Just in time processing on a character stream: Difference between revisions
Just in time processing on a character stream (view source)
Revision as of 19:54, 12 April 2019
, 5 years ago→{{header|Perl 6}}: Add a Perl 6 example
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Silence-Dogood.
</pre>
=={{header|Perl 6}}==
{{works with|Rakudo|2019.03}}
This is a somewhat fragile toy encoder / decoder and shouldn't be used for anything serious.
<lang perl6>#`[
Set srand to set the encode / decode "key", and
generate a lazy, reproducible stream of "random"
characters. Need to use the same key and same
implementation of Perl 6 to encode / decode.
Gain "security" by exchanging keys by a second
channel. Default key is 'Perl 6'
]
unit sub MAIN ($key = 'Perl 6');
srand $key.comb(/<.alnum>/).join.parse-base(36) % 2**63;
# random but reproducible infinite stream of characters
my @stream = (flat ' ' .. '~').roll(*);
sub jit-encode (Str $str) {
my $i = 0;
my $last = 0;
my $enc = '';
for $str.comb -> $c {
my $h;
my $l = '';
++$i until $c eq @stream[$i];
my $o = $i - $last;
$l = $o % 26;
$h = $o - $l if $o > 26;
$l += 10;
$enc ~= ($h ?? $h.base(36).uc !! '') ~ ($l.base(36).lc);
$last = $i;
}
$enc
}
sub jit-decode (Str $str) {
$str ~~ m:g/((.*?) (<:Ll>))/;
my $dec = '';
my $i = 0;
for $/.List -> $l {
my $o = ($l[0][1].Str.parse-base(36) - 10 // 0) +
($l[0][0].Str.parse-base(36) // 0);
$i += $o;
$dec ~= @stream[$i];
}
$dec
}
my $enc = jit-encode('In my opinion, this task is pretty silly.');
say "Encoded\n$enc\n\nDecoded\n", jit-decode($enc);</lang>
<pre>Encoded
26j52dhl2Wp1Gw2WceQj1Go3MyQc1Gd52a1Gb1Ga2Wcq26o4Cwf3MiQsQn2Wglk3MhkQyeQjas3MkQn2Wd26aaQcQj
Decoded
In my opinion, this task is pretty silly.</pre>
=={{header|Python}}==
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