Forum OpenACS Q&A: Response to Non Greedy Regexp for Tag Substitution

Posted by Jerry Asher on
Common thoughts and Synchronicity.

The key to non-greedy expressions is the question-mark.

I just did something similar in my blogging module. Trying to rip off the best, I let blog users access the userland glossary by entering the name of a glossary entry, surrounded by double colons (something like ::daveWinerImage::, ::usFlag::, or ::bill gates::).

I did this with the following, that you might adapt for your own use. The proc, blog_glossary_merge, is what does the non-greedy merge. I added that (and some other mods) to a few choice locations within confirm.tcl.

# userland glossary
proc_doc blog_upload_glossary {} {
    uploads userland glossary into blog shortcut table
} {
    set shortcuts [ns_httpget]
    set counter 0
    set start 0
    while {[regexp -indices -start $start {.*?<name>(.*?)</name>.*?<value>(.*?)</value>} $shortcuts match name value]} {
        set sname  [string range $shortcuts [lindex $name 0] [lindex $name 1]]
        set svalue [string range $shortcuts [lindex $value 0] [lindex $value 1]]
        # ns_log notice name $sname
        # ns_log notice value $svalue
        set start [lindex $value 1]
        incr counter
        nsv_set blog_glossary $sname [util_expand_entities $svalue]
        nsv_lappend blog_glossary words $sname
    nsv_set blog_glossary init 1
    ns_log notice blog_upload_glossary: found $counter entries

if {![nsv_array exists blog_glossary]} {
    nsv_set blog_glossary words [list]
    nsv_set blog_glossary "::::" "::"
    nsv_set blog_glossary "::::::::" "::::"
    ns_schedule_proc -once -thread  5 blog_upload_glossary
    ns_schedule_daily -thread  2 0 blog_upload_glossary

proc blog_glossary_merge {message} {
    if {[nsv_exists blog_glossary init]} {
        set counter 0
        while {[regexp -indices {::(.*?)::} $message match iphrase]} {
            set phrase [string range $message [lindex $iphrase 0] [lindex $iphrase 1]]
            # ns_log notice found phrase $phrase
            if {[empty_string_p $phrase]} {
                set value "::"
            } else {
                if {[nsv_exists blog_glossary $phrase]} {
                    set value " [nsv_get blog_glossary $phrase] "
                } else {
                    set value "::${phrase}::"
            # ns_log notice value is $value
            set newmessage [string replace $message [expr [lindex $iphrase 0] - 2] [expr [lindex $iphrase 1] + 2] $value]
            # ns_log notice message is now $message
            # ns_log notice newmessage is now $newmessage
            set message $newmessage
            incr counter
    } else {
        set fault "
        <center><table border=1 bgcolor=mistyrose cellpadding=10><tr><td>
        The global shortcuts glossary is down, sorry</td></tr></table></center>
        error $fault
    return $message