ulis: If, for some syntax analyzis, you need to strip the braces of a list, here is a tiny proc that do that.
It returns "{this is} a {nested list}" for "{{{this is} a {nested list}}}". You can control the level of stripping, also.
ulis: This proc is wrong.
[striplist {{{this is}}{{a list}}}] returns '{this is}}{{a list}' in place of '{{this is}}{{a list}}'. I'm trying to publish soon a better proc.
proc striplist {text {level -1}} \
{
# expose outer braces
set text [string trim $text]
# while text seems braced and level is not exhausted
while { $level != 0
&& [string index $text 0] == "\{"
&& [string index $text end] == "\}"} \
{
# strip outer braces and expose inners
set text [string trim [string range $text 1 end-1]]
# check if this is too much
set n1 [string first "\{" $text]
set n2 [string first "\}" $text]
if {$n1 != -1 && $n2 != -1 && $n2 < $n1} \
{
# yes, this is too much, restitute outer braces
set text "{$text}"
# and stop
break
}
# check for asked nesting
incr level -1
}
return $text
}Results:
set text "{{{this is} a {nested list}}}"
puts [striplist $text]
-> {this is} a {nested list}
set text "{{{this is} a {nested list}}}"
puts [striplist $text 1]
-> {{this is} a {nested list}}
set text "{{{this is} a {nested list}}}"
puts [striplist $text 2]
-> {this is} a {nested list}AEC, 2002-05-28
I use the built-in command join to do the same thing.
set text "{{{this is} a {nested list}}}"
{{{this is} a {nested list}}}
% set textt [join $text]
{{this is} a {nested list}}
% set textt [join [join $text]]
{this is} a {nested list}
% set textt [join [join [join $text]]]
this is a nested listThis could easily be encapsulated into a proc to simplify use:
proc striplist {args} {
# Usage:
#
# striplist ?-level num? list
#
# Level defaults to 0 if omitted. This means all levels of list nesting
# are removed by the proc. For each level requested, a level of list nesting
# is removed.
#
# determine level
set idx [lsearch $args -level]
if {$idx == 0} {
set level [lindex $args [incr idx]]
set args [lreplace $args [expr $idx - 1] $idx]
} else {
set level 0
}
# while text seems braced and level is not exhausted
while {1} {
# strip outer braces and expose inners
incr level -1
set newargs [join $args]
if {$newargs == $args} {
break
} else {
set args $newargs
}
if {$level == 0} {
break
}
}
return $args
}Example usage:
% set a {this {is a} test}
% striplist -level 1 $a
this {is a} test
% striplist -level 2 $a
this is a test