estraier.h - the core API of Hyper Estraier

#include <estraier.h>

#include <cabin.h>

#include <stdlib.h>

The API for documents aims to handle documents which were registered into the index.

The type of the structure `ESTDOC' is for abstraction of a document. A document is composed of some attributes and some text sentences. No entity of `ESTDOC' is accessed directly, but it is accessed by the pointer. The term of document object means the pointer and its referent. A document object is created by the function `est_doc_new' and destroyed by `est_doc_delete'. Every created document object should be destroyed.

Target documents of search are to be registered in the database beforehand. The ID is assigned to each registered document. When search, they can be retrieved from the database by their ID. The encoding of attributes and text sentences should be UTF-8.

The function `est_doc_new' is used in order to create a document object.

ESTDOC *est_doc_new(void);

The return value is an object of a document.

The function `est_doc_new_from_draft' is used in order to create a document object made from draft data.

ESTDOC *est_doc_new_from_draft(const char *draft);

`draft' specifies a string of draft data. The return value is an object of a document.

The function `est_doc_delete' is used in order to destroy a document object.

void est_doc_delete(ESTDOC *doc);

`doc' specifies a document object.

The function `est_doc_add_attr' is used in order to add an attribute to a document object.

void est_doc_add_attr(ESTDOC *doc, const char *name, const char *value);

`doc' specifies a document object. `name' specifies the name of an attribute. `value' specifies the value of the attribute. If it is `NULL', the attribute is removed.

The function `est_doc_add_text' is used in order to add a sentence of text to a document object.

void est_doc_add_text(ESTDOC *doc, const char *text);

`doc' specifies a document object. `text' specifies a sentence of text.

The function `est_doc_add_hidden_text' is used in order to add a hidden sentence to a document object.

void est_doc_add_hidden_text(ESTDOC *doc, const char *text);

`doc' specifies a document object. `text' specifies a hidden sentence.

The function `est_doc_id' is used in order to get the ID number of a document object.

int est_doc_id(ESTDOC *doc);

`doc' specifies a document object. The return value is the ID number of the document object. If the object has not been registered, -1 is returned.

The function `est_doc_attr_names' is used in order to get a list of attribute names of a document object.

CBLIST *est_doc_attr_names(ESTDOC *doc);

`doc' specifies a document object. The return value is a new list object of attribute names of the document object. Because the object of the return value is opened with the function `cblistopen', it should be closed with the function `cblistclose' if it is no longer in use.

The function `est_doc_attr' is used in order to get the value of an attribute of a document object.

const char *est_doc_attr(ESTDOC *doc, const char *name);

`doc' specifies a document object. `name' specifies the name of an attribute. The return value is the value of the attribute or `NULL' if it does not exist. The life duration of the returned string is synchronous with the one of the document object.

The function `est_doc_texts' is used in order to get a list of sentences of the text of a document object.

const CBLIST *est_doc_texts(ESTDOC *doc);

`doc' specifies a document object. The return value is a list object of sentences of the text of the document object. The life duration of the returned object is synchronous with the one of the document object.

The function `est_doc_cat_texts' is used in order to concatenate sentences of the text of a document object.

char *est_doc_cat_texts(ESTDOC *doc);

`doc' specifies a document object. The return value is concatenated sentences of the document object. Because the region of the return value is allocated with the `malloc' call, it should be released with the `free' call if it is no longer in use.

The function `est_doc_dump_draft' is used in order to dump draft data of a document object.

char *est_doc_dump_draft(ESTDOC *doc);

`doc' specifies a document object. The return value is draft data of the document object. Because the region of the return value is allocated with the `malloc' call, it should be released with the `free' call if it is no longer in use.

The function `est_doc_make_snippet' is used in order to make a snippet of the body text of a document object.

char *est_doc_make_snippet(ESTDOC *doc, const CBLIST *words, int wwidth, int hwidth, int awidth);

`doc' specifies a document object. `word' specifies a list object of words to be highlight. `wwidth' specifies whole width of the result. `hwidth' specifies width of strings picked up from the beginning of the text. `awidth' specifies width of strings picked up around each highlighted word. The return value is a snippet string of the body text of the document object. There are tab separated values. Each line is a string to be shown. Though most lines have only one field, some lines have two fields. If the second field exists, the first field is to be shown with highlighted, and the second field means its normalized form. Because the region of the return value is allocated with the `malloc' call, it should be released with the `free' call if it is no longer in use.

The API for search conditions aims to specify search conditions given to the index.

The type of the structure `ESTCOND' is for abstraction of search conditions. A unit of search conditions is composed of one search phrase, some attribute expressions, and one order expression. No entity of `ESTCOND' is accessed directly, but it is accessed by the pointer. The term of condition object means the pointer and its referent. A condition object is created by the function `est_cond_new' and destroyed by `est_cond_delete'. Every created condition object should be destroyed.

Condition objects are used as a parameter to search for documents registered in the database so that a list of IDs of corresponding documents are returned. See the manual for the formats of expressions. The encoding of conditional expressions should be UTF-8.

The function `est_cond_new' is used in order to create a condition object.

ESTCOND *est_cond_new(void);

The return value is an object of search conditions.

The function `est_cond_delete' is used in order to destroy a condition object.

void est_cond_delete(ESTCOND *cond);

`cond' specifies a condition object.

The function `est_cond_set_phrase' is used in order to set the search phrase to a condition object.

void est_cond_set_phrase(ESTCOND *cond, const char *phrase);

`cond' specifies a condition object. `phrase' specifies a search phrase.

The function `est_cond_add_attr' is used in order to add an expression for an attribute to a condition object.

void est_cond_add_attr(ESTCOND *cond, const char *expr);

`cond' specifies a condition object. `expr' specifies an expression for an attribute.

The function `est_cond_set_order' is used in order to set the order of a condition object.

void est_cond_set_order(ESTCOND *cond, const char *expr);

`cond' specifies a condition object. `expr' specifies an expression for the order. By default, the order is by score descending.

The function `est_cond_set_max' is used in order to set the maximum number of retrieval of a condition object.

void est_cond_set_max(ESTCOND *cond, int max);

`cond' specifies a condition object. `max' specifies the maximum number of retrieval. By default, the number of retrieval is not limited.

The function `est_cond_set_options' is used in order to set options of retrieval of a condition object.

void est_cond_set_options(ESTCOND *cond, int options);

`cond' specifies a condition object. `options' specifies options: `ESTCONDSURE' specifies that it checks every N-gram key, `ESTCONDUSUAL', which is the default, specifies that it checks N-gram keys with skipping one key, `ESTCONDFAST' skips two keys, `ESTCONDAGITO' skips three keys, `ESTCONDNOIDF' specifies not to perform TF-IDF tuning, `ESTCONDSIMPLE' specifies to use simplified phrase, `ESTCONDETCH' specifies to attach the keyword vector (only for the node API), `ESTCONDSCFB' specifies to feed back scores (only for debugging). Each option can be specified at the same time by bitwise or. If keys are skipped, though search speed is improved, the relevance ratio grows less.

The function `est_cond_set_eclipse' is used in order to set the lower limit of similarity eclipse.

void est_cond_set_eclipse(ESTCOND *cond, double limit);

`cond' specifies a condition object. `limit' specifies the lower limit of similarity for documents to be eclipsed. Similarity is between 0.0 and 1.0.

The API for database aims to handle the database of the index.

The type of the structure `ESTDB' is for abstraction of access methods to database. A database has inverted index, document data, and meta data. One of writer or reader is selected when the connection is established. No entity of `ESTDB' is accessed directly, but it is accessed by the pointer. The term of database object means the pointer and its referent. A database object is created by the function `est_db_open' and destroyed by `est_db_close'. Every created database object should be destroyed.

Errors with some operations are informed to by the function `est_db_error'. The meaning of each error code can be gotten as a string by the function `est_err_msg'.

The following constant are defined for error codes.

The function `est_err_msg' is used in order to get the string of an error code.

const char *est_err_msg(int ecode);

`ecode' specifies an error code. The return value is the string of the error code.

The function `est_db_open' is used in order to open a database.

ESTDB *est_db_open(const char *name, int omode, int *ecp);

`name' specifies the name of a database directory. `omode' specifies open modes: `ESTDBWRITER' as a writer, `ESTDBREADER' as a reader. If the mode is `ESTDBWRITER', the following may be added by bitwise or: `ESTDBCREAT', which means it creates a new database if not exist, `ESTDBTRUNC', which means it creates a new database regardless if one exists. Both of `ESTDBREADER' and `ESTDBWRITER' can be added to by bitwise or: `ESTDBNOLCK', which means it opens a database file without file locking, or `ESTDBLCKNB', which means locking is performed without blocking. If `ESTDBNOLCK' is used, the application is responsible for exclusion control. `ESTDBCREAT' can be added to by bitwise or: `ESTDBPERFNG', which means N-gram analysis is performed against European text also. `ecp' specifies the pointer to a variable to which the error code is assigned. The return value is a database object of the database or `NULL' if failure.

The function `est_db_close' is used in order to close a database.

int est_db_close(ESTDB *db, int *ecp);

`db' specifies a database object. `ecp' specifies the pointer to a variable to which the error code is assigned. The return value is true if success, else it is false.

The function `est_db_error' is used in order to get the last happened error code of a database.

int est_db_error(ESTDB *db);

`db' specifies a database object. The return value is the last happened error code of the database.

The function `est_db_fatal' is used in order to check whether a database has a fatal error.

int est_db_fatal(ESTDB *db);

`db' specifies a database object. The return value is true if the database has fatal error, else it is false.

The function `est_db_flush' is used in order to flush index words in the cache of a database.

int est_db_flush(ESTDB *db, int max);

`db' specifies a database object connected as a writer. `max' specifies the maximum number of words to be flushed. If it not more than zero, all words are flushed. The return value is true if success, else it is false.

The function `est_db_sync' is used in order to synchronize updating contents of a database.

int est_db_sync(ESTDB *db);

`db' specifies a database object connected as a writer. The return value is true if success, else it is false.

The function `est_db_optimize' is used in order to optimize a database.

int est_db_optimize(ESTDB *db, int options);

`db' specifies a database object connected as a writer. `options' specifies options: `ESTOPTNOPURGE' to omit purging dispensable region of deleted documents, `ESTOPTNODBOPT' to omit optimization of the database files. The two can be specified at the same time by bitwise or. The return value is true if success, else it is false.

The function `est_db_put_doc' is used in order to add a document to a database.

int est_db_put_doc(ESTDB *db, ESTDOC *doc, int options);

`db' specifies a database object connected as a writer. `doc' specifies a document object. The document object should have the URI attribute. `options' specifies options: `ESTPDCLEAN' to clean up dispensable regions of the overwritten document. The return value is true if success, else it is false. If the URI attribute is same with an existing document in the database, the existing one is deleted.

The function `est_db_out_doc' is used in order to remove a document from a database.

int est_db_out_doc(ESTDB *db, int id, int options);

`db' specifies a database object connected as a writer. `id' specifies the ID number of a registered document. `options' specifies options: `ESTODCLEAN' to clean up dispensable regions of the deleted document. The return value is true if success, else it is false.

The function `est_db_edit_doc' is used in order to edit attributes of a document in a database.

int est_db_edit_doc(ESTDB *db, ESTDOC *doc);

`db' specifies a database object connected as a writer. `doc' specifies a document object. The return value is true if success, else it is false. The ID can not be changed. If the URI is changed and it overlaps the URI of another registered document, this function fails.

The function `est_db_get_doc' is used in order to retrieve a document in a database.

ESTDOC *est_db_get_doc(ESTDB *db, int id, int options);

`db' specifies a database object. `id' specifies the ID number of a registered document. `options' specifies options: `ESTGDNOATTR' to ignore attributes, `ESTGDNOTEXT' to ignore the body text. The two can be specified at the same time by bitwise or. The return value is a document object. On error, `NULL' is returned.

The function `est_db_get_doc_attr' is used in order to retrieve the value of an attribute of a document in a database.

char *est_db_get_doc_attr(ESTDB *db, int id, const char *name);

`db' specifies a database object. `id' specifies the ID number of a registered document. `name' specifies the name of an attribute. The return value is the value of the attribute or `NULL' if it does not exist. Because the region of the return value is allocated with the `malloc' call, it should be released with the `free' call if it is no longer in use.

The function `est_db_uri_to_id' is used in order to get the ID of a document specified by URI.

int est_db_uri_to_id(ESTDB *db, const char *uri);

`db' specifies a database object. `uri' specifies the URI of a registered document. The return value is the ID of the document. On error, -1 is returned.

The function `est_db_name' is used in order to get the name of a database.

const char *est_db_name(ESTDB *db);

`db' specifies a database object. The return value is the name of the database. The life duration of the returned string is synchronous with the one of the database object.

The function `est_db_doc_num' is used in order to get the number of documents in a database.

int est_db_doc_num(ESTDB *db);

`db' specifies a database object. The return value is the number of documents in the database.

The function `est_db_word_num' is used in order to get the number of unique words in a database.

int est_db_word_num(ESTDB *db);

`db' specifies a database object. The return value is the number of unique words in the database.

The function `est_db_size' is used in order to get the size of a database.

double est_db_size(ESTDB *db);

`db' specifies a database object. The return value is the size of the database.

The function `est_db_search' is used in order to search documents corresponding a condition for a database.

int *est_db_search(ESTDB *db, ESTCOND *cond, int *nump, CBMAP *hints);

`db' specifies a database object. `cond' specifies a condition object. `nump' specifies the pointer to a variable to which the number of elements in the result is assigned. `hints' specifies a map object into which the number of documents corresponding to each word is stored. If a word is in a negative condition, the number is negative. The element whose key is an empty string specifies the number of whole result. If it is `NULL', it is not used. The return value is an array whose elements are ID numbers of corresponding documents. This function does never fail. Even if no document corresponds or an error occurs, an empty array is returned. Because the region of the return value is allocated with the `malloc' call, it should be released with the `free' call if it is no longer in use.

The function `est_db_scan_doc' is used in order to check whether a document object matches the phrase of a search condition object definitely.

int est_db_scan_doc(ESTDB *db, ESTDOC *doc, ESTCOND *cond);

`db' specifies a database object. `doc' specifies a document object. `cond' specifies a search condition object. The return value is true if the document matches the phrase of the condition object definitely, else it is false.

The function `est_db_set_cache_size' is used in order to set the maximum size of the cache memory of a database.

void est_db_set_cache_size(ESTDB *db, size_t size, int anum, int tnum, int rnum);

`db' specifies a database object. `size' specifies the maximum size of the index cache. By default, it is 64MB. If it is not more than 0, the current size is not changed. `anum' specifies the maximum number of cached records for document attributes. By default, it is 8192. If it is not more than 0, the current size is not changed. `tnum' specifies the maximum number of cached records for document texts. By default, it is 1024. If it is not more than 0, the current size is not changed. `rnum' specifies the maximum number of cached records for occurrence results. By default, it is 256. If it is not more than 0, the current size is not changed.

Databases of Hyper Estraier are protected by file locking. While a writer is connected to a database, neither readers nor writers can be connected. While a reader is connected to a database, other readers can be connect, but writers can not.

If you use multi thread, it is suggested to use the MT-safe API of Hyper Estraier. It is a wrapper to make the core API thread-safe. As the MT-safe API provides the same functions as with the core API, the following is different.

Hyper Estraier is written by Mikio Hirabayashi. You can contact the author by e-mail to <mikio@users.sourceforge.net>. Any suggestion or bug report is welcome to the author.

Hyper Estraier was developed under management by Fumitoshi Ukai and supports by Exploratory Software Project of Information-technology Promotion Agency, Japan (IPA).

Copyright(c) 2004-2005 Mikio Hirabayashi

Hyper Estraier is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2 of the License, or any later version.

Hyper Estraier is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public License along with Hyper Estraier; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.

estcmd(1), estconfig(1), cabin(3), estnode(3)

Please see http://hyperestraier.sourceforge.net/pguide-en.html for detail.