template::util::lnest (public)

template::util::lnest listref value next [ args... ]

Defined in packages/acs-templating/tcl/util-procs.tcl

Recursive procedure for building a hierarchical or multidimensional data structure in a list.

Parameters:

listref
value - Either a list or scalar value to store in the list.
next - A key value that determines the next node to traverse outward in the data structure.

Source code:

  upvar $listref inlist
  if { ! [info exists inlist] } {
    set inlist [list]
  }

  # inlist represents the top level of the data structure into which
  # we are inserting. We need to turn the list into an array to determine
  # which branch to follow next.

  array set values $inlist
 
  # next determines the next branch to follow as we look for the proper
  # location of the value.  if the key is not found, create a new branch by
  # adding an empty list to inlist

  if { [info exists values($next)] } {
    set next_list $values($next)
  } else {
    set next_list [list]
  }

  # the number of additional arguments after next determines how many
  # more branches or levels we need to traverse before reaching the actual
  # insertion point into the data structure.

  set remaining [llength $args]
  if { $remaining == 0 } {

    # we have reached a leaf
    lappend next_list $value

  } elseif { $remaining == 1 } {

   # continue for one more step to the leaf
   lnest next_list $value [lindex $args 0]

  } else {

   # more branches to go.  Call the procedure recursively starting with
   # the current branch.

   lnest next_list $value [lindex $args 0] [lrange $args 1 end]
  }

  # At this point the branch has been updated.  Update the branch in the
  # array.

  set values($next) $next_list

  # Update inlist.
  
  set inlist [array get values]

XQL Not present:

Generic, PostgreSQL, Oracle