#!/bin/zsh
#
# undual - remove a name from the dual list
# 
# [2000-09-29]
# Version 3.1.6 of zsh automates this functionality with
# typeset -T.  I'll leave this function here for historical purposes.
#
# Usage:
#   undual [name] . . .
#
# where
#   name   is the name of a shell variable to remove from the
#          dual list.  See dual for more.  You can't remove
#          dual itself from the dual list, which is kind of
#          good.
#
# assumes unsetopt shwordsplit
# Might require a POSIX sed, on account of the
# \(:\|$\) (colon or end of line) construct.  In awk it becomes
# (:|$) which is much easier to read.  I use sed because it's a little
# less memory-hungry.
#

# each name . . .
for name
do
  # get uppercase version
  upper=${(U)name}
  # if there is no dual list, quit now.
  if [[ -z "$dual" || -z "$DUAL" ]]
  then
    break
  fi
  # remove the item from the dual list - with dual!
  dual DUAL=$(echo $DUAL | sed "s/:$upper\(:\|$\)/\1/")
  # and remap the dual array to lower case.
  dual=(${(L)dual})
done