[Tutor] Failing regex to identify error stack

[Alan Gauld]

On 20/09/2019 09:09, Asad wrote:
> Hi All ,
>
> I am writing a script in python to read a logfile and identify the first
> error stack :
>
> ?/test/admin/nothing.sql
>
> PL/SQL procedure successfully completed.
> Session altered.
> Package created.
> Session altered.
> Session altered.
> Package body created.
> No errors.
> Session altered.
> PL/SQL procedure successfully completed.
>
> ERROR at line 9:
> Fal-11144: size of object not allowed
>
>
> I am trying to use the following regex :
>
> ^.*/test/admin/.*(?=ERROR at line .*)(?=Fal-.*)

Regex are complex things and hard to debug, I'd probably
use simpler string comparisons and a sentinel.

Something like (untested pseudo code):


inStack = False

stack = []

errorCode = ''

for line in logfile:

     if line.startswith('?/test/admin/'):   #start stack

         inStack = true

         continue

    if line.startswith('ERROR'):   # end of stack

        inStack = False

        continue

    if inStack:

       stack.append(line)

    else:

       errorCode = line

       break


You should wind up with stack containing all the lines
between the filename and ERROR and errorCode with
the line after ERROR.


Finally, you could wrap it in a function that returns a
tuple containing stack and errorCode...


-- 
Alan G
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