Finding matched parentheses

[Peter M. Brigham]

Sorry, in my previous post I did not consider nested parens (I was thinking English text, not C code). The function below should return the offset of the outermost closing paren, the "match" for the first opening paren.

function offsetPair a,b,str
   -- returns offset(a,str) and loads in z offset(b,str) where b is the "matching" member of the pair;
   -- returns 0 if there is no a, empty if there is no match

   -- offsets(b,str) returns a comma-delimited list of all the offsets
   --       of a in str (see below)

   put offsets(a,str) into startOffsets
   if startOffset = 0 then return 0
   put offsets(b,str) into endOffsets
   if endOffsets = 0 then return empty
   if the number of items of startOffsets <> the number of items of endOffsets then
   -- unmatched parens, not grammatical
      return empty
   end if
   put item -1 of endOffsets into lastCloseParen
   if lastCloseParen < item 1 of startOffsets then return empty
   -- right number of open + close parens
   -- but not grammatical
   return item -1 of endOffsets
end offsetPair

-- Peter

Peter M. Brigham
pmbrig at gmail.com
http://home.comcast.net/~pmbrig


On Jul 26, 2013, at 1:35 AM, Mark Wieder wrote:

> Geoff-
> 
> Thursday, July 25, 2013, 9:53:47 PM, you wrote:
> 
>> regex is notoriously unable to handle recursion. To see endless heated
>> debate, search the web for how to parse HTML using regex.
> 
> To be fair, the blame is mostly on HTML, not regex. But there's enough
> blame to go around. No worries.
> 
>> Here is a fairly short function that searches for the outermost matched
>> pairs of characters.
> 
> "outermost" is different from matched. You might want to find the
> matching parenthesis for "lineDelim()" in
> 
> put stripHTML(
>    url("http:://www.www.com"),
>    lineDelim("/n"
>    ),
>    cos(theta)
> )
> 
> -- 
> -Mark Wieder
> mwieder at ahsoftware.net
> 
> 
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