Determining processing based on flags in a URL

I have a URL which will come in as

/features?features=10010001

where each '1' or '0' is a 'flag'. I need to check each flag in turn and depending on its value, XOR it with a matching flag stored as a preset in my iRule, and eventually return the result. The presets will be stored as variables called e.g. 'flag1', 'flag2' etc. So my processing would be to split the '10--01-00---01' string into an array of flags, process each element in the array, match it with the related preset variable, do the XOR and then return the XOR'ed string as a 200 response.

As a start, I'm trying to figure out the best way to convert the '10--01-00---01' string into an array of flags that I can process.

I hope the above makes sense.

application delivery

devops

iRules

nitass_89166
Jun 04, 2014
that kinda works, except that the characters could potentially be 0, 1 or -

may we remove - before scanning?

% scan [string map {"-" ""} 10--01-00---01] %2d%2d%2d%2d a b c d 4 % put "$a $b $c $d" 10 1 0 1

by the way, if flag is only one digit each, can we use split?

% split [string map {"-" ""} 10--01-00---01] {} 1 0 0 1 0 0 0 1

nitass
Employee
Jun 04, 2014
what about scan or regexp?

scan % scan 10010001 %2d%2d%2d%2d a b c d 4 % put "$a $b $c $d" 10 1 0 1 % time "scan 10010001 %2d%2d%2d%2d a b c d" 1000 5.319 microseconds per iteration regexp % regexp {(\d\d)(\d\d)(\d\d)(\d\d)} 10010001 m a b c d 1 % put "$a $b $c $d" 10 01 00 01 % time "regexp {(\d\d)(\d\d)(\d\d)(\d\d)} 10010001 m a b c d" 1000 3.077 microseconds per iteration
- Rory_Hewitt_139
  Nimbostratus
  Jun 04, 2014
  Hey @nitass, that kinda works, except that the characters could potentially be 0, 1 or -, so I can't use %d in scan or \d in regex. I can use %c in scan, but it converts them to a Unicode integer. So for instance, scan $flags %c%c%c%c%c%c%c%c flag1 flag2 flag3 flag4 flag5 flag6 flag7 flag8 gives me "49 45 48 45 45 45 45 49". Any way to simply chop them out as single characters?
- JG
  Cumulonimbus
  Jun 05, 2014
  The test results here seem to go contrary to the prevalent view that prefers "scan" to "regexp" for performance.
nitass_89166
Noctilucent
Jun 04, 2014
what about scan or regexp?

scan % scan 10010001 %2d%2d%2d%2d a b c d 4 % put "$a $b $c $d" 10 1 0 1 % time "scan 10010001 %2d%2d%2d%2d a b c d" 1000 5.319 microseconds per iteration regexp % regexp {(\d\d)(\d\d)(\d\d)(\d\d)} 10010001 m a b c d 1 % put "$a $b $c $d" 10 01 00 01 % time "regexp {(\d\d)(\d\d)(\d\d)(\d\d)} 10010001 m a b c d" 1000 3.077 microseconds per iteration
- Rory_Hewitt_139
  Nimbostratus
  Jun 04, 2014
  Hey @nitass, that kinda works, except that the characters could potentially be 0, 1 or -, so I can't use %d in scan or \d in regex. I can use %c in scan, but it converts them to a Unicode integer. So for instance, scan $flags %c%c%c%c%c%c%c%c flag1 flag2 flag3 flag4 flag5 flag6 flag7 flag8 gives me "49 45 48 45 45 45 45 49". Any way to simply chop them out as single characters?
- JG
  Cumulonimbus
  Jun 05, 2014
  The test results here seem to go contrary to the prevalent view that prefers "scan" to "regexp" for performance.
nitass_89166
Noctilucent
Jun 04, 2014
that kinda works, except that the characters could potentially be 0, 1 or -

may we remove - before scanning?

% scan [string map {"-" ""} 10--01-00---01] %2d%2d%2d%2d a b c d 4 % put "$a $b $c $d" 10 1 0 1

by the way, if flag is only one digit each, can we use split?

% split [string map {"-" ""} 10--01-00---01] {} 1 0 0 1 0 0 0 1
- Rory_Hewitt_139
  Nimbostratus
  Jun 05, 2014
  Nope, we need the '-' in there - it implies 'null'. Although, of course, split would work fine -I don't know why I didn't think of it - probably because I'm not a Tcl programmer :) In any event, I have this working - using substr: for {set x 0} {$x < 8} {incr x} { set flag [string index $flags $x] switch $flag { "0" {...} "1" {...} default {...} } which seems to do the job rather nicely. Thanks for the help!
nitass
Employee
Jun 04, 2014
that kinda works, except that the characters could potentially be 0, 1 or -

may we remove - before scanning?

% scan [string map {"-" ""} 10--01-00---01] %2d%2d%2d%2d a b c d 4 % put "$a $b $c $d" 10 1 0 1

by the way, if flag is only one digit each, can we use split?

% split [string map {"-" ""} 10--01-00---01] {} 1 0 0 1 0 0 0 1
- Rory_Hewitt_139
  Nimbostratus
  Jun 05, 2014
  Nope, we need the '-' in there - it implies 'null'. Although, of course, split would work fine -I don't know why I didn't think of it - probably because I'm not a Tcl programmer :) In any event, I have this working - using substr: for {set x 0} {$x < 8} {incr x} { set flag [string index $flags $x] switch $flag { "0" {...} "1" {...} default {...} } which seems to do the job rather nicely. Thanks for the help!