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Database(3m17n) The m17n Library Database(3m17n)

Database - The m17n database and API for it.


typedef struct MDatabase MDatabase
Type of database.


MDatabase * mdatabase_find (MSymbol tag0, MSymbol tag1, MSymbol tag2, MSymbol tag3)
Look for a data in the database. MPlist * mdatabase_list (MSymbol tag0, MSymbol tag1, MSymbol tag2, MSymbol tag3)
Return a data list of the m17n database. MDatabase * mdatabase_define (MSymbol tag0, MSymbol tag1, MSymbol tag2, MSymbol tag3, void *(*loader)(MSymbol *, void *), void *extra_info)
Define a data of the m17n database. void * mdatabase_load (MDatabase *mdb)
Load a data from the database. MSymbol * mdatabase_tag (MDatabase *mdb)
Get tags of a data.


char * mdatabase_dir
Directory for application specific data.

The m17n database and API for it.

The m17n library acquires various kinds of information from data in the m17n database on demand. Application programs can also add/load their original data to/from the m17n database by setting the variable mdatabase_dir to an application-specific directory and storing data in it. Users can overwrite those data by storing preferable data in the directory specified by the environment variable 'M17NDIR', or if it is not set, in the directory '~/.m17n.d'.

The m17n database contains multiple heterogeneous data, and each data is identified by four tags; TAG0, TAG1, TAG2, TAG3. Each tag must be a symbol.

TAG0 specifies the type of data stored in the database as below.

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If TAG0 is Mchar_table, the data is of the chartable type and provides information about each character. In this case, TAG1 specifies the type of the information and must be Msymbol, Minteger, Mstring, Mtext, or Mplist. TAG2 and TAG3 can be any symbols.

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If TAG0 is Mcharset, the data is of the charset type and provides a decode/encode mapping table for a charset. In this case, TAG1 must be a symbol representing a charset. TAG2 and TAG3 can be any symbols.

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If TAG0 is neither Mchar_table nor Mcharset, the data is of the plist type. See the documentation of the mdatabase_load() function for the details. In this case, TAG1, TAG2, and TAG3 can be any symbols.

The notation <TAG0, TAG1, TAG2, TAG3> means a data with those tags.

Application programs first calls the mdatabase_find() function to get a pointer to an object of the type MDatabase. That object holds information about the specified data. When it is successfully returned, the mdatabase_load() function loads the data. The implementation of the structure MDatabase is concealed from application programs.

Type of database. The type MDatabase is for a database object. Its internal structure is concealed from an application program.

Directory for application specific data. If an application program wants to provide a data specific to the program or a data overriding what supplied by the m17n database, it must set this variable to a name of directory that contains the data files before it calls the macro M17N_INIT(). The directory may contain a file 'mdb.dir' which contains a list of data definitions in the format described in mdbDir(5).

The default value is NULL.

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Copyright (C) 2001 Information-technology Promotion Agency (IPA)
Copyright (C) 2001-2011 National Institute of Advanced Industrial Science and Technology (AIST)
Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License <http://www.gnu.org/licenses/fdl.html>.

12 Jan 2011 Version 1.6.2