-package Tie::Array;
+package Tie::Array;
+use vars qw($VERSION);
+use strict;
+$VERSION = '1.00';
-# No content yet - just pod skeleton.
+# Pod documentation after __END__ below.
+
+sub DESTROY { }
+sub EXTEND { }
+sub UNSHIFT { shift->SPLICE(0,0,@_) }
+sub SHIFT { shift->SPLICE(0,1) }
+sub CLEAR { shift->STORESIZE(0) }
+
+sub PUSH
+{
+ my $obj = shift;
+ my $i = $obj->FETCHSIZE;
+ $obj->STORE($i++, shift) while (@_);
+}
+
+sub POP
+{
+ my $obj = shift;
+ my $newsize = $obj->FETCHSIZE - 1;
+ my $val;
+ if ($newsize >= 0)
+ {
+ $val = $obj->FETCH($newsize);
+ $obj->SETSIZE($newsize);
+ }
+ $val;
+}
+
+sub SPLICE
+{
+ my $obj = shift;
+ my $sz = $obj->FETCHSIZE;
+ my $off = (@_) ? shift : 0;
+ $off += $sz if ($off < 0);
+ my $len = (@_) ? shift : $sz - $off;
+ my @result;
+ for (my $i = 0; $i < $len; $i++)
+ {
+ push(@result,$obj->FETCH($off+$i));
+ }
+ if (@_ > $len)
+ {
+ # Move items up to make room
+ my $d = @_ - $len;
+ my $e = $off+$len;
+ $obj->EXTEND($sz+$d);
+ for (my $i=$sz-1; $i >= $e; $i--)
+ {
+ my $val = $obj->FETCH($i);
+ $obj->STORE($i+$d,$val);
+ }
+ }
+ elsif (@_ < $len)
+ {
+ # Move items down to close the gap
+ my $d = $len - @_;
+ my $e = $off+$len;
+ for (my $i=$off+$len; $i < $sz; $i++)
+ {
+ my $val = $obj->FETCH($i);
+ $obj->STORE($i-$d,$val);
+ }
+ $obj->STORESIZE($sz-$d);
+ }
+ for (my $i=0; $i < @_; $i++)
+ {
+ $obj->STORE($off+$i,$_[$i]);
+ }
+ return @result;
+}
+
+package Tie::StdArray;
+use vars qw(@ISA);
+@ISA = 'Tie::Array';
+
+sub TIEARRAY { bless [], $_[0] }
+sub FETCHSIZE { scalar @{$_[0]} }
+sub STORESIZE { $#{$_[0]} = $_[1]-1 }
+sub STORE { $_[0]->[$_[1]] = $_[2] }
+sub FETCH { $_[0]->[$_[1]] }
+sub CLEAR { @{$_[0]} = () }
+sub POP { pop(@{$_[0]}) }
+sub PUSH { my $o = shift; push(@$o,@_) }
+sub SHIFT { shift(@{$_[0]}) }
+sub UNSHIFT { my $o = shift; unshift(@$o,@_) }
+
+sub SPLICE
+{
+ my $ob = shift;
+ my $sz = $ob->FETCHSIZE;
+ my $off = @_ ? shift : 0;
+ $off += $sz if $off < 0;
+ my $len = @_ ? shift : $sz-$off;
+ return splice(@$ob,$off,$len,@_);
+}
1;
=head1 SYNOPSIS
+ package NewArray;
use Tie::Array;
- @ISA = 'Tie::Array';
-
- sub SIZE { ... }
- sub FETCH { ... }
- sub STORE { ... }
- sub CLEAR { ... }
+ @ISA = ('Tie::Array');
+
+ # mandatory methods
+ sub TIEARRAY { ... }
+ sub FETCH { ... }
+ sub FETCHSIZE { ... }
+
+ sub STORE { ... } # mandatory if elements writeable
+ sub STORESIZE { ... } # mandatory if elements can be added/deleted
+
+ # optional methods - for efficiency
+ sub CLEAR { ... }
sub PUSH { ... }
sub POP { ... }
sub SHIFT { ... }
sub UNSHIFT { ... }
sub SPLICE { ... }
+ sub EXTEND { ... }
+ sub DESTROY { ... }
+
+ package NewStdArray;
+ use Tie::Array;
+
+ @ISA = ('Tie::StdArray');
+
+ # all methods provided by default
+
+ package main;
+
+ $object = tie @somearray,Tie::NewArray;
+ $object = tie @somearray,Tie::StdArray;
+ $object = tie @somearray,Tie::NewStdArray;
+
+
=head1 DESCRIPTION
-This module provides some skeletal methods for array-tying classes.
+This module provides methods for array-tying classes. See
+L<perltie> for a list of the functions required in order to tie an array
+to a package. The basic B<Tie::Array> package provides stub C<DELETE>
+and C<EXTEND> methods, and implementations of C<PUSH>, C<POP>, C<SHIFT>,
+C<UNSHIFT>, C<SPLICE> and C<CLEAR> in terms of basic C<FETCH>, C<STORE>,
+C<FETCHSIZE>, C<STORESIZE>.
+
+The B<Tie::StdHash> package provides efficient methods required for tied arrays
+which are implemented as blessed references to an "inner" perl array.
+It inherits from B<Tie::Array>, and should cause tied arrays to behave exactly
+like standard hashes, allowing for selective overloading of methods.
+
+For developers wishing to write their own tied arrays, the required methods
+are briefly defined below. See the L<perltie> section for more detailed
+descriptive, as well as example code:
+
+=over
+
+=item TIEARRAY classname, LIST
+
+The class method is invoked by the command C<tie @array, classname>. Associates
+an array instance with the specified class. C<LIST> would represent
+additional arguments (along the lines of L<AnyDBM_File> and compatriots) needed
+to complete the association. The method should return an object of a class which
+provides the methods below.
+
+=item STORE this, index, value
+
+Store datum I<value> into I<index> for the tied array assoicated with
+object I<this>. If this makes the array larger then
+class's mapping of C<undef> should be returned for new positions.
+
+=item FETCH this, index
+
+Retrieve the datum in I<index> for the tied array assoicated with
+object I<this>.
+
+=item FETCHSIZE this
+
+Returns the total number of items in the tied array assoicated with
+object I<this>. (Equivalent to C<scalar(@array)>).
+=item STORESIZE this, count
+
+Sets the total number of items in the tied array assoicated with
+object I<this> to be I<count>. If this makes the array larger then
+class's mapping of C<undef> should be returned for new positions.
+If the array becomes smaller then entries beyond count should be
+deleted.
+
+=item EXTEND this, count
+
+Informative call that array is likely to grow to have I<count> entries.
+Can be used to optimize allocation. This method need do nothing.
+
+=item CLEAR this
+
+Clear (remove, delete, ...) all values from the tied array assoicated with
+object I<this>.
+
+=item DESTROY this
+
+Normal object destructor method.
+
+=item PUSH this, LIST
+
+Append elements of LIST to the array.
+
+=item POP this
+
+Remove last element of the array and return it.
+
+=item SHIFT this
+
+Remove the first element of the array (shifting other elements down)
+and return it.
+
+=item UNSHIFT this, LIST
+
+Insert LIST elements at the begining of the array, moving existing elements
+up to make room.
+
+=item SPLICE this, offset, length, LIST
+
+Perform the equivalent of C<splice> on the array.
+
+I<offset> is optional and defaults to zero, negative values count back
+from the end of the array.
+
+I<length> is optional and defaults to rest of the array.
+
+I<LIST> may be empty.
+
+Returns a list of the original I<length> elements at I<offset>.
+
+=back
=head1 CAVEATS
There is no support at present for tied @ISA. There is a potential conflict
between magic entries needed to notice setting of @ISA, and those needed to
-implement 'tie'.
+implement 'tie'.
+
+Very little consideration has been given to the behaviour of tied arrays
+when C<$[> is not default value of zero.
+
+=head1 AUTHOR
+
+Nick Ing-Simmons E<lt>nik@tiuk.ti.comE<gt>
=cut
projects / p5sagit/p5-mst-13.2.git / blobdiff