Regexp to match 't' in a nested list?

Regexp to match 't' in a nested list?

[Thorsten Jolitz]

Hi List, 

for making Emacs Lisp talk to PicoLisp, I have to upcase t and nil (T
and NIL in PicoLisp) in nested lists that contain all kinds of strings
and keywords in possibly many languages. Using the more difficult 't'
case as example, so far I came up with this regexp that doesn't seem to
give false positives: 

,------------------------------------------
| "\\( t \\|(t \\| t)\\|(t)\\|^t \\| t$\\)"
`------------------------------------------

(same thing for nil, just replace t with nil)

But the regexp misses at least one case: a string like 

,----------------
| " t t nil nil "
`----------------

will be converted to 

,----------------
| " T t NIL nil "
`----------------

I cannot find a solution for this case that does not immediately results
in false positives when applied to a string like 

,------------------------------------------------
| " t t nil nil total albanil nilonga tat mitat "
`------------------------------------------------

Any tips/hints would be appreciated.

-- 
cheers,
Thorsten

Re: Regexp to match 't' in a nested list?

[Jambunathan K]

\_<t\_>

See (info "(elisp) Regexp Backslash")

Thorsten Jolitz <tjolitz@gmail.com> writes:

> Hi List, 
>
> for making Emacs Lisp talk to PicoLisp, I have to upcase t and nil (T
> and NIL in PicoLisp) in nested lists that contain all kinds of strings
> and keywords in possibly many languages. Using the more difficult 't'
> case as example, so far I came up with this regexp that doesn't seem to
> give false positives: 
>
> ,------------------------------------------
> | "\\( t \\|(t \\| t)\\|(t)\\|^t \\| t$\\)"
> `------------------------------------------
>
> (same thing for nil, just replace t with nil)
>
> But the regexp misses at least one case: a string like 
>
> ,----------------
> | " t t nil nil "
> `----------------
>
> will be converted to 
>
> ,----------------
> | " T t NIL nil "
> `----------------
>
> I cannot find a solution for this case that does not immediately results
> in false positives when applied to a string like 
>
> ,------------------------------------------------
> | " t t nil nil total albanil nilonga tat mitat "
> `------------------------------------------------
>
> Any tips/hints would be appreciated.

Re: Regexp to match 't' in a nested list?

[Thorsten Jolitz]

Jambunathan K <kjambunathan@gmail.com> writes:

> \_<t\_>
>
> See (info "(elisp) Regexp Backslash")

Great, that works, thank you ... why did I never look at that manual
page? Maybe without a practical use case at hand that section looks a
bit too esoteric...

> Thorsten Jolitz <tjolitz@gmail.com> writes:
>
>> Hi List, 
>>
>> for making Emacs Lisp talk to PicoLisp, I have to upcase t and nil (T
>> and NIL in PicoLisp) in nested lists that contain all kinds of strings
>> and keywords in possibly many languages. Using the more difficult 't'
>> case as example, so far I came up with this regexp that doesn't seem to
>> give false positives: 
>>
>> ,------------------------------------------
>> | "\\( t \\|(t \\| t)\\|(t)\\|^t \\| t$\\)"
>> `------------------------------------------
>>
>> (same thing for nil, just replace t with nil)
>>
>> But the regexp misses at least one case: a string like 
>>
>> ,----------------
>> | " t t nil nil "
>> `----------------
>>
>> will be converted to 
>>
>> ,----------------
>> | " T t NIL nil "
>> `----------------
>>
>> I cannot find a solution for this case that does not immediately results
>> in false positives when applied to a string like 
>>
>> ,------------------------------------------------
>> | " t t nil nil total albanil nilonga tat mitat "
>> `------------------------------------------------
>>
>> Any tips/hints would be appreciated.
>
>

-- 
cheers,
Thorsten