PCRE version 3.2 12-May-2000

/(a)b|/
Capturing subpattern count = 1
No options
No first char
No need char

/abc/
Capturing subpattern count = 0
No options
First char = 'a'
Need char = 'c'
    abc
 0: abc
    defabc
 0: abc
    \Aabc
 0: abc
    *** Failers
No match
    \Adefabc
No match
    ABC
No match

/^abc/
Capturing subpattern count = 0
Options: anchored
No first char
Need char = 'c'
    abc
 0: abc
    \Aabc
 0: abc
    *** Failers
No match
    defabc
No match
    \Adefabc
No match

/a+bc/
Capturing subpattern count = 0
No options
First char = 'a'
Need char = 'c'

/a*bc/
Capturing subpattern count = 0
No options
No first char
Need char = 'c'

/a{3}bc/
Capturing subpattern count = 0
No options
First char = 'a'
Need char = 'c'

/(abc|a+z)/
Capturing subpattern count = 1
No options
First char = 'a'
No need char

/^abc$/
Capturing subpattern count = 0
Options: anchored
No first char
Need char = 'c'
    abc
 0: abc
    *** Failers
No match
    def\nabc
No match

/ab\gdef/X
Failed: unrecognized character follows \ at offset 3

/(?X)ab\gdef/X
Failed: unrecognized character follows \ at offset 7

/x{5,4}/
Failed: numbers out of order in {} quantifier at offset 5

/z{65536}/
Failed: number too big in {} quantifier at offset 7

/[abcd/
Failed: missing terminating ] for character class at offset 5

/[\B]/
Failed: invalid escape sequence in character class at offset 2

/[a-\w]/
Failed: invalid escape sequence in character class at offset 4

/[z-a]/
Failed: range out of order in character class at offset 3

/^*/
Failed: nothing to repeat at offset 1

/(abc/
Failed: missing ) at offset 4

/(?# abc/
Failed: missing ) after comment at offset 7

/(?z)abc/
Failed: unrecognized character after (? at offset 2

/.*b/
Capturing subpattern count = 0
No options
First char at start or follows \n
Need char = 'b'

/.*?b/
Capturing subpattern count = 0
No options
First char at start or follows \n
Need char = 'b'

/cat|dog|elephant/
Capturing subpattern count = 0
No options
No first char
No need char
    this sentence eventually mentions a cat
 0: cat
    this sentences rambles on and on for a while and then reaches elephant
 0: elephant

/cat|dog|elephant/S
Capturing subpattern count = 0
No options
No first char
No need char
Starting character set: c d e 
    this sentence eventually mentions a cat
 0: cat
    this sentences rambles on and on for a while and then reaches elephant
 0: elephant

/cat|dog|elephant/iS
Capturing subpattern count = 0
Options: caseless
No first char
No need char
Starting character set: C D E c d e 
    this sentence eventually mentions a CAT cat
 0: CAT
    this sentences rambles on and on for a while to elephant ElePhant
 0: elephant

/a|[bcd]/S
Capturing subpattern count = 0
No options
No first char
No need char
Starting character set: a b c d 

/(a|[^\dZ])/S
Capturing subpattern count = 1
No options
No first char
No need char
Starting character set: \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 \x20 ! " # $ % & ' ( ) * + , - . / : ; < = > 
  ? @ A B C D E F G H I J K L M N O P Q R S T U V W X Y [ \ ] ^ _ ` a b c d 
  e f g h i j k l m n o p q r s t u v w x y z { | } ~ \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 

/(a|b)*[\s]/S
Capturing subpattern count = 1
No options
No first char
No need char
Starting character set: \x09 \x0a \x0b \x0c \x0d \x20 a b 

/(ab\2)/
Failed: back reference to non-existent subpattern at offset 6

/{4,5}abc/
Failed: nothing to repeat at offset 4

/(a)(b)(c)\2/
Capturing subpattern count = 3
Max back reference = 2
No options
First char = 'a'
Need char = 'c'
    abcb
 0: abcb
 1: a
 2: b
 3: c
    \O0abcb
Matched, but too many substrings
    \O3abcb
Matched, but too many substrings
 0: abcb
    \O6abcb
Matched, but too many substrings
 0: abcb
 1: a
    \O9abcb
Matched, but too many substrings
 0: abcb
 1: a
 2: b
    \O12abcb 
 0: abcb
 1: a
 2: b
 3: c

/(a)bc|(a)(b)\2/
Capturing subpattern count = 3
Max back reference = 2
No options
First char = 'a'
No need char
    abc
 0: abc
 1: a
    \O0abc
Matched, but too many substrings
    \O3abc
Matched, but too many substrings
 0: abc
    \O6abc
 0: abc
 1: a
    aba
 0: aba
 1: <unset>
 2: a
 3: b
    \O0aba
Matched, but too many substrings
    \O3aba
Matched, but too many substrings
 0: aba
    \O6aba
Matched, but too many substrings
 0: aba
 1: <unset>
    \O9aba
Matched, but too many substrings
 0: aba
 1: <unset>
 2: a
    \O12aba
 0: aba
 1: <unset>
 2: a
 3: b

/abc$/E
Capturing subpattern count = 0
Options: dollar_endonly
First char = 'a'
Need char = 'c'
    abc
 0: abc
    *** Failers
No match
    abc\n
No match
    abc\ndef
No match

/(a)(b)(c)(d)(e)\6/
Failed: back reference to non-existent subpattern at offset 17

/the quick brown fox/
Capturing subpattern count = 0
No options
First char = 't'
Need char = 'x'
    the quick brown fox
 0: the quick brown fox
    this is a line with the quick brown fox
 0: the quick brown fox

/the quick brown fox/A
Capturing subpattern count = 0
Options: anchored
No first char
Need char = 'x'
    the quick brown fox
 0: the quick brown fox
    *** Failers
No match
    this is a line with the quick brown fox
No match

/ab(?z)cd/
Failed: unrecognized character after (? at offset 4

/^abc|def/
Capturing subpattern count = 0
No options
No first char
No need char
    abcdef
 0: abc
    abcdef\B
 0: def

/.*((abc)$|(def))/
Capturing subpattern count = 3
No options
First char at start or follows \n
No need char
    defabc
 0: defabc
 1: abc
 2: abc
    \Zdefabc
 0: def
 1: def
 2: <unset>
 3: def

/abc/P
    abc
 0: abc
    *** Failers
No match: POSIX code 17: match failed
    
/^abc|def/P
    abcdef
 0: abc
    abcdef\B
 0: def

/.*((abc)$|(def))/P
    defabc
 0: defabc
 1: abc
 2: abc
    \Zdefabc
 0: def
 1: def
 3: def
  
/the quick brown fox/P
    the quick brown fox
 0: the quick brown fox
    *** Failers 
No match: POSIX code 17: match failed
    The Quick Brown Fox 
No match: POSIX code 17: match failed

/the quick brown fox/Pi
    the quick brown fox
 0: the quick brown fox
    The Quick Brown Fox 
 0: The Quick Brown Fox

/abc.def/P
    *** Failers
No match: POSIX code 17: match failed
    abc\ndef
No match: POSIX code 17: match failed
    
/abc$/P
    abc
 0: abc
    abc\n 
 0: abc

/(abc)\2/P
Failed: POSIX code 15: bad back reference at offset 7     

/(abc\1)/P
    abc
No match: POSIX code 17: match failed

/)/
Failed: unmatched parentheses at offset 0

/a[]b/
Failed: missing terminating ] for character class at offset 4

/[^aeiou ]{3,}/
Capturing subpattern count = 0
No options
No first char
No need char
    co-processors, and for 
 0: -pr
    
/<.*>/
Capturing subpattern count = 0
No options
First char = '<'
Need char = '>'
    abc<def>ghi<klm>nop
 0: <def>ghi<klm>

/<.*?>/
Capturing subpattern count = 0
No options
First char = '<'
Need char = '>'
    abc<def>ghi<klm>nop
 0: <def>

/<.*>/U
Capturing subpattern count = 0
Options: ungreedy
First char = '<'
Need char = '>'
    abc<def>ghi<klm>nop
 0: <def>
    
/<.*>(?U)/
Capturing subpattern count = 0
Options: ungreedy
First char = '<'
Need char = '>'
    abc<def>ghi<klm>nop
 0: <def>

/<.*?>/U
Capturing subpattern count = 0
Options: ungreedy
First char = '<'
Need char = '>'
    abc<def>ghi<klm>nop
 0: <def>ghi<klm>
    
/={3,}/U
Capturing subpattern count = 0
Options: ungreedy
First char = '='
Need char = '='
    abc========def
 0: ===
    
/(?U)={3,}?/
Capturing subpattern count = 0
Options: ungreedy
First char = '='
Need char = '='
    abc========def
 0: ========
    
/(?<!bar|cattle)foo/
Capturing subpattern count = 0
No options
First char = 'f'
Need char = 'o'
    foo
 0: foo
    catfoo 
 0: foo
    *** Failers
No match
    the barfoo
No match
    and cattlefoo   
No match

/(?<=a+)b/
Failed: lookbehind assertion is not fixed length at offset 6

/(?<=aaa|b{0,3})b/
Failed: lookbehind assertion is not fixed length at offset 14

/(?<!(foo)a\1)bar/
Failed: lookbehind assertion is not fixed length at offset 12

/(?i)abc/
Capturing subpattern count = 0
Options: caseless
First char = 'a'
Need char = 'c'

/(a|(?m)a)/
Capturing subpattern count = 1
No options
First char = 'a'
No need char

/(?i)^1234/
Capturing subpattern count = 0
Options: anchored caseless
No first char
Need char = '4'

/(^b|(?i)^d)/
Capturing subpattern count = 1
Options: anchored
Case state changes
No first char
No need char

/(?s).*/
Capturing subpattern count = 0
Options: anchored dotall
No first char
No need char

/[abcd]/S
Capturing subpattern count = 0
No options
No first char
No need char
Starting character set: a b c d 

/(?i)[abcd]/S
Capturing subpattern count = 0
Options: caseless
No first char
No need char
Starting character set: A B C D a b c d 

/(?m)[xy]|(b|c)/S
Capturing subpattern count = 1
Options: multiline
No first char
No need char
Starting character set: b c x y 

/(^a|^b)/m
Capturing subpattern count = 1
Options: multiline
First char at start or follows \n
No need char

/(?i)(^a|^b)/m
Capturing subpattern count = 1
Options: caseless multiline
First char at start or follows \n
No need char

/(a)(?(1)a|b|c)/
Failed: conditional group contains more than two branches at offset 13

/(?(?=a)a|b|c)/
Failed: conditional group contains more than two branches at offset 12

/(?(1a)/
Failed: malformed number after (?( at offset 4

/(?(?i))/
Failed: assertion expected after (?( at offset 3

/(?(abc))/
Failed: assertion expected after (?( at offset 3

/(?(?<ab))/
Failed: unrecognized character after (?< at offset 2

/((?s)blah)\s+\1/
Capturing subpattern count = 1
Max back reference = 1
No options
First char = 'b'
Need char = 'h'

/((?i)blah)\s+\1/
Capturing subpattern count = 1
Max back reference = 1
No options
Case state changes
No first char
Need char = 'h'

/((?i)b)/DS
------------------------------------------------------------------
  0  16 Bra 0
  3   8 Bra 1
  6  01 Opt
  8   1 b
 11   8 Ket
 14  00 Opt
 16  16 Ket
 19     End
------------------------------------------------------------------
Capturing subpattern count = 1
No options
Case state changes
No first char
Need char = 'b'
Starting character set: B b 

/(a*b|(?i:c*(?-i)d))/S
Capturing subpattern count = 1
No options
Case state changes
No first char
No need char
Starting character set: C a b c d 

/a$/
Capturing subpattern count = 0
No options
First char = 'a'
No need char
    a
 0: a
    a\n
 0: a
    *** Failers 
No match
    \Za
No match
    \Za\n   
No match

/a$/m
Capturing subpattern count = 0
Options: multiline
First char = 'a'
No need char
    a
 0: a
    a\n
 0: a
    \Za\n   
 0: a
    *** Failers 
No match
    \Za
No match
    
/\Aabc/m
Capturing subpattern count = 0
Options: anchored multiline
No first char
Need char = 'c'

/^abc/m 
Capturing subpattern count = 0
Options: multiline
First char at start or follows \n
Need char = 'c'

/^((a+)(?U)([ab]+)(?-U)([bc]+)(\w*))/
Capturing subpattern count = 5
Options: anchored
No first char
Need char = 'a'
  aaaaabbbbbcccccdef
 0: aaaaabbbbbcccccdef
 1: aaaaabbbbbcccccdef
 2: aaaaa
 3: b
 4: bbbbccccc
 5: def

/(?<=foo)[ab]/S
Capturing subpattern count = 0
No options
No first char
No need char
Starting character set: a b 

/(?<!foo)(alpha|omega)/S
Capturing subpattern count = 1
No options
No first char
Need char = 'a'
Starting character set: a o 

/(?!alphabet)[ab]/S
Capturing subpattern count = 0
No options
No first char
No need char
Starting character set: a b 

/(?<=foo\n)^bar/m
Capturing subpattern count = 0
Options: multiline
First char at start or follows \n
Need char = 'r'

/(?>^abc)/m
Capturing subpattern count = 0
Options: multiline
First char at start or follows \n
Need char = 'c'
    abc
 0: abc
    def\nabc
 0: abc
    *** Failers
No match
    defabc   
No match

/(?<=ab(c+)d)ef/
Failed: lookbehind assertion is not fixed length at offset 11

/(?<=ab(?<=c+)d)ef/
Failed: lookbehind assertion is not fixed length at offset 12

/(?<=ab(c|de)f)g/
Failed: lookbehind assertion is not fixed length at offset 13

/The next three are in testinput2 because they have variable length branches/
Capturing subpattern count = 0
No options
First char = 'T'
Need char = 's'

/(?<=bullock|donkey)-cart/
Capturing subpattern count = 0
No options
First char = '-'
Need char = 't'
    the bullock-cart
 0: -cart
    a donkey-cart race
 0: -cart
    *** Failers
No match
    cart
No match
    horse-and-cart    
No match
      
/(?<=ab(?i)x|y|z)/
Capturing subpattern count = 0
No options
Case state changes
No first char
No need char

/(?>.*)(?<=(abcd)|(xyz))/
Capturing subpattern count = 2
No options
First char at start or follows \n
No need char
    alphabetabcd
 0: alphabetabcd
 1: abcd
    endingxyz
 0: endingxyz
 1: <unset>
 2: xyz

/(?<=ab(?i)x(?-i)y|(?i)z|b)ZZ/
Capturing subpattern count = 0
No options
Case state changes
First char = 'Z'
Need char = 'Z'
    abxyZZ
 0: ZZ
    abXyZZ
 0: ZZ
    ZZZ
 0: ZZ
    zZZ
 0: ZZ
    bZZ
 0: ZZ
    BZZ     
 0: ZZ
    *** Failers
No match
    ZZ 
No match
    abXYZZ 
No match
    zzz
No match
    bzz  
No match

/(?<!(foo)a)bar/
Capturing subpattern count = 1
No options
First char = 'b'
Need char = 'r'
    bar
 0: bar
    foobbar 
 0: bar
    *** Failers
No match
    fooabar  
No match

/This one is here because Perl 5.005_02 doesn't fail it/
Capturing subpattern count = 0
No options
First char = 'T'
Need char = 't'

/^(a)?(?(1)a|b)+$/
Capturing subpattern count = 1
Options: anchored
No first char
No need char
    *** Failers
No match
    a 
No match

/This one is here because I think Perl 5.005_02 gets the setting of $1 wrong/
Capturing subpattern count = 0
No options
First char = 'T'
Need char = 'g'

/^(a\1?){4}$/
Capturing subpattern count = 1
Max back reference = 1
Options: anchored
No first char
Need char = 'a'
    aaaaaa
 0: aaaaaa
 1: aa
    
/These are syntax tests from Perl 5.005/
Capturing subpattern count = 0
No options
First char = 'T'
Need char = '5'

/a[b-a]/
Failed: range out of order in character class at offset 4

/a[]b/
Failed: missing terminating ] for character class at offset 4

/a[/
Failed: missing terminating ] for character class at offset 2

/*a/
Failed: nothing to repeat at offset 0

/(*)b/
Failed: nothing to repeat at offset 1

/abc)/
Failed: unmatched parentheses at offset 3

/(abc/
Failed: missing ) at offset 4

/a**/
Failed: nothing to repeat at offset 2

/)(/
Failed: unmatched parentheses at offset 0

/\1/
Failed: back reference to non-existent subpattern at offset 2

/\2/
Failed: back reference to non-existent subpattern at offset 2

/(a)|\2/
Failed: back reference to non-existent subpattern at offset 6

/a[b-a]/i
Failed: range out of order in character class at offset 4

/a[]b/i
Failed: missing terminating ] for character class at offset 4

/a[/i
Failed: missing terminating ] for character class at offset 2

/*a/i
Failed: nothing to repeat at offset 0

/(*)b/i
Failed: nothing to repeat at offset 1

/abc)/i
Failed: unmatched parentheses at offset 3

/(abc/i
Failed: missing ) at offset 4

/a**/i
Failed: nothing to repeat at offset 2

/)(/i
Failed: unmatched parentheses at offset 0

/:(?:/
Failed: missing ) at offset 4

/(?<%)b/
Failed: unrecognized character after (?< at offset 0

/a(?{)b/
Failed: unrecognized character after (? at offset 3

/a(?{{})b/
Failed: unrecognized character after (? at offset 3

/a(?{}})b/
Failed: unrecognized character after (? at offset 3

/a(?{"{"})b/
Failed: unrecognized character after (? at offset 3

/a(?{"{"}})b/
Failed: unrecognized character after (? at offset 3

/(?(1?)a|b)/
Failed: malformed number after (?( at offset 4

/(?(1)a|b|c)/
Failed: conditional group contains more than two branches at offset 10

/[a[:xyz:/
Failed: missing terminating ] for character class at offset 8

/(?<=x+)y/
Failed: lookbehind assertion is not fixed length at offset 6

/a{37,17}/
Failed: numbers out of order in {} quantifier at offset 7

/abc/\
Failed: \ at end of pattern at offset 4

/abc/\P
Failed: POSIX code 9: bad escape sequence at offset 4     

/abc/\i
Failed: \ at end of pattern at offset 4

/(a)bc(d)/
Capturing subpattern count = 2
No options
First char = 'a'
Need char = 'd'
    abcd
 0: abcd
 1: a
 2: d
    abcd\C2
 0: abcd
 1: a
 2: d
 2C d (1)
    abcd\C5
 0: abcd
 1: a
 2: d
copy substring 5 failed -7
     
/(.{20})/
Capturing subpattern count = 1
No options
No first char
No need char
    abcdefghijklmnopqrstuvwxyz
 0: abcdefghijklmnopqrst
 1: abcdefghijklmnopqrst
    abcdefghijklmnopqrstuvwxyz\C1
 0: abcdefghijklmnopqrst
 1: abcdefghijklmnopqrst
copy substring 1 failed -6
    abcdefghijklmnopqrstuvwxyz\G1
 0: abcdefghijklmnopqrst
 1: abcdefghijklmnopqrst
 1G abcdefghijklmnopqrst (20)
     
/(.{15})/
Capturing subpattern count = 1
No options
No first char
No need char
    abcdefghijklmnopqrstuvwxyz
 0: abcdefghijklmno
 1: abcdefghijklmno
    abcdefghijklmnopqrstuvwxyz\C1\G1
 0: abcdefghijklmno
 1: abcdefghijklmno
 1C abcdefghijklmno (15)
 1G abcdefghijklmno (15)

/(.{16})/
Capturing subpattern count = 1
No options
No first char
No need char
    abcdefghijklmnopqrstuvwxyz
 0: abcdefghijklmnop
 1: abcdefghijklmnop
    abcdefghijklmnopqrstuvwxyz\C1\G1\L
 0: abcdefghijklmnop
 1: abcdefghijklmnop
copy substring 1 failed -6
 1G abcdefghijklmnop (16)
 0L abcdefghijklmnop
 1L abcdefghijklmnop
    
/^(a|(bc))de(f)/
Capturing subpattern count = 3
Options: anchored
No first char
Need char = 'f'
    adef\G1\G2\G3\G4\L 
 0: adef
 1: a
 2: <unset>
 3: f
 1G a (1)
 2G  (0)
 3G f (1)
get substring 4 failed -7
 0L adef
 1L a
 2L 
 3L f
    bcdef\G1\G2\G3\G4\L 
 0: bcdef
 1: bc
 2: bc
 3: f
 1G bc (2)
 2G bc (2)
 3G f (1)
get substring 4 failed -7
 0L bcdef
 1L bc
 2L bc
 3L f
    adefghijk\C0 
 0: adef
 1: a
 2: <unset>
 3: f
 0C adef (4)
    
/^abc\00def/
Capturing subpattern count = 0
Options: anchored
No first char
Need char = 'f'
    abc\00def\L\C0 
 0: abc\x00def
 0C abc (7)
 0L abc
    
/word ((?:[a-zA-Z0-9]+ )((?:[a-zA-Z0-9]+ )((?:[a-zA-Z0-9]+ )((?:[a-zA-Z0-9]+ 
)((?:[a-zA-Z0-9]+ )((?:[a-zA-Z0-9]+ )((?:[a-zA-Z0-9]+ )((?:[a-zA-Z0-9]+ 
)?)?)?)?)?)?)?)?)?otherword/M
Memory allocation (code space): 428
Capturing subpattern count = 8
No options
First char = 'w'
Need char = 'd'

/.*X/D
------------------------------------------------------------------
  0   8 Bra 0
  3     Any*
  5   1 X
  8   8 Ket
 11     End
------------------------------------------------------------------
Capturing subpattern count = 0
No options
First char at start or follows \n
Need char = 'X'

/.*X/Ds
------------------------------------------------------------------
  0   8 Bra 0
  3     Any*
  5   1 X
  8   8 Ket
 11     End
------------------------------------------------------------------
Capturing subpattern count = 0
Options: anchored dotall
No first char
Need char = 'X'

/(.*X|^B)/D
------------------------------------------------------------------
  0  21 Bra 0
  3   8 Bra 1
  6     Any*
  8   1 X
 11   7 Alt
 14     ^
 15   1 B
 18  15 Ket
 21  21 Ket
 24     End
------------------------------------------------------------------
Capturing subpattern count = 1
No options
First char at start or follows \n
No need char

/(.*X|^B)/Ds
------------------------------------------------------------------
  0  21 Bra 0
  3   8 Bra 1
  6     Any*
  8   1 X
 11   7 Alt
 14     ^
 15   1 B
 18  15 Ket
 21  21 Ket
 24     End
------------------------------------------------------------------
Capturing subpattern count = 1
Options: anchored dotall
No first char
No need char
    
/(?s)(.*X|^B)/D
------------------------------------------------------------------
  0  21 Bra 0
  3   8 Bra 1
  6     Any*
  8   1 X
 11   7 Alt
 14     ^
 15   1 B
 18  15 Ket
 21  21 Ket
 24     End
------------------------------------------------------------------
Capturing subpattern count = 1
Options: anchored dotall
No first char
No need char

/(?s:.*X|^B)/D
------------------------------------------------------------------
  0  27 Bra 0
  3  10 Bra 0
  6  04 Opt
  8     Any*
 10   1 X
 13   9 Alt
 16  04 Opt
 18     ^
 19   1 B
 22  19 Ket
 25  00 Opt
 27  27 Ket
 30     End
------------------------------------------------------------------
Capturing subpattern count = 0
No options
First char at start or follows \n
No need char

/\Biss\B/+
Capturing subpattern count = 0
No options
First char = 'i'
Need char = 's'
    Mississippi
 0: iss
 0+ issippi

/\Biss\B/+P
    Mississippi
 0: iss
 0+ issippi

/iss/G+
Capturing subpattern count = 0
No options
First char = 'i'
Need char = 's'
    Mississippi
 0: iss
 0+ issippi
 0: iss
 0+ ippi

/\Biss\B/G+
Capturing subpattern count = 0
No options
First char = 'i'
Need char = 's'
    Mississippi
 0: iss
 0+ issippi

/\Biss\B/g+
Capturing subpattern count = 0
No options
First char = 'i'
Need char = 's'
    Mississippi
 0: iss
 0+ issippi
 0: iss
 0+ ippi
    *** Failers
No match
    Mississippi\A
No match

/(?<=[Ms])iss/g+
Capturing subpattern count = 0
No options
First char = 'i'
Need char = 's'
    Mississippi
 0: iss
 0+ issippi
 0: iss
 0+ ippi

/(?<=[Ms])iss/G+
Capturing subpattern count = 0
No options
First char = 'i'
Need char = 's'
    Mississippi
 0: iss
 0+ issippi

/^iss/g+
Capturing subpattern count = 0
Options: anchored
No first char
Need char = 's'
    ississippi
 0: iss
 0+ issippi
    
/.*iss/g+
Capturing subpattern count = 0
No options
First char at start or follows \n
Need char = 's'
    abciss\nxyzisspqr 
 0: abciss
 0+ \x0axyzisspqr
 0: xyziss
 0+ pqr

/.i./+g
Capturing subpattern count = 0
No options
No first char
Need char = 'i'
    Mississippi
 0: Mis
 0+ sissippi
 0: sis
 0+ sippi
 0: sip
 0+ pi
    Mississippi\A
 0: Mis
 0+ sissippi
 0: sis
 0+ sippi
 0: sip
 0+ pi
    Missouri river
 0: Mis
 0+ souri river
 0: ri 
 0+ river
 0: riv
 0+ er
    Missouri river\A  
 0: Mis
 0+ souri river

/^.is/+g
Capturing subpattern count = 0
Options: anchored
No first char
Need char = 's'
    Mississippi
 0: Mis
 0+ sissippi

/^ab\n/g+
Capturing subpattern count = 0
Options: anchored
No first char
Need char = 10
    ab\nab\ncd
 0: ab\x0a
 0+ ab\x0acd

/^ab\n/mg+
Capturing subpattern count = 0
Options: multiline
First char at start or follows \n
Need char = 10
    ab\nab\ncd
 0: ab\x0a
 0+ ab\x0acd
 0: ab\x0a
 0+ cd

/abc/
Capturing subpattern count = 0
No options
First char = 'a'
Need char = 'c'

/abc|bac/
Capturing subpattern count = 0
No options
No first char
Need char = 'c'

/(abc|bac)/
Capturing subpattern count = 1
No options
No first char
Need char = 'c'

/(abc|(c|dc))/
Capturing subpattern count = 2
No options
No first char
Need char = 'c'

/(abc|(d|de)c)/
Capturing subpattern count = 2
No options
No first char
Need char = 'c'

/a*/
Capturing subpattern count = 0
No options
No first char
No need char

/a+/
Capturing subpattern count = 0
No options
First char = 'a'
No need char

/(baa|a+)/
Capturing subpattern count = 1
No options
No first char
Need char = 'a'

/a{0,3}/
Capturing subpattern count = 0
No options
No first char
No need char

/baa{3,}/
Capturing subpattern count = 0
No options
First char = 'b'
Need char = 'a'

/"([^\\"]+|\\.)*"/
Capturing subpattern count = 1
No options
First char = '"'
Need char = '"'

/(abc|ab[cd])/
Capturing subpattern count = 1
No options
First char = 'a'
No need char

/(a|.)/
Capturing subpattern count = 1
No options
No first char
No need char

/a|ba|\w/
Capturing subpattern count = 0
No options
No first char
No need char

/abc(?=pqr)/
Capturing subpattern count = 0
No options
First char = 'a'
Need char = 'r'

/...(?<=abc)/
Capturing subpattern count = 0
No options
No first char
No need char

/abc(?!pqr)/
Capturing subpattern count = 0
No options
First char = 'a'
Need char = 'c'

/ab./
Capturing subpattern count = 0
No options
First char = 'a'
Need char = 'b'

/ab[xyz]/
Capturing subpattern count = 0
No options
First char = 'a'
Need char = 'b'

/abc*/
Capturing subpattern count = 0
No options
First char = 'a'
Need char = 'b'

/ab.c*/
Capturing subpattern count = 0
No options
First char = 'a'
Need char = 'b'

/a.c*/
Capturing subpattern count = 0
No options
First char = 'a'
No need char

/.c*/
Capturing subpattern count = 0
No options
No first char
No need char

/ac*/
Capturing subpattern count = 0
No options
First char = 'a'
No need char

/(a.c*|b.c*)/
Capturing subpattern count = 1
No options
No first char
No need char

/a.c*|aba/
Capturing subpattern count = 0
No options
First char = 'a'
No need char

/.+a/
Capturing subpattern count = 0
No options
No first char
Need char = 'a'

/(?=abcda)a.*/
Capturing subpattern count = 0
No options
First char = 'a'
No need char

/(?=a)a.*/
Capturing subpattern count = 0
No options
First char = 'a'
No need char

/a(b)*/
Capturing subpattern count = 1
No options
First char = 'a'
No need char

/a\d*/
Capturing subpattern count = 0
No options
First char = 'a'
No need char

/ab\d*/
Capturing subpattern count = 0
No options
First char = 'a'
Need char = 'b'

/a(\d)*/
Capturing subpattern count = 1
No options
First char = 'a'
No need char

/abcde{0,0}/
Capturing subpattern count = 0
No options
First char = 'a'
Need char = 'd'

/ab\d+/
Capturing subpattern count = 0
No options
First char = 'a'
Need char = 'b'

/a(?(1)b)/
Capturing subpattern count = 0
No options
First char = 'a'
No need char

/a(?(1)bag|big)/
Capturing subpattern count = 0
No options
First char = 'a'
Need char = 'g'

/a(?(1)bag|big)*/
Capturing subpattern count = 0
No options
First char = 'a'
No need char

/a(?(1)bag|big)+/
Capturing subpattern count = 0
No options
First char = 'a'
Need char = 'g'

/a(?(1)b..|b..)/
Capturing subpattern count = 0
No options
First char = 'a'
Need char = 'b'

/ab\d{0}e/
Capturing subpattern count = 0
No options
First char = 'a'
Need char = 'e'

/a?b?/
Capturing subpattern count = 0
No options
No first char
No need char
    a
 0: a
    b
 0: b
    ab
 0: ab
    \
 0: 
    *** Failers
 0: 
    \N     
No match
    
/|-/
Capturing subpattern count = 0
No options
No first char
No need char
    abcd
 0: 
    -abc
 0: 
    \Nab-c
 0: -
    *** Failers
 0: 
    \Nabc     
No match

/a*(b+)(z)(z)/P
    aaaabbbbzzzz
 0: aaaabbbbzz
 1: bbbb
 2: z
 3: z
    aaaabbbbzzzz\O0
    aaaabbbbzzzz\O1
 0: aaaabbbbzz
    aaaabbbbzzzz\O2
 0: aaaabbbbzz
 1: bbbb
    aaaabbbbzzzz\O3
 0: aaaabbbbzz
 1: bbbb
 2: z
    aaaabbbbzzzz\O4
 0: aaaabbbbzz
 1: bbbb
 2: z
 3: z
    aaaabbbbzzzz\O5
 0: aaaabbbbzz
 1: bbbb
 2: z
 3: z
    
/^.?abcd/S 
Capturing subpattern count = 0
Options: anchored
No first char
Need char = 'd'
Study returned NULL

/\(             # ( at start
  (?:           # Non-capturing bracket
  (?>[^()]+)    # Either a sequence of non-brackets (no backtracking)
  |             # Or
  (?R)          # Recurse - i.e. nested bracketed string
  )*            # Zero or more contents
  \)            # Closing )
  /x
Capturing subpattern count = 0
Options: extended
First char = '('
Need char = ')'
    (abcd)
 0: (abcd)
    (abcd)xyz
 0: (abcd)
    xyz(abcd)
 0: (abcd)
    (ab(xy)cd)pqr 
 0: (ab(xy)cd)
    (ab(xycd)pqr 
 0: (xycd)
    () abc () 
 0: ()
    12(abcde(fsh)xyz(foo(bar))lmno)89
 0: (abcde(fsh)xyz(foo(bar))lmno)
    *** Failers
No match
    abcd 
No match
    abcd)
No match
    (abcd  
No match

/\(  ( (?>[^()]+) | (?R) )* \) /xg
Capturing subpattern count = 1
Options: extended
First char = '('
Need char = ')'
    (ab(xy)cd)pqr 
 0: (ab(xy)cd)
 1: cd
    1(abcd)(x(y)z)pqr
 0: (abcd)
 1: abcd
 0: (x(y)z)
 1: z

/\(  (?: (?>[^()]+) | (?R) ) \) /x
Capturing subpattern count = 0
Options: extended
First char = '('
Need char = ')'
    (abcd)
 0: (abcd)
    (ab(xy)cd)
 0: (xy)
    (a(b(c)d)e) 
 0: (c)
    ((ab)) 
 0: ((ab))
    *** Failers
No match
    ()   
No match

/\(  (?: (?>[^()]+) | (?R) )? \) /x
Capturing subpattern count = 0
Options: extended
First char = '('
Need char = ')'
    ()
 0: ()
    12(abcde(fsh)xyz(foo(bar))lmno)89
 0: (fsh)

/\(  ( (?>[^()]+) | (?R) )* \) /x
Capturing subpattern count = 1
Options: extended
First char = '('
Need char = ')'
    (ab(xy)cd)
 0: (ab(xy)cd)
 1: cd

/\( ( ( (?>[^()]+) | (?R) )* ) \) /x
Capturing subpattern count = 2
Options: extended
First char = '('
Need char = ')'
    (ab(xy)cd)
 0: (ab(xy)cd)
 1: ab(xy)cd
 2: cd

/\( (123)? ( ( (?>[^()]+) | (?R) )* ) \) /x
Capturing subpattern count = 3
Options: extended
First char = '('
Need char = ')'
    (ab(xy)cd)
 0: (ab(xy)cd)
 1: <unset>
 2: ab(xy)cd
 3: cd
    (123ab(xy)cd)
 0: (123ab(xy)cd)
 1: 123
 2: ab(xy)cd
 3: cd

/\( ( (123)? ( (?>[^()]+) | (?R) )* ) \) /x
Capturing subpattern count = 3
Options: extended
First char = '('
Need char = ')'
    (ab(xy)cd)
 0: (ab(xy)cd)
 1: ab(xy)cd
 2: <unset>
 3: cd
    (123ab(xy)cd)
 0: (123ab(xy)cd)
 1: 123ab(xy)cd
 2: 123
 3: cd

/\( (((((((((( ( (?>[^()]+) | (?R) )* )))))))))) \) /x
Capturing subpattern count = 11
Options: extended
First char = '('
Need char = ')'
    (ab(xy)cd)
 0: (ab(xy)cd)
 1: ab(xy)cd
 2: ab(xy)cd
 3: ab(xy)cd
 4: ab(xy)cd
 5: ab(xy)cd
 6: ab(xy)cd
 7: ab(xy)cd
 8: ab(xy)cd
 9: ab(xy)cd
10: ab(xy)cd
11: cd

/\( ( ( (?>[^()<>]+) | ((?>[^()]+)) | (?R) )* ) \) /x
Capturing subpattern count = 3
Options: extended
First char = '('
Need char = ')'
    (abcd(xyz<p>qrs)123)
 0: (abcd(xyz<p>qrs)123)
 1: abcd(xyz<p>qrs)123
 2: 123
 3: <p>qrs

/\( ( ( (?>[^()]+) | ((?R)) )* ) \) /x
Capturing subpattern count = 3
Options: extended
First char = '('
Need char = ')'
    (ab(cd)ef)
 0: (ab(cd)ef)
 1: ab(cd)ef
 2: ef
 3: (cd)
    (ab(cd(ef)gh)ij)
 0: (ab(cd(ef)gh)ij)
 1: ab(cd(ef)gh)ij
 2: ij
 3: (cd(ef)gh)

/^[[:alnum:]]/D
------------------------------------------------------------------
  0  37 Bra 0
  3     ^
  4     [0-9A-Za-z]
 37  37 Ket
 40     End
------------------------------------------------------------------
Capturing subpattern count = 0
Options: anchored
No first char
No need char

/^[[:alpha:]]/D
------------------------------------------------------------------
  0  37 Bra 0
  3     ^
  4     [A-Za-z]
 37  37 Ket
 40     End
------------------------------------------------------------------
Capturing subpattern count = 0
Options: anchored
No first char
No need char
             
/^[[:ascii:]]/D
------------------------------------------------------------------
  0  37 Bra 0
  3     ^
  4     [\x00-\x7f]
 37  37 Ket
 40     End
------------------------------------------------------------------
Capturing subpattern count = 0
Options: anchored
No first char
No need char

/^[[:cntrl:]]/D
------------------------------------------------------------------
  0  37 Bra 0
  3     ^
  4     [\x00-\x1f\x7f]
 37  37 Ket
 40     End
------------------------------------------------------------------
Capturing subpattern count = 0
Options: anchored
No first char
No need char

/^[[:digit:]]/D
------------------------------------------------------------------
  0  37 Bra 0
  3     ^
  4     [0-9]
 37  37 Ket
 40     End
------------------------------------------------------------------
Capturing subpattern count = 0
Options: anchored
No first char
No need char

/^[[:graph:]]/D
------------------------------------------------------------------
  0  37 Bra 0
  3     ^
  4     [!-~]
 37  37 Ket
 40     End
------------------------------------------------------------------
Capturing subpattern count = 0
Options: anchored
No first char
No need char

/^[[:lower:]]/D
------------------------------------------------------------------
  0  37 Bra 0
  3     ^
  4     [a-z]
 37  37 Ket
 40     End
------------------------------------------------------------------
Capturing subpattern count = 0
Options: anchored
No first char
No need char

/^[[:print:]]/D
------------------------------------------------------------------
  0  37 Bra 0
  3     ^
  4     [ -~]
 37  37 Ket
 40     End
------------------------------------------------------------------
Capturing subpattern count = 0
Options: anchored
No first char
No need char

/^[[:punct:]]/D
------------------------------------------------------------------
  0  37 Bra 0
  3     ^
  4     [!-/:-@[-`{-~]
 37  37 Ket
 40     End
------------------------------------------------------------------
Capturing subpattern count = 0
Options: anchored
No first char
No need char

/^[[:space:]]/D
------------------------------------------------------------------
  0  37 Bra 0
  3     ^
  4     [\x09-\x0d ]
 37  37 Ket
 40     End
------------------------------------------------------------------
Capturing subpattern count = 0
Options: anchored
No first char
No need char

/^[[:upper:]]/D
------------------------------------------------------------------
  0  37 Bra 0
  3     ^
  4     [A-Z]
 37  37 Ket
 40     End
------------------------------------------------------------------
Capturing subpattern count = 0
Options: anchored
No first char
No need char

/^[[:xdigit:]]/D
------------------------------------------------------------------
  0  37 Bra 0
  3     ^
  4     [0-9A-Fa-f]
 37  37 Ket
 40     End
------------------------------------------------------------------
Capturing subpattern count = 0
Options: anchored
No first char
No need char

/^[[:word:]]/D
------------------------------------------------------------------
  0  37 Bra 0
  3     ^
  4     [0-9A-Z_a-z]
 37  37 Ket
 40     End
------------------------------------------------------------------
Capturing subpattern count = 0
Options: anchored
No first char
No need char

/^[[:^cntrl:]]/D
------------------------------------------------------------------
  0  37 Bra 0
  3     ^
  4     [ -~\x80-\xff]
 37  37 Ket
 40     End
------------------------------------------------------------------
Capturing subpattern count = 0
Options: anchored
No first char
No need char

/^[12[:^digit:]]/D
------------------------------------------------------------------
  0  37 Bra 0
  3     ^
  4     [\x00-/1-2:-\xff]
 37  37 Ket
 40     End
------------------------------------------------------------------
Capturing subpattern count = 0
Options: anchored
No first char
No need char

/[01[:alpha:]%]/D
------------------------------------------------------------------
  0  36 Bra 0
  3     [%0-1A-Za-z]
 36  36 Ket
 39     End
------------------------------------------------------------------
Capturing subpattern count = 0
No options
No first char
No need char

/[[.ch.]]/
Failed: POSIX collating elements are not supported at offset 1

/[[=ch=]]/
Failed: POSIX collating elements are not supported at offset 1

/[[:rhubarb:]]/
Failed: unknown POSIX class name at offset 3

/[[:upper:]]/i
Capturing subpattern count = 0
Options: caseless
No first char
No need char
    A
 0: A
    a 
 0: a
    
/[[:lower:]]/i
Capturing subpattern count = 0
Options: caseless
No first char
No need char
    A
 0: A
    a 
 0: a

/((?-i)[[:lower:]])[[:lower:]]/i
Capturing subpattern count = 1
Options: caseless
Case state changes
No first char
No need char
    ab
 0: ab
 1: a
    aB
 0: aB
 1: a
    *** Failers
 0: ai
 1: a
    Ab
No match
    AB        
No match

/ End of test input /
Capturing subpattern count = 0
No options
First char = ' '
Need char = ' '