#!/bin/bash

#-------------------------------------------------------------------------------
# Example 1 for Bash Tips show 18: transforming words in a string
#
# This is a contrived and overly complex example to show that replacing
# selected words in a phrase by different words is a non-trivial exercise!
#-------------------------------------------------------------------------------

#
# Enable extglob
#
shopt -s extglob

#
# What we'll work on and where we'll store the transformed version
#
phrase='Now is the time for all good men to come to the aid of the party'
newphrase=

#
# How to transform words in the phrase and a place to store the keys
#
declare -A transform=([good]='bad' [men]='people' [party]='Community')
declare -a keys

#
# Build an extglob pattern from the keys of the associative array
#
keys=( ${!transform[@]} )
targets="${keys[*]/%/|}"     # Each key is followed by a '|'
targets="${targets%|}"       # Strip the last '|'
targets="${targets// }"      # Some spaces got in there too
pattern="@(${targets})"      # Make the pattern at last

#
# Go word by word; if a word matches the pattern replace it by what's in the
# 'transform' array. Because the pattern has been built from the array keys
# we'll never have the case where a word doesn't have a transformation.
#
for word in $phrase; do
    if [[ $word == $pattern ]]; then
        word=${transform[$word]}
    fi
    newphrase+="$word "
done
echo "$newphrase"

exit