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lib64/perl5/vendor_perl/Params/Util.pm 0000644 00000053547 15204133367 0013552 0 ustar 00 package Params::Util; =pod =head1 NAME Params::Util - Simple, compact and correct param-checking functions =head1 SYNOPSIS # Import some functions use Params::Util qw{_SCALAR _HASH _INSTANCE}; # If you are lazy, or need a lot of them... use Params::Util ':ALL'; sub foo { my $object = _INSTANCE(shift, 'Foo') or return undef; my $image = _SCALAR(shift) or return undef; my $options = _HASH(shift) or return undef; # etc... } =head1 DESCRIPTION C<Params::Util> provides a basic set of importable functions that makes checking parameters a hell of a lot easier While they can be (and are) used in other contexts, the main point behind this module is that the functions B<both> Do What You Mean, and Do The Right Thing, so they are most useful when you are getting params passed into your code from someone and/or somewhere else and you can't really trust the quality. Thus, C<Params::Util> is of most use at the edges of your API, where params and data are coming in from outside your code. The functions provided by C<Params::Util> check in the most strictly correct manner known, are documented as thoroughly as possible so their exact behaviour is clear, and heavily tested so make sure they are not fooled by weird data and Really Bad Things. To use, simply load the module providing the functions you want to use as arguments (as shown in the SYNOPSIS). To aid in maintainability, C<Params::Util> will B<never> export by default. You must explicitly name the functions you want to export, or use the C<:ALL> param to just have it export everything (although this is not recommended if you have any _FOO functions yourself with which future additions to C<Params::Util> may clash) =head1 FUNCTIONS =cut use 5.00503; use strict; require overload; require Exporter; require Scalar::Util; require DynaLoader; use vars qw{$VERSION @ISA @EXPORT_OK %EXPORT_TAGS}; $VERSION = '1.07'; @ISA = qw{ Exporter DynaLoader }; @EXPORT_OK = qw{ _STRING _IDENTIFIER _CLASS _CLASSISA _SUBCLASS _DRIVER _CLASSDOES _NUMBER _POSINT _NONNEGINT _SCALAR _SCALAR0 _ARRAY _ARRAY0 _ARRAYLIKE _HASH _HASH0 _HASHLIKE _CODE _CODELIKE _INVOCANT _REGEX _INSTANCE _INSTANCEDOES _SET _SET0 _HANDLE }; %EXPORT_TAGS = ( ALL => \@EXPORT_OK ); eval { local $ENV{PERL_DL_NONLAZY} = 0 if $ENV{PERL_DL_NONLAZY}; bootstrap Params::Util $VERSION; 1; } unless $ENV{PERL_PARAMS_UTIL_PP}; # Use a private pure-perl copy of looks_like_number if the version of # Scalar::Util is old (for whatever reason). my $SU = eval "$Scalar::Util::VERSION" || 0; if ( $SU >= 1.18 ) { Scalar::Util->import('looks_like_number'); } else { eval <<'END_PERL'; sub looks_like_number { local $_ = shift; # checks from perlfaq4 return 0 if !defined($_); if (ref($_)) { return overload::Overloaded($_) ? defined(0 + $_) : 0; } return 1 if (/^[+-]?[0-9]+$/); # is a +/- integer return 1 if (/^([+-]?)(?=[0-9]|\.[0-9])[0-9]*(\.[0-9]*)?([Ee]([+-]?[0-9]+))?$/); # a C float return 1 if ($] >= 5.008 and /^(Inf(inity)?|NaN)$/i) or ($] >= 5.006001 and /^Inf$/i); 0; } END_PERL } ##################################################################### # Param Checking Functions =pod =head2 _STRING $string The C<_STRING> function is intended to be imported into your package, and provides a convenient way to test to see if a value is a normal non-false string of non-zero length. Note that this will NOT do anything magic to deal with the special C<'0'> false negative case, but will return it. # '0' not considered valid data my $name = _STRING(shift) or die "Bad name"; # '0' is considered valid data my $string = _STRING($_[0]) ? shift : die "Bad string"; Please also note that this function expects a normal string. It does not support overloading or other magic techniques to get a string. Returns the string as a conveince if it is a valid string, or C<undef> if not. =cut eval <<'END_PERL' unless defined &_STRING; sub _STRING ($) { (defined $_[0] and ! ref $_[0] and length($_[0])) ? $_[0] : undef; } END_PERL =pod =head2 _IDENTIFIER $string The C<_IDENTIFIER> function is intended to be imported into your package, and provides a convenient way to test to see if a value is a string that is a valid Perl identifier. Returns the string as a convenience if it is a valid identifier, or C<undef> if not. =cut eval <<'END_PERL' unless defined &_IDENTIFIER; sub _IDENTIFIER ($) { (defined $_[0] and ! ref $_[0] and $_[0] =~ m/^[^\W\d]\w*\z/s) ? $_[0] : undef; } END_PERL =pod =head2 _CLASS $string The C<_CLASS> function is intended to be imported into your package, and provides a convenient way to test to see if a value is a string that is a valid Perl class. This function only checks that the format is valid, not that the class is actually loaded. It also assumes "normalised" form, and does not accept class names such as C<::Foo> or C<D'Oh>. Returns the string as a convenience if it is a valid class name, or C<undef> if not. =cut eval <<'END_PERL' unless defined &_CLASS; sub _CLASS ($) { (defined $_[0] and ! ref $_[0] and $_[0] =~ m/^[^\W\d]\w*(?:::\w+)*\z/s) ? $_[0] : undef; } END_PERL =pod =head2 _CLASSISA $string, $class The C<_CLASSISA> function is intended to be imported into your package, and provides a convenient way to test to see if a value is a string that is a particularly class, or a subclass of it. This function checks that the format is valid and calls the -E<gt>isa method on the class name. It does not check that the class is actually loaded. It also assumes "normalised" form, and does not accept class names such as C<::Foo> or C<D'Oh>. Returns the string as a convenience if it is a valid class name, or C<undef> if not. =cut eval <<'END_PERL' unless defined &_CLASSISA; sub _CLASSISA ($$) { (defined $_[0] and ! ref $_[0] and $_[0] =~ m/^[^\W\d]\w*(?:::\w+)*\z/s and $_[0]->isa($_[1])) ? $_[0] : undef; } END_PERL =head2 _CLASSDOES $string, $role This routine behaves exactly like C<L</_CLASSISA>>, but checks with C<< ->DOES >> rather than C<< ->isa >>. This is probably only a good idea to use on Perl 5.10 or later, when L<UNIVERSAL::DOES|UNIVERSAL::DOES/DOES> has been implemented. =cut eval <<'END_PERL' unless defined &_CLASSDOES; sub _CLASSDOES ($$) { (defined $_[0] and ! ref $_[0] and $_[0] =~ m/^[^\W\d]\w*(?:::\w+)*\z/s and $_[0]->DOES($_[1])) ? $_[0] : undef; } END_PERL =pod =head2 _SUBCLASS $string, $class The C<_SUBCLASS> function is intended to be imported into your package, and provides a convenient way to test to see if a value is a string that is a subclass of a specified class. This function checks that the format is valid and calls the -E<gt>isa method on the class name. It does not check that the class is actually loaded. It also assumes "normalised" form, and does not accept class names such as C<::Foo> or C<D'Oh>. Returns the string as a convenience if it is a valid class name, or C<undef> if not. =cut eval <<'END_PERL' unless defined &_SUBCLASS; sub _SUBCLASS ($$) { (defined $_[0] and ! ref $_[0] and $_[0] =~ m/^[^\W\d]\w*(?:::\w+)*\z/s and $_[0] ne $_[1] and $_[0]->isa($_[1])) ? $_[0] : undef; } END_PERL =pod =head2 _NUMBER $scalar The C<_NUMBER> function is intended to be imported into your package, and provides a convenient way to test to see if a value is a number. That is, it is defined and perl thinks it's a number. This function is basically a Params::Util-style wrapper around the L<Scalar::Util> C<looks_like_number> function. Returns the value as a convience, or C<undef> if the value is not a number. =cut eval <<'END_PERL' unless defined &_NUMBER; sub _NUMBER ($) { ( defined $_[0] and ! ref $_[0] and looks_like_number($_[0]) ) ? $_[0] : undef; } END_PERL =pod =head2 _POSINT $integer The C<_POSINT> function is intended to be imported into your package, and provides a convenient way to test to see if a value is a positive integer (of any length). Returns the value as a convience, or C<undef> if the value is not a positive integer. The name itself is derived from the XML schema constraint of the same name. =cut eval <<'END_PERL' unless defined &_POSINT; sub _POSINT ($) { (defined $_[0] and ! ref $_[0] and $_[0] =~ m/^[1-9]\d*$/) ? $_[0] : undef; } END_PERL =pod =head2 _NONNEGINT $integer The C<_NONNEGINT> function is intended to be imported into your package, and provides a convenient way to test to see if a value is a non-negative integer (of any length). That is, a positive integer, or zero. Returns the value as a convience, or C<undef> if the value is not a non-negative integer. As with other tests that may return false values, care should be taken to test via "defined" in boolean validy contexts. unless ( defined _NONNEGINT($value) ) { die "Invalid value"; } The name itself is derived from the XML schema constraint of the same name. =cut eval <<'END_PERL' unless defined &_NONNEGINT; sub _NONNEGINT ($) { (defined $_[0] and ! ref $_[0] and $_[0] =~ m/^(?:0|[1-9]\d*)$/) ? $_[0] : undef; } END_PERL =pod =head2 _SCALAR \$scalar The C<_SCALAR> function is intended to be imported into your package, and provides a convenient way to test for a raw and unblessed C<SCALAR> reference, with content of non-zero length. For a version that allows zero length C<SCALAR> references, see the C<_SCALAR0> function. Returns the C<SCALAR> reference itself as a convenience, or C<undef> if the value provided is not a C<SCALAR> reference. =cut eval <<'END_PERL' unless defined &_SCALAR; sub _SCALAR ($) { (ref $_[0] eq 'SCALAR' and defined ${$_[0]} and ${$_[0]} ne '') ? $_[0] : undef; } END_PERL =pod =head2 _SCALAR0 \$scalar The C<_SCALAR0> function is intended to be imported into your package, and provides a convenient way to test for a raw and unblessed C<SCALAR0> reference, allowing content of zero-length. For a simpler "give me some content" version that requires non-zero length, C<_SCALAR> function. Returns the C<SCALAR> reference itself as a convenience, or C<undef> if the value provided is not a C<SCALAR> reference. =cut eval <<'END_PERL' unless defined &_SCALAR0; sub _SCALAR0 ($) { ref $_[0] eq 'SCALAR' ? $_[0] : undef; } END_PERL =pod =head2 _ARRAY $value The C<_ARRAY> function is intended to be imported into your package, and provides a convenient way to test for a raw and unblessed C<ARRAY> reference containing B<at least> one element of any kind. For a more basic form that allows zero length ARRAY references, see the C<_ARRAY0> function. Returns the C<ARRAY> reference itself as a convenience, or C<undef> if the value provided is not an C<ARRAY> reference. =cut eval <<'END_PERL' unless defined &_ARRAY; sub _ARRAY ($) { (ref $_[0] eq 'ARRAY' and @{$_[0]}) ? $_[0] : undef; } END_PERL =pod =head2 _ARRAY0 $value The C<_ARRAY0> function is intended to be imported into your package, and provides a convenient way to test for a raw and unblessed C<ARRAY> reference, allowing C<ARRAY> references that contain no elements. For a more basic "An array of something" form that also requires at least one element, see the C<_ARRAY> function. Returns the C<ARRAY> reference itself as a convenience, or C<undef> if the value provided is not an C<ARRAY> reference. =cut eval <<'END_PERL' unless defined &_ARRAY0; sub _ARRAY0 ($) { ref $_[0] eq 'ARRAY' ? $_[0] : undef; } END_PERL =pod =head2 _ARRAYLIKE $value The C<_ARRAYLIKE> function tests whether a given scalar value can respond to array dereferencing. If it can, the value is returned. If it cannot, C<_ARRAYLIKE> returns C<undef>. =cut eval <<'END_PERL' unless defined &_ARRAYLIKE; sub _ARRAYLIKE { (defined $_[0] and ref $_[0] and ( (Scalar::Util::reftype($_[0]) eq 'ARRAY') or overload::Method($_[0], '@{}') )) ? $_[0] : undef; } END_PERL =pod =head2 _HASH $value The C<_HASH> function is intended to be imported into your package, and provides a convenient way to test for a raw and unblessed C<HASH> reference with at least one entry. For a version of this function that allows the C<HASH> to be empty, see the C<_HASH0> function. Returns the C<HASH> reference itself as a convenience, or C<undef> if the value provided is not an C<HASH> reference. =cut eval <<'END_PERL' unless defined &_HASH; sub _HASH ($) { (ref $_[0] eq 'HASH' and scalar %{$_[0]}) ? $_[0] : undef; } END_PERL =pod =head2 _HASH0 $value The C<_HASH0> function is intended to be imported into your package, and provides a convenient way to test for a raw and unblessed C<HASH> reference, regardless of the C<HASH> content. For a simpler "A hash of something" version that requires at least one element, see the C<_HASH> function. Returns the C<HASH> reference itself as a convenience, or C<undef> if the value provided is not an C<HASH> reference. =cut eval <<'END_PERL' unless defined &_HASH0; sub _HASH0 ($) { ref $_[0] eq 'HASH' ? $_[0] : undef; } END_PERL =pod =head2 _HASHLIKE $value The C<_HASHLIKE> function tests whether a given scalar value can respond to hash dereferencing. If it can, the value is returned. If it cannot, C<_HASHLIKE> returns C<undef>. =cut eval <<'END_PERL' unless defined &_HASHLIKE; sub _HASHLIKE { (defined $_[0] and ref $_[0] and ( (Scalar::Util::reftype($_[0]) eq 'HASH') or overload::Method($_[0], '%{}') )) ? $_[0] : undef; } END_PERL =pod =head2 _CODE $value The C<_CODE> function is intended to be imported into your package, and provides a convenient way to test for a raw and unblessed C<CODE> reference. Returns the C<CODE> reference itself as a convenience, or C<undef> if the value provided is not an C<CODE> reference. =cut eval <<'END_PERL' unless defined &_CODE; sub _CODE ($) { ref $_[0] eq 'CODE' ? $_[0] : undef; } END_PERL =pod =head2 _CODELIKE $value The C<_CODELIKE> is the more generic version of C<_CODE>. Unlike C<_CODE>, which checks for an explicit C<CODE> reference, the C<_CODELIKE> function also includes things that act like them, such as blessed objects that overload C<'&{}'>. Please note that in the case of objects overloaded with '&{}', you will almost always end up also testing it in 'bool' context at some stage. For example: sub foo { my $code1 = _CODELIKE(shift) or die "No code param provided"; my $code2 = _CODELIKE(shift); if ( $code2 ) { print "Got optional second code param"; } } As such, you will most likely always want to make sure your class has at least the following to allow it to evaluate to true in boolean context. # Always evaluate to true in boolean context use overload 'bool' => sub () { 1 }; Returns the callable value as a convenience, or C<undef> if the value provided is not callable. Note - This function was formerly known as _CALLABLE but has been renamed for greater symmetry with the other _XXXXLIKE functions. The use of _CALLABLE has been deprecated. It will continue to work, but with a warning, until end-2006, then will be removed. I apologise for any inconvenience caused. =cut eval <<'END_PERL' unless defined &_CODELIKE; sub _CODELIKE($) { ( (Scalar::Util::reftype($_[0])||'') eq 'CODE' or Scalar::Util::blessed($_[0]) and overload::Method($_[0],'&{}') ) ? $_[0] : undef; } END_PERL =pod =head2 _INVOCANT $value This routine tests whether the given value is a valid method invocant. This can be either an instance of an object, or a class name. If so, the value itself is returned. Otherwise, C<_INVOCANT> returns C<undef>. =cut eval <<'END_PERL' unless defined &_INVOCANT; sub _INVOCANT($) { (defined $_[0] and (defined Scalar::Util::blessed($_[0]) or # We used to check for stash definedness, but any class-like name is a # valid invocant for UNIVERSAL methods, so we stopped. -- rjbs, 2006-07-02 Params::Util::_CLASS($_[0])) ) ? $_[0] : undef; } END_PERL =pod =head2 _INSTANCE $object, $class The C<_INSTANCE> function is intended to be imported into your package, and provides a convenient way to test for an object of a particular class in a strictly correct manner. Returns the object itself as a convenience, or C<undef> if the value provided is not an object of that type. =cut eval <<'END_PERL' unless defined &_INSTANCE; sub _INSTANCE ($$) { (Scalar::Util::blessed($_[0]) and $_[0]->isa($_[1])) ? $_[0] : undef; } END_PERL =head2 _INSTANCEDOES $object, $role This routine behaves exactly like C<L</_INSTANCE>>, but checks with C<< ->DOES >> rather than C<< ->isa >>. This is probably only a good idea to use on Perl 5.10 or later, when L<UNIVERSAL::DOES|UNIVERSAL::DOES/DOES> has been implemented. =cut eval <<'END_PERL' unless defined &_INSTANCEDOES; sub _INSTANCEDOES ($$) { (Scalar::Util::blessed($_[0]) and $_[0]->DOES($_[1])) ? $_[0] : undef; } END_PERL =pod =head2 _REGEX $value The C<_REGEX> function is intended to be imported into your package, and provides a convenient way to test for a regular expression. Returns the value itself as a convenience, or C<undef> if the value provided is not a regular expression. =cut eval <<'END_PERL' unless defined &_REGEX; sub _REGEX ($) { (defined $_[0] and 'Regexp' eq ref($_[0])) ? $_[0] : undef; } END_PERL =pod =head2 _SET \@array, $class The C<_SET> function is intended to be imported into your package, and provides a convenient way to test for set of at least one object of a particular class in a strictly correct manner. The set is provided as a reference to an C<ARRAY> of objects of the class provided. For an alternative function that allows zero-length sets, see the C<_SET0> function. Returns the C<ARRAY> reference itself as a convenience, or C<undef> if the value provided is not a set of that class. =cut eval <<'END_PERL' unless defined &_SET; sub _SET ($$) { my $set = shift; _ARRAY($set) or return undef; foreach my $item ( @$set ) { _INSTANCE($item,$_[0]) or return undef; } $set; } END_PERL =pod =head2 _SET0 \@array, $class The C<_SET0> function is intended to be imported into your package, and provides a convenient way to test for a set of objects of a particular class in a strictly correct manner, allowing for zero objects. The set is provided as a reference to an C<ARRAY> of objects of the class provided. For an alternative function that requires at least one object, see the C<_SET> function. Returns the C<ARRAY> reference itself as a convenience, or C<undef> if the value provided is not a set of that class. =cut eval <<'END_PERL' unless defined &_SET0; sub _SET0 ($$) { my $set = shift; _ARRAY0($set) or return undef; foreach my $item ( @$set ) { _INSTANCE($item,$_[0]) or return undef; } $set; } END_PERL =pod =head2 _HANDLE The C<_HANDLE> function is intended to be imported into your package, and provides a convenient way to test whether or not a single scalar value is a file handle. Unfortunately, in Perl the definition of a file handle can be a little bit fuzzy, so this function is likely to be somewhat imperfect (at first anyway). That said, it is implement as well or better than the other file handle detectors in existance (and we stole from the best of them). =cut # We're doing this longhand for now. Once everything is perfect, # we'll compress this into something that compiles more efficiently. # Further, testing file handles is not something that is generally # done millions of times, so doing it slowly is not a big speed hit. eval <<'END_PERL' unless defined &_HANDLE; sub _HANDLE { my $it = shift; # It has to be defined, of course unless ( defined $it ) { return undef; } # Normal globs are considered to be file handles if ( ref $it eq 'GLOB' ) { return $it; } # Check for a normal tied filehandle # Side Note: 5.5.4's tied() and can() doesn't like getting undef if ( tied($it) and tied($it)->can('TIEHANDLE') ) { return $it; } # There are no other non-object handles that we support unless ( Scalar::Util::blessed($it) ) { return undef; } # Check for a common base classes for conventional IO::Handle object if ( $it->isa('IO::Handle') ) { return $it; } # Check for tied file handles using Tie::Handle if ( $it->isa('Tie::Handle') ) { return $it; } # IO::Scalar is not a proper seekable, but it is valid is a # regular file handle if ( $it->isa('IO::Scalar') ) { return $it; } # Yet another special case for IO::String, which refuses (for now # anyway) to become a subclass of IO::Handle. if ( $it->isa('IO::String') ) { return $it; } # This is not any sort of object we know about return undef; } END_PERL =pod =head2 _DRIVER $string sub foo { my $class = _DRIVER(shift, 'My::Driver::Base') or die "Bad driver"; ... } The C<_DRIVER> function is intended to be imported into your package, and provides a convenient way to load and validate a driver class. The most common pattern when taking a driver class as a parameter is to check that the name is a class (i.e. check against _CLASS) and then to load the class (if it exists) and then ensure that the class returns true for the isa method on some base driver name. Return the value as a convenience, or C<undef> if the value is not a class name, the module does not exist, the module does not load, or the class fails the isa test. =cut eval <<'END_PERL' unless defined &_DRIVER; sub _DRIVER ($$) { (defined _CLASS($_[0]) and eval "require $_[0];" and ! $@ and $_[0]->isa($_[1]) and $_[0] ne $_[1]) ? $_[0] : undef; } END_PERL 1; =pod =head1 TO DO - Add _CAN to help resolve the UNIVERSAL::can debacle - Would be even nicer if someone would demonstrate how the hell to build a Module::Install dist of the ::Util dual Perl/XS type. :/ - Implement an assertion-like version of this module, that dies on error. - Implement a Test:: version of this module, for use in testing =head1 SUPPORT Bugs should be reported via the CPAN bug tracker at L<http://rt.cpan.org/NoAuth/ReportBug.html?Queue=Params-Util> For other issues, contact the author. =head1 AUTHOR Adam Kennedy E<lt>adamk@cpan.orgE<gt> =head1 SEE ALSO L<Params::Validate> =head1 COPYRIGHT Copyright 2005 - 2012 Adam Kennedy. This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself. The full text of the license can be found in the LICENSE file included with this module. =cut lib64/perl5/vendor_perl/List/Util.pm 0000644 00000050056 15204142155 0013225 0 ustar 00 # Copyright (c) 1997-2009 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. # # Maintained since 2013 by Paul Evans <leonerd@leonerd.org.uk> package List::Util; use strict; use warnings; require Exporter; our @ISA = qw(Exporter); our @EXPORT_OK = qw( all any first min max minstr maxstr none notall product reduce sum sum0 shuffle uniq uniqnum uniqstr pairs unpairs pairkeys pairvalues pairmap pairgrep pairfirst ); our $VERSION = "1.49"; our $XS_VERSION = $VERSION; $VERSION = eval $VERSION; require XSLoader; XSLoader::load('List::Util', $XS_VERSION); sub import { my $pkg = caller; # (RT88848) Touch the caller's $a and $b, to avoid the warning of # Name "main::a" used only once: possible typo" warning no strict 'refs'; ${"${pkg}::a"} = ${"${pkg}::a"}; ${"${pkg}::b"} = ${"${pkg}::b"}; goto &Exporter::import; } # For objects returned by pairs() sub List::Util::_Pair::key { shift->[0] } sub List::Util::_Pair::value { shift->[1] } =head1 NAME List::Util - A selection of general-utility list subroutines =head1 SYNOPSIS use List::Util qw( reduce any all none notall first max maxstr min minstr product sum sum0 pairs unpairs pairkeys pairvalues pairfirst pairgrep pairmap shuffle uniq uniqnum uniqstr ); =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. =cut =head1 LIST-REDUCTION FUNCTIONS The following set of functions all reduce a list down to a single value. =cut =head2 reduce $result = reduce { BLOCK } @list Reduces C<@list> by calling C<BLOCK> in a scalar context multiple times, setting C<$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 the C<BLOCK>. If C<@list> is empty then C<undef> is returned. If C<@list> only contains one element then that element is returned and C<BLOCK> is not executed. The following examples all demonstrate how C<reduce> could be used to implement the other list-reduction functions in this module. (They are not in fact implemented like this, but instead in a more efficient manner in individual C functions). $foo = reduce { defined($a) ? $a : $code->(local $_ = $b) ? $b : undef } undef, @list # first $foo = reduce { $a > $b ? $a : $b } 1..10 # max $foo = reduce { $a gt $b ? $a : $b } 'A'..'Z' # maxstr $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 $foo = reduce { $a || $code->(local $_ = $b) } 0, @bar # any $foo = reduce { $a && $code->(local $_ = $b) } 1, @bar # all $foo = reduce { $a && !$code->(local $_ = $b) } 1, @bar # none $foo = reduce { $a || !$code->(local $_ = $b) } 0, @bar # notall # Note that these implementations do not fully short-circuit If your algorithm requires that C<reduce> produce an identity value, then make sure that you always pass that identity value as the first argument to prevent C<undef> being returned $foo = reduce { $a + $b } 0, @values; # sum with 0 identity value The above example code blocks also suggest how to use C<reduce> to build a more efficient combined version of one of these basic functions and a C<map> block. For example, to find the total length of all the strings in a list, we could use $total = sum map { length } @strings; However, this produces a list of temporary integer values as long as the original list of strings, only to reduce it down to a single value again. We can compute the same result more efficiently by using C<reduce> with a code block that accumulates lengths by writing this instead as: $total = reduce { $a + length $b } 0, @strings The remaining list-reduction functions are all specialisations of this generic idea. =head2 any my $bool = any { BLOCK } @list; I<Since version 1.33.> Similar to C<grep> in that it evaluates C<BLOCK> setting C<$_> to each element of C<@list> in turn. C<any> returns true if any element makes the C<BLOCK> return a true value. If C<BLOCK> never returns true or C<@list> was empty then it returns false. Many cases of using C<grep> in a conditional can be written using C<any> instead, as it can short-circuit after the first true result. if( any { length > 10 } @strings ) { # at least one string has more than 10 characters } Note: Due to XS issues the block passed may be able to access the outer @_ directly. This is not intentional and will break under debugger. =head2 all my $bool = all { BLOCK } @list; I<Since version 1.33.> Similar to L</any>, except that it requires all elements of the C<@list> to make the C<BLOCK> return true. If any element returns false, then it returns false. If the C<BLOCK> never returns false or the C<@list> was empty then it returns true. Note: Due to XS issues the block passed may be able to access the outer @_ directly. This is not intentional and will break under debugger. =head2 none =head2 notall my $bool = none { BLOCK } @list; my $bool = notall { BLOCK } @list; I<Since version 1.33.> Similar to L</any> and L</all>, but with the return sense inverted. C<none> returns true only if no value in the C<@list> causes the C<BLOCK> to return true, and C<notall> returns true only if not all of the values do. Note: Due to XS issues the block passed may be able to access the outer @_ directly. This is not intentional and will break under debugger. =head2 first my $val = first { BLOCK } @list; Similar to C<grep> in that it evaluates C<BLOCK> setting C<$_> to each element of C<@list> in turn. C<first> returns the first element where the result from C<BLOCK> is a true value. If C<BLOCK> never returns true or C<@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 =head2 max my $num = 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 =head2 maxstr my $str = maxstr @list; Similar to L</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 =head2 min my $num = min @list; Similar to L</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 =head2 minstr my $str = minstr @list; Similar to L</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 =head2 product my $num = product @list; I<Since version 1.35.> Returns the numerical product of all the elements in C<@list>. If C<@list> is empty then C<1> is returned. $foo = product 1..10 # 3628800 $foo = product 3,9,12 # 324 =head2 sum my $num_or_undef = sum @list; Returns the numerical sum of all the elements in C<@list>. For backwards compatibility, if C<@list> is empty then C<undef> is returned. $foo = sum 1..10 # 55 $foo = sum 3,9,12 # 24 $foo = sum @bar, @baz # whatever =head2 sum0 my $num = sum0 @list; I<Since version 1.26.> Similar to L</sum>, except this returns 0 when given an empty list, rather than C<undef>. =cut =head1 KEY/VALUE PAIR LIST FUNCTIONS The following set of functions, all inspired by L<List::Pairwise>, consume an even-sized list of pairs. The pairs may be key/value associations from a hash, or just a list of values. The functions will all preserve the original ordering of the pairs, and will not be confused by multiple pairs having the same "key" value - nor even do they require that the first of each pair be a plain string. B<NOTE>: At the time of writing, the following C<pair*> functions that take a block do not modify the value of C<$_> within the block, and instead operate using the C<$a> and C<$b> globals instead. This has turned out to be a poor design, as it precludes the ability to provide a C<pairsort> function. Better would be to pass pair-like objects as 2-element array references in C<$_>, in a style similar to the return value of the C<pairs> function. At some future version this behaviour may be added. Until then, users are alerted B<NOT> to rely on the value of C<$_> remaining unmodified between the outside and the inside of the control block. In particular, the following example is B<UNSAFE>: my @kvlist = ... foreach (qw( some keys here )) { my @items = pairgrep { $a eq $_ } @kvlist; ... } Instead, write this using a lexical variable: foreach my $key (qw( some keys here )) { my @items = pairgrep { $a eq $key } @kvlist; ... } =cut =head2 pairs my @pairs = pairs @kvlist; I<Since version 1.29.> A convenient shortcut to operating on even-sized lists of pairs, this function returns a list of C<ARRAY> references, each containing two items from the given list. It is a more efficient version of @pairs = pairmap { [ $a, $b ] } @kvlist It is most convenient to use in a C<foreach> loop, for example: foreach my $pair ( pairs @kvlist ) { my ( $key, $value ) = @$pair; ... } Since version C<1.39> these C<ARRAY> references are blessed objects, recognising the two methods C<key> and C<value>. The following code is equivalent: foreach my $pair ( pairs @kvlist ) { my $key = $pair->key; my $value = $pair->value; ... } =head2 unpairs my @kvlist = unpairs @pairs I<Since version 1.42.> The inverse function to C<pairs>; this function takes a list of C<ARRAY> references containing two elements each, and returns a flattened list of the two values from each of the pairs, in order. This is notionally equivalent to my @kvlist = map { @{$_}[0,1] } @pairs except that it is implemented more efficiently internally. Specifically, for any input item it will extract exactly two values for the output list; using C<undef> if the input array references are short. Between C<pairs> and C<unpairs>, a higher-order list function can be used to operate on the pairs as single scalars; such as the following near-equivalents of the other C<pair*> higher-order functions: @kvlist = unpairs grep { FUNC } pairs @kvlist # Like pairgrep, but takes $_ instead of $a and $b @kvlist = unpairs map { FUNC } pairs @kvlist # Like pairmap, but takes $_ instead of $a and $b Note however that these versions will not behave as nicely in scalar context. Finally, this technique can be used to implement a sort on a keyvalue pair list; e.g.: @kvlist = unpairs sort { $a->key cmp $b->key } pairs @kvlist =head2 pairkeys my @keys = pairkeys @kvlist; I<Since version 1.29.> A convenient shortcut to operating on even-sized lists of pairs, this function returns a list of the the first values of each of the pairs in the given list. It is a more efficient version of @keys = pairmap { $a } @kvlist =head2 pairvalues my @values = pairvalues @kvlist; I<Since version 1.29.> A convenient shortcut to operating on even-sized lists of pairs, this function returns a list of the the second values of each of the pairs in the given list. It is a more efficient version of @values = pairmap { $b } @kvlist =head2 pairgrep my @kvlist = pairgrep { BLOCK } @kvlist; my $count = pairgrep { BLOCK } @kvlist; I<Since version 1.29.> Similar to perl's C<grep> keyword, but interprets the given list as an even-sized list of pairs. It invokes the C<BLOCK> multiple times, in scalar context, with C<$a> and C<$b> set to successive pairs of values from the C<@kvlist>. Returns an even-sized list of those pairs for which the C<BLOCK> returned true in list context, or the count of the B<number of pairs> in scalar context. (Note, therefore, in scalar context that it returns a number half the size of the count of items it would have returned in list context). @subset = pairgrep { $a =~ m/^[[:upper:]]+$/ } @kvlist As with C<grep> aliasing C<$_> to list elements, C<pairgrep> aliases C<$a> and C<$b> to elements of the given list. Any modifications of it by the code block will be visible to the caller. =head2 pairfirst my ( $key, $val ) = pairfirst { BLOCK } @kvlist; my $found = pairfirst { BLOCK } @kvlist; I<Since version 1.30.> Similar to the L</first> function, but interprets the given list as an even-sized list of pairs. It invokes the C<BLOCK> multiple times, in scalar context, with C<$a> and C<$b> set to successive pairs of values from the C<@kvlist>. Returns the first pair of values from the list for which the C<BLOCK> returned true in list context, or an empty list of no such pair was found. In scalar context it returns a simple boolean value, rather than either the key or the value found. ( $key, $value ) = pairfirst { $a =~ m/^[[:upper:]]+$/ } @kvlist As with C<grep> aliasing C<$_> to list elements, C<pairfirst> aliases C<$a> and C<$b> to elements of the given list. Any modifications of it by the code block will be visible to the caller. =head2 pairmap my @list = pairmap { BLOCK } @kvlist; my $count = pairmap { BLOCK } @kvlist; I<Since version 1.29.> Similar to perl's C<map> keyword, but interprets the given list as an even-sized list of pairs. It invokes the C<BLOCK> multiple times, in list context, with C<$a> and C<$b> set to successive pairs of values from the C<@kvlist>. Returns the concatenation of all the values returned by the C<BLOCK> in list context, or the count of the number of items that would have been returned in scalar context. @result = pairmap { "The key $a has value $b" } @kvlist As with C<map> aliasing C<$_> to list elements, C<pairmap> aliases C<$a> and C<$b> to elements of the given list. Any modifications of it by the code block will be visible to the caller. See L</KNOWN BUGS> for a known-bug with C<pairmap>, and a workaround. =cut =head1 OTHER FUNCTIONS =cut =head2 shuffle my @values = shuffle @values; Returns the values of the input in a random order @cards = shuffle 0..51 # 0..51 in a random order =head2 uniq my @subset = uniq @values I<Since version 1.45.> Filters a list of values to remove subsequent duplicates, as judged by a DWIM-ish string equality or C<undef> test. Preserves the order of unique elements, and retains the first value of any duplicate set. my $count = uniq @values In scalar context, returns the number of elements that would have been returned as a list. The C<undef> value is treated by this function as distinct from the empty string, and no warning will be produced. It is left as-is in the returned list. Subsequent C<undef> values are still considered identical to the first, and will be removed. =head2 uniqnum my @subset = uniqnum @values I<Since version 1.44.> Filters a list of values to remove subsequent duplicates, as judged by a numerical equality test. Preserves the order of unique elements, and retains the first value of any duplicate set. my $count = uniqnum @values In scalar context, returns the number of elements that would have been returned as a list. Note that C<undef> is treated much as other numerical operations treat it; it compares equal to zero but additionally produces a warning if such warnings are enabled (C<use warnings 'uninitialized';>). In addition, an C<undef> in the returned list is coerced into a numerical zero, so that the entire list of values returned by C<uniqnum> are well-behaved as numbers. Note also that multiple IEEE C<NaN> values are treated as duplicates of each other, regardless of any differences in their payloads, and despite the fact that C<< 0+'NaN' == 0+'NaN' >> yields false. =head2 uniqstr my @subset = uniqstr @values I<Since version 1.45.> Filters a list of values to remove subsequent duplicates, as judged by a string equality test. Preserves the order of unique elements, and retains the first value of any duplicate set. my $count = uniqstr @values In scalar context, returns the number of elements that would have been returned as a list. Note that C<undef> is treated much as other string operations treat it; it compares equal to the empty string but additionally produces a warning if such warnings are enabled (C<use warnings 'uninitialized';>). In addition, an C<undef> in the returned list is coerced into an empty string, so that the entire list of values returned by C<uniqstr> are well-behaved as strings. =cut =head1 KNOWN BUGS =head2 RT #95409 L<https://rt.cpan.org/Ticket/Display.html?id=95409> If the block of code given to L</pairmap> contains lexical variables that are captured by a returned closure, and the closure is executed after the block has been re-used for the next iteration, these lexicals will not see the correct values. For example: my @subs = pairmap { my $var = "$a is $b"; sub { print "$var\n" }; } one => 1, two => 2, three => 3; $_->() for @subs; Will incorrectly print three is 3 three is 3 three is 3 This is due to the performance optimisation of using C<MULTICALL> for the code block, which means that fresh SVs do not get allocated for each call to the block. Instead, the same SV is re-assigned for each iteration, and all the closures will share the value seen on the final iteration. To work around this bug, surround the code with a second set of braces. This creates an inner block that defeats the C<MULTICALL> logic, and does get fresh SVs allocated each time: my @subs = pairmap { { my $var = "$a is $b"; sub { print "$var\n"; } } } one => 1, two => 2, three => 3; This bug only affects closures that are generated by the block but used afterwards. Lexical variables that are only used during the lifetime of the block's execution will take their individual values for each invocation, as normal. =head2 uniqnum() on oversized bignums Due to the way that C<uniqnum()> compares numbers, it cannot distinguish differences between bignums (especially bigints) that are too large to fit in the native platform types. For example, my $x = Math::BigInt->new( "1" x 100 ); my $y = $x + 1; say for uniqnum( $x, $y ); Will print just the value of C<$x>, believing that C<$y> is a numerically- equivalent value. This bug does not affect C<uniqstr()>, which will correctly observe that the two values stringify to different strings. =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 # How many elements are true sub true { scalar grep { $_ } @_ } # How many elements are false sub false { scalar grep { !$_ } @_ } =head1 SEE ALSO L<Scalar::Util>, L<List::MoreUtils> =head1 COPYRIGHT Copyright (c) 1997-2007 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. Recent additions and current maintenance by Paul Evans, <leonerd@leonerd.org.uk>. =cut 1;
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