Re: Line offset of an item (and other similar functions).

[Alex Tweedly]

Raymond E. Griffith wrote:
Alex Tweedly wrote:
   

Nope, spoke too soon. That looks convincing, and worked on my initial
testing - but doesn't actually work properly in all cases.
The problem is that the CRs are included within items - so given data like
a,abc,1
b,def,2
c,qwe,3
etc.,  item 1 is "a", item 2 is "abc", item 3 is "1
b" (i.e. including the cr), item 4 is "def", etc.
Clearly, that means itemOffset will never match what I think of as items
that are first (or last) on each line.
In the above case, I want to be able to search for the line containing
item "b" and find the second line.
Currently I'm using
   

function findItemAsLineNumber pItem, pData
 local i, L
 set wholeMatches to true
 --  set the itemDel to TAB
 put 0 into i
 repeat for each line L in pData
   add 1 to i
   if itemOffset(pItem, L) > 0 then return i
 end repeat
 return 0
end findItemAsLineNumber
     

but I still think there should be an easier (or at least faster,
shorter, better) way.
-- Alex.
   

Hmmm. Since L is a separate chunk each time (a single Line), I don't know
why it won't work. 

The code fragment above does work - that's my working but 
inefficient/large version.

What fails is the one-liner using
  get the number of lines in item 1 to itemOffset(tNeedle, tData) in tData
That fails because of the CR-within-item issue.
There is also a "filter" pData with pitem -- but you'd need to put pData
into a temporary variable since it eliminates the rest of the data list
except for the line it finds. It also has the the ability to use simple
regex arguments in the filter.
 

As far as I can see, the filter expressions are not capable of 
identifying items within a line, they're just too far short of proper 
regex, so 'filter' can't be used. If there is a way to do it, please let 
me know.

Regex can do it easily enough, so there is the option of
  put "[,^](" & pID & ")[,$]" into tRegex
  put matchChunk(pData, tRegex, t1, t2) into t
  if t then
     get the number of lines in char 1 to t2 of pData
  else
    get 0
  end if
I'm not sure if that is much easier or as readily understandable as the 
longer scripted version - but it's probably faster.

or Robert suggested the alternative of adding extra itemDelimiters at 
the start and end of each line in the data structure, which would be a 
confusing but feasible way to do it.

Thanks everyone - I now have a few ways to do it; I'll stick to the 
scripted version for maintainability, and if performance becomes an 
issue I'll benchmark the regex method and the additional delimiter 
version and see which wins.

Thanks
-- Alex.
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