Regular Expressions 101

Pro

Group 1(\\begin{(.+atrix|.*rray|.*abular)}[^\\]*)

\\the literal \ (92₁₀ / 134₈ / 5C₁₆)

begin{the literal text begin{ (case sensitive)

Group 2(.+atrix|.*rray|.*abular)

1st Alternative.+atrix

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

atrixthe literal text atrix (case sensitive)

2nd Alternative.*rray

.*any character (except for line terminators), repeated any number of times

rraythe literal text rray (case sensitive)

3rd Alternative.*abular

.*any character (except for line terminators), repeated any number of times

abularthe literal text abular (case sensitive)

}the literal } (125₁₀ / 175₈ / 7D₁₆)

Negated Character Class[^\\]*

*matches any number of characters outside the set below:

\\the literal \ (92₁₀ / 134₈ / 5C₁₆)

Group 3( )*

*repeats the group contents below any number of times:

the literal (32₁₀ / 40₈ / 20₁₆)

\vany vertical whitespace character

Group 4(\X*\\end{\g2})

\X*one Unicode extended grapheme cluster, repeated any number of times

\\the literal \ (92₁₀ / 134₈ / 5C₁₆)

end{the literal text end{ (case sensitive)

\g2the text saved by group 2

}the literal } (125₁₀ / 175₈ / 7D₁₆)

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

Ready to run

25 tokens

(\\begin{(.+atrix|.*rray|.*abular)}[^\\]*)( )*\v(\X*\\end{\g2})