Edit file File name : MoreUtils.pm Content :package List::MoreUtils; use 5.00503; use strict; use Exporter (); use DynaLoader (); use vars qw{ $VERSION @ISA @EXPORT_OK %EXPORT_TAGS }; BEGIN { $VERSION = '0.33'; # $VERSION = eval $VERSION; @ISA = qw{ Exporter DynaLoader }; @EXPORT_OK = qw{ any all none notall true false firstidx first_index lastidx last_index insert_after insert_after_string apply indexes after after_incl before before_incl firstval first_value lastval last_value each_array each_arrayref pairwise natatime mesh zip uniq distinct minmax part }; %EXPORT_TAGS = ( all => \@EXPORT_OK, ); # Load the XS at compile-time so that redefinition warnings will be # thrown correctly if the XS versions of part or indexes loaded eval { # PERL_DL_NONLAZY must be false, or any errors in loading will just # cause the perl code to be tested local $ENV{PERL_DL_NONLAZY} = 0 if $ENV{PERL_DL_NONLAZY}; bootstrap List::MoreUtils $VERSION; 1; } unless $ENV{LIST_MOREUTILS_PP}; } eval <<'END_PERL' unless defined &any; # Use pure scalar boolean return values for compatibility with XS use constant YES => ! 0; use constant NO => ! 1; sub any (&@) { my $f = shift; foreach ( @_ ) { return YES if $f->(); } return NO; } sub all (&@) { my $f = shift; foreach ( @_ ) { return NO unless $f->(); } return YES; } sub none (&@) { my $f = shift; foreach ( @_ ) { return NO if $f->(); } return YES; } sub notall (&@) { my $f = shift; foreach ( @_ ) { return YES unless $f->(); } return NO; } sub true (&@) { my $f = shift; my $count = 0; foreach ( @_ ) { $count++ if $f->(); } return $count; } sub false (&@) { my $f = shift; my $count = 0; foreach ( @_ ) { $count++ unless $f->(); } return $count; } sub firstidx (&@) { my $f = shift; foreach my $i ( 0 .. $#_ ) { local *_ = \$_[$i]; return $i if $f->(); } return -1; } sub lastidx (&@) { my $f = shift; foreach my $i ( reverse 0 .. $#_ ) { local *_ = \$_[$i]; return $i if $f->(); } return -1; } sub insert_after (&$\@) { my ($f, $val, $list) = @_; my $c = -1; local *_; foreach my $i ( 0 .. $#$list ) { $_ = $list->[$i]; $c = $i, last if $f->(); } @$list = ( @{$list}[ 0 .. $c ], $val, @{$list}[ $c + 1 .. $#$list ], ) and return 1 if $c != -1; return 0; } sub insert_after_string ($$\@) { my ($string, $val, $list) = @_; my $c = -1; foreach my $i ( 0 .. $#$list ) { local $^W = 0; $c = $i, last if $string eq $list->[$i]; } @$list = ( @{$list}[ 0 .. $c ], $val, @{$list}[ $c + 1 .. $#$list ], ) and return 1 if $c != -1; return 0; } sub apply (&@) { my $action = shift; &$action foreach my @values = @_; wantarray ? @values : $values[-1]; } sub after (&@) { my $test = shift; my $started; my $lag; grep $started ||= do { my $x = $lag; $lag = $test->(); $x }, @_; } sub after_incl (&@) { my $test = shift; my $started; grep $started ||= $test->(), @_; } sub before (&@) { my $test = shift; my $more = 1; grep $more &&= ! $test->(), @_; } sub before_incl (&@) { my $test = shift; my $more = 1; my $lag = 1; grep $more &&= do { my $x = $lag; $lag = ! $test->(); $x }, @_; } sub indexes (&@) { my $test = shift; grep { local *_ = \$_[$_]; $test->() } 0 .. $#_; } sub lastval (&@) { my $test = shift; my $ix; for ( $ix = $#_; $ix >= 0; $ix-- ) { local *_ = \$_[$ix]; my $testval = $test->(); # Simulate $_ as alias $_[$ix] = $_; return $_ if $testval; } return undef; } sub firstval (&@) { my $test = shift; foreach ( @_ ) { return $_ if $test->(); } return undef; } sub pairwise (&\@\@) { my $op = shift; # Symbols for caller's input arrays use vars qw{ @A @B }; local ( *A, *B ) = @_; # Localise $a, $b my ( $caller_a, $caller_b ) = do { my $pkg = caller(); no strict 'refs'; \*{$pkg.'::a'}, \*{$pkg.'::b'}; }; # Loop iteration limit my $limit = $#A > $#B? $#A : $#B; # This map expression is also the return value local( *$caller_a, *$caller_b ); map { # Assign to $a, $b as refs to caller's array elements ( *$caller_a, *$caller_b ) = \( $A[$_], $B[$_] ); # Perform the transformation $op->(); } 0 .. $limit; } sub each_array (\@;\@\@\@\@\@\@\@\@\@\@\@\@\@\@\@\@\@\@\@\@\@\@\@\@) { return each_arrayref(@_); } sub each_arrayref { my @list = @_; # The list of references to the arrays my $index = 0; # Which one the caller will get next my $max = 0; # Number of elements in longest array # Get the length of the longest input array foreach ( @list ) { unless ( ref $_ eq 'ARRAY' ) { require Carp; Carp::croak("each_arrayref: argument is not an array reference\n"); } $max = @$_ if @$_ > $max; } # Return the iterator as a closure wrt the above variables. return sub { if ( @_ ) { my $method = shift; unless ( $method eq 'index' ) { require Carp; Carp::croak("each_array: unknown argument '$method' passed to iterator."); } # Return current (last fetched) index return undef if $index == 0 || $index > $max; return $index - 1; } # No more elements to return return if $index >= $max; my $i = $index++; # Return ith elements return map $_->[$i], @list; } } sub natatime ($@) { my $n = shift; my @list = @_; return sub { return splice @list, 0, $n; } } sub mesh (\@\@;\@\@\@\@\@\@\@\@\@\@\@\@\@\@\@\@\@\@\@\@\@\@\@\@\@\@\@\@\@\@) { my $max = -1; $max < $#$_ && ( $max = $#$_ ) foreach @_; map { my $ix = $_; map $_->[$ix], @_; } 0 .. $max; } sub uniq (@) { my %seen = (); grep { not $seen{$_}++ } @_; } sub minmax (@) { return unless @_; my $min = my $max = $_[0]; for ( my $i = 1; $i < @_; $i += 2 ) { if ( $_[$i-1] <= $_[$i] ) { $min = $_[$i-1] if $min > $_[$i-1]; $max = $_[$i] if $max < $_[$i]; } else { $min = $_[$i] if $min > $_[$i]; $max = $_[$i-1] if $max < $_[$i-1]; } } if ( @_ & 1 ) { my $i = $#_; if ($_[$i-1] <= $_[$i]) { $min = $_[$i-1] if $min > $_[$i-1]; $max = $_[$i] if $max < $_[$i]; } else { $min = $_[$i] if $min > $_[$i]; $max = $_[$i-1] if $max < $_[$i-1]; } } return ($min, $max); } sub part (&@) { my ($code, @list) = @_; my @parts; push @{ $parts[ $code->($_) ] }, $_ foreach @list; return @parts; } sub _XScompiled { return 0; } END_PERL die $@ if $@; # Function aliases *first_index = \&firstidx; *last_index = \&lastidx; *first_value = \&firstval; *last_value = \&lastval; *zip = \&mesh; *distinct = \&uniq; 1; __END__ =pod =head1 NAME List::MoreUtils - Provide the stuff missing in List::Util =head1 SYNOPSIS use List::MoreUtils qw{ any all none notall true false firstidx first_index lastidx last_index insert_after insert_after_string apply indexes after after_incl before before_incl firstval first_value lastval last_value each_array each_arrayref pairwise natatime mesh zip uniq distinct minmax part }; =head1 DESCRIPTION B<List::MoreUtils> provides some trivial but commonly needed functionality on lists which is not going to go into L<List::Util>. All of the below functions are implementable in only a couple of lines of Perl code. Using the functions from this module however should give slightly better performance as everything is implemented in C. The pure-Perl implementation of these functions only serves as a fallback in case the C portions of this module couldn't be compiled on this machine. =over 4 =item any BLOCK LIST Returns a true value if any item in LIST meets the criterion given through BLOCK. Sets C<$_> for each item in LIST in turn: print "At least one value undefined" if any { ! defined($_) } @list; Returns false otherwise, or if LIST is empty. =item all BLOCK LIST Returns a true value if all items in LIST meet the criterion given through BLOCK, or if LIST is empty. Sets C<$_> for each item in LIST in turn: print "All items defined" if all { defined($_) } @list; Returns false otherwise. =item none BLOCK LIST Logically the negation of C<any>. Returns a true value if no item in LIST meets the criterion given through BLOCK, or if LIST is empty. Sets C<$_> for each item in LIST in turn: print "No value defined" if none { defined($_) } @list; Returns false otherwise. =item notall BLOCK LIST Logically the negation of C<all>. Returns a true value if not all items in LIST meet the criterion given through BLOCK. Sets C<$_> for each item in LIST in turn: print "Not all values defined" if notall { defined($_) } @list; Returns false otherwise, or if LIST is empty. =item true BLOCK LIST Counts the number of elements in LIST for which the criterion in BLOCK is true. Sets C<$_> for each item in LIST in turn: printf "%i item(s) are defined", true { defined($_) } @list; =item false BLOCK LIST Counts the number of elements in LIST for which the criterion in BLOCK is false. Sets C<$_> for each item in LIST in turn: printf "%i item(s) are not defined", false { defined($_) } @list; =item firstidx BLOCK LIST =item first_index BLOCK LIST Returns the index of the first element in LIST for which the criterion in BLOCK is true. Sets C<$_> for each item in LIST in turn: my @list = (1, 4, 3, 2, 4, 6); printf "item with index %i in list is 4", firstidx { $_ == 4 } @list; __END__ item with index 1 in list is 4 Returns C<-1> if no such item could be found. C<first_index> is an alias for C<firstidx>. =item lastidx BLOCK LIST =item last_index BLOCK LIST Returns the index of the last element in LIST for which the criterion in BLOCK is true. Sets C<$_> for each item in LIST in turn: my @list = (1, 4, 3, 2, 4, 6); printf "item with index %i in list is 4", lastidx { $_ == 4 } @list; __END__ item with index 4 in list is 4 Returns C<-1> if no such item could be found. C<last_index> is an alias for C<lastidx>. =item insert_after BLOCK VALUE LIST Inserts VALUE after the first item in LIST for which the criterion in BLOCK is true. Sets C<$_> for each item in LIST in turn. my @list = qw/This is a list/; insert_after { $_ eq "a" } "longer" => @list; print "@list"; __END__ This is a longer list =item insert_after_string STRING VALUE LIST Inserts VALUE after the first item in LIST which is equal to STRING. my @list = qw/This is a list/; insert_after_string "a", "longer" => @list; print "@list"; __END__ This is a longer list =item apply BLOCK LIST Applies BLOCK to each item in LIST and returns a list of the values after BLOCK has been applied. In scalar context, the last element is returned. This function is similar to C<map> but will not modify the elements of the input list: my @list = (1 .. 4); my @mult = apply { $_ *= 2 } @list; print "\@list = @list\n"; print "\@mult = @mult\n"; __END__ @list = 1 2 3 4 @mult = 2 4 6 8 Think of it as syntactic sugar for for (my @mult = @list) { $_ *= 2 } =item before BLOCK LIST Returns a list of values of LIST upto (and not including) the point where BLOCK returns a true value. Sets C<$_> for each element in LIST in turn. =item before_incl BLOCK LIST Same as C<before> but also includes the element for which BLOCK is true. =item after BLOCK LIST Returns a list of the values of LIST after (and not including) the point where BLOCK returns a true value. Sets C<$_> for each element in LIST in turn. @x = after { $_ % 5 == 0 } (1..9); # returns 6, 7, 8, 9 =item after_incl BLOCK LIST Same as C<after> but also inclues the element for which BLOCK is true. =item indexes BLOCK LIST Evaluates BLOCK for each element in LIST (assigned to C<$_>) and returns a list of the indices of those elements for which BLOCK returned a true value. This is just like C<grep> only that it returns indices instead of values: @x = indexes { $_ % 2 == 0 } (1..10); # returns 1, 3, 5, 7, 9 =item firstval BLOCK LIST =item first_value BLOCK LIST Returns the first element in LIST for which BLOCK evaluates to true. Each element of LIST is set to C<$_> in turn. Returns C<undef> if no such element has been found. C<first_val> is an alias for C<firstval>. =item lastval BLOCK LIST =item last_value BLOCK LIST Returns the last value in LIST for which BLOCK evaluates to true. Each element of LIST is set to C<$_> in turn. Returns C<undef> if no such element has been found. C<last_val> is an alias for C<lastval>. =item pairwise BLOCK ARRAY1 ARRAY2 Evaluates BLOCK for each pair of elements in ARRAY1 and ARRAY2 and returns a new list consisting of BLOCK's return values. The two elements are set to C<$a> and C<$b>. Note that those two are aliases to the original value so changing them will modify the input arrays. @a = (1 .. 5); @b = (11 .. 15); @x = pairwise { $a + $b } @a, @b; # returns 12, 14, 16, 18, 20 # mesh with pairwise @a = qw/a b c/; @b = qw/1 2 3/; @x = pairwise { ($a, $b) } @a, @b; # returns a, 1, b, 2, c, 3 =item each_array ARRAY1 ARRAY2 ... Creates an array iterator to return the elements of the list of arrays ARRAY1, ARRAY2 throughout ARRAYn in turn. That is, the first time it is called, it returns the first element of each array. The next time, it returns the second elements. And so on, until all elements are exhausted. This is useful for looping over more than one array at once: my $ea = each_array(@a, @b, @c); while ( my ($a, $b, $c) = $ea->() ) { .... } The iterator returns the empty list when it reached the end of all arrays. If the iterator is passed an argument of 'C<index>', then it retuns the index of the last fetched set of values, as a scalar. =item each_arrayref LIST Like each_array, but the arguments are references to arrays, not the plain arrays. =item natatime EXPR, LIST Creates an array iterator, for looping over an array in chunks of C<$n> items at a time. (n at a time, get it?). An example is probably a better explanation than I could give in words. Example: my @x = ('a' .. 'g'); my $it = natatime 3, @x; while (my @vals = $it->()) { print "@vals\n"; } This prints a b c d e f g =item mesh ARRAY1 ARRAY2 [ ARRAY3 ... ] =item zip ARRAY1 ARRAY2 [ ARRAY3 ... ] Returns a list consisting of the first elements of each array, then the second, then the third, etc, until all arrays are exhausted. Examples: @x = qw/a b c d/; @y = qw/1 2 3 4/; @z = mesh @x, @y; # returns a, 1, b, 2, c, 3, d, 4 @a = ('x'); @b = ('1', '2'); @c = qw/zip zap zot/; @d = mesh @a, @b, @c; # x, 1, zip, undef, 2, zap, undef, undef, zot C<zip> is an alias for C<mesh>. =item uniq LIST =item distinct LIST Returns a new list by stripping duplicate values in LIST. The order of elements in the returned list is the same as in LIST. In scalar context, returns the number of unique elements in LIST. my @x = uniq 1, 1, 2, 2, 3, 5, 3, 4; # returns 1 2 3 5 4 my $x = uniq 1, 1, 2, 2, 3, 5, 3, 4; # returns 5 =item minmax LIST Calculates the minimum and maximum of LIST and returns a two element list with the first element being the minimum and the second the maximum. Returns the empty list if LIST was empty. The C<minmax> algorithm differs from a naive iteration over the list where each element is compared to two values being the so far calculated min and max value in that it only requires 3n/2 - 2 comparisons. Thus it is the most efficient possible algorithm. However, the Perl implementation of it has some overhead simply due to the fact that there are more lines of Perl code involved. Therefore, LIST needs to be fairly big in order for C<minmax> to win over a naive implementation. This limitation does not apply to the XS version. =item part BLOCK LIST Partitions LIST based on the return value of BLOCK which denotes into which partition the current value is put. Returns a list of the partitions thusly created. Each partition created is a reference to an array. my $i = 0; my @part = part { $i++ % 2 } 1 .. 8; # returns [1, 3, 5, 7], [2, 4, 6, 8] You can have a sparse list of partitions as well where non-set partitions will be undef: my @part = part { 2 } 1 .. 10; # returns undef, undef, [ 1 .. 10 ] Be careful with negative values, though: my @part = part { -1 } 1 .. 10; __END__ Modification of non-creatable array value attempted, subscript -1 ... Negative values are only ok when they refer to a partition previously created: my @idx = ( 0, 1, -1 ); my $i = 0; my @part = part { $idx[$++ % 3] } 1 .. 8; # [1, 4, 7], [2, 3, 5, 6, 8] =back =head1 EXPORTS Nothing by default. To import all of this module's symbols, do the conventional use List::MoreUtils ':all'; It may make more sense though to only import the stuff your program actually needs: use List::MoreUtils qw{ any firstidx }; =head1 ENVIRONMENT When C<LIST_MOREUTILS_PP> is set, the module will always use the pure-Perl implementation and not the XS one. This environment variable is really just there for the test-suite to force testing the Perl implementation, and possibly for reporting of bugs. I don't see any reason to use it in a production environment. =head1 BUGS There is a problem with a bug in 5.6.x perls. It is a syntax error to write things like: my @x = apply { s/foo/bar/ } qw{ foo bar baz }; It has to be written as either my @x = apply { s/foo/bar/ } 'foo', 'bar', 'baz'; or my @x = apply { s/foo/bar/ } my @dummy = qw/foo bar baz/; Perl 5.5.x and Perl 5.8.x don't suffer from this limitation. If you have a functionality that you could imagine being in this module, please drop me a line. This module's policy will be less strict than L<List::Util>'s when it comes to additions as it isn't a core module. When you report bugs, it would be nice if you could additionally give me the output of your program with the environment variable C<LIST_MOREUTILS_PP> set to a true value. That way I know where to look for the problem (in XS, pure-Perl or possibly both). =head1 SUPPORT Bugs should always be submitted via the CPAN bug tracker. L<http://rt.cpan.org/NoAuth/ReportBug.html?Queue=List-MoreUtils> =head1 THANKS Credits go to a number of people: Steve Purkis for giving me namespace advice and James Keenan and Terrence Branno for their effort of keeping the CPAN tidier by making L<List::Utils> obsolete. Brian McCauley suggested the inclusion of apply() and provided the pure-Perl implementation for it. Eric J. Roode asked me to add all functions from his module C<List::MoreUtil> into this one. With minor modifications, the pure-Perl implementations of those are by him. The bunch of people who almost immediately pointed out the many problems with the glitchy 0.07 release (Slaven Rezic, Ron Savage, CPAN testers). A particularly nasty memory leak was spotted by Thomas A. Lowery. Lars Thegler made me aware of problems with older Perl versions. Anno Siegel de-orphaned each_arrayref(). David Filmer made me aware of a problem in each_arrayref that could ultimately lead to a segfault. Ricardo Signes suggested the inclusion of part() and provided the Perl-implementation. Robin Huston kindly fixed a bug in perl's MULTICALL API to make the XS-implementation of part() work. =head1 TODO A pile of requests from other people is still pending further processing in my mailbox. This includes: =over 4 =item * List::Util export pass-through Allow B<List::MoreUtils> to pass-through the regular L<List::Util> functions to end users only need to C<use> the one module. =item * uniq_by(&@) Use code-reference to extract a key based on which the uniqueness is determined. Suggested by Aaron Crane. =item * delete_index =item * random_item =item * random_item_delete_index =item * list_diff_hash =item * list_diff_inboth =item * list_diff_infirst =item * list_diff_insecond These were all suggested by Dan Muey. =item * listify Always return a flat list when either a simple scalar value was passed or an array-reference. Suggested by Mark Summersault. =back =head1 SEE ALSO L<List::Util> =head1 AUTHOR Adam Kennedy E<lt>adamk@cpan.orgE<gt> Tassilo von Parseval E<lt>tassilo.von.parseval@rwth-aachen.deE<gt> =head1 COPYRIGHT AND LICENSE Some parts copyright 2011 Aaron Crane. Copyright 2004 - 2010 by Tassilo von Parseval This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself, either Perl version 5.8.4 or, at your option, any later version of Perl 5 you may have available. =cut Save