Parses a piece of text and generate terms. More...

#include <termgenerator.h>

Collaboration diagram for Xapian::TermGenerator:

Classes
class	Internal

Public Types
enum	{ FLAG_SPELLING = 128 , FLAG_NGRAMS = 2048 , FLAG_CJK_NGRAM = FLAG_NGRAMS , FLAG_WORD_BREAKS = 4096 }
	Flags to OR together and pass to TermGenerator::set_flags(). More...

enum	stem_strategy { STEM_NONE , STEM_SOME , STEM_ALL , STEM_ALL_Z , STEM_SOME_FULL_POS }
	Stemming strategies, for use with set_stemming_strategy(). More...

enum	stop_strategy { STOP_NONE , STOP_ALL , STOP_STEMMED }
	Stopper strategies, for use with set_stopper_strategy(). More...

typedef int	flags
	For backward compatibility with Xapian 1.2. More...

Public Member Functions
	TermGenerator (const TermGenerator &o)
	Copy constructor. More...

TermGenerator &	operator= (const TermGenerator &o)
	Assignment. More...

	TermGenerator (TermGenerator &&o)
	Move constructor. More...

TermGenerator &	operator= (TermGenerator &&o)
	Move assignment operator. More...

	TermGenerator ()
	Default constructor. More...

	~TermGenerator ()
	Destructor. More...

void	set_stemmer (const Xapian::Stem &stemmer)
	Set the Xapian::Stem object to be used for generating stemmed terms. More...

void	set_stopper (const Xapian::Stopper *stop=NULL)
	Set the Xapian::Stopper object to be used for identifying stopwords. More...

void	set_document (const Xapian::Document &doc)
	Set the current document. More...

const Xapian::Document &	get_document () const
	Get the current document. More...

void	set_database (const Xapian::WritableDatabase &db)
	Set the database to index spelling data to. More...

flags	set_flags (flags toggle, flags mask=flags(0))
	Set flags. More...

void	set_stemming_strategy (stem_strategy strategy)
	Set the stemming strategy. More...

void	set_stopper_strategy (stop_strategy strategy)
	Set the stopper strategy. More...

void	set_max_word_length (unsigned max_word_length)
	Set the maximum length word to index. More...

void	index_text (const Xapian::Utf8Iterator &itor, Xapian::termcount wdf_inc=1, std::string_view prefix={})
	Index some text. More...

void	index_text (std::string_view text, Xapian::termcount wdf_inc=1, std::string_view prefix={})
	Index some text. More...

void	index_text_without_positions (const Xapian::Utf8Iterator &itor, Xapian::termcount wdf_inc=1, std::string_view prefix={})
	Index some text without positional information. More...

void	index_text_without_positions (std::string_view text, Xapian::termcount wdf_inc=1, std::string_view prefix={})
	Index some text without positional information. More...

void	increase_termpos (Xapian::termpos delta=100)
	Increase the term position used by index_text. More...

Xapian::termpos	get_termpos () const
	Get the current term position. More...

void	set_termpos (Xapian::termpos termpos)
	Set the current term position. More...

void	set_termpos_limit (Xapian::termpos termpos_limit)
	Set the term position limit. More...

std::string	get_description () const
	Return a string describing this object. More...

Private Attributes
Xapian::Internal::intrusive_ptr_nonnull< Internal >	internal

Detailed Description

Parses a piece of text and generate terms.

This module takes a piece of text and parses it to produce words which are then used to generate suitable terms for indexing. The terms generated are suitable for use with Query objects produced by the QueryParser class.

Definition at line 49 of file termgenerator.h.

Member Typedef Documentation

◆ flags

typedef int Xapian::TermGenerator::flags

For backward compatibility with Xapian 1.2.

Definition at line 97 of file termgenerator.h.

Member Enumeration Documentation

◆ anonymous enum

anonymous enum

Flags to OR together and pass to TermGenerator::set_flags().

Enumerator
FLAG_SPELLING	Index data required for spelling correction.
FLAG_NGRAMS	Generate n-grams for scripts without explicit word breaks. Spans of characters in such scripts are split into unigrams and bigrams, with the unigrams carrying positional information. Text in other scripts is split into words as normal. The QueryParser::FLAG_NGRAMS flag needs to be passed to QueryParser. This mode can also be enabled in 1.2.8 and later by setting environment variable XAPIAN_CJK_NGRAM to a non-empty value (but doing so was deprecated in 1.4.11). In 1.4.x this feature was specific to CJK (Chinese, Japanese and Korean), but in 2.0.0 it's been extended to other languages. To reflect this change the new and preferred name is FLAG_NGRAMS, which was added as an alias for forward compatibility in Xapian 1.4.23. Use FLAG_CJK_NGRAM instead if you aim to support Xapian < 1.4.23. @since Added in Xapian 1.4.23.
FLAG_CJK_NGRAM	Generate n-grams for scripts without explicit word breaks. Old name - use FLAG_NGRAMS instead unless you aim to support Xapian < 1.4.23. @since Added in Xapian 1.3.4 and 1.2.22.
FLAG_WORD_BREAKS	Find word breaks for text in scripts without explicit word breaks. With this option enabled, spans of text written in such scripts are split into words using ICU (which uses heuristics and/or dictionaries to do so). Text in other scripts is split into words as normal. The QueryParser::FLAG_WORD_BREAKS flag needs to be passed to QueryParser. @since Added in Xapian 2.0.0.

Definition at line 100 of file termgenerator.h.

◆ stem_strategy

enum Xapian::TermGenerator::stem_strategy

Stemming strategies, for use with set_stemming_strategy().

Enumerator
STEM_NONE
STEM_SOME
STEM_ALL
STEM_ALL_Z
STEM_SOME_FULL_POS

Definition at line 153 of file termgenerator.h.

◆ stop_strategy

enum Xapian::TermGenerator::stop_strategy

Stopper strategies, for use with set_stopper_strategy().

Enumerator
STOP_NONE
STOP_ALL
STOP_STEMMED

Definition at line 158 of file termgenerator.h.

Constructor & Destructor Documentation

◆ TermGenerator() [1/3]

TermGenerator::TermGenerator ( const TermGenerator & o )

default

Copy constructor.

◆ TermGenerator() [2/3]

TermGenerator::TermGenerator ( TermGenerator && o )

default

Move constructor.

◆ TermGenerator() [3/3]

TermGenerator::TermGenerator ( )

Default constructor.

Definition at line 46 of file termgenerator.cc.

◆ ~TermGenerator()

TermGenerator::~TermGenerator ( )

Destructor.

Definition at line 48 of file termgenerator.cc.

Member Function Documentation

◆ get_description()

string TermGenerator::get_description ( ) const

Return a string describing this object.

Definition at line 148 of file termgenerator.cc.

References Xapian::TermGenerator::Internal::cur_pos, internal, Xapian::TermGenerator::Internal::stopper, and Xapian::Internal::str().

Referenced by DEFINE_TESTCASE().

◆ get_document()

const Xapian::Document & TermGenerator::get_document ( ) const

Get the current document.

Definition at line 70 of file termgenerator.cc.

◆ get_termpos()

Xapian::termpos TermGenerator::get_termpos ( ) const

Get the current term position.

Definition at line 130 of file termgenerator.cc.

Referenced by DEFINE_TESTCASE().

◆ increase_termpos()

void TermGenerator::increase_termpos ( Xapian::termpos delta = 100 )

Increase the term position used by index_text.

This can be used between indexing text from different fields or other places to prevent phrase searches from spanning between them (e.g. between the title and body text, or between two chapters in a book).

Parameters

delta Amount to increase the term position by (default: 100).

Definition at line 124 of file termgenerator.cc.

Referenced by DEFINE_TESTCASE().

◆ index_text() [1/2]

void TermGenerator::index_text	(	const Xapian::Utf8Iterator &	itor,
		Xapian::termcount	wdf_inc = `1`,
		std::string_view	prefix = `{}`
	)

Index some text.

Parameters

itor	Utf8Iterator pointing to the text to index.
wdf_inc	The wdf increment (default 1).
prefix	The term prefix to use (default is no prefix).

Definition at line 108 of file termgenerator.cc.

Referenced by DEFINE_TESTCASE(), main(), make_netstats1_db(), and make_tg_db().

◆ index_text() [2/2]

void Xapian::TermGenerator::index_text	(	std::string_view	text,
		Xapian::termcount	wdf_inc = `1`,
		std::string_view	prefix = `{}`
	)

inline

Index some text.

Parameters

text	The text to index.
wdf_inc	The wdf increment (default 1).
prefix	The term prefix to use (default is no prefix).

Definition at line 249 of file termgenerator.h.

◆ index_text_without_positions() [1/2]

void TermGenerator::index_text_without_positions	(	const Xapian::Utf8Iterator &	itor,
		Xapian::termcount	wdf_inc = `1`,
		std::string_view	prefix = `{}`
	)

Index some text without positional information.

Just like index_text, but no positional information is generated. This means that the database will be significantly smaller, but that phrase searching and NEAR won't be supported.

Parameters

itor	Utf8Iterator pointing to the text to index.
wdf_inc	The wdf increment (default 1).
prefix	The term prefix to use (default is no prefix).

Definition at line 116 of file termgenerator.cc.

Referenced by DEFINE_TESTCASE().

◆ index_text_without_positions() [2/2]

void Xapian::TermGenerator::index_text_without_positions	(	std::string_view	text,
		Xapian::termcount	wdf_inc = `1`,
		std::string_view	prefix = `{}`
	)

inline

Index some text without positional information.

Just like index_text, but no positional information is generated. This means that the database will be significantly smaller, but that phrase searching and NEAR won't be supported.

Parameters

text	The text to index.
wdf_inc	The wdf increment (default 1).
prefix	The term prefix to use (default is no prefix).

Definition at line 279 of file termgenerator.h.

◆ operator=() [1/2]

TermGenerator & TermGenerator::operator= ( const TermGenerator & o )

default

Assignment.

◆ operator=() [2/2]

TermGenerator & TermGenerator::operator= ( TermGenerator && o )

default

Move assignment operator.

◆ set_database()

void TermGenerator::set_database ( const Xapian::WritableDatabase & db )

Set the database to index spelling data to.

Definition at line 76 of file termgenerator.cc.

Referenced by DEFINE_TESTCASE().

◆ set_document()

void TermGenerator::set_document ( const Xapian::Document & doc )

Set the current document.

Definition at line 63 of file termgenerator.cc.

Referenced by DEFINE_TESTCASE(), main(), make_netstats1_db(), and make_tg_db().

◆ set_flags()

TermGenerator::flags TermGenerator::set_flags	(	flags	toggle,
		flags	mask = `flags(0)`
	)

Set flags.

The new value of flags is: (flags & mask) ^ toggle

To just set the flags, pass the new flags in toggle and the default value for mask.

Parameters

toggle	Flags to XOR.
mask	Flags to AND with first.

Returns: The old flags setting.

Definition at line 82 of file termgenerator.cc.

Referenced by DEFINE_TESTCASE().

◆ set_max_word_length()

void TermGenerator::set_max_word_length ( unsigned max_word_length )

Set the maximum length word to index.

The limit is on the length of a word prior to stemming and prior to adding any term prefix.

The backends mostly impose a limit on the length of terms (often of about 240 bytes), but it's generally useful to have a lower limit to help prevent the index being bloated by useless junk terms from trying to indexing things like binary data, uuencoded data, ASCII art, etc.

Parameters

max_word_length The maximum length word to index, in bytes in UTF-8 representation. Default is 64.

Since: Added in Xapian 1.3.1.

Definition at line 102 of file termgenerator.cc.

Referenced by DEFINE_TESTCASE().

◆ set_stemmer()

void TermGenerator::set_stemmer ( const Xapian::Stem & stemmer )

Set the Xapian::Stem object to be used for generating stemmed terms.

Definition at line 51 of file termgenerator.cc.

References stemmer.

Referenced by DEFINE_TESTCASE(), main(), make_netstats1_db(), and make_tg_db().

◆ set_stemming_strategy()

void TermGenerator::set_stemming_strategy ( stem_strategy strategy )

Set the stemming strategy.

This method controls how the stemming algorithm is applied.

Parameters

strategy

The strategy to use - possible values are:

STEM_NONE: Don't perform any stemming - only unstemmed terms are generated.
STEM_SOME: Generate both stemmed (with a "Z" prefix) and unstemmed terms. No positional information is stored for unstemmed terms. This is the default strategy.
STEM_SOME_FULL_POS: Like STEM_SOME but positional information is stored for both stemmed and unstemmed terms. Added in Xapian 1.4.8.
STEM_ALL: Generate only stemmed terms (but without a "Z" prefix).
STEM_ALL_Z: Generate only stemmed terms (with a "Z" prefix).

Since: Added in Xapian 1.3.1.

Definition at line 90 of file termgenerator.cc.

Referenced by DEFINE_TESTCASE(), main(), and make_netstats1_db().

◆ set_stopper()

void TermGenerator::set_stopper ( const Xapian::Stopper * stop = NULL )

Set the Xapian::Stopper object to be used for identifying stopwords.

Stemmed forms of stopwords aren't indexed, but unstemmed forms still are so that searches for phrases including stop words still work.

Parameters

stop	The Stopper object to set (default NULL, which means no stopwords).

Definition at line 57 of file termgenerator.cc.

Referenced by DEFINE_TESTCASE().

◆ set_stopper_strategy()

void TermGenerator::set_stopper_strategy ( stop_strategy strategy )

Set the stopper strategy.

The method controls how the stopper is used.

You need to also call set_stopper() for this to have any effect.

Parameters

strategy

The strategy to use - possible values are:

STOP_NONE: Don't use the stopper.
STOP_ALL: If a word is identified as a stop word, skip it completely.
STOP_STEMMED: If a word is identified as a stop word, index its unstemmed form but skip the stem. Unstemmed forms are indexed with positional information by default, so this allows searches for phrases containing stopwords to be supported. (This is the default mode).

Since: Added in Xapian 1.4.1.

Definition at line 96 of file termgenerator.cc.

Referenced by DEFINE_TESTCASE().

◆ set_termpos()

void TermGenerator::set_termpos ( Xapian::termpos termpos )

Set the current term position.

Parameters

termpos The new term position to set.

Definition at line 136 of file termgenerator.cc.

Referenced by DEFINE_TESTCASE().

◆ set_termpos_limit()

void TermGenerator::set_termpos_limit ( Xapian::termpos termpos_limit )

Set the term position limit.

Parameters

termpos_limit Upper bound on term positions that can be added.

By default the only limit is the maximum value of the Xapian::termpos type.

Since: Added in Xapian 2.0.0.

Definition at line 142 of file termgenerator.cc.

Referenced by DEFINE_TESTCASE().

Member Data Documentation

◆ internal

Xapian::Internal::intrusive_ptr_nonnull<Internal> Xapian::TermGenerator::internal

private

Reference counted internals.

Definition at line 54 of file termgenerator.h.

Referenced by get_description().

The documentation for this class was generated from the following files:

include/xapian/termgenerator.h
queryparser/termgenerator.cc

Classes

Public Types

Public Member Functions

Private Attributes

Detailed Description

Member Typedef Documentation

◆ flags

Member Enumeration Documentation

◆ anonymous enum

◆ stem_strategy

◆ stop_strategy

Constructor & Destructor Documentation

◆ TermGenerator() [1/3]

◆ TermGenerator() [2/3]

◆ TermGenerator() [3/3]

◆ ~TermGenerator()

Member Function Documentation

◆ get_description()

◆ get_document()

◆ get_termpos()

◆ increase_termpos()

◆ index_text() [1/2]

◆ index_text() [2/2]

◆ index_text_without_positions() [1/2]

◆ index_text_without_positions() [2/2]

◆ operator=() [1/2]

◆ operator=() [2/2]

◆ set_database()

◆ set_document()

◆ set_flags()

◆ set_max_word_length()

◆ set_stemmer()

◆ set_stemming_strategy()

◆ set_stopper()

◆ set_stopper_strategy()

◆ set_termpos()

◆ set_termpos_limit()

Member Data Documentation

◆ internal