# Licensed to the Apache Software Foundation (ASF) under one or more# contributor license agreements.  See the NOTICE file distributed with# this work for additional information regarding copyright ownership.# The ASF licenses this file to You under the Apache License, Version 2.0# (the "License"); you may not use this file except in compliance with# the License.  You may obtain a copy of the License at##      http://www.apache.org/licenses/LICENSE-2.0## Unless required by applicable law or agreed to in writing, software# distributed under the License is distributed on an "AS IS" BASIS,# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.# See the License for the specific language governing permissions and# limitations under the License.# This perl script all combinations of tree structures based on the "args"# array.# For example, if args = ("a", "b", "c"), it will output:## stressTest  a b c# stressTest  a b a.c# stressTest  a b b.c# stressTest  a a.b c# stressTest  a a.b a.c# stressTest  a a.b a.b.c$prefix = "stressTest";@tree = ("");@args = ("a", "b");permute(0, @tree);@args = ("a", "b", "c");permute(0, @tree);@args = ("a", "b", "c", "d");permute(0, @tree);@args = ("a", "b", "c", "d", "e");permute(0, @tree);@args = ("a", "b", "c", "d", "e", "f");permute(0, @tree);sub permute() {  my ($i, @t)  = @_;  #print "Tree is @t\n";  #print "i is  $i \n";    if($i == $#args + 1) {    print "$prefix @t\n";    return;  }    foreach $j (@t) {    #print "J is $j \n";    #print "args[$i]=$args[$i]\n";    if($j eq "") {      $next = "$args[$i]";    }    else {      $next = "$j.$args[$i]";    }	    permute($i+1, (@t, $next));  }  }