VList: Difference between revisions
Rename Perl 6 -> Raku, alphabetize, minor clean-up
m (→{{header|Perl 6}}: insignificant shortening) |
Thundergnat (talk | contribs) (Rename Perl 6 -> Raku, alphabetize, minor clean-up) |
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Mike 1 3
1 Fred 4
</pre>
Line 1,067 ⟶ 957:
See https://github.com/takikawa/tr-pfds/blob/master/pfds/vlist.rkt
for an implementation of VLists.
=={{header|Raku}}==
(formerly Perl 6)
{{trans|Go}}
{{trans|Kotlin}}
<lang perl6>#!/usr/bin/env perl6
class vList {
subset vEle of Any; # or Str
class vSeg {
has $.next is rw is default(Nil) ;
has vEle @.ele is rw ;
}
has vSeg $.base is rw is default(vSeg.new(ele=>()));
has Int $.offset is rw is default(0) ;
method Index(Int $i is copy --> vEle) { # method to locate the kth element
if $i ≥ 0 {
loop ( $i += self.offset, $_ = self.base; $_.defined; $_ := $_.next) {
($i < my $len = .ele.elems) ?? return .ele[$i] !! $i -= $len
}
}
die "index out of range"
}
method cons(vEle \a --> vList) { # method to add an element to the front
if not self.base.ele.Bool { # probably faster than .elems ?
self.base.ele.push: a ;
return self;
} elsif self.offset == 0 {
my \L2offset = (self.base.ele.elems * 2) - 1 ;
my \s = vSeg.new(next => self.base, ele => flat Nil xx L2offset, a);
return vList.new(base => s, offset => L2offset )
}
self.base.ele[--self.offset] = a;
return self
}
# obtain a new array beginning at the second element of an old array
method cdr(--> vList) {
die "cdr on empty vList" unless self.base.defined;
return self if ++self.offset < self.base.ele.elems;
return vList.new(base => self.base.next)
}
method Length(--> Int) { # method to compute the length of the list
return 0 unless self.base.defined;
return self.base.ele.elems*2 - self.offset - 1
}
method gist { # (mis)used to create output similar to Go/Kotlin
return '[]' unless self.base.ele.Bool;
my @sl = self.base.ele[self.offset .. *];
loop ($_=self.base.next; $_.defined; $_:=$_.next) { @sl.append: .ele }
return "[" ~ @sl.Str ~ "]"
}
method printStructure { # One more method for demonstration purposes
say "offset: ", self.offset;
loop ( $_ = self.base; $_.defined ; $_ := $_.next ) { .ele.say }
}
}
my $v := vList.new;
say "zero value for type. empty vList: ", $v;
$v.printStructure;
say " ";
$v := $v.cons($_.Str) for 6 … 1;
say "demonstrate cons. 6 elements added: ", $v;
$v.printStructure;
say " ";
$v := $v.cdr;
say "demonstrate cdr. 1 element removed: ", $v;
$v.printStructure;
say " ";
say "demonstrate length. length = ", $v.Length;
say " ";
say "demonstrate element access. v[3] = ", $v.Index(3) ;
say " ";
$v := $v.cdr.cdr;
say "show cdr releasing segment. 2 elements removed: ", $v;
$v.printStructure;</lang>
{{out}}
<pre>zero value for type. empty vList: []
offset: 0
[]
demonstrate cons. 6 elements added: [1 2 3 4 5 6]
offset: 1
[(vEle) 1 2 3]
[4 5]
[6]
demonstrate cdr. 1 element removed: [2 3 4 5 6]
offset: 2
[(vEle) 1 2 3]
[4 5]
[6]
demonstrate length. length = 5
demonstrate element access. v[3] = 5
show cdr releasing segment. 2 elements removed: [4 5 6]
offset: 0
[4 5]
[6]
</pre>
=={{header|REXX}}==
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