A)A+(*SKIP:B)(B|Z) | AAC/xK
    AAAC
 0: AAC

/a(*PRUNE:X)bc|qq/KY
    ** Failers
No match, mark = X
    axy
No match, mark = X

/a(*THEN:X)bc|qq/KY
    ** Failers
No match, mark = X
    axy
No match, mark = X

/(?=a(*MARK:A)b)..x/K
    abxy
 0: abx
MK: A
    ** Failers
No match
    abpq  
No match

/(?=a(*MARK:A)b)..(*:Y)x/K
    abxy
 0: abx
MK: Y
    ** Failers
No match
    abpq  
No match

/(?=a(*PRUNE:A)b)..x/K
    abxy
 0: abx
MK: A
    ** Failers
No match
    abpq  
No match

/(?=a(*PRUNE:A)b)..(*:Y)x/K
    abxy
 0: abx
MK: Y
    ** Failers
No match
    abpq  
No match

/(?=a(*THEN:A)b)..x/K
    abxy
 0: abx
MK: A
    ** Failers
No match
    abpq  
No match

/(?=a(*THEN:A)b)..(*:Y)x/K
    abxy
 0: abx
MK: Y
    ** Failers
No match
    abpq  
No match

/(another)?(\1?)test/
    hello world test
 0: test
 1: <unset>
 2: 

/(another)?(\1+)test/
    hello world test
No match

/(a(*COMMIT)b){0}a(?1)|aac/
    aac
 0: aac

/((?:a?)*)*c/
  aac   
 0: aac
 1: 

/((?>a?)*)*c/
  aac   
 0: aac
 1: 

/(?>.*?a)(?<=ba)/
    aba
 0: ba

/(?:.*?a)(?<=ba)/
    aba
 0: aba

/.*?a(*PRUNE)b/
    aab
 0: ab

/.*?a(*PRUNE)b/s
    aab
 0: ab

/^a(*PRUNE)b/s
    aab
No match

/.*?a(*SKIP)b/
    aab
 0: ab

/(?>.*?a)b/s
    aab
 0: ab

/(?>.*?a)b/
    aab
 0: ab

/(?>^a)b/s
    aab
No match

/(?>.*?)(?<=(abcd)|(wxyz))/
    alphabetabcd
 0: 
 1: abcd
    endingwxyz 
 0: 
 1: <unset>
 2: wxyz

/(?>.*)(?<=(abcd)|(wxyz))/
    alphabetabcd
 0: alphabetabcd
 1: abcd
    endingwxyz 
 0: endingwxyz
 1: <unset>
 2: wxyz

"(?>.*)foo"
    abcdfooxyz
No match
    
"(?>.*?)foo"
    abcdfooxyz
 0: foo

/(?:(a(*PRUNE)b)){0}(?:(?1)|ac)/
    ac
 0: ac
    
/(?:(a(*SKIP)b)){0}(?:(?1)|ac)/
    ac 
 0: ac

/(?<=(*SKIP)ac)a/
    aa
No match

/A(*MARK:A)A+(*SKIP:B)(B|Z) | AC/xK
    AAAC
 0: AC

/a(*SKIP:m)x|ac(*:n)(*SKIP:n)d|ac/K
    acacd
 0: acd
MK: n

/A(*SKIP:m)x|A(*SKIP:n)x|AB/K
    AB
 0: AB

/((*SKIP:r)d){0}a(*SKIP:m)x|ac(*:n)|ac/K
    acacd
 0: ac
MK: n

/-- Tests that try to figure out how Perl works. My hypothesis is that the
    first verb that is backtracked onto is the one that acts. This seems to be
    the case almost all the time, but there is one exception that is perhaps a 
    bug. --/

/-- This matches "aaaac"; each PRUNE advances one character until the subject
    no longer starts with 5 'a's. --/

/aaaaa(*PRUNE)b|a+c/
    aaaaaac
 0: aaaac

/-- Putting SKIP in front of PRUNE makes no difference, as it is never 
backtracked onto, whether or not it has a label. --/

/aaaaa(*SKIP)(*PRUNE)b|a+c/
    aaaaaac
 0: aaaac

/aaaaa(*SKIP:N)(*PRUNE)b|a+c/
    aaaaaac
 0: aaaac

/aaaa(*:N)a(*SKIP:N)(*PRUNE)b|a+c/
    aaaaaac
 0: aaaac

/-- Putting THEN in front makes no difference. */
    
/aaaaa(*THEN)(*PRUNE)b|a+c/
    aaaaaac
 0: aaaac
 
/-- However, putting COMMIT in front of the prune changes it to "no match". I 
    think this is inconsistent and possibly a bug. For the moment, running this
    test is moved out of the Perl-compatible file. --/

/aaaaa(*COMMIT)(*PRUNE)b|a+c/
    

/---- OK, lets play the same game again using SKIP instead of PRUNE. ----/

/-- This matches "ac" because SKIP forces the next match to start on the
    sixth "a". --/

/aaaaa(*SKIP)b|a+c/
    aaaaaac
 0: ac
 
/-- Putting PRUNE in front makes no difference. --/

/aaaaa(*PRUNE)(*SKIP)b|a+c/
    aaaaaac
 0: ac

/-- Putting THEN in front makes no difference. --/

/aaaaa(*THEN)(*SKIP)b|a+c/
    aaaaaac
 0: ac

/-- In this case, neither does COMMIT. This still matches "ac". --/

/aaaaa(*COMMIT)(*SKIP)b|a+c/
    aaaaaac
 0: ac
    
/-- This gives "no match", as expected. --/

/aaaaa(*COMMIT)b|a+c/
    aaaaaac
No match
    

/------ Tests using THEN ------/

/-- This matches "aaaaaac", as expected. --/

/aaaaa(*THEN)b|a+c/
    aaaaaac
 0: aaaaaac

/-- Putting SKIP in front makes no difference. --/

/aaaaa(*SKIP)(*THEN)b|a+c/
    aaaaaac
 0: aaaaaac
    
/-- Putting PRUNE in front makes no difference. --/

/aaaaa(*PRUNE)(*THEN)b|a+c/
    aaaaaac
 0: aaaaaac
    
/-- Putting COMMIT in front makes no difference. --/

/aaaaa(*COMMIT)(*THEN)b|a+c/
    aaaaaac
 0: aaaaaac
    
/-- End of "priority" tests --/ 

/aaaaa(*:m)(*PRUNE:m)(*SKIP:m)m|a+/
    aaaaaa
 0: a

/aaaaa(*:m)(*MARK:m)(*PRUNE)(*SKIP:m)m|a+/
    aaaaaa
 0: a

/aaaaa(*:n)(*PRUNE:m)(*SKIP:m)m|a+/
    aaaaaa
 0: aaaa

/aaaaa(*:n)(*MARK:m)(*PRUNE)(*SKIP:m)m|a+/
    aaaaaa
 0: a

/a(*MARK:A)aa(*PRUNE:A)a(*SKIP:A)b|a+c/
    aaaac
 0: aac

/a(*MARK:A)aa(*MARK:A)a(*SKIP:A)b|a+c/
    aaaac
 0: ac

/aaa(*PRUNE:A)a(*SKIP:A)b|a+c/
    aaaac
 0: aac

/aaa(*MARK:A)a(*SKIP:A)b|a+c/
    aaaac
 0: ac

/a(*:m)a(*COMMIT)(*SKIP:m)b|a+c/K
    aaaaaac
 0: ac

/.?(a|b(*THEN)c)/
    ba
 0: ba
 1: a

/(a(*COMMIT)b)c|abd/
    abc
 0: abc
 1: ab
    abd
No match

/(?=a(*COMMIT)b)abc|abd/
    abc
 0: abc
    abd
 0: abd

/(?>a(*COMMIT)b)c|abd/
    abc
 0: abc
    abd
 0: abd

/a(?=b(*COMMIT)c)[^d]|abd/
    abd
No match
    abc 
 0: ab

/a(?=bc).|abd/
    abd
 0: abd
    abc 
 0: ab
    
/a(?>b(*COMMIT)c)d|abd/
    abceabd 
No match

/a(?>bc)d|abd/
    abceabd 
 0: abd

/(?>a(*COMMIT)b)c|abd/
    abd
 0: abd

/(?>a(*COMMIT)c)d|abd/
    abd
No match

/((?=a(*COMMIT)b)ab|ac){0}(?:(?1)|a(c))/
    ac 
 0: ac
 1: <unset>
 2: c
    
/-- These tests were formerly in test 2, but changes in PCRE and Perl have
    made them compatible. --/
    
/^(a)?(?(1)a|b)+$/
    *** Failers
No match
    a
No match

/(?=a\Kb)ab/
    ab 
 0: b

/(?!a\Kb)ac/
    ac 
 0: ac
    
/^abc(?<=b\Kc)d/
    abcd
 0: cd

/^abc(?<!b\Kq)d/
    abcd
 0: abcd


/A(*PRUNE:A)A+(*SKIP:A)(B|Z) | AC/xK
    AAAC
No match, mark = A

/^((abc|abcx)(*THEN)y|abcd)/
    abcd
 0: abcd
 1: abcd
    *** Failers 
No match
    abcxy 
No match
    
/^((yes|no)(*THEN)(*F))?/
  yes
No match

/(A (.*)   C? (*THEN)  | A D) (*FAIL)/x
AbcdCBefgBhiBqz
No match

/(A (.*)   C? (*THEN)  | A D) z/x
AbcdCBefgBhiBqz
No match

/(A (.*)   C? (*THEN)  | A D) \s* (*FAIL)/x
AbcdCBefgBhiBqz
No match

/(A (.*)   C? (*THEN)  | A D) \s* z/x
AbcdCBefgBhiBqz
No match

/(A (.*)   (?:C|) (*THEN)  | A D) (*FAIL)/x
AbcdCBefgBhiBqz
No match

/(A (.*)   (?:C|) (*THEN)  | A D) z/x
AbcdCBefgBhiBqz
No match

/(A (.*)   C{0,6} (*THEN)  | A D) (*FAIL)/x
AbcdCBefgBhiBqz
No match

/(A (.*)   C{0,6} (*THEN)  | A D) z/x
AbcdCBefgBhiBqz
No match

/(A (.*)   (CE){0,6} (*THEN)  | A D) (*FAIL)/x
AbcdCEBefgBhiBqz
No match

/(A (.*)   (CE){0,6} (*THEN)  | A D) z/x
AbcdCEBefgBhiBqz
No match

/(A (.*)   (CE*){0,6} (*THEN)  | A D) (*FAIL)/x
AbcdCBefgBhiBqz
No match

/(A (.*)   (CE*){0,6} (*THEN)  | A D) z/x
AbcdCBefgBhiBqz
No match

/(?=a(*COMMIT)b|ac)ac|ac/
    ac
No match

/(?=a(*COMMIT)b|(ac)) ac | (a)c/x
    ac
No match

/--------/

/(?(?!b(*THEN)a)bn|bnn)/
   bnn 
 0: bn

/(?!b(*SKIP)a)bn|bnn/
    bnn
 0: bn
    
/(?(?!b(*SKIP)a)bn|bnn)/
   bnn 
 0: bn

/(?!b(*PRUNE)a)bn|bnn/
    bnn
 0: bn
    
/(?(?!b(*PRUNE)a)bn|bnn)/
   bnn 
 0: bn
   
/(?!b(*COMMIT)a)bn|bnn/
    bnn
 0: bn
    
/(?(?!b(*COMMIT)a)bn|bnn)/
   bnn 
 0: bn

/(?=b(*SKIP)a)bn|bnn/
    bnn
No match

/(?=b(*THEN)a)bn|bnn/
    bnn
 0: bnn
    
 /^(?!a(*SKIP)b)/
     ac
 0: 

 /^(?!a(*SKIP)b)../
     acd
 0: ac

/(?!a(*SKIP)b)../
     acd
 0: ac

/^(?(?!a(*SKIP)b))/
     ac
 0: 

/^(?!a(*PRUNE)b)../
     acd
 0: ac

/(?!a(*PRUNE)b)../
     acd
 0: ac

 /(?!a(*COMMIT)b)ac|cd/
     ac
 0: ac

/\A.*?(?:a|bc)/
    ba
 0: ba

/^(A(*THEN)B|C(*THEN)D)/
    CD           
 0: CD
 1: CD

/(*:m(m)(?&y)(?(DEFINE)(?<y>b))/K
    abc
 0: b
MK: m(m

/(*PRUNE:m(m)(?&y)(?(DEFINE)(?<y>b))/K
    abc
 0: b
MK: m(m

/(*SKIP:m(m)(?&y)(?(DEFINE)(?<y>b))/K
    abc
 0: b

/(*THEN:m(m)(?&y)(?(DEFINE)(?<y>b))/K
    abc
 0: b
MK: m(m

/^\d*\w{4}/
    1234
 0: 1234
    123 
No match

/^[^b]*\w{4}/
    aaaa
 0: aaaa
    aaa     
No match

/^[^b]*\w{4}/i
    aaaa
 0: aaaa
    aaa     
No match

/^a*\w{4}/
    aaaa
 0: aaaa
    aaa     
No match

/^a*\w{4}/i
    aaaa
 0: aaaa
    aaa     
No match

/(?(?=ab)ab)/+
    ca
 0: 
 0+ ca
    cd 
 0: 
 0+ cd

/(?:(?<n>foo)|(?<n>bar))\k<n>/J
    foofoo
 0: foofoo
 1: foo
    barbar
 0: barbar
 1: <unset>
 2: bar

/(?<n>A)(?:(?<n>foo)|(?<n>bar))\k<n>/J
    AfooA
 0: AfooA
 1: A
 2: foo
    AbarA  
 0: AbarA
 1: A
 2: <unset>
 3: bar
    ** Failers 
No match
    Afoofoo
No match
    Abarbar
No match

/^(\d+)\s+IN\s+SOA\s+(\S+)\s+(\S+)\s*\(\s*$/
    1 IN SOA non-sp1 non-sp2(
 0: 1 IN SOA non-sp1 non-sp2(
 1: 1
 2: non-sp1
 3: non-sp2

/^ (?:(?<A>A)|(?'B'B)(?<A>A)) (?('A')x) (?(<B>)y)$/xJ
    Ax
 0: Ax
 1: A
    BAxy 
 0: BAxy
 1: <unset>
 2: B
 3: A
    
/^A\xZ/
    A\0Z 
 0: A\x00Z

/^A\o{123}B/
    A\123B
 0: ASB

/ ^ a + + b $ /x
    aaaab
 0: aaaab
    
/ ^ a + #comment
  + b $ /x
    aaaab
 0: aaaab
    
/ ^ a + #comment
  #comment
  + b $ /x
    aaaab
 0: aaaab
    
/ ^ (?> a + ) b $ /x
    aaaab 
 0: aaaab

/ ^ ( a + ) + + \w $ /x
    aaaab 
 0: aaaab
 1: aaaa

/(?:a\Kb)*+/+
    ababc
 0: b
 0+ c

/(?>a\Kb)*/+
    ababc
 0: b
 0+ c

/(?:a\Kb)*/+
    ababc
 0: b
 0+ c

/(a\Kb)*+/+
    ababc
 0: b
 0+ c
 1: ab

/(a\Kb)*/+
    ababc
 0: b
 0+ c
 1: ab

/(?:x|(?:(xx|yy)+|x|x|x|x|x)|a|a|a)bc/
    acb
No match

'\A(?:[^\"]++|\"(?:[^\"]*+|\"\")*+\")++'
    NON QUOTED \"QUOT\"\"ED\" AFTER \"NOT MATCHED
 0: NON QUOTED "QUOT""ED" AFTER 

'\A(?:[^\"]++|\"(?:[^\"]++|\"\")*+\")++'
    NON QUOTED \"QUOT\"\"ED\" AFTER \"NOT MATCHED
 0: NON QUOTED "QUOT""ED" AFTER 

'\A(?:[^\"]++|\"(?:[^\"]++|\"\")++\")++'
    NON QUOTED \"QUOT\"\"ED\" AFTER \"NOT MATCHED
 0: NON QUOTED "QUOT""ED" AFTER 

'\A([^\"1]++|[\"2]([^\"3]*+|[\"4][\"5])*+[\"6])++'
    NON QUOTED \"QUOT\"\"ED\" AFTER \"NOT MATCHED
 0: NON QUOTED "QUOT""ED" AFTER 
 1:  AFTER 
 2: 

/^\w+(?>\s*)(?<=\w)/
  test test
 0: tes

/(?P<same>a)(?P<same>b)/gJ
    abbaba
 0: ab
 1: a
 2: b
 0: ab
 1: a
 2: b

/(?P<same>a)(?P<same>b)(?P=same)/gJ
    abbaba
 0: aba
 1: a
 2: b

/(?P=same)?(?P<same>a)(?P<same>b)/gJ
    abbaba
 0: ab
 1: a
 2: b
 0: ab
 1: a
 2: b

/(?:(?P=same)?(?:(?P<same>a)|(?P<same>b))(?P=same))+/gJ
    bbbaaabaabb
 0: bbbaaaba
 1: a
 2: b
 0: bb
 1: <unset>
 2: b

/(?:(?P=same)?(?:(?P=same)(?P<same>a)(?P=same)|(?P=same)?(?P<same>b)(?P=same)){2}(?P=same)(?P<same>c)(?P=same)){2}(?P<same>z)?/gJ
    bbbaaaccccaaabbbcc
No match

/(?P<Name>a)?(?P<Name2>b)?(?(<Name>)c|d)*l/
    acl
 0: acl
 1: a
    bdl
 0: bdl
 1: <unset>
 2: b
    adl
 0: dl
    bcl    
 0: l

/\sabc/
    \x{0b}abc
 0: \x0babc

/[\Qa]\E]+/
    aa]]
 0: aa]]

/[\Q]a\E]+/
    aa]]
 0: aa]]

/-- End of testinput1 --/