Regular Expressions 101

Explanation

Pro

^start of line

Negative Lookahead(?!.*\b(\d+)\b.*\b\1\b)

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

\ban ASCII word boundary

Group 1(\d+)

\d+a digit, repeated at least once

\ban ASCII word boundary

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

\ban ASCII word boundary

\1the text saved by group 1

\ban ASCII word boundary

\d+a digit, repeated at least once

Non-Capturing Group(?:([.\s,])\d+)

Group 2([.\s,])

Character Class[.\s,]

.the literal . (46₁₀ / 56₈ / 2E₁₆)

\sany whitespace character

,the literal , (44₁₀ / 54₈ / 2C₁₆)

\d+a digit, repeated at least once

Non-Capturing Group(?:\2\d+)*

*repeats the group contents below any number of times:

\2the text saved by group 2

\d+a digit, repeated at least once

$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

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25 tokens

^(?!.*\b(\d+)\b.*\b\1\b)\d+(?:([.\s,])\d+)(?:\2\d+)*$

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