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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?

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  • Thanks for the help!

    I ended up doing this:
    ; sanitize input field for use as a regex, going character-by-character through the input
    searchString = ""
    foreach(char parseString(QSC_fnData->filter "")
    ; char is either a wildcard which is converted for the regex, a regex special char that is escapted, or passed through
    cond(
    ((char == "*") searchString = strcat(searchString ".*"))
    (stringp(index("^.$|()[]+?" char)) searchString = strcat(searchString "\\" char))
    (t searchString = strcat(searchString char))
    )
    )

    ; put start and end anchors on search string built above
    ; generate assoc list of all nets then regex pattern match for search string, resulting in a list of matching net names
    NetList = mapcar('cadr rexMatchAssocList(strcat("^" searchString "$") mapcar(lambda((item) list(item->name item)) axlDBGetDesign()->nets)))
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  • Thanks for the help!

    I ended up doing this:
    ; sanitize input field for use as a regex, going character-by-character through the input
    searchString = ""
    foreach(char parseString(QSC_fnData->filter "")
    ; char is either a wildcard which is converted for the regex, a regex special char that is escapted, or passed through
    cond(
    ((char == "*") searchString = strcat(searchString ".*"))
    (stringp(index("^.$|()[]+?" char)) searchString = strcat(searchString "\\" char))
    (t searchString = strcat(searchString char))
    )
    )

    ; put start and end anchors on search string built above
    ; generate assoc list of all nets then regex pattern match for search string, resulting in a list of matching net names
    NetList = mapcar('cadr rexMatchAssocList(strcat("^" searchString "$") mapcar(lambda((item) list(item->name item)) axlDBGetDesign()->nets)))
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