perl -e "$s='OOO....MMMM..IIIII';$s=~s/(.)(\.+)/$1.$1 x length($2)/eg;print $s,$/;"
#            OOOOOOOMMMMMMIIIII

##</code><code>##

perl -e "$s='JJ..A....PPPP..HHHH...';$s=~s/(.)(\.+)/$1.$1 x length($2)/eg;print $s,$/;"
#            JJJJAAAAAPPPPPPHHHHHHH