regex101: INI Parser for .NET

1st Alternative(?=\S)(?<text>(?<comment>(?<open>[#;]+)(?:[^\S\r\n]*)(?<value>.+))|(?<section>(?<open>\[)(?:\s*)(?<value>[^\]]*\S+)(?:[^\S\r\n]*)(?<close>\]))|(?<entry>(?<key>[^=\r\n\[\]]*\S)(?:[^\S\r\n]*)(?<delimiter>:|=)(?:\s*(?<value>\{(?:[^{}""]+|""(?:\\.|[^""])*""|(?<o>\{)|(?<-o>\}))*(?(o)(?!))\})|((?:[^\S\r\n]*)(?<value>[^#;\r\n]*))))|(?<undefined>.+))(?<=\S)

Positive Lookahead(?=\S)

\Sany character that is not Unicode whitespace

Group text(?<text>(?<comment>(?<open>[#;]+)(?:[^\S\r\n]*)(?<value>.+))|(?<section>(?<open>\[)(?:\s*)(?<value>[^\]]*\S+)(?:[^\S\r\n]*)(?<close>\]))|(?<entry>(?<key>[^=\r\n\[\]]*\S)(?:[^\S\r\n]*)(?<delimiter>:|=)(?:\s*(?<value>\{(?:[^{}""]+|""(?:\\.|[^""])*""|(?<o>\{)|(?<-o>\}))*(?(o)(?!))\})|((?:[^\S\r\n]*)(?<value>[^#;\r\n]*))))|(?<undefined>.+))

1st Alternative(?<comment>(?<open>[#;]+)(?:[^\S\r\n]*)(?<value>.+))

Group comment(?<comment>(?<open>[#;]+)(?:[^\S\r\n]*)(?<value>.+))

Group open(?<open>[#;]+)

Character Class[#;]+

+matches at least one character from the set below:

#the literal # (35₁₀ / 43₈ / 23₁₆)

;the literal ; (59₁₀ / 73₈ / 3B₁₆)

Non-Capturing Group(?:[^\S\r\n]*)

Negated Character Class[^\S\r\n]*

*matches any number of characters outside the set below:

\Sany character that is not Unicode whitespace

\ra carriage return (ASCII 13)

\na line-feed (newline) character (ASCII 10)

Group value(?<value>.+)

.+any Unicode character (except for line terminators), repeated at least once

2nd Alternative(?<section>(?<open>\[)(?:\s*)(?<value>[^\]]*\S+)(?:[^\S\r\n]*)(?<close>\]))

Group section(?<section>(?<open>\[)(?:\s*)(?<value>[^\]]*\S+)(?:[^\S\r\n]*)(?<close>\]))

Group open(?<open>\[)

\[the literal [ (91₁₀ / 133₈ / 5B₁₆)

Non-Capturing Group(?:\s*)

\s*a Unicode whitespace character, repeated any number of times

Group value(?<value>[^\]]*\S+)

Negated Character Class[^\]]*

*matches any number of characters outside the set below:

\]the literal ] (93₁₀ / 135₈ / 5D₁₆)

\S+any character that is not Unicode whitespace, repeated at least once

Non-Capturing Group(?:[^\S\r\n]*)

Negated Character Class[^\S\r\n]*

*matches any number of characters outside the set below:

\Sany character that is not Unicode whitespace

\ra carriage return (ASCII 13)

\na line-feed (newline) character (ASCII 10)

Group close(?<close>\])

\]the literal ] (93₁₀ / 135₈ / 5D₁₆)

3rd Alternative(?<entry>(?<key>[^=\r\n\[\]]*\S)(?:[^\S\r\n]*)(?<delimiter>:|=)(?:\s*(?<value>\{(?:[^{}""]+|""(?:\\.|[^""])*""|(?<o>\{)|(?<-o>\}))*(?(o)(?!))\})|((?:[^\S\r\n]*)(?<value>[^#;\r\n]*))))

Group entry(?<entry>(?<key>[^=\r\n\[\]]*\S)(?:[^\S\r\n]*)(?<delimiter>:|=)(?:\s*(?<value>\{(?:[^{}""]+|""(?:\\.|[^""])*""|(?<o>\{)|(?<-o>\}))*(?(o)(?!))\})|((?:[^\S\r\n]*)(?<value>[^#;\r\n]*))))

Group key(?<key>[^=\r\n\[\]]*\S)

Negated Character Class[^=\r\n\[\]]*

*matches any number of characters outside the set below:

=the literal = (61₁₀ / 75₈ / 3D₁₆)

\ra carriage return (ASCII 13)

\na line-feed (newline) character (ASCII 10)

\[the literal [ (91₁₀ / 133₈ / 5B₁₆)

\]the literal ] (93₁₀ / 135₈ / 5D₁₆)

\Sany character that is not Unicode whitespace

Non-Capturing Group(?:[^\S\r\n]*)

Negated Character Class[^\S\r\n]*

*matches any number of characters outside the set below:

\Sany character that is not Unicode whitespace

\ra carriage return (ASCII 13)

\na line-feed (newline) character (ASCII 10)

Group delimiter(?<delimiter>:|=)

Non-Capturing Group(?:\s*(?<value>\{(?:[^{}""]+|""(?:\\.|[^""])*""|(?<o>\{)|(?<-o>\}))*(?(o)(?!))\})|((?:[^\S\r\n]*)(?<value>[^#;\r\n]*)))

4th Alternative(?<undefined>.+)

Positive Lookbehind(?<=\S)

2nd Alternative(?<linebreaker>\r\n|\n)

3rd Alternative(?<whitespace>[^\S\r\n]+)

Global pattern flags

i modifier: insensitive. Matches without distinguishing uppercase and lowercase letters

g modifier: global. Finds all matches instead of stopping after the first

Search reference

Regular Expression

(?=\S)(?<text>(?<comment>(?<open>[#;]+)(?:[^\S\r\n]*)(?<value>.+))|(?<section>(?<open>\[)(?:\s*)(?<value>[^\]]*\S+)(?:[^\S\r\n]*)(?<close>\]))|(?<entry>(?<key>[^=\r\n\[\]]*\S)(?:[^\S\r\n]*)(?<delimiter>:|=)(?:\s*(?<value>\{(?:[^{}""]+|""(?:\\.|[^""])*""|(?<o>\{)|(?<-o>\}))*(?(o)(?!))\})|((?:[^\S\r\n]*)(?<value>[^#;\r\n]*))))|(?<undefined>.+))(?<=\S)|(?<linebreaker>\r\n|\n)|(?<whitespace>[^\S\r\n]+)

New

;   Comment above the section
Key0=Value0 # Global entries
[Section 1]
Key=Value 
  [EmptySection]
Dummy text
;Commented Key=Value
;The following empty lines are ignored
;
  #    
   
  [  Section 2  ]#Comment after  [section]
 Key 1 = Value 1
     Key2 =            Value 2 and [text in square brackets]
     EmptyKey=
     JsonKey = 
     {
        "a":"b"
     }
[];Noname section ignored
 [ Section2    ] Dummy text after section
   Key3   =Value 3 (symbols [] are included)  ;Inline comment
   #Key4   =   Value 4 has been commented   

Dummy text before section    [   Sectionnum3   ]      
  Key 5 =   Value    5  
  Key6   =Value6

Regular Expressions 101

Regular Expression

Extraction