use v5.22;
use warnings;

# Causes "Wide Character.." warning for :std
#use utf8;

my %swaps = (
    '91' => '‘',
    '92' => '’',
    '94' => '”',
    '96' => '–',
    'A9' => '©',
);


while (my $line = <DATA>) {
    say "Before=".$line;

    # Works.
    #my ($key) = $line =~ m/(\x92)/;
    # All fail
    #my ($key) = $line =~ /(\\x[[:xdigit:]]{1,3})/;
    #my ($key) = $line =~ m/(\x\d{2})/;
    #my ($key) = $line =~ /(0x[0-9A-F]{1,3})/i;
    #my ($key) = $line =~ m/(0x\d{1,3})/;
    #my ($key) = $line =~ m/(\0x\d{1,3})/;
    my ($key) = $line =~ m/0x(?-i:[\da-f]+)/;


    say "Key=$key";
    $line =~ s/$key/$swaps{$key}/g if $key;
    say "After=".$line;

}


# This sample has \x92 between "heart" and "s".
# In xxd, the line looks like this
# 0000080: 6420 7061 6e73 792c 2068 6561 7274 9273  d pansy, heart.s

__DATA__
"Wild pansy (Viola tricolor), 19th century illustration","19th-century hand painted illustration of wild pansy, heart<92>s ease, or love in idleness (Viola tricolor) flower by Pierre-Joseph Redoute (1759-1840). Published in Choix Des Plus Belles Fleurs, Paris (1827).",N/A,"Pansy, pansies, wild, Viola tricolor, 19th century, painted, Engraving, illustration, nobody, no-one, flower, artwork, Pierre Joseph redoute, bloom, blossom, botanical, botanist, bud, flora, floral, history, historic, horticulture, leaves, petal, petals, plant, vintage, watercolor, flower head, painting, stem, victorian style, botanic, flowers, plants, Botany",,C,Fl,N/A,,,,^M