%
% create b-tree lookup for alphabetic names
%
% stack: name-to-add
%
Tree.Off
%
% descend the tree by seeking the remaining string
% take each letter and seek it as tree member at the
% current parse level
% keep checking tree membership adding each remaining
% letter, if no characters left, this is a new branch to be
% inserted into the tree
%
root\
0
{
%
% stack: name-to-add parse-length
%
% check the next letter combo against the current branch
%
 *alphnpar
 {
%
% there was another letter to add to the combo
%
  *alphnpat
 }
 {
%
% there was not another letter to add to the combo
% cycle through this levels children to see if this combo
% shares the leading part of any of them
%
% stack: name-to-add parse-length
%
  first\?
  {
%
% check remaining seek string against child nodes
%
% stack: name-to-add parse-length child-node
%
   {
%
% stack: name-to-add parse-length child-node
%
    *alphnpau
    {
%
% there was a match of at least one character
%
% stack: name-to-add parse-length child-node position
%
% save the current branch into buffer file
%
     exch
%
% stack: name-to-add parse-length position child-node
%
%
% 0 - item w/children  1 - item only  2 - children only
%
     dup "CopyItem" do
     Mep.Remove
%
% stack: name-to-add parse-length position
%
% create a new sibling with the common text
%
     rot dup third - left
%
% stack: parse-length position name-to-add common
%
     newchild
%
% stack: parse-length position name-to-add common-node
%
     _\
     dup "LoadItem" do

     Mep._Below pop
%
% stack: parse-length position name-to-add orig-node
%
     dup Tree._Text
%
% stack: parse-length position name-to-add orig-node orig-text
%
     fourth - fromleft
%
% stack: parse-length position name-to-add orig-node reduced-orig
%
     exch Tree.!Text
%
% stack: parse-length position name-to-add
%
     exch - fromleft
%
% stack: parse-length remain-to-add
%
     isnull
     {
%
% the remaining string was totally included in child node
%
      pop
     }
     {
%
% there is a remaining part of name to branch off the common node
%
      newchild
     } ifelse
%
% stack: parse-length
%
     empty)( 0 -1
    }
    {
%
% no match with this child
%
     pop
%
% stack: name-to-add parse-length child-node
%
     Mep._Next
    } ifelse
%
% stack: name-to-add parse-length child-node
%
    neg( ?
   } loop
   pop
%
% stack: name-to-add parse-length
%
   pop
   any?
   {
%
% this is what remains, add it
%
    newchild
   } if
  }
  {
%
% there are no other children, just add this one
%
% stack: name-to-add parse-length
%
   pop newchild
  } ifelse
  empty 0
 } ifelse
%
% stack: name-to-add parse-length
%
 second
 isnull)
 ?
} loop
%
% stack: name-to-add parse-length
%
pop2

Tree.On