%
% stack: seek-str
%
">finf\" _\ & log)(

isnull
{
%
% have exhausted help subject to seek
%
 pop "="
} if
%
% stack: seek-str node anchor str-pos
%
{
%
% check for possible operation code in front of remaining seek string
%
 dup 1 left
 <
 |#
%
% absolute xhelp reference
%
  -1 left
%
% peel back all the xhelp layers to the top tree
%
  *unxhelps
%
% the current node is the root of the topmost xhelp tree
%
%%%  select*

 > not
%
% if the char in front is not intercepted
% the flag here will be true for exit
%
 exch isnull
 {
%
% the sub-operation has exhausted the search string, use current node
%
  pop2 false "="
 } if
 exch
%
% stack: seek-remain xhelp-found
%
 ?

} loop
"predecide" log)(
%
% the string remaining is a tree node address
% find it based on the current node
%
dup false _\ @^Seek
"node " &5 &" anchor " &4 &" pos " &3 &" flag" log)(
%
% stack: seek-str node anchor str-pos flag
%
% flag negative is no match, zero is match, and positive is no action
%
<
%
% stack: seek-str node anchor str-pos
%
|-1
"(nomatch" log)(

%
% partial match, node is negative, no equal match occurred
%
% extract matching prefix and remaining suffix
% work with the node that last matched
%
 fourth second - - fromleft
%
% check for descend through linked node
%
% stack: seek-str node anchor str-pos suffix
%
"(partial" log)(
 *xhelfing

|0
%
% full match of seek string, empty suffix to finish
%
 empty
%
% stack: seek-str node anchor str-pos suffix
%
% check for descend through linked node
%
"(full" log)(
 *xhelfing
> not
{
%
% no part of string matched, suffix is the entire search string
%
 0 fourth
%
% stack: seek-str node anchor str-pos suffix
%
% check for descend through linked node
%
"(nopart" log)(
 *xhelfing
} if
%
% stack: found
%

"<finf" log)(