/[wait]/trunk/lib/WAIT/IndexScan.pm
This is repository of my old source code which isn't updated any more. Go to git.rot13.org for current projects!
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revision 112 by dpavlin, Mon May 24 20:57:08 2004 UTC revision 113 by dpavlin, Tue Jul 13 20:28:45 2004 UTC
# Line 4  Line 4 
4  # Author          : Ulrich Pfeifer  # Author          : Ulrich Pfeifer
5  # Created On      : Mon Aug 12 14:05:14 1996  # Created On      : Mon Aug 12 14:05:14 1996
6  # Last Modified By: Ulrich Pfeifer  # Last Modified By: Ulrich Pfeifer
7  # Last Modified On: Sun Nov 22 18:44:43 1998  # Last Modified On: Sat Apr 27 17:46:53 2002
8  # Language        : CPerl  # Language        : CPerl
9  # Update Count    : 65  # Update Count    : 92
10  # Status          : Unknown, Use with caution!  # Status          : Unknown, Use with caution!
11  #  #
12  # Copyright (c) 1996-1997, Ulrich Pfeifer  # Copyright (c) 1996-1997, Ulrich Pfeifer
# Line 15  Line 15 
15  package WAIT::IndexScan;  package WAIT::IndexScan;
16    
17  use strict;  use strict;
18  use DB_File;  use BerkeleyDB;
19  use Fcntl;  use Fcntl;
20    
21  sub new {  sub new {
22    my $type  = shift;    my $type  = shift;
23    my $index = shift;    my $index = shift;
24    my $code  = shift;    my $code  = shift;
25    my ($first, $tid) = ('', '');    my $cursor;
26    
27    # find the first key    # find the first key
28    if ($index->{dbh}->seq($first, $tid, R_FIRST)) {    unless ($cursor = $index->{dbh}->db_cursor()) {
29      require Carp;      require Carp;
30      Carp::croak("Could not open scan");      Carp::croak("Could not open scan");
31    }    }
32    # Not sure about this. R_FIRST sets $tid to no-of-records?    # Not sure about this. DB_FIRST sets $tid to no-of-records?
33    # $index->{dbh}->seq($first, $tid, R_NEXT);    # $index->{dbh}->seq($first, $tid, DB_NEXT);
34    # register to avoid unnecessary position calls    # register to avoid unnecessary position calls
   $index->{scans}++;  
35    
36    bless {Index => $index, code  => $code,    bless {code  => $code, cursor => $cursor, Index => $index},
37           nextk => $first, tid   => $tid}, $type or ref($type);           $type or ref($type);
38  }  }
39    
40  sub next {  sub next {
41    my $self = shift;    my $self = shift;
42    my $dbh  = $self->{Index}->{dbh};    my $cursor = $self->{cursor};
43    my ($key, $tid, $ntid);    my ($key, $tid) = ('', '');
44    
45    if (defined $self->{nextk}) {    $cursor->c_get($key, $tid, DB_NEXT) == 0 or return;
46      unless ($dbh){  
47        require Carp;    my @tuple = split /$;/, $key;
48        Carp::croak("Cannot scan closed index");  
49      }    my %tuple = (_id => $tid);
50      $key = $self->{nextk};    for (@{$self->{Index}->{attr}}) {
51        $tuple{$_} = shift @tuple;
52      if ($self->{Index}->{scans} > 1) {    }
53        # Another scan is open. Reset the cursor  
54        $dbh->seq($key, $tid, R_CURSOR);  
55      } else {    if ($self->{code}) {        # test condition
56        $tid = $self->{tid};      &{$self->{code}}(\%tuple)? %tuple : $self->next;
     }  
     if ($dbh->seq($self->{nextk}, $self->{tid}, R_NEXT)) {  
       # current tuple is last one  
       delete $self->{nextk};  
     }  
   
     my @tuple = split /$;/, $key;  
     my %tuple = (_id => $tid);  
     for (@{$self->{Index}->{attr}}) {  
       $tuple{$_} = shift @tuple;  
     }  
   
     if ($self->{code}) {        # test condition  
       &{$self->{code}}(\%tuple)? %tuple : $self->next;  
     } else {  
       %tuple;  
     }  
57    } else {    } else {
58      return;      %tuple;
59    }    }
60  }  }
61    
62  sub close { undef $_[0]}        # force DESTROY  sub close {
63  sub DESTROY {    my $self = shift;
64    shift->{Index}->{scans}--;    delete $self->{cursor};
65  }  }
66    
67  1;  1;
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