#!./perl
+# This tests the behavior of sort() under the different 'use sort' forms.
+# Algorithm by John P. Linderman.
+
+my ($BigWidth, $BigEnough, $RootWidth, $ItemFormat, @TestSizes, $WellSoaked);
+
BEGIN {
chdir 't' if -d 't';
- @INC = '../lib';
+ @INC = qw(../lib);
+ $BigWidth = 6; # Digits in $BigEnough-1
+ $BigEnough = 10**$BigWidth; # Largest array we'll attempt
+ $RootWidth = int(($BigWidth+1)/2); # Digits in sqrt($BigEnough-1)
+ $ItemFormat = "%0${RootWidth}d%0${BigWidth}d"; # Array item format
+ @TestSizes = (0, 1, 2); # Small special cases
+ # Testing all the way up to $BigEnough takes too long
+ # for casual testing. There are some cutoffs (~256)
+ # in pp_sort that should be tested, but 10_000 is ample.
+ $WellSoaked = 10_000; # <= $BigEnough
+ for (my $ts = 3; $ts < $WellSoaked; $ts *= 10**(1/3)) {
+ push(@TestSizes, int($ts)); # about 3 per decade
+ }
}
-use Test::More tests => 2;
+use strict;
+use warnings;
-BEGIN {
- require "sort.pm"; # require sort; does not work
- ok(sort::current() eq 'mergesort');
+use Test::More tests => @TestSizes * 2 # sort() tests
+ * 4 # number of pragmas to test
+ + 1 # extra test for qsort instability
+ + 3 # tests for sort::current
+ + 3; # tests for "defaults" and "no sort"
+
+# Generate array of specified size for testing sort.
+#
+# We ensure repeated items, where possible, by drawing the $size items
+# from a pool of size sqrt($size). Each randomly chosen item is
+# tagged with the item index, so we can detect original input order,
+# and reconstruct the original array order.
+
+sub genarray {
+ my $size = int(shift); # fractions not welcome
+ my ($items, $i);
+ my @a;
+
+ if ($size < 0) { $size = 0; } # avoid complexity with sqrt
+ elsif ($size > $BigEnough) { $size = $BigEnough; }
+ $#a = $size - 1; # preallocate array
+ $items = int(sqrt($size)); # number of distinct items
+ for ($i = 0; $i < $size; ++$i) {
+ $a[$i] = sprintf($ItemFormat, int($items * rand()), $i);
+ }
+ return \@a;
+}
+
+
+# Check for correct order (including stability)
+
+sub checkorder {
+ my $aref = shift;
+ my $status = ''; # so far, so good
+ my ($i, $disorder);
+
+ for ($i = 0; $i < $#$aref; ++$i) {
+ # Equality shouldn't happen, but catch it in the contents check
+ next if ($aref->[$i] le $aref->[$i+1]);
+ $disorder = (substr($aref->[$i], 0, $RootWidth) eq
+ substr($aref->[$i+1], 0, $RootWidth)) ?
+ "Instability" : "Disorder";
+ # Keep checking if merely unstable... disorder is much worse.
+ $status =
+ "$disorder at element $i between $aref->[$i] and $aref->[$i+1]";
+ last unless ($disorder eq "Instability");
+ }
+ return $status;
+}
+
+
+# Verify that the two array refs reference identical arrays
+
+sub checkequal {
+ my ($aref, $bref) = @_;
+ my $status = '';
+ my $i;
+
+ if (@$aref != @$bref) {
+ $status = "Sizes differ: " . @$aref . " vs " . @$bref;
+ } else {
+ for ($i = 0; $i < @$aref; ++$i) {
+ next if ($aref->[$i] eq $bref->[$i]);
+ $status = "Element $i differs: $aref->[$i] vs $bref->[$i]";
+ last;
+ }
+ }
+ return $status;
+}
+
+
+# Test sort on arrays of various sizes (set up in @TestSizes)
+
+sub main {
+ my ($expect_unstable) = @_;
+ my ($ts, $unsorted, @sorted, $status);
+ my $unstable_num = 0;
+
+ foreach $ts (@TestSizes) {
+ $unsorted = genarray($ts);
+ # Sort only on item portion of each element.
+ # There will typically be many repeated items,
+ # and their order had better be preserved.
+ @sorted = sort { substr($a, 0, $RootWidth)
+ cmp
+ substr($b, 0, $RootWidth) } @$unsorted;
+ $status = checkorder(\@sorted);
+ # Put the items back into the original order.
+ # The contents of the arrays had better be identical.
+ if ($expect_unstable && $status =~ /^Instability/) {
+ $status = '';
+ ++$unstable_num;
+ }
+ is($status, '', "order ok for size $ts");
+ @sorted = sort { substr($a, $RootWidth)
+ cmp
+ substr($b, $RootWidth) } @sorted;
+ $status = checkequal(\@sorted, $unsorted);
+ is($status, '', "contents ok for size $ts");
+ }
+ # If the following test (#58) fails, see the comments in pp_sort.c
+ # for Perl_sortsv().
+ if ($expect_unstable) {
+ ok($unstable_num > 0, 'Instability ok');
+ }
}
-use sort 'fast';
-ok(sort::current() eq 'quicksort fast');
+# Test with no pragma still loaded -- stability expected (this is a mergesort)
+main(0);
+
+# XXX We're using this eval "..." trick to force recompilation,
+# to ensure that the correct pragma is enabled when main() is run.
+# Currently 'use sort' modifies $sort::hints at compile-time, but
+# pp_sort() fetches its value at run-time.
+# The order of those evals is important.
+
+eval q{
+ use sort qw(_qsort);
+ is(sort::current(), 'quicksort', 'sort::current for _qsort');
+ main(1);
+};
+die $@ if $@;
+
+eval q{
+ use sort qw(_mergesort);
+ is(sort::current(), 'mergesort', 'sort::current for _mergesort');
+ main(0);
+};
+die $@ if $@;
+
+eval q{
+ use sort qw(_qsort stable);
+ is(sort::current(), 'quicksort stable', 'sort::current for _qsort stable');
+ main(0);
+};
+die $@ if $@;
+
+# Tests added to check "defaults" subpragma, and "no sort"
+
+eval q{
+ no sort qw(_qsort);
+ is(sort::current(), 'stable', 'sort::current after no _qsort');
+};
+die $@ if $@;
+
+eval q{
+ use sort qw(defaults _qsort);
+ is(sort::current(), 'quicksort', 'sort::current after defaults _qsort');
+};
+die $@ if $@;
+eval q{
+ use sort qw(defaults stable);
+ is(sort::current(), 'stable', 'sort::current after defaults stable');
+};
+die $@ if $@;
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