#!/bin/perl

# This snippet keeps track of strings (collections) I've seen, and tests to see if
# we've seen this next string.  If not, I "remember" it.
#
# To remember strings and to be able to easily check later if I've seen it,
# it's best to use associative arrays like I do here, rather than what I used
# to do with Rexx, keeping it in one long, ever-growing string. and using
# wordpos to search it.  Perl has no wordpos equivalent, forcing me to do my
# own delimiting and checking for space-word-space (yuck!).
#
# The two relevant lines here are $collections_seen{$line} = 1; to set
#                             and if ( $collections_seen{$line} == 1 )  to check.

while (<STDIN>) {
  chomp;
  $line=$_;
  if ( $collections_seen{$line} == 1 ) {
    print "I've seen $line before.\n";
  } else {
    print "I haven't seen $line before.  I'll add it now.\n";
    $collections_seen{$line} = 1;                 #  Remember new string.
#   print "\%collections_seen is now =>", sort keys %collections_seen, "<\n";
  }
}