search-xapian/Xapian/QueryParser.pm

   1 package Search::Xapian::QueryParser;
   2
   3 use 5.006;
   4 use strict;
   5 use warnings;
   6
   7 require DynaLoader;
   8
   9 our @ISA = qw(DynaLoader);
  10
  11 # Preloaded methods go here.
  12
  13 # In a new thread, copy objects of this class to unblessed, undef values.
  14 sub CLONE_SKIP { 1 }
  15
  16 use overload '='  => sub { $_[0]->clone() },
  17              'fallback' => 1;
  18
  19 sub clone() {
  20   my $self = shift;
  21   my $class = ref( $self );
  22   my $copy = new2( $self );
  23   bless $copy, $class;
  24   return $copy;
  25 }
  26
  27 sub new() {
  28   my $class = shift;
  29   my $qp = new0();
  30
  31   bless $qp, $class;
  32   $qp->set_database(@_) if scalar(@_) == 1;
  33
  34   return $qp;
  35 }
  36
  37 1;
  38
  39 __END__
  40
  41 =head1 NAME
  42
  43 Search::Xapian::QueryParser - Parse a query string into a Search::Xapian::Query object
  44
  45 =head1 DESCRIPTION
  46
  47 This module turns a human readable string into something Xapian can
  48 understand.  The syntax supported is designed to be similar to other web
  49 based search engines, so that users familiar with them don't have to learn
  50 a whole new syntax.
  51
  52 =head1 SYNOPSIS
  53
  54   use Search::Xapian qw/:standard/;
  55
  56   my $qp = new Search::Xapian::QueryParser( [$database] );
  57   $qp->set_stemmer(new Search::Xapian::Stem("english"));
  58   $qp->set_default_op(OP_AND);
  59
  60   $database->enquire($qp->parse_query('a NEAR word OR "a phrase" NOT (too difficult) +eh'));
  61
  62 =head1 METHODS
  63
  64 =over 4
  65
  66 =item new <database>
  67
  68 QueryParser constructor.
  69
  70 =item set_stemmer <stemmer>
  71
  72 Set the Search::Xapian::Stem object to be used for stemming query terms.
  73
  74 =item set_stemming_strategy <strategy>
  75
  76 Set the stemming strategy.  Valid values are C<STEM_ALL>, C<STEM_SOME>,
  77 C<STEM_NONE>.
  78
  79 =item set_stopper <stopper>
  80
  81 Set the Search::Xapian::Stopper object to be used for identifying stopwords.
  82
  83 =item set_default_op <operator>
  84
  85 Set the default operator.
  86
  87 This operator is used to combine non-filter query items when no
  88 explicit operator is used.
  89
  90 The most useful values for this are OP_OR (the default) and OP_AND.
  91 OP_NEAR and OP_PHRASE can also be useful.
  92
  93 See L<Search::Xapian> for descriptions of these constants.
  94
  95 =item get_default_op
  96
  97 Returns the current default operator.
  98
  99 =item set_database <database>
 100
 101 Pass a L<Search::Xapian::Database> object which is used to check whether
 102 terms exist in some situations.
 103
 104 =item parse_query <query_string> [<flags>]
 105
 106 Parses the query string according to the rules defined in the query parser
 107 documentation below. You can specify certain flags to modify the
 108 searching behaviour:
 109
 110   FLAG_BOOLEAN, FLAG_PHRASE, FLAG_LOVEHATE, FLAG_BOOLEAN_ANY_CASE,
 111   FLAG_WILDCARD, FLAG_PURE_NOT, FLAG_PARTIAL, FLAG_SPELLING_CORRECTION,
 112   FLAG_SYNONYM, FLAG_AUTO_SYNONYMS, FLAG_AUTO_MULTIWORD_SYNONYMS
 113
 114 To specify multiple flags, "bitwise or" them together (with C<|>).  The
 115 default flags are C<FLAG_PHRASE|FLAG_BOOLEAN|FLAG_LOVEHATE>
 116
 117 =item add_prefix <field> <prefix>
 118
 119 Add a probabilistic term prefix.  E.g. $qp->add_prefix("author", "A");
 120
 121 Allows the user to search for author:orwell which will search for the term
 122 "Aorwel" (assuming English stemming is in use). Multiple fields can be mapped
 123 to the same prefix (so you can e.g. make title: and subject: aliases for each
 124 other).
 125
 126 Parameters:
 127 field   The user visible field name
 128 prefix  The term prefix to map this to
 129
 130 =item add_boolean_prefix <field> prefix
 131
 132 Add a boolean term prefix allowing the user to restrict a search with a
 133 boolean filter specified in the free text query.  E.g.
 134
 135   $p->add_boolean_prefix("site", "H");
 136
 137 Allows the user to restrict a search with site:xapian.org which will be
 138 converted to Hxapian.org combined with any probabilistic query with
 139 C<OP_FILTER>.
 140
 141 Multiple fields can be mapped to the same prefix (so you can e.g. make site:
 142 and domain: aliases for each other).
 143
 144 Parameters:
 145 field   The user visible field name
 146 prefix  The term prefix to map this to
 147
 148 =item stoplist_begin
 149
 150 =item stoplist_end
 151
 152 =item unstem_begin
 153
 154 =item unstem_end
 155
 156 =item get_description
 157
 158 Returns a string describing this object.
 159
 160 =item get_corrected_query_string
 161
 162 Get the spelling-corrected query string.
 163
 164 This will only be set if FLAG_SPELLING_CORRECTION is specified when
 165 QueryParser::parse_query() was last called.
 166
 167 If there were no corrections, an empty string is returned.
 168
 169 =item set_max_wildcard_expansion <limit>
 170
 171 Specify the maximum expansion of a wildcard term.
 172
 173 Note: you must also set FLAG_WILDCARD for wildcard expansion to happen.
 174
 175 Parameter limit is the maximum number of terms each wildcard in the query can
 176 expand to, or 0 for no limit (which is the default).
 177
 178 =cut
 179
 180 =back
 181
 182 =head1 REFERENCE
 183
 184   https://xapian.org/docs/queryparser.html
 185   https://xapian.org/docs/sourcedoc/html/classXapian_1_1QueryParser.html
 186
 187 =cut