3 # This tests the behavior of sort() under the different 'use sort' forms.
4 # Algorithm by John P. Linderman.
6 my ($BigWidth, $BigEnough, $RootWidth, $ItemFormat, @TestSizes, $WellSoaked);
11 $BigWidth = 6; # Digits in $BigEnough-1
12 $BigEnough = 10**$BigWidth; # Largest array we'll attempt
13 $RootWidth = int(($BigWidth+1)/2); # Digits in sqrt($BigEnough-1)
14 $ItemFormat = "%0${RootWidth}d%0${BigWidth}d"; # Array item format
15 @TestSizes = (0, 1, 2); # Small special cases
16 # Testing all the way up to $BigEnough takes too long
17 # for casual testing. There are some cutoffs (~256)
18 # in pp_sort that should be tested, but 10_000 is ample.
19 $WellSoaked = 10_000; # <= $BigEnough
20 for (my $ts = 3; $ts < $WellSoaked; $ts *= 10**(1/3)) {
21 push(@TestSizes, int($ts)); # about 3 per decade
28 use Test::More tests => @TestSizes * 2 # sort() tests
29 * 4 # number of pragmas to test
30 + 1 # extra test for qsort instability
31 + 3; # tests for sort::current
33 # Generate array of specified size for testing sort.
35 # We ensure repeated items, where possible, by drawing the $size items
36 # from a pool of size sqrt($size). Each randomly chosen item is
37 # tagged with the item index, so we can detect original input order,
38 # and reconstruct the original array order.
41 my $size = int(shift); # fractions not welcome
45 if ($size < 0) { $size = 0; } # avoid complexity with sqrt
46 elsif ($size > $BigEnough) { $size = $BigEnough; }
47 $#a = $size - 1; # preallocate array
48 $items = int(sqrt($size)); # number of distinct items
49 for ($i = 0; $i < $size; ++$i) {
50 $a[$i] = sprintf($ItemFormat, int($items * rand()), $i);
56 # Check for correct order (including stability)
60 my $status = ''; # so far, so good
63 for ($i = 0; $i < $#$aref; ++$i) {
64 # Equality shouldn't happen, but catch it in the contents check
65 next if ($aref->[$i] le $aref->[$i+1]);
66 $disorder = (substr($aref->[$i], 0, $RootWidth) eq
67 substr($aref->[$i+1], 0, $RootWidth)) ?
68 "Instability" : "Disorder";
69 # Keep checking if merely unstable... disorder is much worse.
71 "$disorder at element $i between $aref->[$i] and $aref->[$i+1]";
72 last unless ($disorder eq "Instability");
78 # Verify that the two array refs reference identical arrays
81 my ($aref, $bref) = @_;
85 if (@$aref != @$bref) {
86 $status = "Sizes differ: " . @$aref . " vs " . @$bref;
88 for ($i = 0; $i < @$aref; ++$i) {
89 next if ($aref->[$i] eq $bref->[$i]);
90 $status = "Element $i differs: $aref->[$i] vs $bref->[$i]";
98 # Test sort on arrays of various sizes (set up in @TestSizes)
101 my ($expect_unstable) = @_;
102 my ($ts, $unsorted, @sorted, $status);
103 my $unstable_num = 0;
105 foreach $ts (@TestSizes) {
106 $unsorted = genarray($ts);
107 # Sort only on item portion of each element.
108 # There will typically be many repeated items,
109 # and their order had better be preserved.
110 @sorted = sort { substr($a, 0, $RootWidth)
112 substr($b, 0, $RootWidth) } @$unsorted;
113 $status = checkorder(\@sorted);
114 # Put the items back into the original order.
115 # The contents of the arrays had better be identical.
116 if ($expect_unstable && $status =~ /^Instability/) {
120 is($status, '', "order ok for size $ts");
121 @sorted = sort { substr($a, $RootWidth)
123 substr($b, $RootWidth) } @sorted;
124 $status = checkequal(\@sorted, $unsorted);
125 is($status, '', "contents ok for size $ts");
127 # If the following test (#58) fails, see the comments in pp_sort.c
129 if ($expect_unstable) {
130 ok($unstable_num > 0, 'Instability ok');
134 # Test with no pragma still loaded -- stability expected (this is a mergesort)
137 # XXX We're using this eval "..." trick to force recompilation,
138 # to ensure that the correct pragma is enabled when main() is run.
139 # Currently 'use sort' modifies $^H{SORT} at compile-time, but
140 # pp_sort() fetches its value at run-time : thus the lexical scoping
141 # of %^H is of no utility.
142 # The order of those evals is important.
146 is(sort::current(), 'quicksort', 'sort::current for _qsort');
152 use sort qw(_mergesort);
153 is(sort::current(), 'mergesort', 'sort::current for _mergesort');
159 use sort qw(_qsort stable);
160 is(sort::current(), 'quicksort stable', 'sort::current for _qsort stable');