weird "regsub" syntax

Andreas Otto

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Jun 4, 2018, 4:25:11 AM6/4/18

to

Hi,

all i want to do is…

# cut the prefix from a string
set prefix [regsub {^Mq[[:upper:]][[:lower:]]+} $name]

# on tcl I have to do
set prefix [regsub {^(Mq[[:upper:]][[:lower:]]+).*} $name {\1}]

#test…

proc funcDEF {name ret argv} {
...
set prefix [regsub {^(Mq[[:upper:]][[:lower:]]+).*} $name {\1}]
set prefix2 [regsub {Mq[[:upper:]][[:lower:]]+} $name {\0}]
set prefix3 [regsub {Mq[[:upper:]][[:lower:]]+} $name {\1}]
...
Print prefix prefix2 prefix3

#results

funcDEF -> prefix<MqBuffer>, prefix2<MqBufferAppendC>, prefix3<AppendC>,
funcDEF -> prefix<MqBuffer>, prefix2<MqBufferCastTo>, prefix3<CastTo>,
funcDEF -> prefix<MqBuffer>, prefix2<MqBufferCmp>, prefix3<Cmp>,
funcDEF -> prefix<MqBuffer>, prefix2<MqBufferCopy>, prefix3<Copy>,
funcDEF -> prefix<MqBuffer>, prefix2<MqBufferCreate>, prefix3<Create>,
funcDEF -> prefix<MqBuffer>, prefix2<MqBufferCreateB>, prefix3<CreateB>,
funcDEF -> prefix<MqBuffer>, prefix2<MqBufferCreateC>, prefix3<CreateC>,
funcDEF -> prefix<MqBuffer>, prefix2<MqBufferCreateD>, prefix3<CreateD>,
funcDEF -> prefix<MqBuffer>, prefix2<MqBufferCreateF>, prefix3<CreateF>,
funcDEF -> prefix<MqBuffer>, prefix2<MqBufferCreateI>, prefix3<CreateI>,
funcDEF -> prefix<MqBuffer>, prefix2<MqBufferCreateO>, prefix3<CreateO>,

→ only the "prefix"… the FIRST one give the right results…

#conclusion…

there is a requirement for a "regsub" switch… perhaps "-inline"

set prefix [regsub -inline {^Mq[[:upper:]][[:lower:]]+ $name]

mfg

AO

Arjen Markus

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Jun 4, 2018, 6:45:23 AM6/4/18

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On Monday, June 4, 2018 at 10:25:11 AM UTC+2, Andreas Otto wrote:
> Hi,
>
> all i want to do is…
>
> # cut the prefix from a string
> set prefix [regsub {^Mq[[:upper:]][[:lower:]]+} $name]

You are mistaken about the capturing of the substrings. \0 is the total matching substring, \1 is the substring captured by the pair of parentheses starting left-most, \2 the substring captured by the first pair parentheses starting after that etc.

What you are after is, I think:

set suffix [regsub {^Mq[[:upper:]][[:lower:]]+(.*)} $name {\1}]

that is, first determine what the prefix is and CAPTURE the rest.

Regards,

Arjen

heinrichmartin

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Jun 4, 2018, 7:10:33 AM6/4/18

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On Monday, June 4, 2018 at 12:45:23 PM UTC+2, Arjen Markus wrote:
> On Monday, June 4, 2018 at 10:25:11 AM UTC+2, Andreas Otto wrote:
> > # cut the prefix from a string
> > set prefix [regsub {^Mq[[:upper:]][[:lower:]]+} $name]
>

> set suffix [regsub {^Mq[[:upper:]][[:lower:]]+(.*)} $name {\1}]

> funcDEF -> prefix<MqBuffer>, prefix2<MqBufferAppendC>, prefix3<AppendC>,
> funcDEF -> prefix<MqBuffer>, prefix2<MqBufferCastTo>, prefix3<CastTo>,
> funcDEF -> prefix<MqBuffer>, prefix2<MqBufferCmp>, prefix3<Cmp>,
> funcDEF -> prefix<MqBuffer>, prefix2<MqBufferCopy>, prefix3<Copy>,
> funcDEF -> prefix<MqBuffer>, prefix2<MqBufferCreate>, prefix3<Create>,
> funcDEF -> prefix<MqBuffer>, prefix2<MqBufferCreateB>, prefix3<CreateB>,
> funcDEF -> prefix<MqBuffer>, prefix2<MqBufferCreateC>, prefix3<CreateC>,
> funcDEF -> prefix<MqBuffer>, prefix2<MqBufferCreateD>, prefix3<CreateD>,
> funcDEF -> prefix<MqBuffer>, prefix2<MqBufferCreateF>, prefix3<CreateF>,
> funcDEF -> prefix<MqBuffer>, prefix2<MqBufferCreateI>, prefix3<CreateI>,
> funcDEF -> prefix<MqBuffer>, prefix2<MqBufferCreateO>, prefix3<CreateO>,
>
> → only the "prefix"… the FIRST one give the right results…

I am not perfectly sure whether you want to fetch or cut the prefix ...

> set prefix [regsub {^Mq[[:upper:]][[:lower:]]+} $name]

You either copied the wrong thing here - or you received a "wrong # args" error...

set suffix [regsub {^Mq[[:upper:]][[:lower:]]+} $name ""] ;# replace the prefix with the empty string

set prefix [regexp -inline {^Mq[[:upper:]][[:lower:]]+} $name] ;# is empty if no match

if {[regexp {^Mq[[:upper:]][[:lower:]]+} $name prefix]} {
# work with prefix
}

Andreas Otto

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Jun 4, 2018, 3:28:41 PM6/4/18

to

just to be clear I want to have the "prefix" in this example "MqBuffer" … my understanding is that the "reg-expr" (of regsub… or any other command)… fit the part of the string I WANT TO have… my perfect example would be…

set prefix [regsub {^Mq[[:upper:]][[:lower:]]+} $name]

with the "reg-expr" = {^Mq[[:upper:]][[:lower:]]+} is my WANT-TO-HAVE…

mfg.

Eric

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Jun 4, 2018, 4:40:06 PM6/4/18

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Well,

% set name "MqBuffer-27"
% regsub {^Mq[[:upper:]][[:lower:]]+} $name
wrong # args: should be "regsub ?-option ...? exp string subSpec ?varName?"

and

% regsub {^Mq[[:upper:]][[:lower:]]+} $name "XXXX"
XXXX-27

so you can't have what your perfect example (this has already been
said anyway)

% if [regexp {^Mq[[:upper:]][[:lower:]]+} $name prefix] {
puts $prefix
} else {
puts "no match"
}

is the neatest thing I can think of.

Eric
--
ms fnd in a lbry

heinrichmartin

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Jun 4, 2018, 5:22:45 PM6/4/18

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On Monday, June 4, 2018 at 9:28:41 PM UTC+2, Andreas Otto wrote:
> my understanding is that the "reg-expr" (of regsub… or any other command)

This is basically correct, but with regexp returning the match and regsub replacing it with sth else.

On Monday, June 4, 2018 at 10:40:06 PM UTC+2, Eric wrote:
> % if [regexp {^Mq[[:upper:]][[:lower:]]+} $name prefix] {
> puts $prefix
> } else {
> puts "no match"
> }

Stay used to expressions in braces (i.e. if {[regexp]}) for optimized byte code.

Donald Arseneau

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Jun 10, 2018, 10:58:07 AM6/10/18

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Andreas Otto <aotto1...@gmail.com> writes:

> all i want to do is…

Showing failing code is NOT telling what you WANT to do!
Nobody can really know what you intended from your code.

> # cut the prefix from a string
> set prefix [regsub {^Mq[[:upper:]][[:lower:]]+} $name]
>
> # on tcl I have to do
> set prefix [regsub {^(Mq[[:upper:]][[:lower:]]+).*} $name {\1}]

Assuming you want the prefix in the variable "prefix",
then my guess is you meant to use regexp, not regsub.

--
Donald Arseneau as...@triumf.ca