Range expansion
sub range-expand (Str $range-description) {
my token number { '-'? \d+ }
my token range { (<&number>) '-' (<&number>) }
$range-description
.split(',')
.map({ .match(&range) ?? $0..$1 !! +$_ })
.flat
}
say range-expand('-6,-3--1,3-5,7-11,14,15,17-20').join(', ');
Output:
-6, -3, -2, -1, 3, 4, 5, 7, 8, 9, 10, 11, 14, 15, 17, 18, 19, 20
Alternatively, using a grammar:
grammar RangeList {
token TOP { <term>* % ',' { make $<term>.map(*.made) } }
token term { [<range>|<num>] { make ($<num> // $<range>).made } }
token range { <num> '-' <num> { make +$<num>[0] .. +$<num>[1] } }
token num { '-'? \d+ { make +$/ } }
}
say RangeList.parse('-6,-3--1,3-5,7-11,14,15,17-20').made.flat.join(', ');
Output:
-6, -3, -2, -1, 3, 4, 5, 7, 8, 9, 10, 11, 14, 15, 17, 18, 19, 20
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