1 files changed, 265 insertions, 0 deletions
diff --git a/ext/base/lib/base.pm b/ext/base/lib/base.pm
new file mode 100644
index 0000000000..574925fb60
--- /dev/null
+++ b/ext/base/lib/base.pm
@@ -0,0 +1,265 @@
+package base;
+
+use strict 'vars';
+use vars qw($VERSION);
+$VERSION = '2.14';
+$VERSION = eval $VERSION;
+
+# constant.pm is slow
+sub SUCCESS () { 1 }
+
+sub PUBLIC     () { 2**0  }
+sub PRIVATE    () { 2**1  }
+sub INHERITED  () { 2**2  }
+sub PROTECTED  () { 2**3  }
+
+
+my $Fattr = \%fields::attr;
+
+sub has_fields {
+    my($base) = shift;
+    my $fglob = ${"$base\::"}{FIELDS};
+    return( ($fglob && 'GLOB' eq ref($fglob) && *$fglob{HASH}) ? 1 : 0 );
+}
+
+sub has_version {
+    my($base) = shift;
+    my $vglob = ${$base.'::'}{VERSION};
+    return( ($vglob && *$vglob{SCALAR}) ? 1 : 0 );
+}
+
+sub has_attr {
+    my($proto) = shift;
+    my($class) = ref $proto || $proto;
+    return exists $Fattr->{$class};
+}
+
+sub get_attr {
+    $Fattr->{$_[0]} = [1] unless $Fattr->{$_[0]};
+    return $Fattr->{$_[0]};
+}
+
+if ($] < 5.009) {
+    *get_fields = sub {
+        # Shut up a possible typo warning.
+        () = \%{$_[0].'::FIELDS'};
+        my $f = \%{$_[0].'::FIELDS'};
+
+        # should be centralized in fields? perhaps
+        # fields::mk_FIELDS_be_OK. Peh. As long as %{ $package . '::FIELDS' }
+        # is used here anyway, it doesn't matter.
+        bless $f, 'pseudohash' if (ref($f) ne 'pseudohash');
+
+        return $f;
+    }
+}
+else {
+    *get_fields = sub {
+        # Shut up a possible typo warning.
+        () = \%{$_[0].'::FIELDS'};
+        return \%{$_[0].'::FIELDS'};
+    }
+}
+
+sub import {
+    my $class = shift;
+
+    return SUCCESS unless @_;
+
+    # List of base classes from which we will inherit %FIELDS.
+    my $fields_base;
+
+    my $inheritor = caller(0);
+    my @isa_classes;
+
+    my @bases;
+    foreach my $base (@_) {
+        if ( $inheritor eq $base ) {
+            warn "Class '$inheritor' tried to inherit from itself\n";
+        }
+
+        next if grep $_->isa($base), ($inheritor, @bases);
+
+        if (has_version($base)) {
+            ${$base.'::VERSION'} = '-1, set by base.pm' 
+              unless defined ${$base.'::VERSION'};
+        }
+        else {
+            my $sigdie;
+            {
+                local $SIG{__DIE__};
+                eval "require $base";
+                # Only ignore "Can't locate" errors from our eval require.
+                # Other fatal errors (syntax etc) must be reported.
+                die if $@ && $@ !~ /^Can't locate .*? at \(eval /;
+                unless (%{"$base\::"}) {
+                    require Carp;
+                    local $" = " ";
+                    Carp::croak(<<ERROR);
+Base class package "$base" is empty.
+    (Perhaps you need to 'use' the module which defines that package first,
+    or make that module available in \@INC (\@INC contains: @INC).
+ERROR
+                }
+                $sigdie = $SIG{__DIE__} || undef;
+            }
+            # Make sure a global $SIG{__DIE__} makes it out of the localization.
+            $SIG{__DIE__} = $sigdie if defined $sigdie;
+            ${$base.'::VERSION'} = "-1, set by base.pm"
+              unless defined ${$base.'::VERSION'};
+        }
+        push @bases, $base;
+
+        if ( has_fields($base) || has_attr($base) ) {
+            # No multiple fields inheritance *suck*
+            if ($fields_base) {
+                require Carp;
+                Carp::croak("Can't multiply inherit fields");
+            } else {
+                $fields_base = $base;
+            }
+        }
+    }
+    # Save this until the end so it's all or nothing if the above loop croaks.
+    push @{"$inheritor\::ISA"}, @isa_classes;
+
+    push @{"$inheritor\::ISA"}, @bases;
+
+    if( defined $fields_base ) {
+        inherit_fields($inheritor, $fields_base);
+    }
+}
+
+
+sub inherit_fields {
+    my($derived, $base) = @_;
+
+    return SUCCESS unless $base;
+
+    my $battr = get_attr($base);
+    my $dattr = get_attr($derived);
+    my $dfields = get_fields($derived);
+    my $bfields = get_fields($base);
+
+    $dattr->[0] = @$battr;
+
+    if( keys %$dfields ) {
+        warn <<"END";
+$derived is inheriting from $base but already has its own fields!
+This will cause problems.  Be sure you use base BEFORE declaring fields.
+END
+
+    }
+
+    # Iterate through the base's fields adding all the non-private
+    # ones to the derived class.  Hang on to the original attribute
+    # (Public, Private, etc...) and add Inherited.
+    # This is all too complicated to do efficiently with add_fields().
+    while (my($k,$v) = each %$bfields) {
+        my $fno;
+        if ($fno = $dfields->{$k} and $fno != $v) {
+            require Carp;
+            Carp::croak ("Inherited fields can't override existing fields");
+        }
+
+        if( $battr->[$v] & PRIVATE ) {
+            $dattr->[$v] = PRIVATE | INHERITED;
+        }
+        else {
+            $dattr->[$v] = INHERITED | $battr->[$v];
+            $dfields->{$k} = $v;
+        }
+    }
+
+    foreach my $idx (1..$#{$battr}) {
+        next if defined $dattr->[$idx];
+        $dattr->[$idx] = $battr->[$idx] & INHERITED;
+    }
+}
+
+
+1;
+
+__END__
+
+=head1 NAME
+
+base - Establish an ISA relationship with base classes at compile time
+
+=head1 SYNOPSIS
+
+    package Baz;
+    use base qw(Foo Bar);
+
+=head1 DESCRIPTION
+
+Unless you are using the C<fields> pragma, consider this module discouraged
+in favor of the lighter-weight C<parent>.
+
+Allows you to both load one or more modules, while setting up inheritance from
+those modules at the same time.  Roughly similar in effect to
+
+    package Baz;
+    BEGIN {
+        require Foo;
+        require Bar;
+        push @ISA, qw(Foo Bar);
+    }
+
+C<base> employs some heuristics to determine if a module has already been
+loaded, if it has it doesn't try again. If C<base> tries to C<require> the
+module it will not die if it cannot find the module's file, but will die on any
+other error. After all this, should your base class be empty, containing no
+symbols, it will die. This is useful for inheriting from classes in the same
+file as yourself, like so:
+
+        package Foo;
+        sub exclaim { "I can have such a thing?!" }
+        
+        package Bar;
+        use base "Foo";
+
+If $VERSION is not detected even after loading it, <base> will define $VERSION
+in the base package, setting it to the string C<-1, set by base.pm>.
+
+C<base> will also initialize the fields if one of the base classes has it.
+Multiple inheritance of fields is B<NOT> supported, if two or more base classes
+each have inheritable fields the 'base' pragma will croak. See L<fields>,
+L<public> and L<protected> for a description of this feature.
+
+The base class' C<import> method is B<not> called.
+
+
+=head1 DIAGNOSTICS
+
+=over 4
+
+=item Base class package "%s" is empty.
+
+base.pm was unable to require the base package, because it was not
+found in your path.
+
+=item Class 'Foo' tried to inherit from itself
+
+Attempting to inherit from yourself generates a warning.
+
+    use Foo;
+    use base 'Foo';
+
+=back
+
+=head1 HISTORY
+
+This module was introduced with Perl 5.004_04.
+
+=head1 CAVEATS
+
+Due to the limitations of the implementation, you must use
+base I<before> you declare any of your own fields.
+
+
+=head1 SEE ALSO
+
+L<fields>
+
+=cut