regex101: Python Substitution Workspace

Pro

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

Non-Capturing Group(?:\[[^][]*]|$[^()]*$)

1st Alternative\[[^][]*]

\[the literal [ (91₁₀ / 133₈ / 5B₁₆)

Negated Character Class[^][]*

*matches any number of characters outside the set below:

]the literal ] (93₁₀ / 135₈ / 5D₁₆)

[the literal [ (91₁₀ / 133₈ / 5B₁₆)

]the literal ] (93₁₀ / 135₈ / 5D₁₆)

2nd Alternative$[^()]*$

\(the literal ( (40₁₀ / 50₈ / 28₁₆)

Negated Character Class[^()]*

*matches any number of characters outside the set below:

(the literal ( (40₁₀ / 50₈ / 28₁₆)

)the literal ) (41₁₀ / 51₈ / 29₁₆)

\)the literal ) (41₁₀ / 51₈ / 29₁₆)

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

$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

25 tokens

Regular Expression

\s*(?:\[[^][]*]|\([^()]*\))\s*$

New

Old Macdonald had a farm         [Written by ABC rewrite] 
Wheels on the bus                 (Source: Melon)
Tayo the bus                      [Produced by Wills Garage]
James and Giant Apple             (Source: Kismet)
[Old Macdonald] had a farm         [Written by ABC rewrite] 
Wheels on the (old) bus                 (Source: Melon)
Tayo [the [bus]]                      [Produced by Wills Garage]
James () and Giant[] Apple()             (Source: Kismet)

Extraction

Old Macdonald had a farm         [Written by ABC rewrite] 
Wheels on the bus                 (Source: Melon)
Tayo the bus                      [Produced by Wills Garage]
James and Giant Apple             (Source: Kismet)
[Old Macdonald] had a farm         [Written by ABC rewrite] 
Wheels on the (old) bus                 (Source: Melon)
Tayo [the [bus]]                      [Produced by Wills Garage]
James () and Giant[] Apple()             (Source: Kismet)