illumos-port-bash/examples/functions/array-stuff

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#
# Chet Ramey <chet.ramey@case.edu>
#
# Copyright 1999 Chester Ramey
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2, or (at your option)
# any later version.
#
# TThis program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software Foundation,
# Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
# usage: reverse arrayname
reverse()
{
local -a R
local -i i
local rlen temp
# make r a copy of the array whose name is passed as an arg
eval R=\( \"\$\{$1\[@\]\}\" \)
# reverse R
rlen=${#R[@]}
for ((i=0; i < rlen/2; i++ ))
do
temp=${R[i]}
R[i]=${R[rlen-i-1]}
R[rlen-i-1]=$temp
done
# and assign R back to array whose name is passed as an arg
eval $1=\( \"\$\{R\[@\]\}\" \)
}
A=(1 2 3 4 5 6 7)
echo "${A[@]}"
reverse A
echo "${A[@]}"
reverse A
echo "${A[@]}"
# unset last element of A
alen=${#A[@]}
unset A[$alen-1]
echo "${A[@]}"
# ashift -- like shift, but for arrays
ashift()
{
local -a R
local n
case $# in
1) n=1 ;;
2) n=$2 ;;
*) echo "$FUNCNAME: usage: $FUNCNAME array [count]" >&2
exit 2;;
esac
# make r a copy of the array whose name is passed as an arg
eval R=\( \"\$\{$1\[@\]\}\" \)
# shift R
R=( "${R[@]:$n}" )
# and assign R back to array whose name is passed as an arg
eval $1=\( \"\$\{R\[@\]\}\" \)
}
ashift A 2
echo "${A[@]}"
ashift A
echo "${A[@]}"
ashift A 7
echo "${A[@]}"
# Sort the members of the array whose name is passed as the first non-option
# arg. If -u is the first arg, remove duplicate array members.
array_sort()
{
local -a R
local u
case "$1" in
-u) u=-u ; shift ;;
esac
if [ $# -eq 0 ]; then
echo "array_sort: argument expected" >&2
return 1
fi
# make r a copy of the array whose name is passed as an arg
eval R=\( \"\$\{$1\[@\]\}\" \)
# sort R
R=( $( printf "%s\n" "${A[@]}" | sort $u) )
# and assign R back to array whose name is passed as an arg
eval $1=\( \"\$\{R\[@\]\}\" \)
return 0
}
A=(3 1 4 1 5 9 2 6 5 3 2)
array_sort A
echo "${A[@]}"
A=(3 1 4 1 5 9 2 6 5 3 2)
array_sort -u A
echo "${A[@]}"