LCOV - lcov.info - /usr/include/xapian/query.h

LTP GCOV extension - code coverage report
Current view: | directory - usr/include/xapian - query.h
Test: | lcov.info
Date: | 2008-08-14 |  | Instrumented lines: | 11
Code covered: | 72.7 % |  | Executed lines: | 8

           1                 : /** \file query.h
           2                 :  * \brief Classes for representing a query
           3                 :  */
           4                 : /* Copyright 1999,2000,2001 BrightStation PLC
           5                 :  * Copyright 2002 Ananova Ltd
           6                 :  * Copyright 2003,2004,2005,2006,2007 Olly Betts
           7                 :  * Copyright 2006,2007,2008 Lemur Consulting Ltd
           8                 :  *
           9                 :  * This program is free software; you can redistribute it and/or
          10                 :  * modify it under the terms of the GNU General Public License as
          11                 :  * published by the Free Software Foundation; either version 2 of the
          12                 :  * License, or (at your option) any later version.
          13                 :  *
          14                 :  * This program is distributed in the hope that it will be useful,
          15                 :  * but WITHOUT ANY WARRANTY; without even the implied warranty of
          16                 :  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
          17                 :  * GNU General Public License for more details.
          18                 :  *
          19                 :  * You should have received a copy of the GNU General Public License
          20                 :  * along with this program; if not, write to the Free Software
          21                 :  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301
          22                 :  * USA
          23                 :  */
          24                 :
          25                 : #ifndef XAPIAN_INCLUDED_QUERY_H
          26                 : #define XAPIAN_INCLUDED_QUERY_H
          27                 :
          28                 : #include <string>
          29                 : #include <vector>
          30                 :
          31                 : #include <xapian/base.h>
          32                 : #include <xapian/deprecated.h>
          33                 : #include <xapian/types.h>
          34                 : #include <xapian/termiterator.h>
          35                 : #include <xapian/visibility.h>
          36                 :
          37                 : // FIXME: sort this out so we avoid exposing Xapian::Query::Internal
          38                 : // - we need to at present so that the Xapian::Query's template ctors
          39                 : // compile.
          40                 : class LocalSubMatch;
          41                 : class MultiMatch;
          42                 : class QueryOptimiser;
          43                 : struct SortPosName;
          44                 :
          45                 : namespace Xapian {
          46                 :
          47                 : /** Class representing a query.
          48                 :  *
          49                 :  *  Queries are represented as a tree of objects.
          50                 :  */
          51                 : class XAPIAN_VISIBILITY_DEFAULT Query {
          52                 :     public:
          53                 :         /// Class holding details of the query
          54                 :         class Internal;
          55                 :         /// @private @internal Reference counted internals.
          56                 :         Xapian::Internal::RefCntPtr<Internal> internal;
          57                 :
          58                 :         /// Enum of possible query operations
          59                 :         typedef enum {
          60                 :             /// Return iff both subqueries are satisfied
          61                 :             OP_AND,
          62                 :
          63                 :             /// Return if either subquery is satisfied
          64                 :             OP_OR,
          65                 :
          66                 :             /// Return if left but not right satisfied
          67                 :             OP_AND_NOT,
          68                 :
          69                 :             /// Return if one query satisfied, but not both
          70                 :             OP_XOR,
          71                 :
          72                 :             /// Return iff left satisfied, but use weights from both
          73                 :             OP_AND_MAYBE,
          74                 :
          75                 :             /// As AND, but use only weights from left subquery
          76                 :             OP_FILTER,
          77                 :
          78                 :             /** Find occurrences of a list of terms with all the terms
          79                 :              *  occurring within a specified window of positions.
          80                 :              *  Each occurrence of a term must be at a different position,
          81                 :              *  but the order they appear in is irrelevant.
          82                 :              *
          83                 :              *  The window parameter should be specified for this operation,
          84                 :              *  but will default to the number of terms in the list.
          85                 :              */
          86                 :             OP_NEAR,
          87                 :
          88                 :             /** Find occurrences of a list of terms with all the terms
          89                 :              *  occurring within a specified window of positions, and all
          90                 :              *  the terms appearing in the order specified.  Each occurrence
          91                 :              *  of a term must be at a different position.
          92                 :              *
          93                 :              *  The window parameter should be specified for this operation,
          94                 :              *  but will default to the number of terms in the list.
          95                 :              */
          96                 :             OP_PHRASE,
          97                 :
          98                 :             /** Filter by a range test on a document value. */
          99                 :             OP_VALUE_RANGE,
         100                 :
         101                 :             /** Scale the weight of a subquery by the specified factor.
         102                 :              *
         103                 :              *  A factor of 0 means this subquery will contribute no weight to
         104                 :              *  the query - it will act as a purely boolean subquery.
         105                 :              *
         106                 :              *  If the factor is negative, Xapian::InvalidArgumentError will
         107                 :              *  be thrown.
         108                 :              */
         109                 :             OP_SCALE_WEIGHT,
         110                 :
         111                 :             /** Select an elite set from the subqueries, and perform
         112                 :              *  a query with these combined as an OR query.
         113                 :              */
         114                 :             OP_ELITE_SET,
         115                 :
         116                 :             /** Filter by a greater-than-or-equal test on a document value. */
         117                 :             OP_VALUE_GE,
         118                 :
         119                 :             /** Filter by a less-than-or-equal test on a document value. */
         120                 :             OP_VALUE_LE
         121                 :         } op;
         122                 :
         123                 :         /** Copy constructor. */
         124                 :         Query(const Query & copyme);
         125                 :
         126                 :         /** Assignment. */
         127                 :         Query & operator=(const Query & copyme);
         128                 :
         129                 :         /** Default constructor: makes an empty query which matches no
         130                 :          *  documents.
         131                 :          *
         132                 :          *  Also useful for defining a Query object to be assigned to later.
         133                 :          *
         134                 :          *  An exception will be thrown if an attempt is made to use an
         135                 :          *  undefined query when building up a composite query.
         136                 :          */
         137                 :         Query();
         138                 :
         139                 :         /** Destructor. */
         140                 :         ~Query();
         141                 :
         142                 :         /** A query consisting of a single term. */
         143                 :         Query(const std::string & tname_, Xapian::termcount wqf_ = 1,
         144                 :               Xapian::termpos pos_ = 0);
         145                 :
         146                 :         /** A query consisting of two subqueries, opp-ed together. */
         147                 :         Query(Query::op op_, const Query & left, const Query & right);
         148                 :
         149                 :         /** A query consisting of two termnames opp-ed together. */
         150                 :         Query(Query::op op_,
         151                 :               const std::string & left, const std::string & right);
         152                 :
         153                 :         /** Combine a number of Xapian::Query-s with the specified operator.
         154                 :          *
         155                 :          *  The Xapian::Query objects are specified with begin and end
         156                 :          *  iterators.
         157                 :          *
         158                 :          *  AND, OR, NEAR and PHRASE can take any number of subqueries.
         159                 :          *  Other operators take exactly two subqueries.
         160                 :          *
         161                 :          *  The iterators may be to Xapian::Query objects, pointers to
         162                 :          *  Xapian::Query objects, or termnames (std::string-s).
         163                 :          *
         164                 :          *  For NEAR and PHRASE, a window size can be specified in parameter.
         165                 :          *
         166                 :          *  For ELITE_SET, the elite set size can be specified in parameter.
         167                 :          */
         168                 :         template <class Iterator>
         169                 :         Query(Query::op op_, Iterator qbegin, Iterator qend,
         170                 :               Xapian::termcount parameter = 0);
         171                 :
         172                 :         /** Apply the specified operator to a single Xapian::Query object.
         173                 :          *
         174                 :          *  @deprecated This method is deprecated because it isn't useful,
         175                 :          *  since none of the current query operators can be usefully
         176                 :          *  applied to a single subquery with a parameter value.
         177                 :          */
         178                 :         XAPIAN_DEPRECATED(Query(Query::op op_, Xapian::Query q));
         179                 :
         180                 :         /** Apply the specified operator to a single Xapian::Query object, with
         181                 :          *  a double parameter.
         182                 :          */
         183                 :         Query(Query::op op_, Xapian::Query q, double parameter);
         184                 :
         185                 :         /** Construct a value range query on a document value.
         186                 :          *
         187                 :          *  A value range query matches those documents which have a value
         188                 :          *  stored in the slot given by @a valno which is in the range
         189                 :          *  specified by @a begin and @a end (in lexicographical
         190                 :          *  order), including the endpoints.
         191                 :          *
         192                 :          *  @param op_   The operator to use for the query.  Currently, must
         193                 :          *               be OP_VALUE_RANGE.
         194                 :          *  @param valno The slot number to get the value from.
         195                 :          *  @param begin The start of the range.
         196                 :          *  @param end   The end of the range.
         197                 :          */
         198                 :         Query(Query::op op_, Xapian::valueno valno,
         199                 :               const std::string &begin, const std::string &end);
         200                 :
         201                 :         /** Construct a value comparison query on a document value.
         202                 :          *
         203                 :          *  This query matches those documents which have a value stored in the
         204                 :          *  slot given by @a valno which compares, as specified by the
         205                 :          *  operator, to @a value.
         206                 :          *
         207                 :          *  @param op_   The operator to use for the query.  Currently, must
         208                 :          *               be OP_VALUE_GE or OP_VALUE_LE.
         209                 :          *  @param valno The slot number to get the value from.
         210                 :          *  @param value The value to compare.
         211                 :          */
         212                 :         Query(Query::op op_, Xapian::valueno valno, const std::string &value);
         213                 :
         214                 :         /** A query which matches all documents in the database. */
         215                 :         static Xapian::Query MatchAll;
         216                 :
         217                 :         /** A query which matches no documents. */
         218                 :         static Xapian::Query MatchNothing;
         219                 :
         220                 :         /** Get the length of the query, used by some ranking formulae.
         221                 :          *  This value is calculated automatically - if you want to override
         222                 :          *  it you can pass a different value to Enquire::set_query().
         223                 :          */
         224                 :         Xapian::termcount get_length() const;
         225                 :
         226                 :         /** Return a Xapian::TermIterator returning all the terms in the query,
         227                 :          *  in order of termpos.  If multiple terms have the same term
         228                 :          *  position, their order is unspecified.  Duplicates (same term and
         229                 :          *  termpos) will be removed.
         230                 :          */
         231                 :         TermIterator get_terms_begin() const;
         232                 :
         233                 :         /** Return a Xapian::TermIterator to the end of the list of terms in the
         234                 :          *  query.
         235                 :          */
         236                 :         TermIterator get_terms_end() const {
         237                 :             return TermIterator(NULL);
         238                 :         }
         239                 :
         240                 :         /** Test if the query is empty (i.e. was constructed using
         241                 :          *  the default ctor or with an empty iterator ctor).
         242                 :          */
         243                 :         bool empty() const;
         244                 :
         245                 :         /// Return a string describing this object.
         246                 :         std::string get_description() const;
         247                 :
         248                 :     private:
         249                 :         void add_subquery(const Query & subq);
         250                 :         void add_subquery(const Query * subq);
         251                 :         void add_subquery(const std::string & tname);
         252                 :         void start_construction(Query::op op_, Xapian::termcount parameter);
         253                 :         void end_construction();
         254                 :         void abort_construction();
         255                 : };
         256                 :
         257                 : template <class Iterator>
         258              19 : Query::Query(Query::op op_, Iterator qbegin, Iterator qend, termcount parameter)
         259              19 :     : internal(0)
         260                 : {
         261                 :     try {
         262              19 :         start_construction(op_, parameter);
         263                 :
         264                 :         /* Add all the elements */
         265              61 :         while (qbegin != qend) {
         266              23 :             add_subquery(*qbegin);
         267              23 :             ++qbegin;
         268                 :         }
         269                 :
         270              19 :         end_construction();
         271               0 :     } catch (...) {
         272               0 :         abort_construction();
         273               0 :         throw;
         274                 :     }
         275              19 : }
         276                 :
         277                 : /// @internal Internal class, implementing most of Xapian::Query.
         278                 : class XAPIAN_VISIBILITY_DEFAULT Query::Internal : public Xapian::Internal::RefCntBase {
         279                 :     friend class ::LocalSubMatch;
         280                 :     friend class ::MultiMatch;
         281                 :     friend class ::QueryOptimiser;
         282                 :     friend struct ::SortPosName;
         283                 :     friend class Query;
         284                 :     public:
         285                 :         static const int OP_LEAF = -1;
         286                 :
         287                 :         /// The container type for storing pointers to subqueries
         288                 :         typedef std::vector<Internal *> subquery_list;
         289                 :
         290                 :         /// Type storing the operation
         291                 :         typedef int op_t;
         292                 :
         293                 :     private:
         294                 :         /// Operation to be performed at this node
         295                 :         Xapian::Query::Internal::op_t op;
         296                 :
         297                 :         /// Sub queries on which to perform operation
         298                 :         subquery_list subqs;
         299                 :
         300                 :         /** For NEAR or PHRASE, how close terms must be to match: all terms
         301                 :          *  within the operation must occur in a window of this size.
         302                 :          *
         303                 :          * For ELITE_SET, the number of terms to select from those specified.
         304                 :          *
         305                 :          * For RANGE, the value number to apply the range test to.
         306                 :          */
         307                 :         Xapian::termcount parameter;
         308                 :
         309                 :         /** Term that this node represents, or start of a range query.
         310                 :          *
         311                 :          *  For a leaf node, this holds the term name.  For an OP_VALUE_RANGE
         312                 :          *  query this holds the start of the range.  For an OP_VALUE_GE or
         313                 :          *  OP_VALUE_LE query this holds the value to compare against.
         314                 :          */
         315                 :         std::string tname;
         316                 :
         317                 :         /** Used to store the end of a range query. */
         318                 :         std::string str_parameter;
         319                 :
         320                 :         /// Position in query of this term - leaf node only
         321                 :         Xapian::termpos term_pos;
         322                 :
         323                 :         /// Within query frequency of this term - leaf node only
         324                 :         Xapian::termcount wqf;
         325                 :
         326                 :         /** swap the contents of this with another Xapian::Query::Internal,
         327                 :          *  in a way which is guaranteed not to throw.  This is
         328                 :          *  used with the assignment operator to make it exception
         329                 :          *  safe.
         330                 :          *  It's important to adjust swap with any addition of
         331                 :          *  member variables!
         332                 :          */
         333                 :         void swap(Query::Internal &other);
         334                 :
         335                 :         /// Copy another Xapian::Query::Internal into self.
         336                 :         void initialise_from_copy(const Query::Internal & copyme);
         337                 :
         338                 :         void accumulate_terms(
         339                 :             std::vector<std::pair<std::string, Xapian::termpos> > &terms) const;
         340                 :
         341                 :         /** Simplify the query.
         342                 :          *  For example, an AND query with only one subquery would become the
         343                 :          *  subquery itself.
         344                 :          */
         345                 :         Internal * simplify_query();
         346                 :
         347                 :         /** Perform checks that query is valid. (eg, has correct number of
         348                 :          *  sub queries.)  Throw an exception if not.  This is initially called
         349                 :          *  on the query before any simplifications have been made, and after
         350                 :          *  simplications.
         351                 :          */
         352                 :         void validate_query() const;
         353                 :
         354                 :         /** Simplify any matchnothing subqueries, either eliminating them,
         355                 :          *  or setting this query to matchnothing, depending on the query
         356                 :          *  operator.  Returns true if simplification resulted in a
         357                 :          *  matchnothing query.
         358                 :          */
         359                 :         bool simplify_matchnothing();
         360                 :
         361                 :         /** Get a string describing the given query type.
         362                 :          */
         363                 :         static std::string get_op_name(Xapian::Query::Internal::op_t op);
         364                 :
         365                 :         /** Collapse the subqueries together if appropriate.
         366                 :          */
         367                 :         void collapse_subqs();
         368                 :
         369                 :         /** Flatten a query structure, by changing, for example,
         370                 :          *  "A NEAR (B AND C)" to "(A NEAR B) AND (A NEAR C)"
         371                 :          */
         372                 :         void flatten_subqs();
         373                 :
         374                 :         /** Implementation of serialisation; called recursively.
         375                 :          */
         376                 :         std::string serialise(Xapian::termpos & curpos) const;
         377                 :
         378                 :     public:
         379                 :         /** Copy constructor. */
         380                 :         Internal(const Query::Internal & copyme);
         381                 :
         382                 :         /** Assignment. */
         383                 :         void operator=(const Query::Internal & copyme);
         384                 :
         385                 :         /** A query consisting of a single term. */
         386                 :         explicit Internal(const std::string & tname_, Xapian::termcount wqf_ = 1,
         387                 :                           Xapian::termpos term_pos_ = 0);
         388                 :
         389                 :         /** Create internals given only the operator and a parameter. */
         390                 :         Internal(op_t op_, Xapian::termcount parameter);
         391                 :
         392                 :         /** Construct a range query on a document value. */
         393                 :         Internal(op_t op_, Xapian::valueno valno,
         394                 :                  const std::string &begin, const std::string &end);
         395                 :
         396                 :         /** Construct a value greater-than-or-equal query on a document value.
         397                 :          */
         398                 :         Internal(op_t op_, Xapian::valueno valno, const std::string &value);
         399                 :
         400                 :         /** Destructor. */
         401                 :         ~Internal();
         402                 :
         403                 :         static Xapian::Query::Internal * unserialise(const std::string &s);
         404                 :
         405                 :         /** Add a subquery.
         406                 :          */
         407                 :         void add_subquery(const Query::Internal * subq);
         408                 :
         409                 :         void set_dbl_parameter(double dbl_parameter_);
         410                 :
         411                 :         double get_dbl_parameter() const;
         412                 :
         413                 :         /** Finish off the construction.
         414                 :          */
         415                 :         Query::Internal * end_construction();
         416                 :
         417                 :         /** Return a string in an easily parsed form
         418                 :          *  which contains all the information in a query.
         419                 :          */
         420                 :         std::string serialise() const {
         421                 :             Xapian::termpos curpos = 1;
         422                 :             return serialise(curpos);
         423                 :         }
         424                 :
         425                 :         /// Return a string describing this object.
         426                 :         std::string get_description() const;
         427                 :
         428                 :         /** Get the numeric parameter used in this query.
         429                 :          *
         430                 :          *  This is used by the QueryParser to get the value number for
         431                 :          *  VALUE_RANGE queries.  It should be replaced by a public method on
         432                 :          *  the Query class at some point, but the API which should be used for
         433                 :          *  that is unclear, so this is a temporary workaround.
         434                 :          */
         435                 :         Xapian::termcount get_parameter() const { return parameter; }
         436                 :
         437                 :         /** Get the length of the query, used by some ranking formulae.
         438                 :          *  This value is calculated automatically - if you want to override
         439                 :          *  it you can pass a different value to Enquire::set_query().
         440                 :          */
         441                 :         Xapian::termcount get_length() const;
         442                 :
         443                 :         /** Return an iterator over all the terms in the query,
         444                 :          *  in order of termpos.  If multiple terms have the same term
         445                 :          *  position, their order is unspecified.  Duplicates (same term and
         446                 :          *  termpos) will be removed.
         447                 :          */
         448                 :         TermIterator get_terms() const;
         449                 : };
         450                 :
         451                 : }
         452                 :
         453                 : #endif /* XAPIAN_INCLUDED_QUERY_H */

Generated by: LTP GCOV extension version 1.6