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author | Staszek Wawrykiewicz <staw@gust.org.pl> | 2006-12-18 03:24:34 +0000 |
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committer | Staszek Wawrykiewicz <staw@gust.org.pl> | 2006-12-18 03:24:34 +0000 |
commit | fbf4a6e8014789c67a381e0b4f05de5bdadbce24 (patch) | |
tree | 20cc48dd29799a673fe0a628e825114d823493b1 /Master/perltl/lib/List | |
parent | 34c11d2616bb32772199abf210ae88d99665a824 (diff) |
perltl added
git-svn-id: svn://tug.org/texlive/trunk@2778 c570f23f-e606-0410-a88d-b1316a301751
Diffstat (limited to 'Master/perltl/lib/List')
-rw-r--r-- | Master/perltl/lib/List/Util.pm | 194 |
1 files changed, 194 insertions, 0 deletions
diff --git a/Master/perltl/lib/List/Util.pm b/Master/perltl/lib/List/Util.pm new file mode 100644 index 00000000000..7686ffe82cd --- /dev/null +++ b/Master/perltl/lib/List/Util.pm @@ -0,0 +1,194 @@ +# List::Util.pm +# +# Copyright (c) 1997-2001 Graham Barr <gbarr@pobox.com>. All rights reserved. +# This program is free software; you can redistribute it and/or +# modify it under the same terms as Perl itself. + +package List::Util; + +require Exporter; +require DynaLoader; + +our @ISA = qw(Exporter DynaLoader); +our @EXPORT_OK = qw(first min max minstr maxstr reduce sum shuffle); +our $VERSION = "1.07_00"; +our $XS_VERSION = $VERSION; +$VERSION = eval $VERSION; + +bootstrap List::Util $XS_VERSION; + +1; + +__END__ + +=head1 NAME + +List::Util - A selection of general-utility list subroutines + +=head1 SYNOPSIS + + use List::Util qw(first max maxstr min minstr reduce shuffle sum); + +=head1 DESCRIPTION + +C<List::Util> contains a selection of subroutines that people have +expressed would be nice to have in the perl core, but the usage would +not really be high enough to warrant the use of a keyword, and the size +so small such that being individual extensions would be wasteful. + +By default C<List::Util> does not export any subroutines. The +subroutines defined are + +=over 4 + +=item first BLOCK LIST + +Similar to C<grep> in that it evaluates BLOCK setting C<$_> to each element +of LIST in turn. C<first> returns the first element where the result from +BLOCK is a true value. If BLOCK never returns true or LIST was empty then +C<undef> is returned. + + $foo = first { defined($_) } @list # first defined value in @list + $foo = first { $_ > $value } @list # first value in @list which + # is greater than $value + +This function could be implemented using C<reduce> like this + + $foo = reduce { defined($a) ? $a : wanted($b) ? $b : undef } undef, @list + +for example wanted() could be defined() which would return the first +defined value in @list + +=item max LIST + +Returns the entry in the list with the highest numerical value. If the +list is empty then C<undef> is returned. + + $foo = max 1..10 # 10 + $foo = max 3,9,12 # 12 + $foo = max @bar, @baz # whatever + +This function could be implemented using C<reduce> like this + + $foo = reduce { $a > $b ? $a : $b } 1..10 + +=item maxstr LIST + +Similar to C<max>, but treats all the entries in the list as strings +and returns the highest string as defined by the C<gt> operator. +If the list is empty then C<undef> is returned. + + $foo = maxstr 'A'..'Z' # 'Z' + $foo = maxstr "hello","world" # "world" + $foo = maxstr @bar, @baz # whatever + +This function could be implemented using C<reduce> like this + + $foo = reduce { $a gt $b ? $a : $b } 'A'..'Z' + +=item min LIST + +Similar to C<max> but returns the entry in the list with the lowest +numerical value. If the list is empty then C<undef> is returned. + + $foo = min 1..10 # 1 + $foo = min 3,9,12 # 3 + $foo = min @bar, @baz # whatever + +This function could be implemented using C<reduce> like this + + $foo = reduce { $a < $b ? $a : $b } 1..10 + +=item minstr LIST + +Similar to C<min>, but treats all the entries in the list as strings +and returns the lowest string as defined by the C<lt> operator. +If the list is empty then C<undef> is returned. + + $foo = minstr 'A'..'Z' # 'A' + $foo = minstr "hello","world" # "hello" + $foo = minstr @bar, @baz # whatever + +This function could be implemented using C<reduce> like this + + $foo = reduce { $a lt $b ? $a : $b } 'A'..'Z' + +=item reduce BLOCK LIST + +Reduces LIST by calling BLOCK multiple times, setting C<$a> and C<$b> +each time. The first call will be with C<$a> and C<$b> set to the first +two elements of the list, subsequent calls will be done by +setting C<$a> to the result of the previous call and C<$b> to the next +element in the list. + +Returns the result of the last call to BLOCK. If LIST is empty then +C<undef> is returned. If LIST only contains one element then that +element is returned and BLOCK is not executed. + + $foo = reduce { $a < $b ? $a : $b } 1..10 # min + $foo = reduce { $a lt $b ? $a : $b } 'aa'..'zz' # minstr + $foo = reduce { $a + $b } 1 .. 10 # sum + $foo = reduce { $a . $b } @bar # concat + +=item shuffle LIST + +Returns the elements of LIST in a random order + + @cards = shuffle 0..51 # 0..51 in a random order + +=item sum LIST + +Returns the sum of all the elements in LIST. + + $foo = sum 1..10 # 55 + $foo = sum 3,9,12 # 24 + $foo = sum @bar, @baz # whatever + +This function could be implemented using C<reduce> like this + + $foo = reduce { $a + $b } 1..10 + +=back + +=head1 KNOWN BUGS + +With perl versions prior to 5.005 there are some cases where reduce +will return an incorrect result. This will show up as test 7 of +reduce.t failing. + +=head1 SUGGESTED ADDITIONS + +The following are additions that have been requested, but I have been reluctant +to add due to them being very simple to implement in perl + + # One argument is true + + sub any { $_ && return 1 for @_; 0 } + + # All arguments are true + + sub all { $_ || return 0 for @_; 1 } + + # All arguments are false + + sub none { $_ && return 0 for @_; 1 } + + # One argument is false + + sub notall { $_ || return 1 for @_; 0 } + + # How many elements are true + + sub true { scalar grep { $_ } @_ } + + # How many elements are false + + sub false { scalar grep { !$_ } @_ } + +=head1 COPYRIGHT + +Copyright (c) 1997-2001 Graham Barr <gbarr@pobox.com>. All rights reserved. +This program is free software; you can redistribute it and/or +modify it under the same terms as Perl itself. + +=cut |