package Search::Xapian::PositionIterator;

use 5.006;
use strict;
use warnings;
use Carp;

use UNIVERSAL qw( isa );

require Exporter;
require DynaLoader;

our @ISA = qw(Exporter DynaLoader);
# Items to export into callers namespace by default. Note: do not export
# names by default without a very good reason. Use EXPORT_OK instead.
# Do not simply export all your public functions/methods/constants.

# If you do not need this, moving things directly into @EXPORT or @EXPORT_OK
# will save memory.
our @EXPORT_OK = ( );

our @EXPORT = qw( );

=head1 NAME 

Search::Xapian::PositionIterator - Iterate over sets of positions.

=head1 DESCRIPTION

This iterator represents a stream of positions for a term. It overloads 
++ for incrementing the iterator, or you can explicitly call the inc 
method.  This class also overloads 'eq',ne, and "" (stringification)

=head1 METHODS

=over 4

=item new 

Constructor. Defaults to a uninitialized iterator.

=item clone

=item inc

Increase the iterator by one. (Called implictly by '++' overloading )

=item skip_to <tname>

Skip the iterator to term tname, or the first term after tname if tname 
isn't in the list of terms being iterated. 

=item get_position

Returns the current position.

=item get_description

Returns a string describing this object.  (for introspection)

=item equal <term>

Checks if a term is the same as this term. Also overloaded to the 'eq'
operator.

=item nequal <term>

Checks if a term is dfferent from this term. Also overloaded to the 'ne'
operator.

=item get_termpos <term>

Return the term position the iterator is currently on. also implemented
as stringification.

=cut


# Preloaded methods go here.

use overload '++' => sub { $_[0]->inc() },
             '='  => sub { $_[0]->clone() },
	     'eq' => sub { $_[0]->equal($_[1]) },
	     'ne' => sub { $_[0]->nequal($_[1]) },
	     '==' => sub { $_[0]->equal($_[1]) },
	     '!=' => sub { $_[0]->nequal($_[1]) },
             '""' => sub { $_[0]->get_description() },
             '0+' => sub { $_[0]->get_termpos() },
             'fallback' => 1;

sub clone() {
  my $self = shift;
  my $class = ref( $self );
  my $copy = new2( $self );
  bless $copy, $class;
  return $copy;
}

sub equal() {
  my ($self, $other) = @_;
  if( isa($other, 'Search::Xapian::PositionIterator') ) {
    $self->equal1($other);
  } else {
    ($self+0) == ($other+0);
  }
}

sub nequal() {
  my ($self, $other) = @_;
  if( isa($other, 'Search::Xapian::PositionIterator') ) {
    $self->nequal1($other);
  } else {
    ($self+0) != +($other+0);
  }
}


sub new() {
  my $class = shift;
  my $iterator;
  my $invalid_args;
  if( scalar(@_) == 0 ) {
    $iterator = new1();
  } elsif( scalar(@_) == 1 and ref( $_[1] ) eq $class ) {
    $iterator = new2(@_);
  } else {
    $invalid_args = 1;
  }
  if( $invalid_args ) {
    Carp::carp( "USAGE: $class->new(), $class->new(\$iterator)" );
    exit;
  }
  bless $iterator, $class;
  return $iterator;
}

1;

=back

=head1 SEE ALSO

L<Search::Xapian>,L<Search::Xapian::Document>

=cut