/*****************************************************************************\
 *  Copyright (c) Athena Dev Teams - Licensed under GNU GPL                  *
 *  For more information, see LICENCE in the main folder                     *
 *                                                                           *
 *  This file is separated in two sections:                                  *
 *  (1) public typedefs, enums, unions, structures and defines               *
 *  (2) public functions                                                     *
 *                                                                           *
 *  <B>Notes on the release system:</B>                                      *
 *  Whenever an entry is removed from the database both the key and the      *
 *  data are requested to be released.                                       *
 *  At least one entry is removed when replacing an entry, removing an       *
 *  entry, clearing the database or destroying the database.                 *
 *  What is actually released is defined by the release function, the        *
 *  functions of the database only ask for the key and/or data to be         *
 *  released.                                                                *
 *                                                                           *
 *  TODO:                                                                    *
 *  - create an enum for the data (with int, unsigned int and void *)        *
 *  - create a custom database allocator                                     *
 *  - see what functions need or should be added to the database interface   *
 *                                                                           *
 *  HISTORY:                                                                 *
 *    2007/11/09 - Added an iterator to the database.
 *    2.1 (Athena build #???#) - Portability fix                             *
 *      - Fixed the portability of casting to union and added the functions  *
 *        {@link DBMap#ensure(DBMap,DBKey,DBCreateData,...)} and             *
 *        {@link DBMap#clear(DBMap,DBApply,...)}.                            *
 *    2.0 (Athena build 4859) - Transition version                           *
 *      - Almost everything recoded with a strategy similar to objects,      *
 *        database structure is maintained.                                  *
 *    1.0 (up to Athena build 4706)                                          *
 *      - Previous database system.                                          *
 *                                                                           *
 * @version 2.1 (Athena build #???#) - Portability fix                       *
 * @author (Athena build 4859) Flavio @ Amazon Project                       *
 * @author (up to Athena build 4706) Athena Dev Teams                        *
 * @encoding US-ASCII                                                        *
 * @see common#db.c                                                          *
\*****************************************************************************/
#ifndef _DB_H_
#define _DB_H_

#include "../common/cbasetypes.h"
#include <stdarg.h>

/*****************************************************************************\
 *  (1) Section with public typedefs, enums, unions, structures and defines. *
 *  DB_MANUAL_CAST_TO_UNION - Define when the compiler doesn't allow casting *
 *           to unions.                                                      *
 *  DBRelease    - Enumeration of release options.                           *
 *  DBType       - Enumeration of database types.                            *
 *  DBOptions    - Bitfield enumeration of database options.                 *
 *  DBKey        - Union of used key types.                                  *
 *  DBApply      - Format of functions applyed to the databases.             *
 *  DBMatcher    - Format of matchers used in DBMap::getall.                 *
 *  DBComparator - Format of the comparators used by the databases.          *
 *  DBHasher     - Format of the hashers used by the databases.              *
 *  DBReleaser   - Format of the releasers used by the databases.            *
 *  DBIterator   - Database iterator.                                        *
 *  DBMap        - Database interface.                                       *
\*****************************************************************************/

/**
 * Define this to enable the functions that cast to unions.
 * Required when the compiler doesn't support casting to unions.
 * NOTE: It is recommened that the conditional tests to determine if this 
 * should be defined be located in the configure script or a header file 
 * specific for compatibility and portability issues.
 * @public
 * @see #db_i2key(int)
 * @see #db_ui2key(unsigned int)
 * @see #db_str2key(unsigned char *)
 */
//#define DB_MANUAL_CAST_TO_UNION

/**
 * Bitfield with what should be released by the releaser function (if the
 * function supports it).
 * @public
 * @see #DBReleaser
 * @see #db_custom_release(DBRelease)
 */
typedef enum DBRelease {
	DB_RELEASE_NOTHING = 0,
	DB_RELEASE_KEY     = 1,
	DB_RELEASE_DATA    = 2,
	DB_RELEASE_BOTH    = 3
} DBRelease;

/**
 * Supported types of database.
 * See {@link #db_fix_options(DBType,DBOptions)} for restrictions of the 
 * types of databases.
 * @param DB_INT Uses int's for keys
 * @param DB_UINT Uses unsigned int's for keys
 * @param DB_STRING Uses strings for keys.
 * @param DB_ISTRING Uses case insensitive strings for keys.
 * @public
 * @see #DBOptions
 * @see #DBKey
 * @see #db_fix_options(DBType,DBOptions)
 * @see #db_default_cmp(DBType)
 * @see #db_default_hash(DBType)
 * @see #db_default_release(DBType,DBOptions)
 * @see #db_alloc(const char *,int,DBType,DBOptions,unsigned short)
 */
typedef enum DBType {
	DB_INT,
	DB_UINT,
	DB_STRING,
	DB_ISTRING
} DBType;

/**
 * Bitfield of options that define the behaviour of the database.
 * See {@link #db_fix_options(DBType,DBOptions)} for restrictions of the 
 * types of databases.
 * @param DB_OPT_BASE Base options: does not duplicate keys, releases nothing
 *          and does not allow NULL keys or NULL data.
 * @param DB_OPT_DUP_KEY Duplicates the keys internally. If DB_OPT_RELEASE_KEY 
 *          is defined, the real key is freed as soon as the entry is added.
 * @param DB_OPT_RELEASE_KEY Releases the key.
 * @param DB_OPT_RELEASE_DATA Releases the data whenever an entry is removed 
 *          from the database.
 *          WARNING: for funtions that return the data (like DBMap::remove),
 *          a dangling pointer will be returned.
 * @param DB_OPT_RELEASE_BOTH Releases both key and data.
 * @param DB_OPT_ALLOW_NULL_KEY Allow NULL keys in the database.
 * @param DB_OPT_ALLOW_NULL_DATA Allow NULL data in the database.
 * @public
 * @see #db_fix_options(DBType,DBOptions)
 * @see #db_default_release(DBType,DBOptions)
 * @see #db_alloc(const char *,int,DBType,DBOptions,unsigned short)
 */
typedef enum DBOptions {
	DB_OPT_BASE            = 0,
	DB_OPT_DUP_KEY         = 1,
	DB_OPT_RELEASE_KEY     = 2,
	DB_OPT_RELEASE_DATA    = 4,
	DB_OPT_RELEASE_BOTH    = 6,
	DB_OPT_ALLOW_NULL_KEY  = 8,
	DB_OPT_ALLOW_NULL_DATA = 16,
} DBOptions;

/**
 * Union of key types used by the database.
 * @param i Type of key for DB_INT databases
 * @param ui Type of key for DB_UINT databases
 * @param str Type of key for DB_STRING and DB_ISTRING databases
 * @public
 * @see #DBType
 * @see DBMap#get
 * @see DBMap#put
 * @see DBMap#remove
 */
typedef union DBKey {
	int i;
	unsigned int ui;
	const char *str;
} DBKey;

/**
 * Format of funtions that create the data for the key when the entry doesn't 
 * exist in the database yet.
 * @param key Key of the database entry
 * @param args Extra arguments of the funtion
 * @return Data identified by the key to be put in the database
 * @public
 * @see DBMap#vensure
 * @see DBMap#ensure
 */
typedef void* (*DBCreateData)(DBKey key, va_list args);

/**
 * Format of functions to be applyed to an unspecified quantity of entries of 
 * a database.
 * Any function that applies this function to the database will return the sum 
 * of values returned by this function.
 * @param key Key of the database entry
 * @param data Data of the database entry
 * @param args Extra arguments of the funtion
 * @return Value to be added up by the funtion that is applying this
 * @public
 * @see DBMap#vforeach
 * @see DBMap#foreach
 * @see DBMap#vdestroy
 * @see DBMap#destroy
 */
typedef int (*DBApply)(DBKey key, void* data, va_list args);

/**
 * Format of functions that match database entries.
 * The purpose of the match depends on the function that is calling the matcher.
 * Returns 0 if it is a match, another number otherwise.
 * @param key Key of the database entry
 * @param data Data of the database entry
 * @param args Extra arguments of the function
 * @return 0 if a match, another number otherwise
 * @public
 * @see DBMap#getall
 */
typedef int (*DBMatcher)(DBKey key, void* data, va_list args);

/**
 * Format of the comparators used internally by the database system.
 * Compares key1 to key2.
 * <code>maxlen</code> is the maximum number of character used in DB_STRING and 
 * DB_ISTRING databases. If 0, the maximum number of maxlen is used (64K).
 * Returns 0 is equal, negative if lower and positive is higher.
 * @param key1 Key being compared
 * @param key2 Key we are comparing to
 * @param maxlen Maximum number of characters used in DB_STRING and DB_ISTRING
 *          databases.
 * @return 0 if equal, negative if lower and positive if higher
 * @public
 * @see #db_default_cmp(DBType)
 */
typedef int (*DBComparator)(DBKey key1, DBKey key2, unsigned short maxlen);

/**
 * Format of the hashers used internally by the database system.
 * Creates the hash of the key.
 * <code>maxlen</code> is the maximum number of character used in DB_STRING and 
 * DB_ISTRING databases. If 0, the maximum number of maxlen is used (64K).
 * @param key Key being hashed
 * @param maxlen Maximum number of characters used in DB_STRING and DB_ISTRING
 *          databases.
 * @return Hash of the key
 * @public
 * @see #db_default_hash(DBType)
 */
typedef unsigned int (*DBHasher)(DBKey key, unsigned short maxlen);

/**
 * Format of the releaser used by the database system.
 * Releases nothing, the key, the data or both.
 * All standard releasers use aFree to release.
 * @param key Key of the database entry
 * @param data Data of the database entry
 * @param which What is being requested to be released
 * @public
 * @see #DBRelease
 * @see #db_default_releaser(DBType,DBOptions)
 * @see #db_custom_release(DBRelease)
 */
typedef void (*DBReleaser)(DBKey key, void* data, DBRelease which);



typedef struct DBIterator DBIterator;
typedef struct DBMap DBMap;



/**
 * Database iterator.
 * Supports forward iteration, backward iteration and removing entries from the database.
 * The iterator is initially positioned before the first entry of the database.
 * While the iterator exists the database is locked internally, so invoke 
 * {@link DBIterator#destroy} as soon as possible.
 * @public
 * @see #DBMap
 */
struct DBIterator
{

	/**
	 * Fetches the first entry in the database.
	 * Returns the data of the entry.
	 * Puts the key in out_key, if out_key is not NULL.
	 * @param self Iterator
	 * @param out_key Key of the entry
	 * @return Data of the entry
	 * @protected
	 */
	void* (*first)(DBIterator* self, DBKey* out_key);

	/**
	 * Fetches the last entry in the database.
	 * Returns the data of the entry.
	 * Puts the key in out_key, if out_key is not NULL.
	 * @param self Iterator
	 * @param out_key Key of the entry
	 * @return Data of the entry
	 * @protected
	 */
	void* (*last)(DBIterator* self, DBKey* out_key);

	/**
	 * Fetches the next entry in the database.
	 * Returns the data of the entry.
	 * Puts the key in out_key, if out_key is not NULL.
	 * @param self Iterator
	 * @param out_key Key of the entry
	 * @return Data of the entry
	 * @protected
	 */
	void* (*next)(DBIterator* self, DBKey* out_key);

	/**
	 * Fetches the previous entry in the database.
	 * Returns the data of the entry.
	 * Puts the key in out_key, if out_key is not NULL.
	 * @param self Iterator
	 * @param out_key Key of the entry
	 * @return Data of the entry
	 * @protected
	 */
	void* (*prev)(DBIterator* self, DBKey* out_key);

	/**
	 * Returns true if the fetched entry exists.
	 * The databases entries might have NULL data, so use this to to test if 
	 * the iterator is done.
	 * @param self Iterator
	 * @return true is the entry exists
	 * @protected
	 */
	bool (*exists)(DBIterator* self);

	/**
	 * Removes the current entry from the database.
	 * NOTE: {@link DBIterator#exists} will return false until another entry 
	 *       is fethed
	 * Returns the data of the entry.
	 * @param self Iterator
	 * @return The data of the entry or NULL if not found
	 * @protected
	 * @see DBMap#remove
	 */
	void* (*remove)(DBIterator* self);

	/**
	 * Destroys this iterator and unlocks the database.
	 * @param self Iterator
	 * @protected
	 */
	void (*destroy)(DBIterator* self);

};

/**
 * Public interface of a database. Only contains funtions.
 * All the functions take the interface as the first argument.
 * @public
 * @see #db_alloc(const char*,int,DBType,DBOptions,unsigned short)
 */
struct DBMap {

	/**
	 * Returns a new iterator for this database.
	 * The iterator keeps the database locked until it is destroyed.
	 * The database will keep functioning normally but will only free internal 
	 * memory when unlocked, so destroy the iterator as soon as possible.
	 * @param self Database
	 * @return New iterator
	 * @protected
	 */
	DBIterator* (*iterator)(DBMap* self);

	/**
	 * Get the data of the entry identifid by the key.
	 * @param self Database
	 * @param key Key that identifies the entry
	 * @return Data of the entry or NULL if not found
	 * @protected
	 */
	void* (*get)(DBMap* self, DBKey key);

	/**
	 * Just calls {@link DBMap#vgetall}.
	 * Get the data of the entries matched by <code>match</code>.
	 * It puts a maximum of <code>max</code> entries into <code>buf</code>.
	 * If <code>buf</code> is NULL, it only counts the matches.
	 * Returns the number of entries that matched.
	 * NOTE: if the value returned is greater than <code>max</code>, only the 
	 * first <code>max</code> entries found are put into the buffer.
	 * @param self Database
	 * @param buf Buffer to put the data of the matched entries
	 * @param max Maximum number of data entries to be put into buf
	 * @param match Function that matches the database entries
	 * @param ... Extra arguments for match
	 * @return The number of entries that matched
	 * @protected
	 * @see DBMap#vgetall(DBMap*,void **,unsigned int,DBMatcher,va_list)
	 */
	unsigned int (*getall)(DBMap* self, void** buf, unsigned int max, DBMatcher match, ...);

	/**
	 * Get the data of the entries matched by <code>match</code>.
	 * It puts a maximum of <code>max</code> entries into <code>buf</code>.
	 * If <code>buf</code> is NULL, it only counts the matches.
	 * Returns the number of entries that matched.
	 * NOTE: if the value returned is greater than <code>max</code>, only the 
	 * first <code>max</code> entries found are put into the buffer.
	 * @param self Database
	 * @param buf Buffer to put the data of the matched entries
	 * @param max Maximum number of data entries to be put into buf
	 * @param match Function that matches the database entries
	 * @param ... Extra arguments for match
	 * @return The number of entries that matched
	 * @protected
	 * @see DBMap#getall(DBMap*,void **,unsigned int,DBMatcher,...)
	 */
	unsigned int (*vgetall)(DBMap* self, void** buf, unsigned int max, DBMatcher match, va_list args);

	/**
	 * Just calls {@link DBMap#vensure}.
	 * Get the data of the entry identified by the key.
	 * If the entry does not exist, an entry is added with the data returned by 
	 * <code>create</code>.
	 * @param self Database
	 * @param key Key that identifies the entry
	 * @param create Function used to create the data if the entry doesn't exist
	 * @param ... Extra arguments for create
	 * @return Data of the entry
	 * @protected
	 * @see DBMap#vensure(DBMap*,DBKey,DBCreateData,va_list)
	 */
	void* (*ensure)(DBMap* self, DBKey key, DBCreateData create, ...);

	/**
	 * Get the data of the entry identified by the key.
	 * If the entry does not exist, an entry is added with the data returned by 
	 * <code>create</code>.
	 * @param self Database
	 * @param key Key that identifies the entry
	 * @param create Function used to create the data if the entry doesn't exist
	 * @param args Extra arguments for create
	 * @return Data of the entry
	 * @protected
	 * @see DBMap#ensure(DBMap*,DBKey,DBCreateData,...)
	 */
	void* (*vensure)(DBMap* self, DBKey key, DBCreateData create, va_list args);

	/**
	 * Put the data identified by the key in the database.
	 * Returns the previous data if the entry exists or NULL.
	 * NOTE: Uses the new key, the old one is released.
	 * @param self Database
	 * @param key Key that identifies the data
	 * @param data Data to be put in the database
	 * @return The previous data if the entry exists or NULL
	 * @protected
	 */
	void* (*put)(DBMap* self, DBKey key, void* data);

	/**
	 * Remove an entry from the database.
	 * Returns the data of the entry.
	 * NOTE: The key (of the database) is released.
	 * @param self Database
	 * @param key Key that identifies the entry
	 * @return The data of the entry or NULL if not found
	 * @protected
	 */
	void* (*remove)(DBMap* self, DBKey key);

	/**
	 * Just calls {@link DBMap#vforeach}.
	 * Apply <code>func</code> to every entry in the database.
	 * Returns the sum of values returned by func.
	 * @param self Database
	 * @param func Function to be applyed
	 * @param ... Extra arguments for func
	 * @return Sum of the values returned by func
	 * @protected
	 * @see DBMap#vforeach(DBMap*,DBApply,va_list)
	 */
	int (*foreach)(DBMap* self, DBApply func, ...);

	/**
	 * Apply <code>func</code> to every entry in the database.
	 * Returns the sum of values returned by func.
	 * @param self Database
	 * @param func Function to be applyed
	 * @param args Extra arguments for func
	 * @return Sum of the values returned by func
	 * @protected
	 * @see DBMap#foreach(DBMap*,DBApply,...)
	 */
	int (*vforeach)(DBMap* self, DBApply func, va_list args);

	/**
	 * Just calls {@link DBMap#vclear}.
	 * Removes all entries from the database.
	 * Before deleting an entry, func is applyed to it.
	 * Releases the key and the data.
	 * Returns the sum of values returned by func, if it exists.
	 * @param self Database
	 * @param func Function to be applyed to every entry before deleting
	 * @param ... Extra arguments for func
	 * @return Sum of values returned by func
	 * @protected
	 * @see DBMap#vclear(DBMap*,DBApply,va_list)
	 */
	int (*clear)(DBMap* self, DBApply func, ...);

	/**
	 * Removes all entries from the database.
	 * Before deleting an entry, func is applyed to it.
	 * Releases the key and the data.
	 * Returns the sum of values returned by func, if it exists.
	 * @param self Database
	 * @param func Function to be applyed to every entry before deleting
	 * @param args Extra arguments for func
	 * @return Sum of values returned by func
	 * @protected
	 * @see DBMap#clear(DBMap*,DBApply,...)
	 */
	int (*vclear)(DBMap* self, DBApply func, va_list args);

	/**
	 * Just calls {@link DBMap#vdestroy}.
	 * Finalize the database, feeing all the memory it uses.
	 * Before deleting an entry, func is applyed to it.
	 * Releases the key and the data.
	 * Returns the sum of values returned by func, if it exists.
	 * NOTE: This locks the database globally. Any attempt to insert or remove 
	 * a database entry will give an error and be aborted (except for clearing).
	 * @param self Database
	 * @param func Function to be applyed to every entry before deleting
	 * @param ... Extra arguments for func
	 * @return Sum of values returned by func
	 * @protected
	 * @see DBMap#vdestroy(DBMap*,DBApply,va_list)
	 */
	int (*destroy)(DBMap* self, DBApply func, ...);

	/**
	 * Finalize the database, feeing all the memory it uses.
	 * Before deleting an entry, func is applyed to it.
	 * Returns the sum of values returned by func, if it exists.
	 * NOTE: This locks the database globally. Any attempt to insert or remove 
	 * a database entry will give an error and be aborted (except for clearing).
	 * @param self Database
	 * @param func Function to be applyed to every entry before deleting
	 * @param args Extra arguments for func
	 * @return Sum of values returned by func
	 * @protected
	 * @see DBMap#destroy(DBMap*,DBApply,...)
	 */
	int (*vdestroy)(DBMap* self, DBApply func, va_list args);

	/**
	 * Return the size of the database (number of items in the database).
	 * @param self Database
	 * @return Size of the database
	 * @protected
	 */
	unsigned int (*size)(DBMap* self);

	/**
	 * Return the type of the database.
	 * @param self Database
	 * @return Type of the database
	 * @protected
	 */
	DBType (*type)(DBMap* self);

	/**
	 * Return the options of the database.
	 * @param self Database
	 * @return Options of the database
	 * @protected
	 */
	DBOptions (*options)(DBMap* self);

};

//For easy access to the common functions.
#ifdef DB_MANUAL_CAST_TO_UNION
#	define i2key   db_i2key
#	define ui2key  db_ui2key
#	define str2key db_str2key
#else /* not DB_MANUAL_CAST_TO_UNION */
#	define i2key(k)   ((DBKey)(int)(k))
#	define ui2key(k)  ((DBKey)(unsigned int)(k))
#	define str2key(k) ((DBKey)(const char *)(k))
#endif /* not DB_MANUAL_CAST_TO_UNION */

#define db_get(db,k)    ( (db)->get((db),(k)) )
#define idb_get(db,k)   ( (db)->get((db),i2key(k)) )
#define uidb_get(db,k)  ( (db)->get((db),ui2key(k)) )
#define strdb_get(db,k) ( (db)->get((db),str2key(k)) )

#define db_put(db,k,d)    ( (db)->put((db),(k),(d)) )
#define idb_put(db,k,d)   ( (db)->put((db),i2key(k),(d)) )
#define uidb_put(db,k,d)  ( (db)->put((db),ui2key(k),(d)) )
#define strdb_put(db,k,d) ( (db)->put((db),str2key(k),(d)) )

#define db_remove(db,k)    ( (db)->remove((db),(k)) )
#define idb_remove(db,k)   ( (db)->remove((db),i2key(k)) )
#define uidb_remove(db,k)  ( (db)->remove((db),ui2key(k)) )
#define strdb_remove(db,k) ( (db)->remove((db),str2key(k)) )

//These are discarding the possible vargs you could send to the function, so those
//that require vargs must not use these defines.
#define db_ensure(db,k,f)    ( (db)->ensure((db),(k),(f)) )
#define idb_ensure(db,k,f)   ( (db)->ensure((db),i2key(k),(f)) )
#define uidb_ensure(db,k,f)  ( (db)->ensure((db),ui2key(k),(f)) )
#define strdb_ensure(db,k,f) ( (db)->ensure((db),str2key(k),(f)) )

// Database creation and destruction macros
#define idb_alloc(opt)            db_alloc(__FILE__,__LINE__,DB_INT,(opt),sizeof(int))
#define uidb_alloc(opt)           db_alloc(__FILE__,__LINE__,DB_UINT,(opt),sizeof(unsigned int))
#define strdb_alloc(opt,maxlen)   db_alloc(__FILE__,__LINE__,DB_STRING,(opt),(maxlen))
#define stridb_alloc(opt,maxlen)  db_alloc(__FILE__,__LINE__,DB_ISTRING,(opt),(maxlen))
#define db_destroy(db)            ( (db)->destroy((db),NULL) )
// Other macros
#define db_iterator(db)     ( (db)->iterator(db) )
#define dbi_first(dbi)      ( (dbi)->first(dbi,NULL) )
#define dbi_last(dbi)       ( (dbi)->last(dbi,NULL) )
#define dbi_next(dbi)       ( (dbi)->next(dbi,NULL) )
#define dbi_prev(dbi)       ( (dbi)->prev(dbi,NULL) )
#define dbi_exists(dbi)     ( (dbi)->exists(dbi) )
#define dbi_destroy(dbi)    ( (dbi)->destroy(dbi) )

/*****************************************************************************\
 *  (2) Section with public functions.                                       *
 *  db_fix_options     - Fix the options for a type of database.             *
 *  db_default_cmp     - Get the default comparator for a type of database.  *
 *  db_default_hash    - Get the default hasher for a type of database.      *
 *  db_default_release - Get the default releaser for a type of database     *
 *           with the fixed options.                                         *
 *  db_custom_release  - Get the releaser that behaves as specified.         *
 *  db_alloc           - Allocate a new database.                            *
 *  db_i2key           - Manual cast from 'int' to 'DBKey'.                  *
 *  db_ui2key          - Manual cast from 'unsigned int' to 'DBKey'.         *
 *  db_str2key         - Manual cast from 'unsigned char *' to 'DBKey'.      *
 *  db_init            - Initialise the database system.                     *
 *  db_final           - Finalise the database system.                       *
\*****************************************************************************/

/**
 * Returns the fixed options according to the database type.
 * Sets required options and unsets unsupported options.
 * For numeric databases DB_OPT_DUP_KEY and DB_OPT_RELEASE_KEY are unset.
 * @param type Type of the database
 * @param options Original options of the database
 * @return Fixed options of the database
 * @private
 * @see #DBType
 * @see #DBOptions
 * @see #db_default_release(DBType,DBOptions)
 */
DBOptions db_fix_options(DBType type, DBOptions options);

/**
 * Returns the default comparator for the type of database.
 * @param type Type of database
 * @return Comparator for the type of database or NULL if unknown database
 * @public
 * @see #DBType
 * @see #DBComparator
 */
DBComparator db_default_cmp(DBType type);

/**
 * Returns the default hasher for the specified type of database.
 * @param type Type of database
 * @return Hasher of the type of database or NULL if unknown database
 * @public
 * @see #DBType
 * @see #DBHasher
 */
DBHasher db_default_hash(DBType type);

/**
 * Returns the default releaser for the specified type of database with the 
 * specified options.
 * NOTE: the options are fixed by {@link #db_fix_options(DBType,DBOptions)}
 * before choosing the releaser
 * @param type Type of database
 * @param options Options of the database
 * @return Default releaser for the type of database with the fixed options
 * @public
 * @see #DBType
 * @see #DBOptions
 * @see #DBReleaser
 * @see #db_fix_options(DBType,DBOptions)
 * @see #db_custom_release(DBRelease)
 */
DBReleaser db_default_release(DBType type, DBOptions options);

/**
 * Returns the releaser that behaves as <code>which</code> specifies.
 * @param which Defines what the releaser releases
 * @return Releaser for the specified release options
 * @public
 * @see #DBRelease
 * @see #DBReleaser
 * @see #db_default_release(DBType,DBOptions)
 */
DBReleaser db_custom_release(DBRelease which);

/**
 * Allocate a new database of the specified type.
 * It uses the default comparator, hasher and releaser of the specified 
 * database type and fixed options.
 * NOTE: the options are fixed by {@link #db_fix_options(DBType,DBOptions)}
 * before creating the database.
 * @param file File where the database is being allocated
 * @param line Line of the file where the database is being allocated
 * @param type Type of database
 * @param options Options of the database
 * @param maxlen Maximum length of the string to be used as key in string 
 *          databases
 * @return The interface of the database
 * @public
 * @see #DBType
 * @see #DBMap
 * @see #db_default_cmp(DBType)
 * @see #db_default_hash(DBType)
 * @see #db_default_release(DBType,DBOptions)
 * @see #db_fix_options(DBType,DBOptions)
 */
DBMap* db_alloc(const char *file, int line, DBType type, DBOptions options, unsigned short maxlen);

#ifdef DB_MANUAL_CAST_TO_UNION
/**
 * Manual cast from 'int' to the union DBKey.
 * Created for compilers that don't support casting to unions.
 * @param key Key to be casted
 * @return The key as a DBKey union
 * @public
 * @see #DB_MANUAL_CAST_TO_UNION
 */
DBKey db_i2key(int key);

/**
 * Manual cast from 'unsigned int' to the union DBKey.
 * Created for compilers that don't support casting to unions.
 * @param key Key to be casted
 * @return The key as a DBKey union
 * @public
 * @see #DB_MANUAL_CAST_TO_UNION
 */
DBKey db_ui2key(unsigned int key);

/**
 * Manual cast from 'unsigned char *' to the union DBKey.
 * Created for compilers that don't support casting to unions.
 * @param key Key to be casted
 * @return The key as a DBKey union
 * @public
 * @see #DB_MANUAL_CAST_TO_UNION
 */
DBKey db_str2key(const char *key);
#endif /* DB_MANUAL_CAST_TO_UNION */

/**
 * Initialize the database system.
 * @public
 * @see #db_final(void)
 */
void db_init(void);

/**
 * Finalize the database system.
 * Frees the memory used by the block reusage system.
 * @public
 * @see #db_init(void)
 */
void db_final(void);

// Link DB System - From jAthena
struct linkdb_node {
	struct linkdb_node *next;
	struct linkdb_node *prev;
	void               *key;
	void               *data;
};

void  linkdb_insert ( struct linkdb_node** head, void *key, void* data); // 重複を考慮しない
void  linkdb_replace( struct linkdb_node** head, void *key, void* data); // 重複を考慮する
void* linkdb_search ( struct linkdb_node** head, void *key);
void* linkdb_erase  ( struct linkdb_node** head, void *key);
void  linkdb_final  ( struct linkdb_node** head );



/// Finds an entry in an array.
/// ex: ARR_FIND(0, size, i, list[i] == target);
///
/// @param __start   Starting index (ex: 0)
/// @param __end     End index (ex: size of the array)
/// @param __var     Index variable
/// @param __cmp     Expression that returns true when the target entry is found
#define ARR_FIND(__start, __end, __var, __cmp) \
	do{ \
		for( (__var) = (__start); (__var) < (__end); ++(__var) ) \
			if( __cmp ) \
				break; \
	}while(0)



/// Moves an entry of the array.
/// Use ARR_MOVERIGHT/ARR_MOVELEFT if __from and __to are direct numbers.
/// ex: ARR_MOVE(i, 0, list, int);// move index i to index 0
///
///
/// @param __from   Initial index of the entry
/// @param __to     Target index of the entry
/// @param __arr    Array
/// @param __type   Type of entry
#define ARR_MOVE(__from, __to, __arr, __type) \
	do{ \
		if( (__from) != (__to) ) \
		{ \
			__type __backup__; \
			memmove(&__backup__, (__arr)+(__from), sizeof(__type)); \
			if( (__from) < (__to) ) \
				memmove((__arr)+(__from), (__arr)+(__from)+1, ((__to)-(__from))*sizeof(__type)); \
			else if( (__from) > (__to) ) \
				memmove((__arr)+(__to)+1, (__arr)+(__to), ((__from)-(__to))*sizeof(__type)); \
			memmove((__arr)+(__to), &__backup__, sizeof(__type)); \
		} \
	}while(0)



/// Moves an entry of the array to the right.
/// ex: ARR_MOVERIGHT(1, 4, list, int);// move index 1 to index 4
///
/// @param __from   Initial index of the entry
/// @param __to     Target index of the entry
/// @param __arr    Array
/// @param __type   Type of entry
#define ARR_MOVERIGHT(__from, __to, __arr, __type) \
	do{ \
		__type __backup__; \
		memmove(&__backup__, (__arr)+(__from), sizeof(__type)); \
		memmove((__arr)+(__from), (__arr)+(__from)+1, ((__to)-(__from))*sizeof(__type)); \
		memmove((__arr)+(__to), &__backup__, sizeof(__type)); \
	}while(0)



/// Moves an entry of the array to the left.
/// ex: ARR_MOVELEFT(3, 0, list, int);// move index 3 to index 0
///
/// @param __from   Initial index of the entry
/// @param __end    Target index of the entry
/// @param __arr    Array
/// @param __type   Type of entry
#define ARR_MOVELEFT(__from, __to, __arr, __type) \
	do{ \
		__type __backup__; \
		memmove(&__backup__, (__arr)+(__from), sizeof(__type)); \
		memmove((__arr)+(__to)+1, (__arr)+(__to), ((__from)-(__to))*sizeof(__type)); \
		memmove((__arr)+(__to), &__backup__, sizeof(__type)); \
	}while(0)



/////////////////////////////////////////////////////////////////////
// Vector library based on defines. (dynamic array)
// uses aMalloc, aRealloc, aFree



/// Declares an anonymous vector struct.
///
/// @param __type Type of data
#define VECTOR_DECL(__type) \
	struct { \
		size_t _max_; \
		size_t _len_; \
		__type* _data_; \
	}



/// Declares a named vector struct.
///
/// @param __name Structure name
/// @param __type Type of data
#define VECTOR_STRUCT_DECL(__name,__type) \
	struct __name { \
		size_t _max_; \
		size_t _len_; \
		__type* _data_; \
	}



/// Declares and initializes an anonymous vector variable.
///
/// @param __type Type of data
/// @param __var Variable name
#define VECTOR_VAR(__type,__var) \
	VECTOR_DECL(__type) __var = {0,0,NULL}



/// Declares and initializes a named vector variable.
///
/// @param __name Structure name
/// @param __var Variable name
#define VECTOR_STRUCT_VAR(__name,__var) \
	struct __name __var = {0,0,NULL}



/// Initializes a vector.
///
/// @param __vec Vector
#define VECTOR_INIT(__vec) \
	memset(&(__vec), 0, sizeof(__vec))



/// Returns the internal array of values.
///
/// @param __vec Vector
/// @return Array of values
#define VECTOR_DATA(__vec) \
	( (__vec)._data_ )



/// Returns the length of the vector.
///
/// @param __vec Vector
/// @return Length
#define VECTOR_LENGTH(__vec) \
	( (__vec)._len_ )



/// Returns the capacity of the vector.
///
/// @param __vec Vector
/// @return Capacity
#define VECTOR_CAPACITY(__vec) \
	( (__vec)._max_ )



/// Returns the value at the target index.
/// Assumes the index exists.
///
/// @param __vec Vector
/// @param __idx Index
/// @return Value
#define VECTOR_INDEX(__vec,__idx) \
	( VECTOR_DATA(__vec)[__idx] )



/// Returns the first value of the vector.
/// Assumes the array is not empty.
///
/// @param __vec Vector
/// @return First value
#define VECTOR_FIRST(__vec) \
	( VECTOR_INDEX(__vec,0) )



/// Returns the last value of the vector.
/// Assumes the array is not empty.
///
/// @param __vec Vector
/// @return Last value
#define VECTOR_LAST(__vec) \
	( VECTOR_INDEX(__vec,VECTOR_LENGTH(__vec)-1) )



/// Resizes the vector.
/// Excess values are discarded, new positions are zeroed.
///
/// @param __vec Vector
/// @param __n Size
#define VECTOR_RESIZE(__vec,__n) \
	do{ \
		if( (__n) > VECTOR_CAPACITY(__vec) ) \
		{ /* increase size */ \
			if( VECTOR_CAPACITY(__vec) == 0 ) VECTOR_DATA(__vec) = aMalloc((__n)*sizeof(VECTOR_FIRST(__vec))); /* allocate new */ \
			else VECTOR_DATA(__vec) = aRealloc(VECTOR_DATA(__vec),(__n)*sizeof(VECTOR_FIRST(__vec))); /* reallocate */ \
			memset(VECTOR_DATA(__vec)+VECTOR_LENGTH(__vec), 0, (VECTOR_CAPACITY(__vec)-VECTOR_LENGTH(__vec))*sizeof(VECTOR_FIRST(__vec))); /* clear new data */ \
			VECTOR_CAPACITY(__vec) = (__n); /* update capacity */ \
		} \
		else if( (__n) == 0 && VECTOR_CAPACITY(__vec) ) \
		{ /* clear vector */ \
			aFree(VECTOR_DATA(__vec)); VECTOR_DATA(__vec) = NULL; /* free data */ \
			VECTOR_CAPACITY(__vec) = 0; /* clear capacity */ \
			VECTOR_LENGTH(__vec) = 0; /* clear length */ \
		} \
		else if( (__n) < VECTOR_CAPACITY(__vec) ) \
		{ /* reduce size */ \
			VECTOR_DATA(__vec) = aRealloc(VECTOR_DATA(__vec),(__n)*sizeof(VECTOR_FIRST(__vec))); /* reallocate */ \
			VECTOR_CAPACITY(__vec) = (__n); /* update capacity */ \
			if( VECTOR_LENGTH(__vec) > (__n) ) VECTOR_LENGTH(__vec) = (__n); /* update length */ \
		} \
	}while(0)



/// Ensures that the array has the target number of empty positions.
/// Increases the capacity in multiples of __step.
///
/// @param __vec Vector
/// @param __n Empty positions
/// @param __step Increase
#define VECTOR_ENSURE(__vec,__n,__step) \
	do{ \
		size_t _empty_ = VECTOR_CAPACITY(__vec)-VECTOR_LENGTH(__vec); \
		while( (__n) > _empty_ ) _empty_ += (__step); \
		if( _empty_ != VECTOR_CAPACITY(__vec)-VECTOR_LENGTH(__vec) ) VECTOR_RESIZE(__vec,_empty_+VECTOR_LENGTH(__vec)); \
	}while(0)



/// Inserts a value in the target index. (using the '=' operator)
/// Assumes the index is valid and there is enough capacity.
///
/// @param __vec Vector
/// @param __idx Index
/// @param __val Value
#define VECTOR_INSERT(__vec,__idx,__val) \
	do{ \
		if( (__idx) < VECTOR_LENGTH(__vec) ) /* move data */ \
			memmove(&VECTOR_INDEX(__vec,(__idx)+1),&VECTOR_INDEX(__vec,__idx),(VECTOR_LENGTH(__vec)-(__idx))*sizeof(VECTOR_FIRST(__vec))); \
		VECTOR_INDEX(__vec,__idx) = (__val); /* set value */ \
		++VECTOR_LENGTH(__vec); /* increase length */ \
	}while(0)



/// Inserts a value in the target index. (using memcpy)
/// Assumes the index is valid and there is enough capacity.
///
/// @param __vec Vector
/// @param __idx Index
/// @param __val Value
#define VECTOR_INSERTCOPY(__vec,__idx,__val) \
	VECTOR_INSERTARRAY(__vec,__idx,&(__val),1)



/// Inserts the values of the array in the target index. (using memcpy)
/// Assumes the index is valid and there is enough capacity.
///
/// @param __vec Vector
/// @param __idx Index
/// @param __pval Array of values
/// @param __n Number of values
#define VECTOR_INSERTARRAY(__vec,__idx,__pval,__n) \
	do{ \
		if( (__idx) < VECTOR_LENGTH(__vec) ) /* move data */ \
			memmove(&VECTOR_INDEX(__vec,(__idx)+(__n)),&VECTOR_INDEX(__vec,__idx),(VECTOR_LENGTH(__vec)-(__idx))*sizeof(VECTOR_FIRST(__vec))); \
		memcpy(&VECTOR_INDEX(__vec,__idx), (__pval), (__n)*sizeof(VECTOR_FIRST(__vec))); /* set values */ \
		VECTOR_LENGTH(__vec) += (__n); /* increase length */ \
	}while(0)



/// Inserts a value in the end of the vector. (using the '=' operator)
/// Assumes there is enough capacity.
///
/// @param __vec Vector
/// @param __val Value
#define VECTOR_PUSH(__vec,__val) \
	do{ \
		VECTOR_INDEX(__vec,VECTOR_LENGTH(__vec)) = (__val); /* set value */ \
		++VECTOR_LENGTH(__vec); /* increase length */ \
	}while(0)



/// Inserts a value in the end of the vector. (using memcpy)
/// Assumes there is enough capacity.
///
/// @param __vec Vector
/// @param __val Value
#define VECTOR_PUSHCOPY(__vec,__val) \
	VECTOR_PUSHARRAY(__vec,&(__val),1)



/// Inserts the values of the array in the end of the vector. (using memcpy)
/// Assumes there is enough capacity.
///
/// @param __vec Vector
/// @param __pval Array of values
/// @param __n Number of values
#define VECTOR_PUSHARRAY(__vec,__pval,__n) \
	do{ \
		memcpy(&VECTOR_INDEX(__vec,VECTOR_LENGTH(__vec)), (__pval), (__n)*sizeof(VECTOR_FIRST(__vec))); /* set values */ \
		VECTOR_LENGTH(__vec) += (__n); /* increase length */ \
	}while(0)



/// Removes and returns the last value of the vector.
/// Assumes the array is not empty.
///
/// @param __vec Vector
/// @return Removed value
#define VECTOR_POP(__vec) \
	( VECTOR_INDEX(__vec,--VECTOR_LENGTH(__vec)) )



/// Removes the last N values of the vector and returns the value of the last pop.
/// Assumes there are enough values.
///
/// @param __vec Vector
/// @param __n Number of pops
/// @return Last removed value
#define VECTOR_POPN(__vec,__n) \
	( VECTOR_INDEX(__vec,(VECTOR_LENGTH(__vec)-=(__n))) )



/// Removes the target index from the vector.
/// Assumes the index is valid and there are enough values.
///
/// @param __vec Vector
/// @param __idx Index
#define VECTOR_ERASE(__vec,__idx) \
	VECTOR_ERASEN(__vec,__idx,1)



/// Removes N values from the target index of the vector.
/// Assumes the index is valid and there are enough values.
///
/// @param __vec Vector
/// @param __idx Index
/// @param __n Number of values
#define VECTOR_ERASEN(__vec,__idx,__n) \
	do{ \
		if( (__idx) < VECTOR_LENGTH(__vec)-(__n) ) /* move data */ \
			memmove(&VECTOR_INDEX(__vec,__idx),&VECTOR_INDEX(__vec,(__idx)+(__n)),(VECTOR_LENGTH(__vec)-((__idx)+(__n)))*sizeof(VECTOR_FIRST(__vec))); \
		VECTOR_LENGTH(__vec) -= (__n); /* decrease length */ \
	}while(0)



/// Clears the vector, freeing allocated data.
///
/// @param __vec Vector
#define VECTOR_CLEAR(__vec) \
	do{ \
		if( VECTOR_CAPACITY(__vec) ) \
		{ \
			aFree(VECTOR_DATA(__vec)); VECTOR_DATA(__vec) = NULL; /* clear allocated array */ \
			VECTOR_CAPACITY(__vec) = 0; /* clear capacity */ \
			VECTOR_LENGTH(__vec) = 0; /* clear length */ \
		} \
	}while(0)



#endif /* _DB_H_ */