devdaily home | apple | java | perl | unix | directory | blog

What this is

This file is included in the DevDaily.com "Perl Source Code Warehouse" project. The intent of this project is to help you "Learn Perl by Example" TM.

Other links

The source code

#!./perl

BEGIN {
    chdir 't' if -d 't';
    @INC = '../lib';
}

require './test.pl';
plan(tests => 41);

# compile time

is('-' x 5, '-----',    'compile time x');
is('-' x 3.1, '---',    'compile time 3.1');
is('-' x 3.9, '---',    'compile time 3.9');
is('-' x 1, '-',        '  x 1');
is('-' x 0, '',         '  x 0');
is('-' x -1, '',        '  x -1');
is('-' x undef, '',     '  x undef');
is('-' x "foo", '',     '  x "foo"');
is('-' x "3rd", '---',  '  x "3rd"');

is('ab' x 3, 'ababab',  '  more than one char');

# run time

$a = '-';
is($a x 5, '-----',     'run time x');
is($a x 3.1, '---',     '  x 3.1');
is($a x 3.9, '---',     '  x 3.9');
is($a x 1, '-',         '  x 1');
is($a x 0, '',          '  x 0');
is($a x -3, '',         '  x -3');
is($a x undef, '',      '  x undef');
is($a x "foo", '',      '  x "foo"');
is($a x "3rd", '---',   '  x "3rd"');

$a = 'ab';
is($a x 3, 'ababab',    '  more than one char');
$a = 'ab';
is($a x 0, '',          '  more than one char');
$a = 'ab';
is($a x -12, '',        '  more than one char');

$a = 'xyz';
$a x= 2;
is($a, 'xyzxyz',        'x=2');
$a x= 1;
is($a, 'xyzxyz',        'x=1');
$a x= 0;
is($a, '',              'x=0');

@x = (1,2,3);

is(join('', @x x 4),        '3333',                 '@x x Y');
is(join('', (@x) x 4),      '123123123123',         '(@x) x Y');
is(join('', (@x,()) x 4),   '123123123123',         '(@x,()) x Y');
is(join('', (@x,1) x 4),    '1231123112311231',     '(@x,1) x Y');
is(join(':', () x 4),       '',                     '() x Y');
is(join(':', (9) x 4),      '9:9:9:9',              '(X) x Y');
is(join(':', (9,9) x 4),    '9:9:9:9:9:9:9:9',      '(X,X) x Y');
is(join('', (split(//,"123")) x 2), '123123',       'split and x');

is(join('', @x x -12),      '',                     '@x x -12');
is(join('', (@x) x -14),    '',                     '(@x) x -14');


# This test is actually testing for Digital C compiler optimizer bug,
# present in Dec C versions 5.* and 6.0 (used in Digital UNIX and VMS),
# found in December 1998.  The bug was reported to Digital^WCompaq as
#     DECC 2745 (21-Dec-1998)
# GEM_BUGS 7619 (23-Dec-1998)
# As of April 1999 the bug has been fixed in Tru64 UNIX 5.0 and is planned
# to be fixed also in 4.0G.
#
# The bug was as follows: broken code was produced for util.c:repeatcpy()
# (a utility function for the 'x' operator) in the case *all* these
# four conditions held:
#
# (1) len == 1
# (2) "from" had the 8th bit on in its single character
# (3) count > 7 (the 'x' count > 16)
# (4) the highest optimization level was used in compilation
#     (which is the default when compiling Perl)
#
# The bug looked like this (. being the eight-bit character and ? being \xff):
#
# 16 ................
# 17 .........???????.
# 18 .........???????..
# 19 .........???????...
# 20 .........???????....
# 21 .........???????.....
# 22 .........???????......
# 23 .........???????.......
# 24 .........???????.???????
# 25 .........???????.???????.
#
# The bug was triggered in the "if (len == 1)" branch.  The fix
# was to introduce a new temporary variable.  In diff -u format:
#
#     register char *frombase = from;
# 
#     if (len == 1) {
#-       todo = *from;
#+       register char c = *from;
#        while (count-- > 0)
#-           *to++ = todo;
#+           *to++ = c;
#        return;
#     }
#
# The bug could also be (obscurely) avoided by changing "from" to
# be an unsigned char pointer.
#
# This obscure bug was not found by the then test suite but instead
# by Mark.Martinec@nsc.ijs.si while trying to install Digest-MD5-2.00.
#
# jhi@iki.fi
#
is("\xdd" x 24, "\xdd\xdd\xdd\xdd\xdd\xdd\xdd\xdd\xdd\xdd\xdd\xdd\xdd\xdd\xdd\xdd\xdd\xdd\xdd\xdd\xdd\xdd\xdd\xdd", 'Dec C bug');


# When we use a list repeat in a scalar context, it behaves like
# a scalar repeat. Make sure that works properly, and doesn't leave
# extraneous values on the stack.
#  -- robin@kitsite.com

my ($x, $y) = scalar ((1,2)x2);
is($x, "22",    'list repeat in scalar context');
is($y, undef,   '  no extra values on stack');

# Make sure the stack doesn't get truncated too much - the left
# operand of the eq binop needs to remain!
is(77, scalar ((1,7)x2),    'stack truncation');


# perlbug 20011113.110 works in 5.6.1, broken in 5.7.2
{
    my $x= [("foo") x 2];
    is( join('', @$x), 'foofoo', 'list repeat in anon array ref broken [ID 20011113.110]' );
}

# [ID 20010809.028] x operator not copying elements in 'for' list?
{
    local $TODO = "x operator not copying elements in 'for' list? [ID 20010809.028]";
    my $x = 'abcd';
    my $y = '';
    for (($x =~ /./g) x 2) {
	$y .= chop;
    }
    is($y, 'abcdabcd');
}




Copyright 1998-2008 Alvin Alexander
All Rights Reserved.
 
devdaily.com is based in louisville, kentucky, and this web site is hosted by godaddy.com