MCE/Shared/Array.pm

###############################################################################
## ----------------------------------------------------------------------------
## Array helper class.
##
###############################################################################

package MCE::Shared::Array;

use strict;
use warnings;

use 5.010001;

no warnings qw( threads recursion uninitialized numeric );

our $VERSION = '1.874';

## no critic (TestingAndDebugging::ProhibitNoStrict)

use MCE::Shared::Base ();
use base 'MCE::Shared::Base::Common';

use overload (
   q("")    => \&MCE::Shared::Base::_stringify,
   q(0+)    => \&MCE::Shared::Base::_numify,
   fallback => 1
);

###############################################################################
## ----------------------------------------------------------------------------
## Based on Tie::StdArray from Tie::Array.
##
###############################################################################

sub TIEARRAY {
   my $self = bless [], shift;
   @{ $self } = @_ if @_;

   $self;
}

sub EXTEND { }

sub FETCHSIZE { scalar @{ $_[0] } }
sub STORESIZE { $#{ $_[0] } = $_[1] - 1 }

sub STORE     { $_[0]->[ $_[1] ] = $_[2] }
sub FETCH     { $_[0]->[ $_[1] ] }
sub DELETE    { delete $_[0]->[ $_[1] ] }
sub EXISTS    { exists $_[0]->[ $_[1] ] }
sub CLEAR     { @{ $_[0] } = () }
sub POP       { pop @{ $_[0] } }
sub PUSH      { my $ob = shift; push @{ $ob }, @_ }
sub SHIFT     { shift @{ $_[0] } }
sub UNSHIFT   { my $ob = shift; unshift @{ $ob }, @_ }

# SPLICE ( offset [, length [, list ] ] )

sub SPLICE {
   my $ob  = shift;
   my $sz  = $ob->FETCHSIZE;
   my $off = @_ ? shift : 0;
   $off   += $sz if $off < 0;
   my $len = @_ ? shift : $sz-$off;

   splice @{ $ob }, $off, $len, @_;
}

###############################################################################
## ----------------------------------------------------------------------------
## _find, clone, flush, iterator, keys, pairs, values
##
###############################################################################

# _find ( { getkeys => 1 }, "query string" )
# _find ( { getvals => 1 }, "query string" )
# _find ( "query string" ) # pairs

sub _find {
   my $self   = shift;
   my $params = ref($_[0]) eq 'HASH' ? shift : {};
   my $query  = shift;

   MCE::Shared::Base::_find_array( $self, $params, $query );
}

# clone ( key [, key, ... ] )
# clone ( )

sub clone {
   my $self = shift;
   my $params = ref($_[0]) eq 'HASH' ? shift : {};
   my @data = ( @_ ) ? @{ $self }[ @_ ] : @{ $self };

   $self->clear() if $params->{'flush'};

   bless \@data, ref $self;
}

# flush ( key [, key, ... ] )
# flush ( )

sub flush {
   shift()->clone( { flush => 1 }, @_ );
}

# iterator ( key [, key, ... ] )
# iterator ( "query string" )
# iterator ( )

sub iterator {
   my ( $self, @keys ) = @_;

   if ( ! @keys ) {
      @keys = ( 0 .. $#{ $self } );
   }
   elsif ( @keys == 1 && $keys[0] =~ /^(?:key|val)[ ]+\S\S?[ ]+\S/ ) {
      @keys = $self->keys($keys[0]);
   }

   return sub {
      return unless @keys;
      my $key = shift @keys;
      return ( $key => $self->[ $key ] );
   };
}

# keys ( key [, key, ... ] )
# keys ( "query string" )
# keys ( )

sub keys {
   my $self = shift;

   if ( @_ == 1 && $_[0] =~ /^(?:key|val)[ ]+\S\S?[ ]+\S/ ) {
      $self->_find({ getkeys => 1 }, @_);
   }
   elsif ( wantarray ) {
      @_ ? map { exists $self->[ $_ ] ? $_ : undef } @_
         : ( 0 .. $#{ $self } );
   }
   else {
      scalar @{ $self };
   }
}

# pairs ( key [, key, ... ] )
# pairs ( "query string" )
# pairs ( )

sub pairs {
   my $self = shift;

   if ( @_ == 1 && $_[0] =~ /^(?:key|val)[ ]+\S\S?[ ]+\S/ ) {
      $self->_find(@_);
   }
   elsif ( wantarray ) {
      @_ ? map { $_ => $self->[ $_ ] } @_
         : map { $_ => $self->[ $_ ] } 0 .. $#{ $self };
   }
   else {
      scalar @{ $self };
   }
}

# values ( key [, key, ... ] )
# values ( "query string" )
# values ( )

sub values {
   my $self = shift;

   if ( @_ == 1 && $_[0] =~ /^(?:key|val)[ ]+\S\S?[ ]+\S/ ) {
      $self->_find({ getvals => 1 }, @_);
   }
   elsif ( wantarray ) {
      @_ ? @{ $self }[ @_ ]
         : @{ $self }
   }
   else {
      scalar @{ $self };
   }
}

###############################################################################
## ----------------------------------------------------------------------------
## assign, mdel, mexists, mget, mset, range, sort
##
###############################################################################

# assign ( value [, value, ... ] )

sub assign {
   $_[0]->clear; shift()->push(@_);
}

# mdel ( index [, index, ... ] )

sub mdel {
   my $self = shift;
   my ( $cnt, $key ) = ( 0 );

   while ( @_ ) {
      $key = shift;
      $cnt++, delete($self->[ $key ]) if ( exists $self->[ $key ] );
   }

   $cnt;
}

# mexists ( index [, index, ... ] )

sub mexists {
   my $self = shift;
   my $key;

   while ( @_ ) {
      $key = shift;
      return '' unless ( exists $self->[ $key ] );
   }

   1;
}

# mget ( index [, index, ... ] )

sub mget {
   my $self = shift;

   @_ ? @{ $self }[ @_ ] : ();
}

# mset ( index, value [, index, value, ... ] )

sub mset {
   my ( $self, $key ) = ( shift );

   while ( @_ ) {
      $key = shift, $self->[ $key ] = shift;
   }

   defined wantarray ? scalar @{ $self } : ();
}

# range ( start, stop )

sub range {
   my ( $self, $start, $stop ) = @_;

   if ( $start !~ /^\-?\d+$/ || $stop !~ /^\-?\d+$/ || $start > $#{ $self } ) {
      return ();
   }

   if ( $start < 0 ) {
      $start = @{ $self } + $start;
      $start = 0 if $start < 0;
   }

   if ( $stop < 0 ) {
      $stop = @{ $self } + $stop;
      $stop = 0 if $stop < 0;
   }
   else {
      $stop = $#{ $self } if $stop > $#{ $self };
   }

   @{ $self }[ $start .. $stop ];
}

# sort ( "BY val [ ASC | DESC ] [ ALPHA ]" )
# sort ( "[ ASC | DESC ] [ ALPHA ]" ) # same as "BY val ..."

sub sort {
   my ( $self, $request ) = @_;
   my ( $alpha, $desc ) = ( 0, 0 );

   if ( length $request ) {
      $alpha = 1 if ( $request =~ /\balpha\b/i );
      $desc  = 1 if ( $request =~ /\bdesc\b/i );
   }

   # Return sorted values, leaving the data intact.

   if ( defined wantarray ) {
      if ( $alpha ) { ( $desc )
         ? CORE::sort { $b cmp $a } @{ $self }
         : CORE::sort { $a cmp $b } @{ $self };
      }
      else { ( $desc )
         ? CORE::sort { $b <=> $a } @{ $self }
         : CORE::sort { $a <=> $b } @{ $self };
      }
   }

   # Sort values in-place otherwise, in void context.

   elsif ( $alpha ) { ( $desc )
      ? do { @{ $self } = CORE::sort { $b cmp $a } @{ $self } }
      : do { @{ $self } = CORE::sort { $a cmp $b } @{ $self } };
   }
   else { ( $desc )
      ? do { @{ $self } = CORE::sort { $b <=> $a } @{ $self } }
      : do { @{ $self } = CORE::sort { $a <=> $b } @{ $self } };
   }
}

###############################################################################
## ----------------------------------------------------------------------------
## Sugar API, mostly resembles http://redis.io/commands#string primitives.
##
###############################################################################

# append ( index, string )

sub append {
   length( $_[0]->[ $_[1] ] .= $_[2] // '' );
}

# decr    ( index )
# decrby  ( index, number )
# incr    ( index )
# incrby  ( index, number )
# getdecr ( index )
# getincr ( index )

sub decr    { --$_[0]->[ $_[1] ]               }
sub decrby  {   $_[0]->[ $_[1] ] -= $_[2] || 0 }
sub incr    { ++$_[0]->[ $_[1] ]               }
sub incrby  {   $_[0]->[ $_[1] ] += $_[2] || 0 }
sub getdecr {   $_[0]->[ $_[1] ]--        // 0 }
sub getincr {   $_[0]->[ $_[1] ]++        // 0 }

# getset ( index, value )

sub getset {
   my $old = $_[0]->[ $_[1] ];
   $_[0]->[ $_[1] ] = $_[2];

   $old;
}

# len ( index )
# len ( )

sub len {
   ( defined $_[1] )
      ? length $_[0]->[ $_[1] ]
      : scalar @{ $_[0] };
}

{
   no strict 'refs';

   *{ __PACKAGE__.'::new'     } = \&TIEARRAY;
   *{ __PACKAGE__.'::set'     } = \&STORE;
   *{ __PACKAGE__.'::get'     } = \&FETCH;
   *{ __PACKAGE__.'::delete'  } = \&DELETE;
   *{ __PACKAGE__.'::exists'  } = \&EXISTS;
   *{ __PACKAGE__.'::clear'   } = \&CLEAR;
   *{ __PACKAGE__.'::pop'     } = \&POP;
   *{ __PACKAGE__.'::push'    } = \&PUSH;
   *{ __PACKAGE__.'::shift'   } = \&SHIFT;
   *{ __PACKAGE__.'::unshift' } = \&UNSHIFT;
   *{ __PACKAGE__.'::splice'  } = \&SPLICE;
   *{ __PACKAGE__.'::del'     } = \&delete;
   *{ __PACKAGE__.'::merge'   } = \&mset;
   *{ __PACKAGE__.'::vals'    } = \&values;
}

1;

__END__

###############################################################################
## ----------------------------------------------------------------------------
## Module usage.
##
###############################################################################

=head1 NAME

MCE::Shared::Array - Array helper class

=head1 VERSION

This document describes MCE::Shared::Array version 1.874

=head1 DESCRIPTION

An array helper class for use as a standalone or managed by L<MCE::Shared>.

=head1 SYNOPSIS

 # non-shared or local construction for use by a single process

 use MCE::Shared::Array;

 my $ar = MCE::Shared::Array->new( @list );

 # construction for sharing with other threads and processes

 use MCE::Shared;

 my $ar = MCE::Shared->array( @list );

 # array-like dereferencing

 my $val = $ar->[$index];
 $ar->[$index] = $val;

 @{$ar} = ();

 # OO interface

 $val   = $ar->set( $index, $val );
 $val   = $ar->get( $index);
 $val   = $ar->delete( $index );            # del is an alias for delete
 $bool  = $ar->exists( $index );
 void   = $ar->clear();
 $len   = $ar->len();                       # scalar @{ $ar }
 $len   = $ar->len( $index );               # length $ar->[ $index ]
 $val   = $ar->pop();
 $len   = $ar->push( @list );
 $val   = $ar->shift();
 $len   = $ar->unshift( @list );
 @list  = $ar->splice( $offset, $length, @list );

 $ar2   = $ar->clone( @indices );           # @indices is optional
 $ar3   = $ar->flush( @indices );
 $iter  = $ar->iterator( @indices );        # ($idx, $val) = $iter->()
 @keys  = $ar->keys( @indices );
 %pairs = $ar->pairs( @indices );
 @vals  = $ar->values( @indices );          # vals is an alias for values

 $len   = $ar->assign( $idx/$val pairs );   # equivalent to ->clear, ->push
 $cnt   = $ar->mdel( @indices );
 @vals  = $ar->mget( @indices );
 $bool  = $ar->mexists( @indices );         # true if all indices exists
 $len   = $ar->mset( $idx/$val pairs );     # merge is an alias for mset

 @vals  = $ar->range( $start, $stop );

 @vals  = $ar->sort();                      # $a <=> $b default
 @vals  = $ar->sort( "desc" );              # $b <=> $a
 @vals  = $ar->sort( "alpha" );             # $a cmp $b
 @vals  = $ar->sort( "alpha desc" );        # $b cmp $a

 # included, sugar methods without having to call set/get explicitly

 $len   = $ar->append( $index, $string );   #   $val .= $string
 $val   = $ar->decr( $index );              # --$val
 $val   = $ar->decrby( $index, $number );   #   $val -= $number
 $val   = $ar->getdecr( $index );           #   $val--
 $val   = $ar->getincr( $index );           #   $val++
 $val   = $ar->incr( $index );              # ++$val
 $val   = $ar->incrby( $index, $number );   #   $val += $number
 $old   = $ar->getset( $index, $new );      #   $o = $v, $v = $n, $o

 # pipeline, provides atomicity for shared objects, MCE::Shared v1.09+

 @vals  = $ar->pipeline(                    # ( "a_a", "b_b", "c_c" )
    [ "set", 0 => "a_a" ],
    [ "set", 1 => "b_b" ],
    [ "set", 2 => "c_c" ],
    [ "mget", qw/ 0 1 2 / ]
 );

For normal array behavior, the TIE interface is supported.

 # non-shared or local construction for use by a single process

 use MCE::Shared::Array;

 tie my @ar, "MCE::Shared::Array";

 # construction for sharing with other threads and processes

 use MCE::Shared;

 tie my @ar, "MCE::Shared";

 # usage

 my $val;

 if ( !defined ( $val = $ar[some_index] ) ) {
    $val = $ar[some_index] = "some_value";
 }

 $ar[some_index] = 0;

 tied(@ar)->incrby("some_index", 20);
 tied(@ar)->incrby(some_index => 20);

=head1 SYNTAX for QUERY STRING

Several methods take a query string for an argument. The format of the string
is described below. In the context of sharing, the query mechanism is beneficial
for the shared-manager process. It is able to perform the query where the data
resides versus the client-process grep locally involving lots of IPC.

 o Basic demonstration

   @keys = $ar->keys( "query string given here" );
   @keys = $ar->keys( "val =~ /pattern/" );

 o Supported operators: =~ !~ eq ne lt le gt ge == != < <= > >=
 o Multiple expressions delimited by :AND or :OR, mixed case allowed

   "key == 3 :or (val > 5 :and val < 9)"
   "key =~ /pattern/i :And val =~ /pattern/i"
   "val eq foo baz :OR key !~ /pattern/i"

   * key matches on indices in the array
   * likewise, val matches on values

 o Quoting is optional inside the string

   "key =~ /pattern/i :AND val eq 'foo bar'"   # val eq "foo bar"
   "key =~ /pattern/i :AND val eq foo bar"     # val eq "foo bar"

Examples.

 # search capability key/val: =~ !~ eq ne lt le gt ge == != < <= > >=
 # key/val means to match against actual key/val respectively

 @keys  = $ar->keys( "key == 3 :or (val > 5 :and val < 9)" );

 @keys  = $ar->keys( "key =~ /$pattern/i" );
 @keys  = $ar->keys( "key !~ /$pattern/i" );
 @keys  = $ar->keys( "val =~ /$pattern/i" );
 @keys  = $ar->keys( "val !~ /$pattern/i" );

 %pairs = $ar->pairs( "key == $number" );
 %pairs = $ar->pairs( "key != $number :and val > 100" );
 %pairs = $ar->pairs( "key <  $number :or key > $number" );
 %pairs = $ar->pairs( "val <= $number" );
 %pairs = $ar->pairs( "val >  $number" );
 %pairs = $ar->pairs( "val >= $number" );

 @vals  = $ar->vals( "key eq $string" );
 @vals  = $ar->vals( "key ne $string with space" );
 @vals  = $ar->vals( "key lt $string :or val =~ /$pat1|$pat2/" );
 @vals  = $ar->vals( "val le $string :and val eq 'foo bar'" );
 @vals  = $ar->vals( "val le $string :and val eq foo bar" );
 @vals  = $ar->vals( "val gt $string" );
 @vals  = $ar->vals( "val ge $string" );

=head1 API DOCUMENTATION

This module may involve TIE when accessing the object via array-like behavior.
Only shared instances are impacted if doing so. Although likely fast enough for
many use cases, the OO interface is recommended for best performance.

=head2 MCE::Shared::Array->new ( val [, val, ... ] )

=head2 MCE::Shared->array ( val [, val, ... ] )

Constructs a new object, with an optional list of values.

 # non-shared or local construction for use by a single process

 use MCE::Shared::Array;

 $ar = MCE::Shared::Array->new( @list );
 $ar = MCE::Shared::Array->new( );

 # construction for sharing with other threads and processes

 use MCE::Shared;

 $ar = MCE::Shared->array( @list );
 $ar = MCE::Shared->array( );

=head2 assign ( value [, value, ... ] )

Clears the list, then appends one or multiple values and returns the new length.
This is equivalent to C<clear>, C<push>.

 $len = $ar->assign( "val1", "val2" );
 $len = @{$ar} = ( "val1", "val2" );

API available since 1.007.

=head2 clear

Removes all elements from the array.

 $ar->clear;
 @{$ar} = ();

=head2 clone ( index [, index, ... ] )

Creates a shallow copy, a C<MCE::Shared::Array> object. It returns an exact
copy if no arguments are given. Otherwise, the object includes only the given
indices in the same order. Indices that do not exist in the array will have
the C<undef> value.

 $ar2 = $ar->clone( 0, 1 );
 $ar2 = $ar->clone;

=head2 delete ( index )

Deletes and returns the value associated by index or C<undef> if index exceeds
the size of the list.

 $val = $ar->delete( 20 );
 $val = delete $ar->[ 20 ];

=head2 del

C<del> is an alias for C<delete>.

=head2 exists ( index )

Determines if an element by its index exists in the array. The behavior is
strongly tied to the use of delete on lists.

 $ar->push(qw/ value0 value1 value2 value3 /);

 $ar->exists( 2 );   # True
 $ar->delete( 2 );   # value2
 $ar->exists( 2 );   # False

 $ar->exists( 3 );   # True
 exists $ar->[ 3 ];  # True

=head2 flush ( index [, index, ... ] )

Same as C<clone>. Though, clears all existing items before returning.

=head2 get ( index )

Gets the value of an element by its index or C<undef> if the index does not
exists.

 $val = $ar->get( 2 );
 $val = $ar->[ 2 ];

=head2 iterator ( index [, index, ... ] )

Returns a code reference for iterating a list of index-value pairs stored in
the array when no arguments are given. Otherwise, returns a code reference for
iterating the given indices in the same order. Indices that do not exist will
have the C<undef> value.

The list of indices to return is set when the closure is constructed. New
indices added later are not included. Subsequently, the C<undef> value is
returned for deleted indices.

 $iter = $ar->iterator;
 $iter = $ar->iterator( 0, 1 );

 while ( my ( $index, $val ) = $iter->() ) {
    ...
 }

=head2 iterator ( "query string" )

Returns a code reference for iterating a list of index-value pairs that match
the given criteria. It returns an empty list if the search found nothing.
The syntax for the C<query string> is described above.

 $iter = $ar->iterator( "val eq some_value" );
 $iter = $ar->iterator( "key >= 50 :AND val =~ /sun|moon|air|wind/" );
 $iter = $ar->iterator( "val eq sun :OR val eq moon :OR val eq foo" );
 $iter = $ar->iterator( "key =~ /$pattern/" );

 while ( my ( $index, $val ) = $iter->() ) {
    ...
 }

=head2 keys ( index [, index, ... ] )

Returns all indices in the array when no arguments are given. Otherwise,
returns the given indices in the same order. Indices that do not exist will
have the C<undef> value. In scalar context, returns the size of the array.

 @keys = $ar->keys( 0, 1 );

 @keys = $ar->keys;     # faster
 @keys = keys @{$ar};   # involves TIE overhead

 $len  = $ar->keys;     # ditto
 $len  = keys @{$ar};

=head2 keys ( "query string" )

Returns only indices that match the given criteria. It returns an empty list
if the search found nothing. The syntax for the C<query string> is described
above. In scalar context, returns the size of the resulting list.

 @keys = $ar->keys( "val eq some_value" );
 @keys = $ar->keys( "key >= 50 :AND val =~ /sun|moon|air|wind/" );
 @keys = $ar->keys( "val eq sun :OR val eq moon :OR val eq foo" );
 $len  = $ar->keys( "key =~ /$pattern/" );

=head2 len ( index )

Returns the size of the array when no arguments are given. For the given
index, returns the length of the value stored at index or the C<undef> value
if the index does not exists.

 $len = $ar->len;
 $len = $ar->len( 0 );
 $len = length $ar->[ 0 ];

=head2 mdel ( index [, index, ... ] )

Deletes one or more elements by its index and returns the number of indices
deleted. A given index which does not exist in the list is not counted.

 $cnt = $ar->mdel( 0, 1 );

=head2 mexists ( index [, index, ... ] )

Returns a true value if all given indices exists in the list. A false value is
returned otherwise.

 if ( $ar->mexists( 0, 1 ) ) { ... }

=head2 mget ( index [, index, ... ] )

Gets multiple values from the list by its index. It returns C<undef> for indices
which do not exists in the list.

 ( $val1, $val2 ) = $ar->mget( 0, 1 );

=head2 mset ( index, value [, index, value, ... ] )

Sets multiple index-value pairs in the list and returns the length of the list.

 $len = $ar->mset( 0 => "val1", 1 => "val2" );

=head2 merge

C<merge> is an alias for C<mset>.

=head2 pairs ( index [, index, ... ] )

Returns index-value pairs in the array when no arguments are given. Otherwise,
returns index-value pairs for the given indices in the same order. Indices that
do not exist will have the C<undef> value. In scalar context, returns the size
of the array.

 @pairs = $ar->pairs( 0, 1 );

 @pairs = $ar->pairs;
 $len   = $ar->pairs;

=head2 pairs ( "query string" )

Returns only index-value pairs that match the given criteria. It returns an
empty list if the search found nothing. The syntax for the C<query string> is
described above. In scalar context, returns the size of the resulting list.

 @pairs = $ar->pairs( "val eq some_value" );
 @pairs = $ar->pairs( "key >= 50 :AND val =~ /sun|moon|air|wind/" );
 @pairs = $ar->pairs( "val eq sun :OR val eq moon :OR val eq foo" );
 $len   = $ar->pairs( "key =~ /$pattern/" );

=head2 pipeline ( [ func1, @args ], [ func2, @args ], ... )

Combines multiple commands for the object to be processed serially. For shared
objects, the call is made atomically due to single IPC to the shared-manager
process. The C<pipeline> method is fully C<wantarray>-aware and receives a list
of commands and their arguments. In scalar or list context, it returns data
from the last command in the pipeline.

 @vals = $ar->pipeline(                     # ( "a_a", "b_b", "c_c" )
    [ "set", 0 => "a_a" ],
    [ "set", 1 => "b_b" ],
    [ "set", 2 => "c_c" ],
    [ "mget", qw/ 0 1 2 / ]
 );

 $len = $ar->pipeline(                      # 3, same as $ar->len
    [ "set", 0 => "i_i" ],
    [ "set", 1 => "j_j" ],
    [ "set", 2 => "k_k" ],
    [ "len" ]
 );

 $ar->pipeline(
    [ "set", 0 => "m_m" ],
    [ "set", 1 => "n_n" ],
    [ "set", 2 => "o_o" ]
 );

Current API available since 1.809.

=head2 pipeline_ex ( [ func1, @args ], [ func2, @args ], ... )

Same as C<pipeline>, but returns data for every command in the pipeline.

 @vals = $ar->pipeline_ex(                  # ( "a_a", "b_b", "c_c" )
    [ "set", 0 => "a_a" ],
    [ "set", 1 => "b_b" ],
    [ "set", 2 => "c_c" ]
 );

Current API available since 1.809.

=head2 pop

Removes and returns the last value of the list. If there are no elements in the
list, returns the undefined value.

 $val = $ar->pop;
 $val = pop @{$ar};

=head2 push ( value [, value, ... ] )

Appends one or multiple values to the tail of the list and returns the new
length.

 $len = $ar->push( "val1", "val2" );
 $len = push @{$ar}, "val1", "val2";

=head2 set ( index, value )

Sets the value of the given array index and returns its new value.

 $val = $ar->set( 2, "value" );
 $val = $ar->[ 2 ] = "value";

=head2 shift

Removes and returns the first value of the list. If there are no elements in the
list, returns the undefined value.

 $val = $ar->shift;
 $val = shift @{$ar};

=head2 range ( start, stop )

Returns the specified elements of the list. The offsets C<start> and C<stop>
can also be negative numbers indicating offsets starting at the end of the
list.

An empty list is returned if C<start> is larger than the end of the list.
C<stop> is set to the last index of the list if larger than the actual end
of the list.

 @list = $ar->range( 20, 29 );
 @list = $ar->range( -4, -1 );

=head2 sort ( "BY val [ ASC | DESC ] [ ALPHA ]" )

Returns sorted values in list context, leaving the elements intact. In void
context, sorts the list in-place. By default, sorting is numeric when no
arguments are given. The C<BY val> modifier is optional and may be omitted.

 @vals = $ar->sort( "BY val" );

 $ar->sort();

If the list contains string values and you want to sort them lexicographically,
specify the C<ALPHA> modifier.

 @vals = $ar->sort( "BY val ALPHA" );

 $ar->sort( "ALPHA" );

The default is C<ASC> for sorting the list from small to large. In order to
sort the list from large to small, specify the C<DESC> modifier.

 @vals = $ar->sort( "DESC ALPHA" );

 $ar->sort( "DESC ALPHA" );

=head2 splice ( offset [, length [, list ] ] )

Removes the elements designated by C<offset> and C<length> from the array, and
replaces them with the elements of C<list>, if any. The behavior is similar to
the Perl C<splice> function.

 @items = $ar->splice( 20, 2, @list );
 @items = $ar->splice( 20, 2 );
 @items = $ar->splice( 20 );

=head2 unshift ( value [, value, ... ] )

Prepends one or multiple values to the head of the list and returns the new
length.

 $len = $ar->unshift( "val1", "val2" );
 $len = unshift @{$ar}, "val1", "val2";

=head2 values ( index [, index, ... ] )

Returns all values in the array when no arguments are given. Otherwise, returns
values for the given indices in the same order. Indices that do not exist will
have the C<undef> value. In scalar context, returns the size of the array.

 @vals = $ar->values( 0, 1 );

 @vals = $ar->values;     # faster
 @vals = values @{$ar};   # involves TIE overhead

 $len  = $ar->values;     # ditto
 $len  = values @{$ar};

=head2 values ( "query string" )

Returns only values that match the given criteria. It returns an empty list
if the search found nothing. The syntax for the C<query string> is described
above. In scalar context, returns the size of the resulting list.

 @keys = $ar->values( "val eq some_value" );
 @keys = $ar->values( "key >= 50 :AND val =~ /sun|moon|air|wind/" );
 @keys = $ar->values( "val eq sun :OR val eq moon :OR val eq foo" );
 $len  = $ar->values( "key =~ /$pattern/" );

=head2 vals

C<vals> is an alias for C<values>.

=head1 SUGAR METHODS

This module is equipped with sugar methods to not have to call C<set>
and C<get> explicitly. In shared context, the benefit is atomicity and
reduction in inter-process communication.

The API resembles a subset of the Redis primitives
L<http://redis.io/commands#strings> with key representing the array index.

=head2 append ( key, string )

Appends a value to a key and returns its new length.

 $len = $ar->append( 0, "foo" );

=head2 decr ( key )

Decrements the value of a key by one and returns its new value.

 $num = $ar->decr( 0 );

=head2 decrby ( key, number )

Decrements the value of a key by the given number and returns its new value.

 $num = $ar->decrby( 0, 2 );

=head2 getdecr ( key )

Decrements the value of a key by one and returns its old value.

 $old = $ar->getdecr( 0 );

=head2 getincr ( key )

Increments the value of a key by one and returns its old value.

 $old = $ar->getincr( 0 );

=head2 getset ( key, value )

Sets the value of a key and returns its old value.

 $old = $ar->getset( 0, "baz" );

=head2 incr ( key )

Increments the value of a key by one and returns its new value.

 $num = $ar->incr( 0 );

=head2 incrby ( key, number )

Increments the value of a key by the given number and returns its new value.

 $num = $ar->incrby( 0, 2 );

=head1 CREDITS

The implementation is inspired by L<Tie::StdArray>.

=head1 INDEX

L<MCE|MCE>, L<MCE::Hobo>, L<MCE::Shared>

=head1 AUTHOR

Mario E. Roy, S<E<lt>marioeroy AT gmail DOT comE<gt>>

=cut