regex101: PCRE (Legacy) Match Workspace

Group link_all(?<link_all> # Check it was not escaped with a \ (?:(?:\\|\!)\[(*SKIP)(*FAIL)|\[) # Cannot be preceded by an anti-slash nor an exclamation mark (image) (?<link_name> (?!\^) # Make sure, this is not confused with a footnote (?>\\[\[\]]|[^\[\]])*+ # Link text ) (?<!\\) \] (?: (?: [ ]? # possibly followed by some spaces (?:\n[ ]*)? # and a new line with some space (?<!\\)\[ (?!\^) # Make sure, this is not confused with a footnote (?<link_id>.*?) (?<!\\)\] # with the link id in brackets, but may be empty ) | (?: (?<!\\)\( # Get the link, from the most specific to the least one [ \t]* (?: <(?<link_url>.*?)> # link url within <>; or | (?<link_url> # link url without <> (?:(?:http|https):\/\/(?:(?:(?:(?:(?:(?:[a-zA-Z0-9][-a-zA-Z0-9]*)?[a-zA-Z0-9])[.])*(?:[a-zA-Z][-a-zA-Z0-9]*[a-zA-Z0-9]|[a-zA-Z])[.]?)|(?:[0-9]+[.][0-9]+[.][0-9]+[.][0-9]+)))(?::(?:(?:[0-9]*)))?(?:\/(?:(?:(?:(?:(?:(?:[a-zA-Z0-9\-_.!~*'():@&=+\$,]+|(?:%[a-fA-F0-9][a-fA-F0-9]))*)(?:;(?:(?:[a-zA-Z0-9\-_.!~*'():@&=+\$,]+|(?:%[a-fA-F0-9][a-fA-F0-9]))*))*)(?:\/(?:(?:(?:[a-zA-Z0-9\-_.!~*'():@&=+\$,]+|(?:%[a-fA-F0-9][a-fA-F0-9]))*)(?:;(?:(?:[a-zA-Z0-9\-_.!~*'():@&=+\$,]+|(?:%[a-fA-F0-9][a-fA-F0-9]))*))*))*))(?:[?](?:(?:(?:[;\/?:@&=+\$,a-zA-Z0-9\-_.!~*'()]+|(?:%[a-fA-F0-9][a-fA-F0-9]))*)))?))?) ) | (?<link_url>.*?) ) [ \t]* # possibly followed by some spaces or tabs (?: (?<link_title_container>['"]) # Title is surrounded ether by double or single quotes (?<link_title>.*?) # actual title, but could be empty as in "" \g{link_title_container} # make sure the enclosing mark balance )? [ \t]* (?<!\\)\) (?![[:blank:]\h]+["'][^"']+["']) ) ) )

Comment: Check it was not escaped with a \

Non-Capturing Group(?:(?:\\|\!)\[(*SKIP)(*FAIL)|\[)

1st Alternative(?:\\|\!)\[(*SKIP)(*FAIL)

Non-Capturing Group(?:\\|\!)

1st Alternative\\

\\the literal \ (92₁₀ / 134₈ / 5C₁₆)

2nd Alternative\!

\!the literal ! (33₁₀ / 41₈ / 21₁₆)

\[the literal [ (91₁₀ / 133₈ / 5B₁₆)

(*SKIP)acts like (*PRUNE), but the next unanchored match attempt starts where (*SKIP) was reached instead of at the next subject character

(*FAIL)forces the current match attempt to fail at this position

2nd Alternative\[

\[the literal [ (91₁₀ / 133₈ / 5B₁₆)

Comment: Cannot be preceded by an anti-slash nor an exclamation mark (image)

Group link_name(?<link_name> (?!\^) # Make sure, this is not confused with a footnote (?>\\[\[\]]|[^\[\]])*+ # Link text )

Negative Lookahead(?!\^)

\^the literal ^ (94₁₀ / 136₈ / 5E₁₆)

Comment: Make sure, this is not confused with a footnote

Atomic Group(?>\\[\[\]]|[^\[\]])*+

*+repeats the group contents below any number of times:

1st Alternative\\[\[\]]

\\the literal \ (92₁₀ / 134₈ / 5C₁₆)

Character Class[\[\]]

\[the literal [ (91₁₀ / 133₈ / 5B₁₆)

\]the literal ] (93₁₀ / 135₈ / 5D₁₆)

2nd Alternative[^\[\]]

Negated Character Class[^\[\]]

\[the literal [ (91₁₀ / 133₈ / 5B₁₆)

\]the literal ] (93₁₀ / 135₈ / 5D₁₆)

Comment: Link text

Negative Lookbehind(?<!\\)

\\the literal \ (92₁₀ / 134₈ / 5C₁₆)

\]the literal ] (93₁₀ / 135₈ / 5D₁₆)

Non-Capturing Group(?: (?: [ ]? # possibly followed by some spaces (?:\n[ ]*)? # and a new line with some space (?<!\\)\[ (?!\^) # Make sure, this is not confused with a footnote (?<link_id>.*?) (?<!\\)\] # with the link id in brackets, but may be empty ) | (?: (?<!\\)\( # Get the link, from the most specific to the least one [ \t]* (?: <(?<link_url>.*?)> # link url within <>; or | (?<link_url> # link url without <> (?:(?:http|https):\/\/(?:(?:(?:(?:(?:(?:[a-zA-Z0-9][-a-zA-Z0-9]*)?[a-zA-Z0-9])[.])*(?:[a-zA-Z][-a-zA-Z0-9]*[a-zA-Z0-9]|[a-zA-Z])[.]?)|(?:[0-9]+[.][0-9]+[.][0-9]+[.][0-9]+)))(?::(?:(?:[0-9]*)))?(?:\/(?:(?:(?:(?:(?:(?:[a-zA-Z0-9\-_.!~*'():@&=+\$,]+|(?:%[a-fA-F0-9][a-fA-F0-9]))*)(?:;(?:(?:[a-zA-Z0-9\-_.!~*'():@&=+\$,]+|(?:%[a-fA-F0-9][a-fA-F0-9]))*))*)(?:\/(?:(?:(?:[a-zA-Z0-9\-_.!~*'():@&=+\$,]+|(?:%[a-fA-F0-9][a-fA-F0-9]))*)(?:;(?:(?:[a-zA-Z0-9\-_.!~*'():@&=+\$,]+|(?:%[a-fA-F0-9][a-fA-F0-9]))*))*))*))(?:[?](?:(?:(?:[;\/?:@&=+\$,a-zA-Z0-9\-_.!~*'()]+|(?:%[a-fA-F0-9][a-fA-F0-9]))*)))?))?) ) | (?<link_url>.*?) ) [ \t]* # possibly followed by some spaces or tabs (?: (?<link_title_container>['"]) # Title is surrounded ether by double or single quotes (?<link_title>.*?) # actual title, but could be empty as in "" \g{link_title_container} # make sure the enclosing mark balance )? [ \t]* (?<!\\)\) (?![[:blank:]\h]+["'][^"']+["']) ) )

1st Alternative (?: [ ]? # possibly followed by some spaces (?:\n[ ]*)? # and a new line with some space (?<!\\)\[ (?!\^) # Make sure, this is not confused with a footnote (?<link_id>.*?) (?<!\\)\] # with the link id in brackets, but may be empty )

Non-Capturing Group(?: [ ]? # possibly followed by some spaces (?:\n[ ]*)? # and a new line with some space (?<!\\)\[ (?!\^) # Make sure, this is not confused with a footnote (?<link_id>.*?) (?<!\\)\] # with the link id in brackets, but may be empty )

Character Class[ ]?

?matches at most one character from the set below:

the literal (32₁₀ / 40₈ / 20₁₆)

Comment: possibly followed by some spaces

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

?repeats the group contents below at most once:

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

Character Class[ ]*

*matches any number of characters from the set below:

the literal (32₁₀ / 40₈ / 20₁₆)

Comment: and a new line with some space

Negative Lookbehind(?<!\\)

\\the literal \ (92₁₀ / 134₈ / 5C₁₆)

\[the literal [ (91₁₀ / 133₈ / 5B₁₆)

Negative Lookahead(?!\^)

\^the literal ^ (94₁₀ / 136₈ / 5E₁₆)

Comment: Make sure, this is not confused with a footnote

Group link_id(?<link_id>.*?)

.*?any character, repeated any number of times

Negative Lookbehind(?<!\\)

\\the literal \ (92₁₀ / 134₈ / 5C₁₆)

\]the literal ] (93₁₀ / 135₈ / 5D₁₆)

Comment: with the link id in brackets, but may be empty

2nd Alternative (?: (?<!\\)\( # Get the link, from the most specific to the least one [ \t]* (?: <(?<link_url>.*?)> # link url within <>; or | (?<link_url> # link url without <> (?:(?:http|https):\/\/(?:(?:(?:(?:(?:(?:[a-zA-Z0-9][-a-zA-Z0-9]*)?[a-zA-Z0-9])[.])*(?:[a-zA-Z][-a-zA-Z0-9]*[a-zA-Z0-9]|[a-zA-Z])[.]?)|(?:[0-9]+[.][0-9]+[.][0-9]+[.][0-9]+)))(?::(?:(?:[0-9]*)))?(?:\/(?:(?:(?:(?:(?:(?:[a-zA-Z0-9\-_.!~*'():@&=+\$,]+|(?:%[a-fA-F0-9][a-fA-F0-9]))*)(?:;(?:(?:[a-zA-Z0-9\-_.!~*'():@&=+\$,]+|(?:%[a-fA-F0-9][a-fA-F0-9]))*))*)(?:\/(?:(?:(?:[a-zA-Z0-9\-_.!~*'():@&=+\$,]+|(?:%[a-fA-F0-9][a-fA-F0-9]))*)(?:;(?:(?:[a-zA-Z0-9\-_.!~*'():@&=+\$,]+|(?:%[a-fA-F0-9][a-fA-F0-9]))*))*))*))(?:[?](?:(?:(?:[;\/?:@&=+\$,a-zA-Z0-9\-_.!~*'()]+|(?:%[a-fA-F0-9][a-fA-F0-9]))*)))?))?) ) | (?<link_url>.*?) ) [ \t]* # possibly followed by some spaces or tabs (?: (?<link_title_container>['"]) # Title is surrounded ether by double or single quotes (?<link_title>.*?) # actual title, but could be empty as in "" \g{link_title_container} # make sure the enclosing mark balance )? [ \t]* (?<!\\)\) (?![[:blank:]\h]+["'][^"']+["']) )

Global pattern flags

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

m modifier: multiline. Causes ^ and $ to match the start and end of each line, not only the start and end of the string

x modifier: extended. Ignores unescaped whitespace and comments outside character classes

J modifier: Allow duplicate subpattern names

s modifier: single line. Allows a dot to match line terminators

25 tokens

Regular Expression

(?<link_all>                                        # Check it was not escaped with a \
    (?:(?:\\|\!)\[(*SKIP)(*FAIL)|\[)                # Cannot be preceded by an anti-slash nor an exclamation mark (image)
    (?<link_name>
        (?!\^)                                      # Make sure, this is not confused with a footnote
        (?>\\[\[\]]|[^\[\]])*+                      # Link text
    )
    (?<!\\)
    \]
    (?:
        (?:
            [ ]?                                    # possibly followed by some spaces
            (?:\n[ ]*)?                             # and a new line with some space
            (?<!\\)\[
                (?!\^)                              # Make sure, this is not confused with a footnote
                (?<link_id>.*?)
            (?<!\\)\]                               # with the link id in brackets, but may be empty
        )
        |
        (?:
            (?<!\\)\(                               # Get the link, from the most specific to the least one
                [ \t]*
                (?:
                    <(?<link_url>.*?)>              # link url within <>; or
                    |
                    (?<link_url>                    # link url without <>
(?:(?:http|https):\/\/(?:(?:(?:(?:(?:(?:[a-zA-Z0-9][-a-zA-Z0-9]*)?[a-zA-Z0-9])[.])*(?:[a-zA-Z][-a-zA-Z0-9]*[a-zA-Z0-9]|[a-zA-Z])[.]?)|(?:[0-9]+[.][0-9]+[.][0-9]+[.][0-9]+)))(?::(?:(?:[0-9]*)))?(?:\/(?:(?:(?:(?:(?:(?:[a-zA-Z0-9\-_.!~*'():@&=+\$,]+|(?:%[a-fA-F0-9][a-fA-F0-9]))*)(?:;(?:(?:[a-zA-Z0-9\-_.!~*'():@&=+\$,]+|(?:%[a-fA-F0-9][a-fA-F0-9]))*))*)(?:\/(?:(?:(?:[a-zA-Z0-9\-_.!~*'():@&=+\$,]+|(?:%[a-fA-F0-9][a-fA-F0-9]))*)(?:;(?:(?:[a-zA-Z0-9\-_.!~*'():@&=+\$,]+|(?:%[a-fA-F0-9][a-fA-F0-9]))*))*))*))(?:[?](?:(?:(?:[;\/?:@&=+\$,a-zA-Z0-9\-_.!~*'()]+|(?:%[a-fA-F0-9][a-fA-F0-9]))*)))?))?)
                    )
                    |
                    (?<link_url>.*?)
                )
                [ \t]*                              # possibly followed by some spaces or tabs
                (?:
                    (?<link_title_container>['"])   # Title is surrounded ether by double or single quotes
                    (?<link_title>.*?)              # actual title, but could be empty as in ""
                    \g{link_title_container}        # make sure the enclosing mark balance
                )?
                [ \t]*
            (?<!\\)\)
            (?![[:blank:]\h]+["'][^"']+["'])
        )
    )
)

New

[Inline link 3 with non-escaped parens](/url(test) "title")

Foo [bar]

This one has a [line
break][].

Foo [^bar][]

Should not match this one:
![Alt text](/path/to/img.jpg)

Nor this one:
\[Alt text](/path/to/img.jpg)

[URL and title](/url/ "title has spaces afterward"  ).

[With parens in the URL](http://en.wikipedia.org/wiki/WIMP_(computing))