[Stefan]

How can i utilize this feature please?

(?n:true_expression:false_expression)

Found at:
http://www.emeditor.com/modules/feature1/rewrite/tc_35.html
EmEditor Professional 9 New Features
The replace format “(?n:true_expression:false_expression)”
was added to regular expression replace formats.

[JohnQSmith]

I played with it a while and finally figured it out. Here’s an example.

Input document

TheGreenAile TheGreenBile TheGreenCile TheGreenDile

	TheGreenEile TheGreenFile TheGreenGile TheGreenHile

	TheGreenIile TheGreenJile TheGreenKile TheGreenLile

	TheGreenNile TheGreenOile TheGreenPile TheGreenQile

	TheGreenRile TheGreenSile TheGreenUile TheGreenVile

	TheGreenWile TheGreenXile TheGreenYile TheGreenZile

	

Search string

(?:([BFNPR])|([^BFNPR]))(ile)

	

Replace string

(?1:M:T)3

Replace all and output is

TheGreenTile TheGreenMile TheGreenTile TheGreenTile

	TheGreenTile TheGreenMile TheGreenTile TheGreenTile

	TheGreenTile TheGreenTile TheGreenTile TheGreenTile

	TheGreenMile TheGreenTile TheGreenMile TheGreenTile

	TheGreenMile TheGreenTile TheGreenTile TheGreenTile

	TheGreenTile TheGreenTile TheGreenTile TheGreenTile

I color coded it to help you see what’s happening.

Oh yeah, the Boost regex docs helped me figure it out.

[Stefan]

Thanks John!

I see it, but i don’t understand it.
Will have an closer look and read the Boost help…

[Stefan]

Conditionals
The character ‘?’ begins a conditional expression, the general form is:
?Ntrue-expression:false-expression
where N is decimal digit.
If sub-expression N was matched, then true-expression is evaluated and sent to output,
otherwise false-expression is evaluated and sent to output.
You will normally need to surround a conditional-expression with parenthesis in order to prevent ambiguities.
For example, the format string “(?1foo:bar)” will replace each match found with “foo” if the sub-expression $1 was matched,
and with “bar” otherwise.
For sub-expressions with an index greater than 9, or for access to named sub-expressions use:
?{INDEX}true-expression:false-expression
or
?{NAME}true-expression:false-expression

conditional expression ?Ntrue-expression:false-expression

In addition, conditional expressions of the following form are recognized:
?Ntrue-expression:false-expression
where N is a decimal digit representing a sub-match.
If the corresponding sub-match participated in the full match, then the substitution is true-expression.
Otherwise, it is false-expression. In this mode, you can use parens () for grouping.
If you want a literal paren, you must escape it as (.

Seams clear, but i have still problems using this.
Some tests:

	conditional expression 

	'?Ntrue-expression:false-expression' test 1

	

	I have:

	Test Price 1000

	Test Price 100

	Test Price 800

	---

	Find: (.+) (.+) (d{3})(d)

	Replace: (?4: too expensive: affordable)

	[X] Use RegEx

	---

	Result:

	Test Price 1000 too expensive

	Test Price 100

	Test Price 800

	---

	Expected:

	Test Price 1000 too expensive

	Test Price 100 affordable

	Test Price 800 affordable

	---

	Explanation: 

	If sub-expression No. 4 match THEN 

	use 'true-expression' 

	else 'false-expression'

	

	conditional expression 

	'?Ntrue-expression:false-expression' test 2

	

	I have:

	Color 1 green

	Color 2 blue

	Color 3 red

	The available colors are either green, blue or red.

	---

	Find: (Color d) (.+)

	Replace: (?1:1 2-ich:1 -2-)

	[X] Use RegEx

	---

	Result:

	Color 1 green-ich

	Color 2 blue-ich

	Color 3 red-ich

	The available colors are either green, blue or red.

	---

	Expected:

	Color 1 green-ich

	Color 2 blue-ich

	Color 3 red-ich

	The available colors are either -green-, -blue- or -red-.

	---

	Explanation: 

	Only if sub-expression No. 1 will match THEN

	use 'true-expression'

	else 'false-expression'

	

OK, i will test some more.

[JohnQSmith]

I see the problem with both of your tests. It’s the same thing that took me so long to figure out how it works.

Here’s the key…
The whole RegEx must match in order for it to work. In other words, you have to set up the RegEx with an alternation so that it has both a success and a failure point.

In your first test, only the first line matched your RegEx (I’m using underscores as filler to demonstrate).

	Test Price 100______0

	(.+) (.+)  (d{3}) (d)   <-- this matches

	

	Test Price 100________

	(.+) (.+)  (d{3}) (d)   <-- this doesn't match, there is no final (d)

	

	Test Price 800________

	(.+) (.+)  (d{3}) (d)   <-- also doesn't match

	

Here’s how I changed your RegEx to work.

	        Note the success ----.  and failure points

	                             |  |

	                             v  v

	Find: ^(.+) (.+) (d{3})(?:(d)|$)

	Replace:  (?4:too expensive:affordable)

Your second example is the same thing.

	Color_ 1__ green

	(Color d) (.+)   <-- match

	

	Color_ 2__ blue

	(Color d) (.+)   <-- match

	

	Color_ 3__ red

	(Color d) (.+)   <-- match

	

	The available colors are either green, blue or red.

	(Color d) (.+)   <-- no match anywhere on line

	

Hope this helps.

[Stefan]

Thank you.

My understanding right now:
You have to set up the FIND RegEx with an alternation so that it has both a success and a failure point.
As the REPLACE have too possibilities too: (?n:true_expression:false_expression)

Test:

	I have:

	Test Price 1000

	Test Price 100

	Test Price 800

	

	Find: (.+) (.+) (d{3})(d)*

	Repl: (?4: too expensive: affordable)

	[X] Use RegEx

	

	Result:

	Test Price 1000 too expensive

	Test Price 100 affordable

	Test Price 800 affordable

Thanks again. I still have to do some test, but i think you showed me the way.

–
BTW, good idea :lol: of you:
Replace: (?4:too expensive:affordable)
–

[JohnQSmith]

My understanding right now:
You have to set up the FIND RegEx with an alternation so that it has both a success and a failure point.
As the REPLACE have too possibilities too: (?n:true_expression:false_expression)

Absolutely correct. I like your FIND RegEx better. It will be much easier to use than mine. Just adding the zero or more switch makes it much simpler than a non-matching alternation grouping.

What helped me the most in figuring out how it works was how EmEditor highlights all matches when you do a search. When I tried your first search, only the first “Test Price” line was highlighted, but when I removed the final “(d)”, all the lines were marked. This showed me that the problem was with the RegEx.

The first and foremost thing to remember is that the WHOLE RegEx expression must match before you can do any further matching and testing with a SUBexpression.

BTW, good idea :lol: of you:
Replace: (?4:too expensive:affordable)

Thanks! :-D

[Author]

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