regex101: Python Match Workspace

^start of line

Comment: A block, 0 or several times, with 2 alternatives:

Non-Capturing Group(?: # A valid char: letter, space or a simple punctuation char. [\w \-.,:;!?'\"] | # Brackets with a var of max 15 chars, with optional spaces around: \[\s* # Opening bracket and optional spaces. [a-z][a-z_0-9]{,14} # A valid variable name. \s*\] # Optional spaces and closing bracket. )*

*repeats the group contents below any number of times:

1st Alternative # A valid char: letter, space or a simple punctuation char. [\w \-.,:;!?'\"]

Comment: A valid char: letter, space or a simple punctuation char.

Character Class[\w \-.,:;!?'\"]

\wa Unicode word character

the literal (32₁₀ / 40₈ / 20₁₆)

\-the literal - (45₁₀ / 55₈ / 2D₁₆)

.the literal . (46₁₀ / 56₈ / 2E₁₆)

,the literal , (44₁₀ / 54₈ / 2C₁₆)

:the literal : (58₁₀ / 72₈ / 3A₁₆)

;the literal ; (59₁₀ / 73₈ / 3B₁₆)

!the literal ! (33₁₀ / 41₈ / 21₁₆)

?the literal ? (63₁₀ / 77₈ / 3F₁₆)

'the literal ' (39₁₀ / 47₈ / 27₁₆)

\"the literal " (34₁₀ / 42₈ / 22₁₆)

2nd Alternative # Brackets with a var of max 15 chars, with optional spaces around: \[\s* # Opening bracket and optional spaces. [a-z][a-z_0-9]{,14} # A valid variable name. \s*\] # Optional spaces and closing bracket.

Comment: Brackets with a var of max 15 chars, with optional spaces around:

\[the literal [ (91₁₀ / 133₈ / 5B₁₆)

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

Comment: Opening bracket and optional spaces.

Character Class[a-z]

a-zone character from a (97₁₀) to z (122₁₀) (case insensitive)

Character Class[a-z_0-9]{,14}

{,14}matches between 0 and 14 characters from the set below:

a-zone character from a (97₁₀) to z (122₁₀) (case insensitive)

_the literal _ (95₁₀ / 137₈ / 5F₁₆)

0-9one character from 0 (48₁₀) to 9 (57₁₀)

Comment: A valid variable name.

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

\]the literal ] (93₁₀ / 135₈ / 5D₁₆)

Comment: Optional spaces and closing bracket.

$end of line

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

u modifier: unicode. Makes \w, \W, \b, \B, \d, \D, \s, and \S use Unicode semantics (redundant in Python 3)

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

Search reference

Regular Expression

^
# A block, 0 or several times, with 2 alternatives:
(?:
  # A valid char: letter, space or a simple punctuation char.
  [\w \-.,:;!?'\"]
|
  # Brackets with a var of max 15 chars, with optional spaces around:
  \[\s*                # Opening bracket and optional spaces.
  [a-z][a-z_0-9]{,14}  # A valid variable name.
  \s*\]                # Optional spaces and closing bracket.
)*
$

Test String
New

### Valid

Your [text] message here
[username] wrote [text]
your_text_message [text]
With optional spaces in around the word [ text ] [ user_id]
A message without brackets, but with "valid" punctuation.
Accents allowed with unicode support, it's Okây?

### Invalid

Your [] message here
[] message
Missing text between brackets [   ]
To much stuff between brackets [A23456789B123456]
Again word more than 15 chars [ this_one_is_long ]
Invalid var name: [not-valid-var]
Invalid var name: [2do]
Invalid var name: [user.name], could be accepted if you change the rule.

Regular Expressions 101

Regular Expression

Test String
New

Substitution
Processing...

Regular Expression

Test StringNew

SubstitutionProcessing...

Test String
New

Substitution
Processing...