Regular Expressions 101

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/
(?:^.*\s([^:,\s]+):\s+([^:\n]+)|\G(?!\A))\s*at\s+(\S+)\((\w+\.\w+):(\d+)\)$
/
gm
Non-capturing group
(?:^.*\s([^:,\s]+):\s+([^:\n]+)|\G(?!\A))
1st Alternative
^.*\s([^:,\s]+):\s+([^:\n]+)
^ asserts position at start of a line
.
matches any character (except for line terminators)
* matches the previous token between zero and unlimited times, as many times as possible, giving back as needed (greedy)
\s matches any whitespace character (equivalent to [\r\n\t\f\v ])
1st Capturing Group
([^:,\s]+)
Match a single character not present in the list below
[^:,\s]
+ matches the previous token between one and unlimited times, as many times as possible, giving back as needed (greedy)
:,
matches a single character in the list :, (case sensitive)
\s matches any whitespace character (equivalent to [\r\n\t\f\v ])
: matches the character : with index 5810 (3A16 or 728) literally (case sensitive)
\s
matches any whitespace character (equivalent to [\r\n\t\f\v ])
+ matches the previous token between one and unlimited times, as many times as possible, giving back as needed (greedy)
2nd Capturing Group
([^:\n]+)
Match a single character not present in the list below
[^:\n]
+ matches the previous token between one and unlimited times, as many times as possible, giving back as needed (greedy)
: matches the character : with index 5810 (3A16 or 728) literally (case sensitive)
\n matches a line-feed (newline) character (ASCII 10)
2nd Alternative
\G(?!\A)
\G asserts position at the end of the previous match or the start of the string for the first match
Negative Lookahead
(?!\A)
Assert that the Regex below does not match
\A asserts position at start of the string
\s
matches any whitespace character (equivalent to [\r\n\t\f\v ])
* matches the previous token between zero and unlimited times, as many times as possible, giving back as needed (greedy)
at
matches the characters at literally (case sensitive)
\s
matches any whitespace character (equivalent to [\r\n\t\f\v ])
+ matches the previous token between one and unlimited times, as many times as possible, giving back as needed (greedy)
3rd Capturing Group
(\S+)
\S
matches any non-whitespace character (equivalent to [^\r\n\t\f\v ])
+ matches the previous token between one and unlimited times, as many times as possible, giving back as needed (greedy)
\( matches the character ( with index 4010 (2816 or 508) literally (case sensitive)
4th Capturing Group
(\w+\.\w+)
\w
matches any word character (equivalent to [a-zA-Z0-9_])
+ matches the previous token between one and unlimited times, as many times as possible, giving back as needed (greedy)
\. matches the character . with index 4610 (2E16 or 568) literally (case sensitive)
\w
matches any word character (equivalent to [a-zA-Z0-9_])
+ matches the previous token between one and unlimited times, as many times as possible, giving back as needed (greedy)
: matches the character : with index 5810 (3A16 or 728) literally (case sensitive)
5th Capturing Group
(\d+)
\d
matches a digit (equivalent to [0-9])
+ matches the previous token between one and unlimited times, as many times as possible, giving back as needed (greedy)
\) matches the character ) with index 4110 (2916 or 518) literally (case sensitive)
$ asserts position at the end of a line
Global pattern flags
g modifier: global. All matches (don't return after first match)
m modifier: multi line. Causes ^ and $ to match the begin/end of each line (not only begin/end of string)
Your regular expression does not match the subject string.Try launching the debugger to find out why.

Regular Expression
No Match

/
/
gm

Test String