Natural sorting
In Raku it is very easy to modify the default sorting order by passing in a transform routine to the sort function. If the transform routines are arity one, the sort function will apply a Schwartzian Transform so it only needs to calculate the transform once. Note that the transforms are non-destructive; The sort function returns the original strings.
The following are a series of subroutines to perform the various natural sorting transforms. They may be applied individually or mixed and matched to get the particular result desired. When more than one is strung together, they apply left to right. Some combinations may yield different results depending on the order they are applied.
# Sort groups of digits in number order. Sort by order of magnitude then lexically.
sub naturally ($a) { $a.lc.subst(/(\d+)/, ->$/ {0~$0.chars.chr~$0},:g) ~"\x0"~$a }
# Collapse multiple ws characters to a single.
sub collapse ($a) { $a.subst( / ( \s ) $0+ /, -> $/ { $0 }, :g ) }
# Convert all ws characters to a space.
sub normalize ($a) { $a.subst( / ( \s ) /, ' ', :g ) }
# Ignore common leading articles for title sorts
sub title ($a) { $a.subst( / :i ^ ( a | an | the ) >> \s* /, '' ) }
# Decompose ISO-Latin1 glyphs to their base character.
sub latin1_decompose ($a) {
$a.trans: <
Æ AE æ ae Þ TH þ th Ð TH ð th ß ss À A Á A Â A Ã A Ä A Å A à a á a
â a ã a ä a å a Ç C ç c È E É E Ê E Ë E è e é e ê e ë e Ì I Í I Î
I Ï I ì i í i î i ï i Ò O Ó O Ô O Õ O Ö O Ø O ò o ó o ô o õ o ö o
ø o Ñ N ñ n Ù U Ú U Û U Ü U ù u ú u û u ü u Ý Y ÿ y ý y
>.hash;
}
# Used as:
my @tests = (
[
"Task 1a\nSort while ignoring leading spaces.",
[
'ignore leading spaces: 1', ' ignore leading spaces: 4',
' ignore leading spaces: 3', ' ignore leading spaces: 2'
],
{.trim} # builtin method.
],
[
"Task 1b\nSort while ignoring multiple adjacent spaces.",
[
'ignore m.a.s spaces: 3', 'ignore m.a.s spaces: 1',
'ignore m.a.s spaces: 4', 'ignore m.a.s spaces: 2'
],
{.&collapse}
],
[
"Task 2\nSort with all white space normalized to regular spaces.",
[
"Normalized\tspaces: 4", "Normalized\xa0spaces: 1",
"Normalized\x20spaces: 2", "Normalized\nspaces: 3"
],
{.&normalize}
],
[
"Task 3\nSort case independently.",
[
'caSE INDEPENDENT: 3', 'casE INDEPENDENT: 2',
'cASE INDEPENDENT: 4', 'case INDEPENDENT: 1'
],
{.lc} # builtin method
],
[
"Task 4\nSort groups of digits in natural number order.",
[
<Foo100bar99baz0.txt foo100bar10baz0.txt foo1000bar99baz10.txt
foo1000bar99baz9.txt 201st 32nd 3rd 144th 17th 2 95>
],
{.&naturally}
],
[
"Task 5 ( mixed with 1, 2, 3 & 4 )\n"
~ "Sort titles, normalize white space, collapse multiple spaces to\n"
~ "single, trim leading white space, ignore common leading articles\n"
~ 'and sort digit groups in natural order.',
[
'The Wind in the Willows 8', ' The 39 Steps 3',
'The 7th Seal 1', 'Wanda 6',
'A Fish Called Wanda 5', ' The Wind and the Lion 7',
'Any Which Way But Loose 4', '12 Monkeys 2'
],
{.&normalize.&collapse.trim.&title.&naturally}
],
[
"Task 6, 7, 8\nMap letters in Latin1 that have accents or decompose to two\n"
~ 'characters to their base characters for sorting.',
[
<apple Ball bald car Card above Æon æon aether
niño nina e-mail Évian evoke außen autumn>
],
{.&latin1_decompose.&naturally}
]
);
for @tests -> $case {
my $code_ref = $case.pop;
my @array = $case.pop.list;
say $case.pop, "\n";
say "Standard Sort:\n";
.say for @array.sort;
say "\nNatural Sort:\n";
.say for @array.sort: {.$code_ref};
say "\n" ~ '*' x 40 ~ "\n";
}Sample output:
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