Hi Howard,
Here is a commented version of your regular expression.
(?x) (?# Allow whitespace and comments.
)
( (?# Opening of capture 1.
)
. (?# Any single character.
)
) (?# Closing of capture 1.
)
(?! (?# Opening negative lookahead assertion.
)
[^(]* (?# Zero or more characters that are not a opening parenthesis.
)
\) (?# A closing parenthesis.
)
) (?# Closing negative lookahead assertion.
)
(?!...) is a Negative lookahead assertion.
It basically says: find occurrences of 'this' that are not followed by
'that' but don't include the 'not that' in the match –– hence the
'lookahead'.
For a detailed explanation check the *excellent* grep documentation in *menu
Help > BBEdit Help > Grep Reference* link.
So that says:
"Any single character that is not followed by zero or more characters that
are not the opening parenthesis, followed by a closing parenthesis."
The double negation makes it difficult to fathom.
The negative lookahead assertion says: skip any match that is followed by
'...)' where ... are zero of more not '('.
The digits of the first line are not followed by '...)' -> match.
The first character of the second line '(' is followed by '10)' -> skip
The second character of the second line '1' is followed by '0)' -> skip
The third character of the second line '0' is followed by ')' -> skip
The fourth character of the second line ')' is not followed by '...)' ->
match
...
A simpler regular expression that will give the same result (and probably
be more performant) is:
(\([^\)]*\)|\d)
"Match any parentheses block or any single digits outside of parentheses
blocks."
HTH
Jean Jourdain
On Saturday, July 31, 2021 at 6:52:48 PM UTC+2 TJ Luoma wrote:
>
> Try pasting it into https://regexr.com
>
> That's what I usually use to translate regex into English :-)
>
>
>
> On Sat, Jul 31, 2021 at 10:20 AM Howard <[email protected]> wrote:
>
>> Can someone explain how the REGEX code below works?
>> *(.)(?![^(]*\))*
>>
>> I know it looks for digits, including two-digit numbers in parentheses,
>> and extracts them and inserts a space after each one, but I do not know how
>> the code starting with *(?* works.
>>
>> Here is sample data for it:
>> 010000000
>> (10)1140006x
>> 002200010
>> 00000(11)01x
>> 311200
>>
>> Here is output:
>> 0 1 0 0 0 0 0 0 0
>> (10) 1 1 4 0 0 0 6 x
>> 0 0 2 2 0 0 0 1 0
>> 0 0 0 0 0 (11) 0 1 x
>> 3 1 1 2 0 0
>>
>>
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