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#!/usr/bin/perl -w |
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|
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package Hash::Merge; |
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|
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|
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# Id: Merge.pm,v 0.07 2002/02/19 00:21:27 mneylon Exp |
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# Revision: 0.07 |
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# Author: mneylon |
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# Date: 2002/02/19 00:21:27 |
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# Log: Merge.pm,v |
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# Revision 0.07 2002/02/19 00:21:27 mneylon |
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# Fixed problem with ActiveState Perl's Clone.pm implementation. |
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# Fixed typo in POD. |
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# Fixed formatting of code in general. |
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# |
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# Revision 0.06.01.2 2002/02/17 03:18:20 mneylon |
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# Fixed problem with ActiveState Perl's Clone.pm implementation. |
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# Fixed typo in POD. |
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# Fixed formatting of code in general. |
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# |
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# Revision 0.06.01.1 2002/02/17 02:48:54 mneylon |
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# Branched version. |
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# |
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# Revision 0.06 2001/11/10 03:30:34 mneylon |
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# Version 0.06 release (and more CVS fixes) |
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# |
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# Revision 0.05.02.2 2001/11/10 03:22:58 mneylon |
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# Updated documentation |
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# |
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# Revision 0.05.02.1 2001/11/08 00:14:48 mneylon |
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# Fixing CVS problems |
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# |
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# Revision 0.05.01.1 2001/11/06 03:26:56 mneylon |
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# Fixed some undefined variable problems for 5.005. |
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# Added cloning of data and set/get_clone_behavior functions |
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# Added associated testing of data cloning |
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# Fixed some problems with POD |
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# |
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# Revision 0.05 2001/11/02 02:15:54 mneylon |
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# Yet another fix to Test::More requirement (=> 0.33) |
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# |
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# Revision 0.04 2001/10/31 03:59:03 mneylon |
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# Forced Test::More requirement in makefile |
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# Fixed problems with pod documentation |
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# |
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# Revision 0.03 2001/10/28 23:36:12 mneylon |
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# CPAN Release with CVS fixes |
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# |
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# Revision 0.02 2001/10/28 23:05:03 mneylon |
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# CPAN release |
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# |
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# Revision 0.01.1.1 2001/10/23 03:01:34 mneylon |
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# Slight fixes |
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# |
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# Revision 0.01 2001/10/23 03:00:21 mneylon |
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# Initial Release to PerlMonks |
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# |
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# |
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#============================================================================= |
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|
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use strict; |
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use Clone qw(clone); |
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|
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BEGIN { |
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use Exporter (); |
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use vars qw($VERSION @ISA @EXPORT @EXPORT_OK |
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%EXPORT_TAGS $CLONE_SUPPORT); |
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$VERSION = sprintf( "%d.%02d", q($Revision: 0.07 $) =~ /\s(\d+)\.(\d+)/ ); |
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@ISA = qw(Exporter); |
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@EXPORT = qw(); |
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@EXPORT_OK = qw( merge _hashify _merge_hashes ); |
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%EXPORT_TAGS = ( custom => [ qw( _hashify _merge_hashes )] ); |
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$CLONE_SUPPORT = ( $Clone::VERSION > 0.09 ); |
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|
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} |
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|
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my %left_precedent = ( |
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SCALAR => { |
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SCALAR => sub { $_[0] }, |
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ARRAY => sub { $_[0] }, |
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HASH => sub { $_[0] } }, |
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ARRAY => { |
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SCALAR => sub { [ @{$_[0]}, $_[1] ] }, |
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ARRAY => sub { [ @{$_[0]}, @{$_[1]} ] }, |
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HASH => sub { [ @{$_[0]}, values %{$_[1]} ] } }, |
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HASH => { |
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SCALAR => sub { $_[0] }, |
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ARRAY => sub { $_[0] }, |
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HASH => sub { _merge_hashes( $_[0], $_[1] ) } } |
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); |
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|
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my %right_precedent = ( |
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SCALAR => { |
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SCALAR => sub { $_[1] }, |
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ARRAY => sub { [ $_[0], @{$_[1]} ] }, |
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HASH => sub { $_[1] } }, |
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ARRAY => { |
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SCALAR => sub { $_[1] }, |
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ARRAY => sub { [ @{$_[0]}, @{$_[1]} ] }, |
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HASH => sub { $_[1] } }, |
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HASH => { |
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SCALAR => sub { $_[1] }, |
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ARRAY => sub { [ values %{$_[0]}, @{$_[1]} ] }, |
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HASH => sub { _merge_hashes( $_[0], $_[1] ) } } |
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); |
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|
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my %storage_precedent = ( |
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SCALAR => { |
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SCALAR => sub { $_[0] }, |
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ARRAY => sub { [ $_[0], @{$_[1]} ] }, |
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HASH => sub { $_[1] } }, |
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ARRAY => { |
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SCALAR => sub { [ @{$_[0]}, $_[1] ] }, |
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ARRAY => sub { [ @{$_[0]}, @{$_[1]} ] }, |
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HASH => sub { $_[1] } }, |
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HASH => { |
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SCALAR => sub { $_[0] }, |
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ARRAY => sub { $_[0] }, |
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HASH => sub { _merge_hashes( $_[0], $_[1] ) } } |
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); |
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|
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my %retainment_precedent = ( |
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SCALAR => { |
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SCALAR => sub { [ $_[0], $_[1] ] }, |
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ARRAY => sub { [ $_[0], @{$_[1]} ] }, |
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HASH => sub { _merge_hashes( _hashify( $_[0] ), $_[1] ) } }, |
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ARRAY => { |
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SCALAR => sub { [ @{$_[0]}, $_[1] ] }, |
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ARRAY => sub { [ @{$_[0]}, @{$_[1]} ] }, |
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HASH => sub { _merge_hashes( _hashify( $_[0] ), $_[1] ) } }, |
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HASH => { |
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SCALAR => sub { _merge_hashes( $_[0], _hashify( $_[1] ) ) }, |
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ARRAY => sub { _merge_hashes( $_[0], _hashify( $_[1] ) ) }, |
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HASH => sub { _merge_hashes( $_[0], $_[1] ) } } |
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); |
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|
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my %behaviors = ( |
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LEFT_PRECEDENT => \%left_precedent, |
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RIGHT_PRECEDENT => \%right_precedent, |
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STORAGE_PRECEDENT => \%storage_precedent, |
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RETAINMENT_PRECEDENT => \%retainment_precedent |
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); |
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|
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my $merge_behavior = 'LEFT_PRECEDENT'; |
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my $merge_matrix = \%{ $behaviors{ $merge_behavior } }; |
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|
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my $clone_behavior = 1; |
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|
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sub set_behavior { |
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my $value = uc(shift); |
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die "Behavior must be one of : " , join ' ', keys %behaviors |
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unless exists $behaviors{ $value }; |
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$merge_behavior = $value; |
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$merge_matrix = \%{ $behaviors{ $merge_behavior } }; |
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} |
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|
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sub get_behavior { |
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return $merge_behavior; |
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} |
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|
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sub specify_behavior { |
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my $matrix = shift; |
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my $name = shift || "user defined"; |
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my @required = qw ( SCALAR ARRAY HASH ); |
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|
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foreach my $left ( @required ) { |
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foreach my $right ( @required ) { |
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die "Behavior does not specify action for $left merging with $right" |
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unless exists $matrix->{ $left }->{ $right }; |
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} |
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} |
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|
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$merge_behavior = $name; |
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$merge_matrix = $matrix; |
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} |
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|
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sub set_clone_behavior { |
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my $temp = shift; |
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$clone_behavior = ( $temp ) ? 1 : 0; |
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} |
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|
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sub get_clone_behavior { |
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return $clone_behavior; |
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} |
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|
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sub merge { |
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my ( $left, $right ) = ( shift, shift ); |
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|
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# For the general use of this module, we want to create duplicates |
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# of all data that is merged. This behavior can be shut off, but |
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# can mess havoc if references are used heavily. |
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|
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my ( $lefttype, $righttype ); |
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if ( !defined( $left ) ) { # Perl 5.005 compatibility |
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$lefttype = 'SCALAR'; |
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} elsif ( UNIVERSAL::isa( $left, 'HASH' ) ) { |
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$lefttype = 'HASH'; |
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} elsif ( UNIVERSAL::isa( $left, 'ARRAY' ) ) { |
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$lefttype = 'ARRAY'; |
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} else { |
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$lefttype = 'SCALAR'; |
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} |
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|
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if ( !defined( $right ) ) { # Perl 5.005 compatibility |
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$righttype = 'SCALAR'; |
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} elsif ( UNIVERSAL::isa( $right, 'HASH' ) ) { |
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$righttype = 'HASH'; |
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} elsif ( UNIVERSAL::isa( $right, 'ARRAY' ) ) { |
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$righttype = 'ARRAY'; |
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} else { |
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$righttype = 'SCALAR'; |
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} |
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|
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if ( $clone_behavior ) { |
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$left = _my_clone ( $left, 1 ); |
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$right = _my_clone ( $right, 1 ); |
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} |
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|
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return &{ $merge_matrix->{ $lefttype }->{ $righttype }} |
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( $left, $right ); |
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} |
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|
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# This does a straight merge of hashes, delegating the merge-specific |
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# work to 'merge' |
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|
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sub _merge_hashes { |
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my ( $left, $right ) = ( shift, shift ); |
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die "Arguments for _merge_hashes must be hash references" unless |
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UNIVERSAL::isa( $left, 'HASH' ) && UNIVERSAL::isa( $right, 'HASH' ); |
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|
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my %newhash; |
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foreach my $leftkey ( keys %$left ) { |
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if ( exists $right->{ $leftkey } ) { |
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$newhash{ $leftkey } = |
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merge ( $left->{ $leftkey }, $right->{ $leftkey } ) |
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} else { |
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$newhash{ $leftkey } = |
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( $clone_behavior ) ? _my_clone( $left->{ $leftkey } ) |
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: $left->{ $leftkey }; |
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} |
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} |
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foreach my $rightkey ( keys %$right ) { |
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if ( !exists $left->{ $rightkey } ) { |
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$newhash{ $rightkey } = |
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( $clone_behavior ) ? _my_clone( $right->{ $rightkey } ) |
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: $right->{ $rightkey }; |
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} |
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} |
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return \%newhash; |
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} |
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|
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# Given a scalar or an array, creates a new hash where for each item in |
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# the passed scalar or array, the key is equal to the value. Returns |
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# this new hash |
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|
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sub _hashify { |
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my $arg = shift; |
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die "Arguement for _hashify must not be a HASH ref" if |
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UNIVERSAL::isa( $arg, 'HASH' ); |
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|
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my %newhash; |
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if ( UNIVERSAL::isa( $arg, 'ARRAY' ) ) { |
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foreach my $item ( @$arg ) { |
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my $suffix = 2; |
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my $name = $item; |
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while ( exists $newhash{ $name } ) { |
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$name = $item . $suffix++; |
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} |
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$newhash{ $name } = $item; |
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} |
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} else { |
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$newhash{ $arg } = $arg; |
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} |
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return \%newhash; |
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} |
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|
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# This adds some checks to the clone process, to deal with problems that |
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# the current distro of ActiveState perl has (specifically, it uses 0.09 |
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# of Clone, which does not support the cloning of scalars). This simply |
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# wraps around clone as to prevent a scalar from being cloned via a |
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# Clone 0.09 process. This might mean that CODEREFs and anything else |
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# not a HASH or ARRAY won't be cloned. |
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|
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sub _my_clone { |
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my ( $arg, $depth ) = @_; |
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if ( !$CLONE_SUPPORT && |
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!UNIVERSAL::isa( $arg, 'HASH' ) && |
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!UNIVERSAL::isa( $arg, 'ARRAY' )) { |
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my $var = $arg; # Forced clone |
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return $var; |
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} else { |
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if ($depth ) { |
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return clone( $arg, $depth ); |
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} else { |
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return clone( $arg ); |
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} |
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} |
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} |
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|
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1; |
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__END__ |
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|
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=head1 NAME |
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|
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Hash::Merge - Merges arbitrarily deep hashes into a single hash |
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|
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=head1 SYNOPSIS |
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|
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use Hash::Merge qw( merge ); |
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my %a = ( foo => 1, |
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bar => [ a, b, e ], |
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querty => { bob => alice } ); |
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my %b = ( foo => 2, |
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bar => [ c, d ], |
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querty => { ted => margeret } ); |
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|
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my %c = %{ merge( \%a, \%b ) }; |
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|
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Hash::Merge::set_behavior( RIGHT_PRECEDENT ); |
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|
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# This is the same as above |
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|
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Hash::Merge::specify_behavior( { |
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SCALAR => { |
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SCALAR => sub { $_[1] }, |
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ARRAY => sub { [ $_[0], @{$_[1]} ] }, |
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HASH => sub { $_[1] } }, |
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ARRAY => { |
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SCALAR => sub { $_[1] }, |
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ARRAY => sub { [ @{$_[0]}, @{$_[1]} ] }, |
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HASH => sub { $_[1] } }, |
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HASH => { |
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SCALAR => sub { $_[1] }, |
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ARRAY => sub { [ values %{$_[0]}, @{$_[1]} ] }, |
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HASH => sub { Hash::Merge::_merge_hashes( $_[0], $_[1] ) } } |
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}, "My Behavior" ); |
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|
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=head1 DESCRIPTION |
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|
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Hash::Merge merges two arbitrarily deep hashes into a single hash. That |
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is, at any level, it will add non-conflicting key-value pairs from one |
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hash to the other, and follows a set of specific rules when there are key |
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value conflicts (as outlined below). The hash is followed recursively, |
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so that deeply nested hashes that are at the same level will be merged |
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when the parent hashes are merged. B<Please note that self-referencing |
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hashes, or recursive references, are not handled well by this method.> |
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|
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Values in hashes are considered to be either ARRAY references, |
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HASH references, or otherwise are treated as SCALARs. By default, the |
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data passed to the merge function will be cloned using the Clone module; |
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however, if necessary, this behavior can be changed to use as many of |
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the original values as possible. (See C<set_clone_behavior>). |
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|
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Because there are a number of possible ways that one may want to merge |
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values when keys are conflicting, Hash::Merge provides several preset |
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methods for your convenience, as well as a way to define you own. |
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These are (currently): |
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|
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=over |
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|
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=item Left Precedence |
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|
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The values buried in the left hash will never |
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be lost; any values that can be added from the right hash will be |
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attempted. |
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|
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=item Right Precedence |
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|
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Same as Left Precedence, but with the right |
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hash values never being lost |
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|
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=item Storage Precedence |
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|
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If conflicting keys have two different |
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storage mediums, the 'bigger' medium will win; arrays are preferred over |
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scalars, hashes over either. The other medium will try to be fitted in |
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the other, but if this isn't possible, the data is dropped. |
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|
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=item Retainment Precedence |
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|
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No data will be lost; scalars will be joined |
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with arrays, and scalars and arrays will be 'hashified' to fit them into |
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a hash. |
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|
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=back |
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|
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Specific descriptions of how these work are detailed below. |
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|
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=over |
| 390 |
|
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=item merge ( <hashref>, <hashref> ) |
| 392 |
|
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Merges two hashes given the rules specified. Returns a reference to |
| 394 |
the new hash. |
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|
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=item _hashify( <scalar>|<arrayref> ) -- INTERNAL FUNCTION |
| 397 |
|
| 398 |
Returns a reference to a hash created from the scalar or array reference, |
| 399 |
where, for the scalar value, or each item in the array, there is a key |
| 400 |
and it's value equal to that specific value. Example, if you pass scalar |
| 401 |
'3', the hash will be { 3 => 3 }. |
| 402 |
|
| 403 |
=item _merge_hashes( <hashref>, <hashref> ) -- INTERNAL FUNCTION |
| 404 |
|
| 405 |
Actually does the key-by-key evaluation of two hashes and returns |
| 406 |
the new merged hash. Note that this recursively calls C<merge>. |
| 407 |
|
| 408 |
=item set_clone_behavior( <scalar> ) |
| 409 |
|
| 410 |
Sets how the data cloning is handled by Hash::Merge. If this is true, |
| 411 |
then data will be cloned; if false, then original data will be used |
| 412 |
whenever possible. By default, cloning is on (set to true). |
| 413 |
|
| 414 |
=item get_clone_behavior( ) |
| 415 |
|
| 416 |
Returns the current behavior for data cloning. |
| 417 |
|
| 418 |
=item set_behavior( <scalar> ) |
| 419 |
|
| 420 |
Specify which built-in behavior for merging that is desired. The scalar |
| 421 |
must be one of those given below. |
| 422 |
|
| 423 |
=item get_behavior( ) |
| 424 |
|
| 425 |
Returns the behavior that is currently in use by Hash::Merge. |
| 426 |
|
| 427 |
=item specify_behavior( <hashref>, [<name>] ) |
| 428 |
|
| 429 |
Specify a custom merge behavior for Hash::Merge. This must be a hashref |
| 430 |
defined with (at least) 3 keys, SCALAR, ARRAY, and HASH; each of those |
| 431 |
keys must have another hashref with (at least) the same 3 keys defined. |
| 432 |
Furthermore, the values in those hashes must be coderefs. These will be |
| 433 |
called with two arguments, the left and right values for the merge. |
| 434 |
Your coderef should return either a scalar or an array or hash reference |
| 435 |
as per your planned behavior. If necessary, use the functions |
| 436 |
_hashify and _merge_hashes as helper functions for these. For example, |
| 437 |
if you want to add the left SCALAR to the right ARRAY, you can have your |
| 438 |
behavior specification include: |
| 439 |
|
| 440 |
%spec = ( ...SCALAR => { ARRAY => sub { [ $_[0], @$_[1] ] }, ... } } ); |
| 441 |
|
| 442 |
Note that you can import _hashify and _merge_hashes into your program's |
| 443 |
namespace with the 'custom' tag. |
| 444 |
|
| 445 |
=back |
| 446 |
|
| 447 |
=head1 BUILT-IN BEHAVIORS |
| 448 |
|
| 449 |
Here is the specifics on how the current internal behaviors are called, |
| 450 |
and what each does. Assume that the left value is given as $a, and |
| 451 |
the right as $b (these are either scalars or appropriate references) |
| 452 |
|
| 453 |
LEFT TYPE RIGHT TYPE LEFT_PRECEDENT RIGHT_PRECEDENT |
| 454 |
SCALAR SCALAR $a $b |
| 455 |
SCALAR ARRAY $a ( $a, @$b ) |
| 456 |
SCALAR HASH $a %$b |
| 457 |
ARRAY SCALAR ( @$a, $b ) $b |
| 458 |
ARRAY ARRAY ( @$a, @$b ) ( @$a, @$b ) |
| 459 |
ARRAY HASH ( @$a, values %$b ) %$b |
| 460 |
HASH SCALAR %$a $b |
| 461 |
HASH ARRAY %$a ( values %$a, @$b ) |
| 462 |
HASH HASH merge( %$a, %$b ) merge( %$a, %$b ) |
| 463 |
|
| 464 |
LEFT TYPE RIGHT TYPE STORAGE_PRECEDENT RETAINMENT_PRECEDENT |
| 465 |
SCALAR SCALAR $a ( $a ,$b ) |
| 466 |
SCALAR ARRAY ( $a, @$b ) ( $a, @$b ) |
| 467 |
SCALAR HASH %$b merge( hashify( $a ), %$b ) |
| 468 |
ARRAY SCALAR ( @$a, $b ) ( @$a, $b ) |
| 469 |
ARRAY ARRAY ( @$a, @$b ) ( @$a, @$b ) |
| 470 |
ARRAY HASH %$b merge( hashify( @$a ), %$b ) |
| 471 |
HASH SCALAR %$a merge( %$a, hashify( $b ) ) |
| 472 |
HASH ARRAY %$a merge( %$a, hashify( @$b ) ) |
| 473 |
HASH HASH merge( %$a, %$b ) merge( %$a, %$b ) |
| 474 |
|
| 475 |
|
| 476 |
(*) note that merge calls _merge_hashes, hashify calls _hashify. |
| 477 |
|
| 478 |
=head1 CAVEATS |
| 479 |
|
| 480 |
This will not handle self-referencing/recursion within hashes well. |
| 481 |
Plans for a future version include incorporate deep recursion protection. |
| 482 |
|
| 483 |
As of Feb 16, 2002, ActiveState Perl's PPM of Clone.pm is only at |
| 484 |
0.09. This version does not support the cloning of scalars if passed |
| 485 |
to the function. This is fixed by 0.10 (and currently, Clone.pm is at |
| 486 |
0.13). So while most other users can upgrade their Clone.pm |
| 487 |
appropriately (and I could put this as a requirement into the |
| 488 |
Makefile.PL), those using ActiveState would lose out on the ability to |
| 489 |
use this module. (Clone.pm is not pure perl, so it's not simply a |
| 490 |
matter of moving the newer file into place). Thus, for the time |
| 491 |
being, a check is done at the start of loading of this module to see |
| 492 |
if a newer version of clone is around. Then, all cloning calls have |
| 493 |
been wrapped in the internal _my_clone function to block any scalar |
| 494 |
clones if Clone.pm is too old. However, this also prevents the |
| 495 |
cloning of anything that isn't a hash or array under the same |
| 496 |
conditions. Once ActiveState updates their Clone, I'll remove this |
| 497 |
wrapper. |
| 498 |
|
| 499 |
=head1 AUTHOR |
| 500 |
|
| 501 |
Michael K. Neylon E<lt>mneylon-pm@masemware.comE<gt> |
| 502 |
|
| 503 |
=head1 COPYRIGHT |
| 504 |
|
| 505 |
Copyright (c) 2001,2002 Michael K. Neylon. All rights reserved. |
| 506 |
|
| 507 |
This library is free software. You can redistribute it and/or modify it |
| 508 |
under the same terms as Perl itself. |
| 509 |
|
| 510 |
=head1 HISTORY |
| 511 |
|
| 512 |
$Log: Merge.pm,v $ |
| 513 |
Revision 0.07 2002/02/19 00:21:27 mneylon |
| 514 |
Fixed problem with ActiveState Perl's Clone.pm implementation. |
| 515 |
Fixed typo in POD. |
| 516 |
Fixed formatting of code in general. |
| 517 |
|
| 518 |
Revision 0.06.01.2 2002/02/17 03:18:20 mneylon |
| 519 |
Fixed problem with ActiveState Perl's Clone.pm implementation. |
| 520 |
Fixed typo in POD. |
| 521 |
Fixed formatting of code in general. |
| 522 |
|
| 523 |
Revision 0.06.01.1 2002/02/17 02:48:54 mneylon |
| 524 |
Branched version. |
| 525 |
|
| 526 |
Revision 0.06 2001/11/10 03:30:34 mneylon |
| 527 |
Version 0.06 release (and more CVS fixes) |
| 528 |
|
| 529 |
Revision 0.05.02.2 2001/11/10 03:22:58 mneylon |
| 530 |
Updated documentation |
| 531 |
|
| 532 |
Revision 0.05.02.1 2001/11/08 00:14:48 mneylon |
| 533 |
Fixing CVS problems |
| 534 |
|
| 535 |
Revision 0.05.01.1 2001/11/06 03:26:56 mneylon |
| 536 |
Fixed some undefined variable problems for 5.005. |
| 537 |
Added cloning of data and set/get_clone_behavior functions |
| 538 |
Added associated testing of data cloning |
| 539 |
Fixed some problems with POD |
| 540 |
|
| 541 |
Revision 0.05 2001/11/02 02:15:54 mneylon |
| 542 |
Yet another fix to Test::More requirement (=> 0.33) |
| 543 |
|
| 544 |
Revision 0.04 2001/10/31 03:59:03 mneylon |
| 545 |
Forced Test::More requirement in makefile |
| 546 |
Fixed problems with pod documentation |
| 547 |
|
| 548 |
Revision 0.03 2001/10/28 23:36:12 mneylon |
| 549 |
CPAN Release with CVS fixes |
| 550 |
|
| 551 |
Revision 0.02 2001/10/28 23:05:03 mneylon |
| 552 |
CPAN release |
| 553 |
|
| 554 |
=cut |
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