checking string on occurrence of characters

I'm not sure how to use a ] in a string match character set. This works for a [:

% string match {[[]} \[

1

But none of these work for a ]:

% string match {[]]} \]

0

% string match {[\]]} \]

0

% string match {[\\]]} \]

0

% string match {[\\\]]} \]

0

% string match {[\\\\]]} \]

0

Escaping the right square brace with a backslash works when the brace is not in a string match character set:

% string match {\]} \]

1

For scan, you can put the right square bracket first in the character list and it works:

% scan \] {%[]]} match; puts $match

]

So if you can assume there is at least one non-matching character first, you could try this:

scan $string {%*[^][{}]%[][{}]%*s} match

Or if you can't guarantee at least one non-matching character first, you could try this:

if { [scan $string {%*[^][{}]%[][{}]%*s} match] == 1 || [scan $string {%[][{}]%*s} match]} {
    found $match
} else {
    no match
}

Aaron