package Tie::Array; use 5.006_001; use strict; use Carp; our $VERSION = '1.07'; # Pod documentation after __END__ below. sub DESTROY { } sub EXTEND { } sub UNSHIFT { scalar 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); $obj->STORESIZE($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; $len += $sz - $off if $len < 0; my @result; for (my $i = 0; $i < $len; $i++) { push(@result,$obj->FETCH($off+$i)); } $off = $sz if $off > $sz; $len -= $off + $len - $sz if $off + $len > $sz; 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 wantarray ? @result : pop @result; } sub EXISTS { my $pkg = ref $_[0]; croak "$pkg doesn't define an EXISTS method"; } sub DELETE { my $pkg = ref $_[0]; croak "$pkg doesn't define a DELETE method"; } package Tie::StdArray; our @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 EXISTS { exists $_[0]->[$_[1]] } sub DELETE { delete $_[0]->[$_[1]] } 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; __END__ =head1 NAME Tie::Array - base class for tied arrays =head1 SYNOPSIS package Tie::NewArray; use Tie::Array; @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 sub EXISTS { ... } # mandatory if exists() expected to work sub DELETE { ... } # mandatory if delete() expected to work # optional methods - for efficiency sub CLEAR { ... } sub PUSH { ... } sub POP { ... } sub SHIFT { ... } sub UNSHIFT { ... } sub SPLICE { ... } sub EXTEND { ... } sub DESTROY { ... } package Tie::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 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<DESTROY>, and C<EXTEND> methods that do nothing, stub C<DELETE> and C<EXISTS> methods that croak() if the delete() or exists() builtins are ever called on the tied array, 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::StdArray> 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 arrays, 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 4 =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 associated 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 associated with object I<this>. =item FETCHSIZE this Returns the total number of items in the tied array associated with object I<this>. (Equivalent to C<scalar(@array)>). =item STORESIZE this, count Sets the total number of items in the tied array associated 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 EXISTS this, key Verify that the element at index I<key> exists in the tied array I<this>. The B<Tie::Array> implementation is a stub that simply croaks. =item DELETE this, key Delete the element at index I<key> from the tied array I<this>. The B<Tie::Array> implementation is a stub that simply croaks. =item CLEAR this Clear (remove, delete, ...) all values from the tied array associated 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 beginning 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'. =head1 AUTHOR Nick Ing-Simmons E<lt>nik@tiuk.ti.comE<gt> =cut SIMPAN PERUBAHAN