segtermenum.pm

外国人写的Perl搜索引擎程序

package KinoSearch::Index::SegTermEnum;
use strict;
use warnings;
use KinoSearch::Util::ToolSet;
use base qw( KinoSearch::Util::Class );

BEGIN {
    __PACKAGE__->init_instance_vars(
        # constructor params
        finfos   => undef,
        instream => undef,
        is_index => 0,
    );
}
our %instance_vars;

use KinoSearch::Index::Term;
use KinoSearch::Index::TermInfo;
use KinoSearch::Index::TermBuffer;

sub new {
    # verify params
    my $ignore = shift;
    my %args = ( %instance_vars, @_ );
    confess kerror() unless verify_args( \%instance_vars, %args );

    # get a TermBuffer helper object
    my $term_buffer
        = KinoSearch::Index::TermBuffer->new( finfos => $args{finfos}, );

    return _new_helper( @args{ 'instream', 'is_index', 'finfos', },
        $term_buffer );
}

sub clone_enum {
    my $self = shift;

    # dupe instream and seek it to the start of the file, so init works right
    my $instream   = $self->_get_instream;
    my $new_stream = $instream->clone_stream;
    $new_stream->seek(0);

    # create a new object and seek it to the right term/terminfo
    my $evil_twin = __PACKAGE__->new(
        finfos   => $self->_get_finfos,
        instream => $new_stream,
        is_index => $self->is_index,
    );
    $evil_twin->seek(
        $instream->tell,       $self->_get_position,
        $self->get_termstring, $self->get_term_info
    );
    return $evil_twin;
}

# Locate the Enum to a particular spot.
sub seek {
    my ( $self, $pointer, $position, $termstring, $tinfo ) = @_;

    # seek the filehandle
    my $instream = $self->_get_instream;
    $instream->seek($pointer);

    # set values as if we'd scanned here from the start of the Enum
    $self->_set_position($position);
    $self->_set_termstring($termstring);
    $self->_set_term_info($tinfo);
}

sub close {
    my $instream = $_[0]->_get_instream;
    $instream->close;
}

# return a Term, if the Enum is currently valid.
sub get_term {
    my $self       = shift;
    my $termstring = $self->get_termstring;
    return unless defined $termstring;
    return KinoSearch::Index::Term->new_from_string( $termstring,
        $self->_get_finfos );
}

1;

__END__

__XS__

MODULE = KinoSearch   PACKAGE = KinoSearch::Index::SegTermEnum 


SegTermEnum*
_new_helper(instream_sv, is_index, finfos_sv, term_buffer_sv)
    SV         *instream_sv;
    I32         is_index;
    SV         *finfos_sv
    SV         *term_buffer_sv;
CODE:
    RETVAL = Kino_SegTermEnum_new_helper(instream_sv, is_index, finfos_sv,
        term_buffer_sv);
OUTPUT: RETVAL


=for comment

fill_cache() loads the entire Enum into memory.  This should only be called
for index Enums -- never for primary Enums.

=cut

void
fill_cache(obj)
    SegTermEnum *obj;
PPCODE:
    Kino_SegTermEnum_fill_cache(obj);


=begin comment

scan_to() iterates through the Enum until the Enum's state is ge the target.
This is called on the main Enum, after seek() has gotten it close.  You don't
want to scan through the entire main Enum, just through a small part.

Scanning through an Enum is an involved process, due to the heavy data
compression.  See the Java Lucene File Format definition for details.

=end comment
=cut

void
scan_to(obj, target_termstring_sv)
    SegTermEnum *obj;
    SV          *target_termstring_sv;
PREINIT:
    char *ptr;
    STRLEN len;
PPCODE:
    ptr = SvPV(target_termstring_sv, len);
    if (len < 2)
        Kino_confess("length of termstring < 2: %"UVuf, (UV)len);
    Kino_SegTermEnum_scan_to(obj, ptr, len);


=for comment

Reset the Enum to the top, so that after next() is called, the Enum is located
at the first term in the segment.

=cut

void
reset(obj)
    SegTermEnum *obj;
PPCODE:
    Kino_SegTermEnum_reset(obj);


=for comment

next() advances the state of the Enum one term.  If the current position of
the Enum is valid, it returns 1; when the Enum is exhausted, it returns 0.

=cut

IV
next(obj)
    SegTermEnum *obj;
CODE:
    RETVAL = Kino_SegTermEnum_next(obj);
OUTPUT: RETVAL


=for comment

For an Enum which has been loaded into memory, scan to the target as quickly
as possible.

=cut

I32
scan_cache(obj, target_termstring_sv)
    SegTermEnum  *obj;
    SV           *target_termstring_sv;
PREINIT:
    char *ptr;
    STRLEN len;
CODE:
    ptr = SvPV(target_termstring_sv, len);
    if (len < 2)
        Kino_confess("length of termstring < 2: %"UVuf, (UV)len);
    RETVAL = Kino_SegTermEnum_scan_cache(obj, ptr, len);
OUTPUT: RETVAL


=for comment

Setters and getters for members in the SegTermEnum struct. Not all of these 
are useful.

=cut

SV*
_set_or_get(obj, ...)
    SegTermEnum *obj;
ALIAS:
        _set_instream        = 1
        _get_instream        = 2
        _set_finfos          = 3
        _get_finfos          = 4
        _set_size            = 5
    get_size                 = 6  
        _set_termstring      = 7
    get_termstring           = 8
        _set_term_info       = 9
    get_term_info            = 10
        _set_index_interval  = 11
    get_index_interval       = 12
        _set_skip_interval   = 13
    get_skip_interval        = 14
        _set_position        = 15
        _get_position        = 16
        _set_is_index        = 17
    is_index                 = 18
CODE:
{
    KINO_START_SET_OR_GET_SWITCH

    case 0:  croak("can't call _get_or_set on it's own");
             break; /* probably unreachable */

    case 1:  SvREFCNT_dec(obj->instream_sv);
             obj->instream_sv = newSVsv( ST(1) );
             /* fall through */
    case 2:  RETVAL = newSVsv(obj->instream_sv); 
             break;

    case 3:  SvREFCNT_dec(obj->finfos);
             obj->finfos = newSVsv( ST(1) );
             /* fall through */
    case 4:  RETVAL = newSVsv(obj->finfos); 
             break;

    case 5:  obj->enum_size = (I32)SvIV( ST(1) ); 
             /* fall through */
    case 6:  RETVAL = newSViv(obj->enum_size); 
             break;

    case 7:  if ( SvOK( ST(1) ) ) {
                 STRLEN len = SvCUR( ST(1) );
                 if (len < KINO_FIELD_NUM_LEN)
                    Kino_confess("Internal error: termstring too short");
                 Kino_TermBuf_set_termstring(obj->term_buf, 
                    SvPVX(ST(1)), len);
             }
             else {
                 Kino_TermBuf_reset(obj->term_buf);
             }
             /* fall through */
    case 8:  RETVAL = (obj->term_buf->termstring == NULL) 
                 ? &PL_sv_undef
                 : newSVpv( obj->term_buf->termstring->ptr,
                     obj->term_buf->termstring->size ); 
             break;

    case 9:  {
                TermInfo* new_tinfo;
                Kino_extract_struct( ST(1), new_tinfo, TermInfo*, 
                    "KinoSearch::Index::TermInfo");
                Kino_TInfo_destroy(obj->tinfo);
                obj->tinfo = Kino_TInfo_dupe(new_tinfo);
             }
             /* fall through */
    case 10: {
                TermInfo* new_tinfo;
                RETVAL = newSV(0);
                new_tinfo = Kino_TInfo_dupe(obj->tinfo);
                sv_setref_pv(RETVAL, "KinoSearch::Index::TermInfo", 
                              (void*)new_tinfo);
             }
             break;

    case 11: obj->index_interval = SvIV( ST(1) );
             /* fall through */
    case 12: RETVAL = newSViv(obj->index_interval);
             break;

    case 13: obj->skip_interval = SvIV( ST(1) );
             /* fall through */
    case 14: RETVAL = newSViv(obj->skip_interval);
             break;

    case 15: obj->position = SvIV( ST(1) );
             /* fall through */
    case 16: RETVAL = newSViv(obj->position);
             break;