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RazvanN7 2016-12-15 17:42:10 +02:00
parent 72af0090db
commit 17e3e642e9
1 changed files with 39 additions and 23 deletions
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62
std/random.d
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@ -2160,6 +2160,7 @@ struct RandomCover(Range, UniformRNG = void)
private bool[] _chosen; private bool[] _chosen;
private size_t _current; private size_t _current;
private size_t _alreadyChosen = 0; private size_t _alreadyChosen = 0;
private bool _isEmpty = false;
static if (is(UniformRNG == void)) static if (is(UniformRNG == void))
{ {
@ -2167,9 +2168,13 @@ struct RandomCover(Range, UniformRNG = void)
{ {
_input = input; _input = input;
_chosen.length = _input.length; _chosen.length = _input.length;
if (_chosen.length == 0) if (_input.empty)
{ {
_alreadyChosen = 1; _isEmpty = true;
}
else
{
_current = uniform(0, _chosen.length);
} }
} }
} }
@ -2182,9 +2187,13 @@ struct RandomCover(Range, UniformRNG = void)
_input = input; _input = input;
_rng = rng; _rng = rng;
_chosen.length = _input.length; _chosen.length = _input.length;
if (_chosen.length == 0) if (_input.empty)
{ {
_alreadyChosen = 1; _isEmpty = true;
}
else
{
_current = uniform(0, _chosen.length, rng);
} }
} }
@ -2198,39 +2207,32 @@ struct RandomCover(Range, UniformRNG = void)
{ {
@property size_t length() @property size_t length()
{ {
if (_alreadyChosen == 0) return _input.length - _alreadyChosen;
{
return _input.length;
}
else
{
return (1 + _input.length) - _alreadyChosen;
}
} }
} }
@property auto ref front() @property auto ref front()
{ {
if (_alreadyChosen == 0) assert(!_isEmpty);
{
popFront();
}
return _input[_current]; return _input[_current];
} }
void popFront() void popFront()
{ {
if (_alreadyChosen >= _input.length) assert(!_isEmpty);
size_t k = _input.length - _alreadyChosen - 1;
if (k == 0)
{ {
// No more elements _isEmpty = true;
++_alreadyChosen; // means we're done ++_alreadyChosen;
return; return;
} }
size_t k = _input.length - _alreadyChosen;
size_t i; size_t i;
foreach (e; _input) foreach (e; _input)
{ {
if (_chosen[i]) { ++i; continue; } if (_chosen[i] || i == _current) { ++i; continue; }
// Roll a dice with k faces // Roll a dice with k faces
static if (is(UniformRNG == void)) static if (is(UniformRNG == void))
{ {
@ -2243,7 +2245,7 @@ struct RandomCover(Range, UniformRNG = void)
assert(k > 1 || chooseMe); assert(k > 1 || chooseMe);
if (chooseMe) if (chooseMe)
{ {
_chosen[i] = true; _chosen[_current] = true;
_current = i; _current = i;
++_alreadyChosen; ++_alreadyChosen;
return; return;
@ -2264,7 +2266,7 @@ struct RandomCover(Range, UniformRNG = void)
} }
} }
@property bool empty() { return _alreadyChosen > _input.length; } @property bool empty() { return _isEmpty; }
} }
/// Ditto /// Ditto
@ -2286,6 +2288,7 @@ auto randomCover(Range)(Range r)
import std.algorithm; import std.algorithm;
import std.conv; import std.conv;
int[] a = [ 0, 1, 2, 3, 4, 5, 6, 7, 8 ]; int[] a = [ 0, 1, 2, 3, 4, 5, 6, 7, 8 ];
int[] c;
foreach (UniformRNG; std.meta.AliasSeq!(void, PseudoRngTypes)) foreach (UniformRNG; std.meta.AliasSeq!(void, PseudoRngTypes))
{ {
static if (is(UniformRNG == void)) static if (is(UniformRNG == void))
@ -2302,6 +2305,8 @@ auto randomCover(Range)(Range r)
// check for constructor passed a value-type RNG // check for constructor passed a value-type RNG
auto rc2 = RandomCover!(int[], UniformRNG)(a, UniformRNG(unpredictableSeed)); auto rc2 = RandomCover!(int[], UniformRNG)(a, UniformRNG(unpredictableSeed));
static assert(isForwardRange!(typeof(rc2))); static assert(isForwardRange!(typeof(rc2)));
auto rcEmpty = randomCover(c, rng);
assert(rcEmpty.length == 0);
} }
int[] b = new int[9]; int[] b = new int[9];
@ -2323,6 +2328,17 @@ auto randomCover(Range)(Range r)
auto rc = randomCover(r); auto rc = randomCover(r);
assert(rc.length == 0); assert(rc.length == 0);
assert(rc.empty); assert(rc.empty);
// Bugzilla 16724
import std.range : iota;
auto range = iota(10);
auto randy = range.randomCover;
for (int i=1; i<=range.length; i++)
{
randy.popFront;
assert(randy.length == range.length - i);
}
} }
// RandomSample // RandomSample