Regular Expressions 101

Pro

^start of string

Group weekdays(?<weekdays> ( \b (?<weeks>mon|tue|wed|thu|fri|sat|sun) (?:\.\.(?&weeks))? ,? )+ )

Group 2( \b (?<weeks>mon|tue|wed|thu|fri|sat|sun) (?:\.\.(?&weeks))? ,? )+

+repeats the group contents below at least once:

\ban ASCII word boundary

Group weeks(?<weeks>mon|tue|wed|thu|fri|sat|sun)

1st Alternativemon

monthe literal text mon (case insensitive)

2nd Alternativetue

tuethe literal text tue (case insensitive)

3rd Alternativewed

wedthe literal text wed (case insensitive)

4th Alternativethu

thuthe literal text thu (case insensitive)

5th Alternativefri

frithe literal text fri (case insensitive)

6th Alternativesat

satthe literal text sat (case insensitive)

7th Alternativesun

sunthe literal text sun (case insensitive)

Non-Capturing Group(?:\.\.(?&weeks))?

?repeats the group contents below at most once:

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

(?&weeks)calls group weeks as a subroutine

,?optionally matches the literal , (44₁₀ / 54₈ / 2C₁₆)

$end of string, or before its final line terminator

Global pattern flags

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

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

Ready to run

25 tokens

^(?<weekdays>
    (                        
        \b
        (?<weeks>mon|tue|wed|thu|fri|sat|sun)
        (?:\.\.(?&weeks))?
        ,?
    )+
)$