Regex capture date if it exists in a block but match the block anyway

John Slee

I am using this regex expression

(^(@X\d.+F\.$\R)(?s:.*?)(^\d\d \D\D\D \d\d\d\d\.)?(?s:.*?)(?=@|==))

to capture two groups and capture an optional date in a test sample block:

== Ma ==
@X1@ F.
line 1
line 2
@X2@ F.
line 3.
line 4
02 FEB 1842.
line 6
==

This matches two groups

**@X1@ F.**
line 1
line 2

and

**@X2@ F.**
line 3.
line 4
02 FEB 1842.
line 6

but does not capture the date

whereas

^(@X\d.+F\.$\R)(?s:.*?)(^\d\d \D\D\D \d\d\d\d\.)(?s:.*?)(?=@|==)

matches just one group (but both of the required groups)

**@X1@ F.**
line 1
line 2
@X2@ F.
line 3.
line 4
**02 FEB 1842.**
line 6

and captures the date.

Can someone (guy038?) produce a regex that will capture the two groups AND the optional date?

Alan Kilborn

@John-Slee

What does “optional date” mean?

Does it mean your “before” block could look like this (exactly as you show):

== Ma ==
@X1@ F.
line 1
line 2
@X2@ F.
line 3.
line 4
02 FEB 1842.
line 6
==

Or it (the “before” block) could look like this:

== Ma ==
@X1@ F.
line 1
line 2
@X2@ F.
line 3.
line 4
line 6
==

John Slee

it means it could be

== Ma ==
@X1@ F.
line 1
line 2
@X2@ F.
line 3.
03 MAR 1806.
line 6
==

== Ma ==
@X1@ F.
line 1
line 2
@X2@ F.
line 3.
line 4
line 6
==

or

== Ma ==
@X1@ F.
line 1
04 FEB 1811.
line 2
@X2@ F.
line 3.
03 MAR 1806.
line 6
==

or

== Ma ==
@X1@ F.
line 1
04 JUN 1961.
line 2
@X2@ F.
line 3.
line 6
==

Each block begins with the @…@ F. line and can have a variable number of lines, one of which can be the date line.
I want to match each block and capture the date where it occurs.

guy038

Hello, @john-slee, @alan-kilborn and All,

I think that the following regex S/R should be OK !

SEARCH (?-s)^@X.+\R(?:(?s:[^@]*?)(\d\d\x20\w\w\w\x20\d\d\d\d)\.(?s:.*?)|(?s:.*?))(?=^@X|^==|\Z)

If we use the in-line modifier (?x) we can build the corresponding multi-lines regex, with explanations in comments :

(?x)                           # FREE-SPACING mode
(?-s)                          # Forces the DOT regex symbol to match a SINGLE STANDARD character , only ( Not EOL chars )
^@X.+\R                        # An ENTIRE Line BEGINNING with @X
(?:                            # NON-capturing group, beginning 2 ALTERNATIVES
(?s:[^@]*?)                    #     SHORTEST range of chars, even NULL, DIFFERENT from @, till the DATE, in a NON-capturing group
(\d\d\x20\w\w\w\x20\d\d\d\d)\. #     DATE, stored in CAPTURING group 1, followed with a DOT
(?s:.*?)                       #     SHORTEST range of chars till the LOOK-AROUND, in a NON-capturing group
|                              #   OR
(?s:.*?)                       #     SHORTEST range of chars, even NULL, till the LOOK-AROUND, in a NON-capturing group
)                              # END of the NON-capturing group
(?=^@X|^==|\Z)                 # LOOK-AROUND ( if FOLLOWED with @X or ==, BEGINNING a line, or the END of file [ possibly PRECDEDED with EMPTY lines ] )

You can select all that block, with Ctrl+C and paste it, with Ctrl + V, in the Find what zone of the Find dialog ;-))

Notes :

Each matched multi-lines block, from a line ^@X... to the next line ^@X, excluded, can be used in replacement with the $0 syntax ( The overall match )
The group 1 stores the date, when present in current block and is an empty string when the date is absent from block and you can re-use the date, in replacement, with the \1 or $1 syntaxes

Best Regards,

guy038

John Slee

@guy038 Thank you so much, Guy. In order to achieve what I want, I adjusted the search regex slightly, so that the whole block, the label line (^@X[/d]+@ F./R) and date are all captured:

(?-s)((^@X.+\R)(?:(?s:[^@]*?)(\d\d\x20\w\w\w\x20\d\d\d\d)\.(?s:.*?)|(?s:.*?)))(?=^@X|^==|\Z)

Best Regards. Stay safe!
John