Hi,

I don't know if the TCL community is the right place to post a Regular-Expression (RG) enhancement, but let me try :-)

problem: howto put MULTIPLE "regsub" statements into ONE single
(probably more efficient) together.

lets start with "string map…"

string map { old1 new1 old2 new2 … } STRING

ONE command is doing MULTIPLE replacement.

I want to do the same with "regsub" BUT with a RG string, proposal:

regsub {…(old1|old2|…)…} STRING {\?1(new1|new2|…)} OUTVAR

"old1" will be replaced with "new1" … etc

example: >>>>>

string="MyName§E other-thing"

regsub {(\w+)§(E|S|U)} $string {\?2(enum|struct|union) \1} OUTVAR

OUTVAR="enum MyName other-thing"

<<<<<<<<<<<<<<

new is the "\?2(…)"

\2 would replace the match-string and "\?2(…)" will use the
index of the match-string and pig-up the idx-replacement from the "(…}"


mfg

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On Sunday, May 1, 2022 at 3:00:02 PM UTC+2, aotto1 wrote:

Hi,

I don't know if the TCL community is the right place to post a Regular-Expression (RG) enhancement, but let me try :-)

problem: howto put MULTIPLE "regsub" statements into ONE single
(probably more efficient) together.

lets start with "string map…"

string map { old1 new1 old2 new2 … } STRING

ONE command is doing MULTIPLE replacement.

I want to do the same with "regsub" BUT with a RG string, proposal:

regsub {…(old1|old2|…)…} STRING {\?1(new1|new2|…)} OUTVAR

"old1" will be replaced with "new1" … etc

example: >>>>>

string="MyName§E other-thing"

regsub {(\w+)§(E|S|U)} $string {\?2(enum|struct|union) \1} OUTVAR

OUTVAR="enum MyName other-thing"

<<<<<<<<<<<<<<

new is the "\?2(…)"

\2 would replace the match-string and "\?2(…)" will use the
index of the match-string and pig-up the idx-replacement from the "(…}"

mfg

A feature of [string map] is that the substitutions are defined in pairs, whereas your suggested syntax interferes with the alternatives already defined in regular expressions. I suspect there are more interferences lurking in there, besides the obvious
one. Is the benefit over a sequence of regsubs really worth the trouble? I am not an expert wrt the machinery of regular expression matching, but I can imagine this would be quite complicated to getright, even at the definition level.

Regards,

Arjen

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On 01/05/2022 14:59, aotto1968 wrote:

problem: howto put MULTIPLE "regsub" statements into ONE single
(probably more efficient) together.

In Tcl 8.7, the regsub command has a new -command option that may be of
use (tip #463: https://core.tcl-lang.org/tips/doc/trunk/tip/463.md).

At least it can handle your example with a single regsub:

regsub -command {(\w+)§[ESU]} $string [list apply [list {match prefix} {
set ch [string index $match end]
string cat [string map {E enum S struct U union} $ch] " " $prefix
}]] OUTVAR


Schelte.

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On 02/05/2022 14:04, Schelte wrote:

regsub -command {(\w+)§[ESU]} $string [list apply [list {match prefix} {
    set ch [string index $match end]
    string cat [string map {E enum S struct U union} $ch] " " $prefix
}]] OUTVAR

Of course that can be simplified to:
regsub -command {(\w+)§([ESU])} $string [list apply [list {match prefix
ch} {
string cat [string map {E enum S struct U union} $ch] " " $prefix
}]] OUTVAR


Schelte

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Am 02.05.2022 um 14:12 schrieb Schelte:

On 02/05/2022 14:04, Schelte wrote:

regsub -command {(\w+)§[ESU]} $string [list apply [list {match prefix} {
     set ch [string index $match end]
     string cat [string map {E enum S struct U union} $ch] " " $prefix >> }]] OUTVAR

Of course that can be simplified to:
regsub -command {(\w+)§([ESU])} $string [list apply [list {match prefix
ch} {
    string cat [string map {E enum S struct U union} $ch] " " $prefix
}]] OUTVAR

Schelte

Schelte,
I appreciate your high level answers and deep knowledge of TCL.
I always learn from them!
Thank you for that,
Harald

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Hi,

*regsub* and *regexp* are used to apply a *regexpression* on a string.
In difference to *regexp* the *regsub* is used to modify the string.

I have the following problem:

→ I want to modify the string *config_error_text* to *configErrorText*.

this looks like a simple *regsub* job like:

regsub -all {_(\w)} "config_error_text" {\1??}

but as you see I can not uppercase the '\1' to just do the job I want.
I cant even call a *proc* in the *{\1??}* to do an arbitrary
post-processing.


mfg

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On Friday, June 24, 2022 at 10:02:13 AM UTC+2, aotto1 wrote:

Hi,

*regsub* and *regexp* are used to apply a *regexpression* on a string.
In difference to *regexp* the *regsub* is used to modify the string.

I have the following problem:

→ I want to modify the string *config_error_text* to *configErrorText*.

this looks like a simple *regsub* job like:

regsub -all {_(\w)} "config_error_text" {\1??}

but as you see I can not uppercase the '\1' to just do the job I want.
I cant even call a *proc* in the *{\1??}* to do an arbitrary post-processing.

mfg

If I remember correctly, Tcl 8.7 does allow you to specify a procedure like that.

Regards,

Arjen

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On 6/24/22 03:02, aotto1968 wrote:

Hi,

*regsub* and *regexp* are used to apply a *regexpression* on a string.
In difference to *regexp* the *regsub* is used to modify the string.

I have the following problem:

→ I want to modify the string *config_error_text* to *configErrorText*.

this looks like a simple *regsub* job like:

regsub -all {_(\w)} "config_error_text" {\1??}

but as you see I can not uppercase the '\1' to just do the job I want.
I cant even call a *proc* in the *{\1??}* to do an arbitrary
post-processing.

mfg

You may want to consider using the *string map* command instead.

--
+----------------------------------------------------------------------+
| Gerald W. Lester, President, KNG Consulting LLC |
| Email: Gerald.Lester@kng-consulting.net | +----------------------------------------------------------------------+

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The Tcl string functions are often faster than regexp (and regsub) for fairly complex string manipulations.

For instance to convert snake to camel case:

join [lmap x [split $str _] {string toupper $x 0 0}] ""

is faster than:

regsub -all {_(\w)} $str {\1}

And the regsub only removes the "_", it does not capitalize the following character.

There are some differences in the results for "odd" cases. The first one will eat multiple or trailing "_", and the regexp will leave some of them.

Dave B

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In article
<a81653bf-f4f0-4532-b4b2-d5e971b8cd27n@googlegroups.com>,
Arjen Markus <arjen.markus895@gmail.com> wrote:

this looks like a simple *regsub* job like:

regsub -all {_(\w)} "config_error_text" {\1??}

but as you see I can not uppercase the '\1' to just do the job I want.
I cant even call a *proc* in the *{\1??}* to do an arbitrary post-processing.

mfg

If I remember correctly, Tcl 8.7 does allow you to specify a procedure like that.

Making every conceivable and inconceivable (and I do know its
meaning) edit possible results in a bloat of never used options.

while {[regexp {^(.*)_(¥w)(.*)$} $string - pre letter post]} {
set string $pre[string toupper $letter]$post
}

And if I do uae this pattern a lot:
proc regall {string re args} {
set script [lindex $args end]
set vars [lrange $args 0 end-1]
while {[llength [set vals [regexp -inline $string $re]]]}
{
uplevel 1 [list lassign [lrange $vals 1 end] $vars]
set string [uplevel 1 $script]
}
return $string
}

regall $string {^(.*)_(¥w)(.*)$} pre letter post {concat
$pre[string toupper $letter]$post]}

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