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Accepting user input with wildcards (regex help)

EvanShultz

I want to accept user input that contains wildcards for ref des and net names. The basic solution isn't difficult and I get good results with:

; build regular expression pattern of filter text
; put start and end anchors on text and all asterisks match "any character zero or more times"
rexCompile(buildString(parseString(strcat("^" "input_string" "$") "*") ".*"))

(I know I can use the PCRE functions, but I started with the basic ones since they worked.)

Trouble came when I tried to find pathological cases and realized that regex special chars are common in net names (especially "+" like in "+5V"). Some regex special chars are ".\*+^$".

Starting with the first problem I encountered, I was able to modify the following code to handle a plus sign:

pat = pcreCompile("[\\+]")
rexCompile(buildString(parseString(strcat("^" pcreReplace(pat "input_string" "\\\\+" 0) "$") "*") ".*"))

This does work and I can then accept an asterisk as a wildcard on the input and match "+5V", "+3.3V", etc. in my net names. But this is just one of the special chars. As the special chars could be in any position of the input string (ref des or net name), I don't see any one regex pattern to handle it all and doing them individually looks miserable. There must be a better way which I don't see. Searching on the forums and reading sklangref again haven't lit a bulb over my head, but it may be because I'm just daft.

Moving through the string character-by-character and replacing special chars with escaped versions would be an option, but that's rather painful and sure to incur a delay that users would notice on a big design (I tried using axlDBCloak while comparing the input string to the regex and didn't see a speed up, possibly because I'm only doing a database read?). The "Find by Name or Property" form does the same thing but query results appear instantly. It even handles multiple wildcards properly, so there's a way to do it well but I haven't figured it out. Can anyone help?

Parents

  • 2 things, 

    i would do a parse string on the search string, convert it and then replace the regex characters with something else. Place them in a new list and build the list again. The resulting string is then the search string. 

    l_str = parseString("+sdrsf*" "")
    new_str = nil
    while(l_str
    str=car(l_str)
    l_str=cdr(l_str)
      case(str
      ("+" push(".+" new_str))
      ("*" push(".*" new_str))
      (t push(str new_str))
    )
    )
    new_str= buildString(new_str "")
    pp(new_str)

    2nd, if you first make an assoc list of the nets (netname net dbID) then you can use the pcreMatchAssocList to do a complete match of the lists of nets. This runs fast on my PC. 

    l_assocNet= mapcar( lambda((item) list(item->name item)) axlDBGetDesign()->nets)
    pcre= pcreCompile(".*3V.*" 1)
    l_nets= pcreMatchAssocList(pcre l_assocNet)

    The '1' in the pcreComplie is to ignore case sensitive.

    The l_nets contains an assoc list, like:

    ("+3V3" dbid:394326552)
    ("3V3_FB" dbid:394326384)
    ("3V3_COMP" dbid:394326272)

    To keep only the dbid's you can do a mapcar:

    l_nets= mapcar('cadr l_nets)

Reply

  • 2 things, 

    i would do a parse string on the search string, convert it and then replace the regex characters with something else. Place them in a new list and build the list again. The resulting string is then the search string. 

    l_str = parseString("+sdrsf*" "")
    new_str = nil
    while(l_str
    str=car(l_str)
    l_str=cdr(l_str)
      case(str
      ("+" push(".+" new_str))
      ("*" push(".*" new_str))
      (t push(str new_str))
    )
    )
    new_str= buildString(new_str "")
    pp(new_str)

    2nd, if you first make an assoc list of the nets (netname net dbID) then you can use the pcreMatchAssocList to do a complete match of the lists of nets. This runs fast on my PC. 

    l_assocNet= mapcar( lambda((item) list(item->name item)) axlDBGetDesign()->nets)
    pcre= pcreCompile(".*3V.*" 1)
    l_nets= pcreMatchAssocList(pcre l_assocNet)

    The '1' in the pcreComplie is to ignore case sensitive.

    The l_nets contains an assoc list, like:

    ("+3V3" dbid:394326552)
    ("3V3_FB" dbid:394326384)
    ("3V3_COMP" dbid:394326272)

    To keep only the dbid's you can do a mapcar:

    l_nets= mapcar('cadr l_nets)

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