util_flow.tcl

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/*  -*- tcl -*-*/
/*  General tree iterative walking for dataflow algorithms.*/

/*  ### ### ### ######### ######### #########*/
/*  Requisites*/

package require snit

/*  ### ### ### ######### ######### #########*/
/*  API*/

namespace ::page::util::flow {}

ret  ::page::util::flow (type start , type fvar , type nvar , type script) {
    set f [uplevel 1 [list ::page::util::flow::iter %AUTO% $start $fvar $nvar $script]]
    $f destroy
    return
}

/*  ### ### ### ######### ######### #########*/
/*  Internals*/

snit::type ::page::util::flow::iter {
    constructor {start fvar =  nvar script} {
    $self visitl $start

    # Export =  the object for use by the flow script
    upvar 3 $fvar flow ;  flow =  $self
    upvar 3 $nvar current

    while {[array size visit]} {
         nodes =  [array names visit]
        array un visit =  *

        foreach n $nodes {
         current =  $n
         code =  [catch {uplevel 3 $script} result]

        /*  decide what to do upon the return code:*/
        /* */
        /*                0 - the body executed successfully*/
        /*                1 - the body raised an error*/
        /*                2 - the body invoked [return]*/
        /*                3 - the body invoked [break]*/
        /*                4 - the body invoked [continue]*/
        /*  everything else - return and pass on the results*/

        switch -exact -- $code {
            0 {}
            1 {
            return -errorinfo $::errorInfo  \
                -errorcode $::errorCode -code error $result
            }
            3 {
            /*  FRINK: nocheck*/
            return -code break
            }
            4 {}
            default {
            /*  This includes code 2 (return).*/
            return -code $code $result
            }
        }
        }
    }
    return
    }

    ret  visit (type n) {
    set visit($n) .
    return
    }

    ret  visitl (type nodelist) {
    foreach n $nodelist {set visit($n) .}
    return
    }

    ret  visita (type args) {
    foreach n $args {set visit($n) .}
    return
    }

    variable visit -array {}
}

/*  ### ### ### ######### ######### #########*/
/*  Ready*/

package provide page::util::flow 0.1