/*************************************************************************************************
 * C language binding
 *                                                               Copyright (C) 2009-2012 FAL Labs
 * This file is part of Kyoto Cabinet.
 * This program is free software: you can redistribute it and/or modify it under the terms of
 * the GNU General Public License as published by the Free Software Foundation, either version
 * 3 of the License, or any later version.
 * This program 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 General Public License for more details.
 * You should have received a copy of the GNU General Public License along with this program.
 * If not, see <http://www.gnu.org/licenses/>.
 *************************************************************************************************/


#ifndef _KCLANGC_H                       /* duplication check */
#define _KCLANGC_H

#if defined(__cplusplus)
extern "C" {
#endif

#if !defined(__STDC_LIMIT_MACROS)
#define __STDC_LIMIT_MACROS  1           /**< enable limit macros for C++ */
#endif

#include <assert.h>
#include <ctype.h>
#include <errno.h>
#include <float.h>
#include <limits.h>
#include <locale.h>
#include <math.h>
#include <setjmp.h>
#include <stdarg.h>
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include <signal.h>
#include <string.h>
#include <time.h>
#include <stdint.h>


/**
 * C wrapper of polymorphic database.
 */
typedef struct {
  void* db;                              /**< dummy member */
} KCDB;


/**
 * C wrapper of polymorphic cursor.
 */
typedef struct {
  void* cur;                             /**< dummy member */
} KCCUR;


/**
 * Binary string of byte array.
 */
typedef struct {
  char* buf;                             /**< pointer to the data region */
  size_t size;                           /**< size of the data region */
} KCSTR;


/**
 * Key-Value record.
 */
typedef struct {
  KCSTR key;                             /**< key string */
  KCSTR value;                           /**< value string */
} KCREC;


/**
 * Error codes.
 */
enum {
  KCESUCCESS,                            /**< success */
  KCENOIMPL,                             /**< not implemented */
  KCEINVALID,                            /**< invalid operation */
  KCENOREPOS,                            /**< no repository */
  KCENOPERM,                             /**< no permission */
  KCEBROKEN,                             /**< broken file */
  KCEDUPREC,                             /**< record duplication */
  KCENOREC,                              /**< no record */
  KCELOGIC,                              /**< logical inconsistency */
  KCESYSTEM,                             /**< system error */
  KCEMISC = 15                           /**< miscellaneous error */
};


/**
 * Open modes.
 */
enum {
  KCOREADER = 1 << 0,                    /**< open as a reader */
  KCOWRITER = 1 << 1,                    /**< open as a writer */
  KCOCREATE = 1 << 2,                    /**< writer creating */
  KCOTRUNCATE = 1 << 3,                  /**< writer truncating */
  KCOAUTOTRAN = 1 << 4,                  /**< auto transaction */
  KCOAUTOSYNC = 1 << 5,                  /**< auto synchronization */
  KCONOLOCK = 1 << 6,                    /**< open without locking */
  KCOTRYLOCK = 1 << 7,                   /**< lock without blocking */
  KCONOREPAIR = 1 << 8                   /**< open without auto repair */
};


/**
 * Merge modes.
 */
enum {
  KCMSET,                                /**< overwrite the existing value */
  KCMADD,                                /**< keep the existing value */
  KCMREPLACE,                            /**< modify the existing record only */
  KCMAPPEND                              /**< append the new value */
};


/** The package version. */
extern const char* const KCVERSION;


/** Special pointer for no operation by the visiting function. */
extern const char* const KCVISNOP;


/** Special pointer to remove the record by the visiting function. */
extern const char* const KCVISREMOVE;


/**
 * Call back function to visit a full record.
 * @param kbuf the pointer to the key region.
 * @param ksiz the size of the key region.
 * @param vbuf the pointer to the value region.
 * @param vsiz the size of the value region.
 * @param sp the pointer to the variable into which the size of the region of the return
 * value is assigned.
 * @param opq an opaque pointer.
 * @return If it is the pointer to a region, the value is replaced by the content.  If it
 * is KCVISNOP, nothing is modified.  If it is KCVISREMOVE, the record is removed.
 */
typedef const char* (*KCVISITFULL)(const char* kbuf, size_t ksiz,
                                   const char* vbuf, size_t vsiz, size_t* sp, void* opq);


/**
 * Call back function to visit an empty record.
 * @param kbuf the pointer to the key region.
 * @param ksiz the size of the key region.
 * @param sp the pointer to the variable into which the size of the region of the return
 * value is assigned.
 * @param opq an opaque pointer.
 * @return If it is the pointer to a region, the value is replaced by the content.  If it
 * is KCVISNOP or KCVISREMOVE, nothing is modified.
 */
typedef const char* (*KCVISITEMPTY)(const char* kbuf, size_t ksiz, size_t* sp, void* opq);


/**
 * Call back function to process the database file.
 * @param path the path of the database file.
 * @param count the number of records.
 * @param size the size of the available region.
 * @param opq an opaque pointer.
 * @return true on success, or false on failure.
 */
typedef int32_t (*KCFILEPROC)(const char* path, int64_t count, int64_t size, void* opq);


/**
 * Allocate a region on memory.
 * @param size the size of the region.
 * @return the pointer to the allocated region.  The region of the return value should be
 * released with the kcfree function when it is no longer in use.
 */
void* kcmalloc(size_t size);


/**
 * Release a region allocated in the library.
 * @param ptr the pointer to the region.
 */
void kcfree(void* ptr);


/**
 * Get the time of day in seconds.
 * @return the time of day in seconds.  The accuracy is in microseconds.
 */
double kctime(void);


/**
 * Convert a string to an integer.
 * @param str specifies the string.
 * @return the integer.  If the string does not contain numeric expression, 0 is returned.
 */
int64_t kcatoi(const char* str);


/**
 * Convert a string with a metric prefix to an integer.
 * @param str the string, which can be trailed by a binary metric prefix.  "K", "M", "G", "T",
 * "P", and "E" are supported.  They are case-insensitive.
 * @return the integer.  If the string does not contain numeric expression, 0 is returned.  If
 * the integer overflows the domain, INT64_MAX or INT64_MIN is returned according to the
 * sign.
 */
int64_t kcatoix(const char* str);


/**
 * Convert a string to a real number.
 * @param str specifies the string.
 * @return the real number.  If the string does not contain numeric expression, 0.0 is
 * returned.
 */
double kcatof(const char* str);


/**
 * Get the hash value by MurMur hashing.
 * @param buf the source buffer.
 * @param size the size of the source buffer.
 * @return the hash value.
 */
uint64_t kchashmurmur(const void* buf, size_t size);


/**
 * Get the hash value by FNV hashing.
 * @param buf the source buffer.
 * @param size the size of the source buffer.
 * @return the hash value.
 */
uint64_t kchashfnv(const void* buf, size_t size);


/**
 * Calculate the levenshtein distance of two regions.
 * @param abuf the pointer to the region of one buffer.
 * @param asiz the size of the region of one buffer.
 * @param bbuf the pointer to the region of the other buffer.
 * @param bsiz the size of the region of the other buffer.
 * @param utf flag to treat keys as UTF-8 strings.
 * @return the levenshtein distance of two regions.
 */
size_t kclevdist(const void* abuf, size_t asiz, const void* bbuf, size_t bsiz, int32_t utf);


/**
 * Get the quiet Not-a-Number value.
 * @return the quiet Not-a-Number value.
 */
double kcnan();


/**
 * Get the positive infinity value.
 * @return the positive infinity value.
 */
double kcinf();


/**
 * Check a number is a Not-a-Number value.
 * @return true for the number is a Not-a-Number value, or false if not.
 */
int32_t kcchknan(double num);


/**
 * Check a number is an infinity value.
 * @return true for the number is an infinity value, or false if not.
 */
int32_t kcchkinf(double num);


/**
 * Get the readable string of an error code.
 * @param code the error code.
 * @return the readable string of the error code.
 */
const char* kcecodename(int32_t code);


/**
 * Create a polymorphic database object.
 * @return the created database object.
 * @note The object of the return value should be released with the kcdbdel function when it is
 * no longer in use.
 */
KCDB* kcdbnew(void);


/**
 * Destroy a database object.
 * @param db the database object.
 */
void kcdbdel(KCDB* db);


/**
 * Open a database file.
 * @param db a database object.
 * @param path the path of a database file.  If it is "-", the database will be a prototype
 * hash database.  If it is "+", the database will be a prototype tree database.  If it is ":",
 * the database will be a stash database.  If it is "*", the database will be a cache hash
 * database.  If it is "%", the database will be a cache tree database.  If its suffix is
 * ".kch", the database will be a file hash database.  If its suffix is ".kct", the database
 * will be a file tree database.  If its suffix is ".kcd", the database will be a directory
 * hash database.  If its suffix is ".kcf", the database will be a directory tree database.
 * If its suffix is ".kcx", the database will be a plain text database.  Otherwise, this
 * function fails.  Tuning parameters can trail the name, separated by "#".  Each parameter is
 * composed of the name and the value, separated by "=".  If the "type" parameter is specified,
 * the database type is determined by the value in "-", "+", ":", "*", "%", "kch", "kct",
 * "kcd", kcf", and "kcx".  All database types support the logging parameters of "log",
 * "logkinds", and "logpx".  The prototype hash database and the prototype tree database do
 * not support any other tuning parameter.  The stash database supports "bnum".  The cache
 * hash database supports "opts", "bnum", "zcomp", "capcnt", "capsiz", and "zkey".  The cache
 * tree database supports all parameters of the cache hash database except for capacity
 * limitation, and supports "psiz", "rcomp", "pccap" in addition.  The file hash database
 * supports "apow", "fpow", "opts", "bnum", "msiz", "dfunit", "zcomp", and "zkey".  The file
 * tree database supports all parameters of the file hash database and "psiz", "rcomp",
 * "pccap" in addition.  The directory hash database supports "opts", "zcomp", and "zkey".
 * The directory tree database supports all parameters of the directory hash database and
 * "psiz", "rcomp", "pccap" in addition.  The plain text database does not support any other
 * tuning parameter.
 * @param mode the connection mode.  KCOWRITER as a writer, KCOREADER as a reader.
 * The following may be added to the writer mode by bitwise-or: KCOCREATE, which means
 * it creates a new database if the file does not exist, KCOTRUNCATE, which means it
 * creates a new database regardless if the file exists, KCOAUTOTRAN, which means each
 * updating operation is performed in implicit transaction, KCOAUTOSYNC, which means
 * each updating operation is followed by implicit synchronization with the file system.  The
 * following may be added to both of the reader mode and the writer mode by bitwise-or:
 * KCONOLOCK, which means it opens the database file without file locking,
 * KCOTRYLOCK, which means locking is performed without blocking, KCONOREPAIR, which
 * means the database file is not repaired implicitly even if file destruction is detected.
 * @return true on success, or false on failure.
 * @note The tuning parameter "log" is for the original "tune_logger" and the value specifies
 * the path of the log file, or "-" for the standard output, or "+" for the standard error.
 * "logkinds" specifies kinds of logged messages and the value can be "debug", "info", "warn",
 * or "error".  "logpx" specifies the prefix of each log message.  "opts" is for "tune_options"
 * and the value can contain "s" for the small option, "l" for the linear option, and "c" for
 * the compress option.  "bnum" corresponds to "tune_bucket".  "zcomp" is for "tune_compressor"
 * and the value can be "zlib" for the ZLIB raw compressor, "def" for the ZLIB deflate
 * compressor, "gz" for the ZLIB gzip compressor, "lzo" for the LZO compressor, "lzma" for the
 * LZMA compressor, or "arc" for the Arcfour cipher.  "zkey" specifies the cipher key of the
 * compressor.  "capcount" is for "cap_count".  "capsize" is for "cap_size".  "psiz" is for
 * "tune_page".  "rcomp" is for "tune_comparator" and the value can be "lex" for the lexical
 * comparator or "dec" for the decimal comparator.  "pccap" is for "tune_page_cache".  "apow"
 * is for "tune_alignment".  "fpow" is for "tune_fbp".  "msiz" is for "tune_map".  "dfunit" is
 * for "tune_defrag".  Every opened database must be closed by the kcdbclose method when it is
 * no longer in use.  It is not allowed for two or more database objects in the same process to
 * keep their connections to the same database file at the same time.
 */
int32_t kcdbopen(KCDB* db, const char* path, uint32_t mode);


/**
 * Close the database file.
 * @param db a database object.
 * @return true on success, or false on failure.
 */
int32_t kcdbclose(KCDB* db);


/**
 * Get the code of the last happened error.
 * @param db a database object.
 * @return the code of the last happened error.
 */
int32_t kcdbecode(KCDB* db);


/**
 * Get the supplement message of the last happened error.
 * @param db a database object.
 * @return the supplement message of the last happened error.
 */
const char* kcdbemsg(KCDB* db);


/**
 * Accept a visitor to a record.
 * @param db a database object.
 * @param kbuf the pointer to the key region.
 * @param ksiz the size of the key region.
 * @param fullproc a call back function to visit a record.
 * @param emptyproc a call back function to visit an empty record space.
 * @param opq an opaque pointer to be given to the call back functions.
 * @param writable true for writable operation, or false for read-only operation.
 * @return true on success, or false on failure.
 * @note The operation for each record is performed atomically and other threads accessing the
 * same record are blocked.  To avoid deadlock, any explicit database operation must not be
 * performed in this function.
 */
int32_t kcdbaccept(KCDB* db, const char* kbuf, size_t ksiz,
                   KCVISITFULL fullproc, KCVISITEMPTY emptyproc, void* opq, int32_t writable);


/**
 * Accept a visitor to multiple records at once.
 * @param db a database object.
 * @param keys specifies an array of binary strings of the keys.
 * @param knum specifies the number of the keys.
 * @param fullproc a call back function to visit a record.
 * @param emptyproc a call back function to visit an empty record space.
 * @param opq an opaque pointer to be given to the call back functions.
 * @param writable true for writable operation, or false for read-only operation.
 * @return true on success, or false on failure.
 * @note The operations for specified records are performed atomically and other threads
 * accessing the same records are blocked.  To avoid deadlock, any explicit database operation
 * must not be performed in this function.
 */
int32_t kcdbacceptbulk(KCDB* db, const KCSTR* keys, size_t knum,
                       KCVISITFULL fullproc, KCVISITEMPTY emptyproc,
                       void* opq, int32_t writable);


/**
 * Iterate to accept a visitor for each record.
 * @param db a database object.
 * @param fullproc a call back function to visit a record.
 * @param opq an opaque pointer to be given to the call back function.
 * @param writable true for writable operation, or false for read-only operation.
 * @return true on success, or false on failure.
 * @note The whole iteration is performed atomically and other threads are blocked.  To avoid
 * deadlock, any explicit database operation must not be performed in this function.
 */
int32_t kcdbiterate(KCDB* db, KCVISITFULL fullproc, void* opq, int32_t writable);


/**
 * Scan each record in parallel.
 * @param db a database object.
 * @param fullproc a call back function to visit a record.
 * @param opq an opaque pointer to be given to the call back function.
 * @param thnum the number of worker threads.
 * @return true on success, or false on failure.
 * @note This function is for reading records and not for updating ones.  The return value of
 * the visitor is just ignored.  To avoid deadlock, any explicit database operation must not
 * be performed in this function.
 */
int32_t kcdbscanpara(KCDB* db, KCVISITFULL fullproc, void* opq, size_t thnum);


/**
 * Set the value of a record.
 * @param db a database object.
 * @param kbuf the pointer to the key region.
 * @param ksiz the size of the key region.
 * @param vbuf the pointer to the value region.
 * @param vsiz the size of the value region.
 * @return true on success, or false on failure.
 * @note If no record corresponds to the key, a new record is created.  If the corresponding
 * record exists, the value is overwritten.
 */
int32_t kcdbset(KCDB* db, const char* kbuf, size_t ksiz, const char* vbuf, size_t vsiz);


/**
 * Add a record.
 * @param db a database object.
 * @param kbuf the pointer to the key region.
 * @param ksiz the size of the key region.
 * @param vbuf the pointer to the value region.
 * @param vsiz the size of the value region.
 * @return true on success, or false on failure.
 * @note If no record corresponds to the key, a new record is created.  If the corresponding
 * record exists, the record is not modified and false is returned.
 */
int32_t kcdbadd(KCDB* db, const char* kbuf, size_t ksiz, const char* vbuf, size_t vsiz);


/**
 * Replace the value of a record.
 * @param db a database object.
 * @param kbuf the pointer to the key region.
 * @param ksiz the size of the key region.
 * @param vbuf the pointer to the value region.
 * @param vsiz the size of the value region.
 * @return true on success, or false on failure.
 * @note If no record corresponds to the key, no new record is created and false is returned.
 * If the corresponding record exists, the value is modified.
 */
int32_t kcdbreplace(KCDB* db, const char* kbuf, size_t ksiz, const char* vbuf, size_t vsiz);


/**
 * Append the value of a record.
 * @param db a database object.
 * @param kbuf the pointer to the key region.
 * @param ksiz the size of the key region.
 * @param vbuf the pointer to the value region.
 * @param vsiz the size of the value region.
 * @return true on success, or false on failure.
 * @note If no record corresponds to the key, a new record is created.  If the corresponding
 * record exists, the given value is appended at the end of the existing value.
 */
int32_t kcdbappend(KCDB* db, const char* kbuf, size_t ksiz, const char* vbuf, size_t vsiz);


/**
 * Add a number to the numeric value of a record.
 * @param db a database object.
 * @param kbuf the pointer to the key region.
 * @param ksiz the size of the key region.
 * @param num the additional number.
 * @param orig the origin number if no record corresponds to the key.  If it is INT64_MIN and
 * no record corresponds, this function fails.  If it is INT64_MAX, the value is set as the
 * additional number regardless of the current value.
 * @return the result value, or INT64_MIN on failure.
 * @note The value is serialized as an 8-byte binary integer in big-endian order, not a decimal
 * string.  If existing value is not 8-byte, this function fails.
 */
int64_t kcdbincrint(KCDB* db, const char* kbuf, size_t ksiz, int64_t num, int64_t orig);


/**
 * Add a number to the numeric value of a record.
 * @param db a database object.
 * @param kbuf the pointer to the key region.
 * @param ksiz the size of the key region.
 * @param num the additional number.
 * @param orig the origin number if no record corresponds to the key.  If it is negative
 * infinity and no record corresponds, this function fails.  If it is positive infinity, the
 * value is set as the additional number regardless of the current value.
 * @return the result value, or Not-a-number on failure.
 * @note The value is serialized as an 16-byte binary fixed-point number in big-endian order,
 * not a decimal string.  If existing value is not 16-byte, this function fails.
 */
double kcdbincrdouble(KCDB* db, const char* kbuf, size_t ksiz, double num, double orig);


/**
 * Perform compare-and-swap.
 * @param db a database object.
 * @param kbuf the pointer to the key region.
 * @param ksiz the size of the key region.
 * @param ovbuf the pointer to the old value region.  NULL means that no record corresponds.
 * @param ovsiz the size of the old value region.
 * @param nvbuf the pointer to the new value region.  NULL means that the record is removed.
 * @param nvsiz the size of new old value region.
 * @return true on success, or false on failure.
 */
int32_t kcdbcas(KCDB* db, const char* kbuf, size_t ksiz,
                const char* ovbuf, size_t ovsiz, const char* nvbuf, size_t nvsiz);


/**
 * Remove a record.
 * @param db a database object.
 * @param kbuf the pointer to the key region.
 * @param ksiz the size of the key region.
 * @return true on success, or false on failure.
 * @note If no record corresponds to the key, false is returned.
 */
int32_t kcdbremove(KCDB* db, const char* kbuf, size_t ksiz);


/**
 * Retrieve the value of a record.
 * @param db a database object.
 * @param kbuf the pointer to the key region.
 * @param ksiz the size of the key region.
 * @param sp the pointer to the variable into which the size of the region of the return
 * value is assigned.
 * @return the pointer to the value region of the corresponding record, or NULL on failure.
 * @note If no record corresponds to the key, NULL is returned.  Because an additional zero
 * code is appended at the end of the region of the return value, the return value can be
 * treated as a C-style string.  The region of the return value should be released with the
 * kcfree function when it is no longer in use.
 */
char* kcdbget(KCDB* db, const char* kbuf, size_t ksiz, size_t* sp);


/**
 * Check the existence of a record.
 * @param db a database object.
 * @param kbuf the pointer to the key region.
 * @param ksiz the size of the key region.
 * @return the size of the value, or -1 on failure.
 */
int32_t kcdbcheck(KCDB* db, const char* kbuf, size_t ksiz);


/**
 * Retrieve the value of a record.
 * @param db a database object.
 * @param kbuf the pointer to the key region.
 * @param ksiz the size of the key region.
 * @param vbuf the pointer to the buffer into which the value of the corresponding record is
 * written.
 * @param max the size of the buffer.
 * @return the size of the value, or -1 on failure.
 */
int32_t kcdbgetbuf(KCDB* db, const char* kbuf, size_t ksiz, char* vbuf, size_t max);


/**
 * Retrieve the value of a record and remove it atomically.
 * @param db a database object.
 * @param kbuf the pointer to the key region.
 * @param ksiz the size of the key region.
 * @param sp the pointer to the variable into which the size of the region of the return
 * value is assigned.
 * @return the pointer to the value region of the corresponding record, or NULL on failure.
 * @note If no record corresponds to the key, NULL is returned.  Because an additional zero
 * code is appended at the end of the region of the return value, the return value can be
 * treated as a C-style string.  The region of the return value should be released with the
 * kcfree function when it is no longer in use.
 */
char* kcdbseize(KCDB* db, const char* kbuf, size_t ksiz, size_t* sp);


/**
 * Store records at once.
 * @param db a database object.
 * @param recs the records to store.
 * @param rnum specifies the number of the records.
 * @param atomic true to perform all operations atomically, or false for non-atomic operations.
 * @return the number of stored records, or -1 on failure.
 */
int64_t kcdbsetbulk(KCDB* db, const KCREC* recs, size_t rnum, int32_t atomic);


/**
 * Remove records at once.
 * @param db a database object.
 * @param keys the keys of the records to remove.
 * @param knum specifies the number of the keys.
 * @param atomic true to perform all operations atomically, or false for non-atomic operations.
 * @return the number of removed records, or -1 on failure.
 */
int64_t kcdbremovebulk(KCDB* db, const KCSTR* keys, size_t knum, int32_t atomic);


/**
 * Retrieve records at once.
 * @param db a database object.
 * @param keys the keys of the records to retrieve.
 * @param knum specifies the number of the keys.
 * @param recs an array to contain the result.  Its size must be sufficient.
 * @param atomic true to perform all operations atomically, or false for non-atomic operations.
 * @return the number of retrieved records, or -1 on failure.
 * @note The regions of the key and the value of each element of the result should be released
 * with the kcfree function when it is no longer in use.
 */
int64_t kcdbgetbulk(KCDB* db, const KCSTR* keys, size_t knum, KCREC* recs, int32_t atomic);


/**
 * Synchronize updated contents with the file and the device.
 * @param db a database object.
 * @param hard true for physical synchronization with the device, or false for logical
 * synchronization with the file system.
 * @param proc a postprocessor call back function.  If it is NULL, no postprocessing is
 * performed.
 * @param opq an opaque pointer to be given to the call back function.
 * @return true on success, or false on failure.
 * @note The operation of the postprocessor is performed atomically and other threads accessing
 * the same record are blocked.  To avoid deadlock, any explicit database operation must not
 * be performed in this function.
 */
int32_t kcdbsync(KCDB* db, int32_t hard, KCFILEPROC proc, void* opq);


/**
 * Occupy database by locking and do something meanwhile.
 * @param db a database object.
 * @param writable true to use writer lock, or false to use reader lock.
 * @param proc a processor object.  If it is NULL, no processing is performed.
 * @param opq an opaque pointer to be given to the call back function.
 * @return true on success, or false on failure.
 * @note The operation of the processor is performed atomically and other threads accessing
 * the same record are blocked.  To avoid deadlock, any explicit database operation must not
 * be performed in this function.
 */
int32_t kcdboccupy(KCDB* db, int32_t writable, KCFILEPROC proc, void* opq);


/**
 * Create a copy of the database file.
 * @param db a database object.
 * @param dest the path of the destination file.
 * @return true on success, or false on failure.
 */
int32_t kcdbcopy(KCDB* db, const char* dest);


/**
 * Begin transaction.
 * @param db a database object.
 * @param hard true for physical synchronization with the device, or false for logical
 * synchronization with the file system.
 * @return true on success, or false on failure.
 */
int32_t kcdbbegintran(KCDB* db, int32_t hard);


/**
 * Try to begin transaction.
 * @param db a database object.
 * @param hard true for physical synchronization with the device, or false for logical
 * synchronization with the file system.
 * @return true on success, or false on failure.
 */
int32_t kcdbbegintrantry(KCDB* db, int32_t hard);


/**
 * End transaction.
 * @param db a database object.
 * @param commit true to commit the transaction, or false to abort the transaction.
 * @return true on success, or false on failure.
 */
int32_t kcdbendtran(KCDB* db, int32_t commit);


/**
 * Remove all records.
 * @param db a database object.
 * @return true on success, or false on failure.
 */
int32_t kcdbclear(KCDB* db);


/**
 * Dump records into a file.
 * @param db a database object.
 * @param dest the path of the destination file.
 * @return true on success, or false on failure.
 */
int32_t kcdbdumpsnap(KCDB* db, const char* dest);


/**
 * Load records from a file.
 * @param db a database object.
 * @param src the path of the source file.
 * @return true on success, or false on failure.
 */
int32_t kcdbloadsnap(KCDB* db, const char* src);


/**
 * Get the number of records.
 * @param db a database object.
 * @return the number of records, or -1 on failure.
 */
int64_t kcdbcount(KCDB* db);


/**
 * Get the size of the database file.
 * @param db a database object.
 * @return the size of the database file in bytes, or -1 on failure.
 */
int64_t kcdbsize(KCDB* db);


/**
 * Get the path of the database file.
 * @param db a database object.
 * @return the path of the database file, or an empty string on failure.
 * @note The region of the return value should be released with the kcfree function when it is
 * no longer in use.
 */
char* kcdbpath(KCDB* db);


/**
 * Get the miscellaneous status information.
 * @param db a database object.
 * @return the result string of tab saparated values, or NULL on failure.  Each line consists of
 * the attribute name and its value separated by a tab character.
 * @note The region of the return value should be released with the kcfree function when it is
 * no longer in use.
 */
char* kcdbstatus(KCDB* db);


/**
 * Get keys matching a prefix string.
 * @param db a database object.
 * @param prefix the prefix string.
 * @param strary an array to contain the result.  Its size must be sufficient.
 * @param max the maximum number to retrieve.
 * @return the number of retrieved keys or -1 on failure.
 * @note The region of each element of the result should be released with the kcfree function
 * when it is no longer in use.
 */
int64_t kcdbmatchprefix(KCDB* db, const char* prefix, char** strary, size_t max);


/**
 * Get keys matching a regular expression string.
 * @param db a database object.
 * @param regex the regular expression string.
 * @param strary an array to contain the result.  Its size must be sufficient.
 * @param max the maximum number to retrieve.
 * @return the number of retrieved keys or -1 on failure.
 * @note The region of each element of the result should be released with the kcfree function
 * when it is no longer in use.
 */
int64_t kcdbmatchregex(KCDB* db, const char* regex, char** strary, size_t max);


/**
 * Get keys similar to a string in terms of the levenshtein distance.
 * @param db a database object.
 * @param origin the origin string.
 * @param range the maximum distance of keys to adopt.
 * @param utf flag to treat keys as UTF-8 strings.
 * @param strary an array to contain the result.  Its size must be sufficient.
 * @param max the maximum number to retrieve.
 * @return the number of retrieved keys or -1 on failure.
 * @note The region of each element of the result should be released with the kcfree function
 * when it is no longer in use.
 */
int64_t kcdbmatchsimilar(KCDB* db, const char* origin, uint32_t range, int32_t utf,
                         char** strary, size_t max);


/**
 * Merge records from other databases.
 * @param db a database object.
 * @param srcary an array of the source detabase objects.
 * @param srcnum the number of the elements of the source array.
 * @param mode the merge mode.  KCMSET to overwrite the existing value, KCMADD to keep the
 * existing value, KCMREPLACE to modify the existing record only, KCMAPPEND to append the new
 * value.
 * @return true on success, or false on failure.
 */
int32_t kcdbmerge(KCDB* db, KCDB** srcary, size_t srcnum, uint32_t mode);


/**
 * Create a polymorphic cursor object.
 * @param db a database object.
 * @return the return value is the created cursor object.
 * @note The object of the return value should be released with the kccurdel function when it is
 * no longer in use.
 */
KCCUR* kcdbcursor(KCDB* db);


/**
 * Destroy a cursor object.
 * @param cur the cursor object.
 */
void kccurdel(KCCUR* cur);


/**
 * Accept a visitor to the current record.
 * @param cur a cursor object.
 * @param fullproc a call back function to visit a record.
 * @param opq an opaque pointer to be given to the call back functions.
 * @param writable true for writable operation, or false for read-only operation.
 * @param step true to move the cursor to the next record, or false for no move.
 * @return true on success, or false on failure.
 * @note The operation for each record is performed atomically and other threads accessing
 * the same record are blocked.  To avoid deadlock, any explicit database operation must not
 * be performed in this function.
 */
int32_t kccuraccept(KCCUR* cur, KCVISITFULL fullproc, void* opq,
                    int32_t writable, int32_t step);


/**
 * Set the value of the current record.
 * @param cur a cursor object.
 * @param vbuf the pointer to the value region.
 * @param vsiz the size of the value region.
 * @param step true to move the cursor to the next record, or false for no move.
 * @return true on success, or false on failure.
 */
int32_t kccursetvalue(KCCUR* cur, const char* vbuf, size_t vsiz, int32_t step);


/**
 * Remove the current record.
 * @param cur a cursor object.
 * @return true on success, or false on failure.
 * @note If no record corresponds to the key, false is returned.  The cursor is moved to the
 * next record implicitly.
 */
int32_t kccurremove(KCCUR* cur);


/**
 * Get the key of the current record.
 * @param cur a cursor object.
 * @param sp the pointer to the variable into which the size of the region of the return value
 * is assigned.
 * @param step true to move the cursor to the next record, or false for no move.
 * @return the pointer to the key region of the current record, or NULL on failure.
 * @note If the cursor is invalidated, NULL is returned.  Because an additional zero
 * code is appended at the end of the region of the return value, the return value can be
 * treated as a C-style string.  The region of the return value should be released with the
 * kcfree function when it is no longer in use.
 */
char* kccurgetkey(KCCUR* cur, size_t* sp, int32_t step);


/**
 * Get the value of the current record.
 * @param cur a cursor object.
 * @param sp the pointer to the variable into which the size of the region of the return value
 * is assigned.
 * @param step true to move the cursor to the next record, or false for no move.
 * @return the pointer to the value region of the current record, or NULL on failure.
 * @note If the cursor is invalidated, NULL is returned.  Because an additional zero
 * code is appended at the end of the region of the return value, the return value can be
 * treated as a C-style string.  The region of the return value should be released with the
 * kcfree function when it is no longer in use.
 */
char* kccurgetvalue(KCCUR* cur, size_t* sp, int32_t step);


/**
 * Get a pair of the key and the value of the current record.
 * @param cur a cursor object.
 * @param ksp the pointer to the variable into which the size of the region of the return
 * value is assigned.
 * @param vbp the pointer to the variable into which the pointer to the value region is
 * assigned.
 * @param vsp the pointer to the variable into which the size of the value region is
 * assigned.
 * @param step true to move the cursor to the next record, or false for no move.
 * @return the pointer to the pair of the key region, or NULL on failure.
 * @note If the cursor is invalidated, NULL is returned.  Because an additional zero code is
 * appended at the end of each region of the key and the value, each region can be treated
 * as a C-style string.  The region of the return value should be released with the kcfree
 * function when it is no longer in use.
 */
char* kccurget(KCCUR* cur, size_t* ksp, const char** vbp, size_t* vsp, int32_t step);


/**
 * Get a pair of the key and the value of the current record and remove it atomically.
 * @param cur a cursor object.
 * @param ksp the pointer to the variable into which the size of the region of the return
 * value is assigned.
 * @param vbp the pointer to the variable into which the pointer to the value region is
 * assigned.
 * @param vsp the pointer to the variable into which the size of the value region is
 * assigned.
 * @return the pointer to the pair of the key region, or NULL on failure.
 * @note If the cursor is invalidated, NULL is returned.  Because an additional zero code is
 * appended at the end of each region of the key and the value, each region can be treated
 * as a C-style string.  The region of the return value should be released with the kcfree
 * function when it is no longer in use.  The cursor is moved to the next record implicitly.
 */
char* kccurseize(KCCUR* cur, size_t* ksp, const char** vbp, size_t* vsp);


/**
 * Jump the cursor to the first record for forward scan.
 * @param cur a cursor object.
 * @return true on success, or false on failure.
 */
int32_t kccurjump(KCCUR* cur);


/**
 * Jump the cursor to a record for forward scan.
 * @param cur a cursor object.
 * @param kbuf the pointer to the key region.
 * @param ksiz the size of the key region.
 * @return true on success, or false on failure.
 */
int32_t kccurjumpkey(KCCUR* cur, const char* kbuf, size_t ksiz);


/**
 * Jump the cursor to the last record for backward scan.
 * @param cur a cursor object.
 * @return true on success, or false on failure.
 * @note This method is dedicated to tree databases.  Some database types, especially hash
 * databases, may provide a dummy implementation.
 */
int32_t kccurjumpback(KCCUR* cur);


/**
 * Jump the cursor to a record for backward scan.
 * @param cur a cursor object.
 * @param kbuf the pointer to the key region.
 * @param ksiz the size of the key region.
 * @return true on success, or false on failure.
 * @note This method is dedicated to tree databases.  Some database types, especially hash
 * databases, will provide a dummy implementation.
 */
int32_t kccurjumpbackkey(KCCUR* cur, const char* kbuf, size_t ksiz);


/**
 * Step the cursor to the next record.
 * @param cur a cursor object.
 * @return true on success, or false on failure.
 */
int32_t kccurstep(KCCUR* cur);


/**
 * Step the cursor to the previous record.
 * @param cur a cursor object.
 * @return true on success, or false on failure.
 * @note This method is dedicated to tree databases.  Some database types, especially hash
 * databases, may provide a dummy implementation.
 */
int32_t kccurstepback(KCCUR* cur);


/**
 * Get the database object.
 * @param cur a cursor object.
 * @return the database object.
 */
KCDB* kccurdb(KCCUR* cur);


/**
 * Get the code of the last happened error.
 * @param cur a cursor object.
 * @return the code of the last happened error.
 */
int32_t kccurecode(KCCUR* cur);


/**
 * Get the supplement message of the last happened error.
 * @param cur a cursor object.
 * @return the supplement message of the last happened error.
 */
const char* kccuremsg(KCCUR* cur);


/**
 * C wrapper of index database.
 */
typedef struct {
  void* db;                              /**< dummy member */
} KCIDX;


/**
 * Create an index database object.
 * @return the created database object.
 * @note The object of the return value should be released with the kcidxdel function when it is
 * no longer in use.
 */
KCIDX* kcidxnew(void);


/**
 * Destroy a database object.
 * @param idx the database object.
 */
void kcidxdel(KCIDX* idx);


/**
 * Open a database file.
 * @param idx a database object.
 * @param path the path of a database file.  The same as with the polymorphic database.
 * @param mode the connection mode.  The same as with the polymorphic database.
 * @return true on success, or false on failure.
 */
int32_t kcidxopen(KCIDX* idx, const char* path, uint32_t mode);


/**
 * Close the database file.
 * @param idx a database object.
 * @return true on success, or false on failure.
 */
int32_t kcidxclose(KCIDX* idx);


/**
 * Get the code of the last happened error.
 * @param idx a database object.
 * @return the code of the last happened error.
 */
int32_t kcidxecode(KCIDX* idx);


/**
 * Get the supplement message of the last happened error.
 * @param idx a database object.
 * @return the supplement message of the last happened error.
 */
const char* kcidxemsg(KCIDX* idx);


/**
 * Set the value of a record.
 * @param idx a database object.
 * @param kbuf the pointer to the key region.
 * @param ksiz the size of the key region.
 * @param vbuf the pointer to the value region.
 * @param vsiz the size of the value region.
 * @return true on success, or false on failure.
 * @note If no record corresponds to the key, a new record is created.  If the corresponding
 * record exists, the value is overwritten.
 */
int32_t kcidxset(KCIDX* idx, const char* kbuf, size_t ksiz, const char* vbuf, size_t vsiz);


/**
 * Add a record.
 * @param idx a database object.
 * @param kbuf the pointer to the key region.
 * @param ksiz the size of the key region.
 * @param vbuf the pointer to the value region.
 * @param vsiz the size of the value region.
 * @return true on success, or false on failure.
 * @note If no record corresponds to the key, a new record is created.  If the corresponding
 * record exists, the record is not modified and false is returned.
 */
int32_t kcidxadd(KCIDX* idx, const char* kbuf, size_t ksiz, const char* vbuf, size_t vsiz);


/**
 * Replace the value of a record.
 * @param idx a database object.
 * @param kbuf the pointer to the key region.
 * @param ksiz the size of the key region.
 * @param vbuf the pointer to the value region.
 * @param vsiz the size of the value region.
 * @return true on success, or false on failure.
 * @note If no record corresponds to the key, no new record is created and false is returned.
 * If the corresponding record exists, the value is modified.
 */
int32_t kcidxreplace(KCIDX* idx, const char* kbuf, size_t ksiz, const char* vbuf, size_t vsiz);


/**
 * Append the value of a record.
 * @param idx a database object.
 * @param kbuf the pointer to the key region.
 * @param ksiz the size of the key region.
 * @param vbuf the pointer to the value region.
 * @param vsiz the size of the value region.
 * @return true on success, or false on failure.
 * @note If no record corresponds to the key, a new record is created.  If the corresponding
 * record exists, the given value is appended at the end of the existing value.
 */
int32_t kcidxappend(KCIDX* idx, const char* kbuf, size_t ksiz, const char* vbuf, size_t vsiz);


/**
 * Remove a record.
 * @param idx a database object.
 * @param kbuf the pointer to the key region.
 * @param ksiz the size of the key region.
 * @return true on success, or false on failure.
 * @note If no record corresponds to the key, false is returned.
 */
int32_t kcidxremove(KCIDX* idx, const char* kbuf, size_t ksiz);


/**
 * Retrieve the value of a record.
 * @param idx a database object.
 * @param kbuf the pointer to the key region.
 * @param ksiz the size of the key region.
 * @param sp the pointer to the variable into which the size of the region of the return
 * value is assigned.
 * @return the pointer to the value region of the corresponding record, or NULL on failure.
 * @note If no record corresponds to the key, NULL is returned.  Because an additional zero
 * code is appended at the end of the region of the return value, the return value can be
 * treated as a C-style string.  The region of the return value should be released with the
 * kcfree function when it is no longer in use.
 */
char* kcidxget(KCIDX* idx, const char* kbuf, size_t ksiz, size_t* sp);


/**
 * Synchronize updated contents with the file and the device.
 * @param idx a database object.
 * @param hard true for physical synchronization with the device, or false for logical
 * synchronization with the file system.
 * @param proc a postprocessor call back function.  If it is NULL, no postprocessing is
 * performed.
 * @param opq an opaque pointer to be given to the call back function.
 * @return true on success, or false on failure.
 * @note The operation of the postprocessor is performed atomically and other threads accessing
 * the same record are blocked.  To avoid deadlock, any explicit database operation must not
 * be performed in this function.
 */
int32_t kcidxsync(KCIDX* idx, int32_t hard, KCFILEPROC proc, void* opq);


/**
 * Remove all records.
 * @param idx a database object.
 * @return true on success, or false on failure.
 */
int32_t kcidxclear(KCIDX* idx);


/**
 * Get the number of records.
 * @param idx a database object.
 * @return the number of records, or -1 on failure.
 */
int64_t kcidxcount(KCIDX* idx);


/**
 * Get the size of the database file.
 * @param idx a database object.
 * @return the size of the database file in bytes, or -1 on failure.
 */
int64_t kcidxsize(KCIDX* idx);


/**
 * Get the path of the database file.
 * @param idx a database object.
 * @return the path of the database file, or an empty string on failure.
 * @note The region of the return value should be released with the kcfree function when it is
 * no longer in use.
 */
char* kcidxpath(KCIDX* idx);


/**
 * Get the miscellaneous status information.
 * @param idx a database object.
 * @return the result string of tab saparated values, or NULL on failure.  Each line consists of
 * the attribute name and its value separated by a tab character.
 * @note The region of the return value should be released with the kcfree function when it is
 * no longer in use.
 */
char* kcidxstatus(KCIDX* idx);


/**
 * Reveal the inner database object.
 * @return the inner database object, or NULL on failure.
 */
KCDB* kcidxrevealinnerdb(KCIDX* idx);


/**
 * C wrapper of memory-saving string hash map.
 */
typedef struct {
  void* map;                             /**< dummy member */
} KCMAP;


/**
 * C wrapper of iterator of memory-saving string hash map.
 */
typedef struct {
  void* iter;                            /**< dummy member */
} KCMAPITER;


/**
 * C wrapper of sorter of memory-saving string hash map.
 */
typedef struct {
  void* iter;                            /**< dummy member */
} KCMAPSORT;


/**
 * Create a string hash map object.
 * @param bnum the number of buckets of the hash table.  If it is not more than 0, the default
 * setting 31 is specified.
 * @return the created map object.
 * @note The object of the return value should be released with the kcmapdel function when it is
 * no longer in use.
 */
KCMAP* kcmapnew(size_t bnum);


/**
 * Destroy a map object.
 * @param map the map object.
 */
void kcmapdel(KCMAP* map);


/**
 * Set the value of a record.
 * @param map the map object.
 * @param kbuf the pointer to the key region.
 * @param ksiz the size of the key region.
 * @param vbuf the pointer to the value region.
 * @param vsiz the size of the value region.
 * @note If no record corresponds to the key, a new record is created.  If the corresponding
 * record exists, the value is overwritten.
 */
void kcmapset(KCMAP* map, const char* kbuf, size_t ksiz, const char* vbuf, size_t vsiz);


/**
 * Add a record.
 * @param map the map object.
 * @param kbuf the pointer to the key region.
 * @param ksiz the size of the key region.
 * @param vbuf the pointer to the value region.
 * @param vsiz the size of the value region.
 * @return true on success, or false on failure.
 * @note If no record corresponds to the key, a new record is created.  If the corresponding
 * record exists, the record is not modified and false is returned.
 */
int32_t kcmapadd(KCMAP* map, const char* kbuf, size_t ksiz, const char* vbuf, size_t vsiz);


/**
 * Replace the value of a record.
 * @param map the map object.
 * @param kbuf the pointer to the key region.
 * @param ksiz the size of the key region.
 * @param vbuf the pointer to the value region.
 * @param vsiz the size of the value region.
 * @return true on success, or false on failure.
 * @note If no record corresponds to the key, no new record is created and false is returned.
 * If the corresponding record exists, the value is modified.
 */
int32_t kcmapreplace(KCMAP* map, const char* kbuf, size_t ksiz, const char* vbuf, size_t vsiz);


/**
 * Append the value of a record.
 * @param map the map object.
 * @param kbuf the pointer to the key region.
 * @param ksiz the size of the key region.
 * @param vbuf the pointer to the value region.
 * @param vsiz the size of the value region.
 * @note If no record corresponds to the key, a new record is created.  If the corresponding
 * record exists, the given value is appended at the end of the existing value.
 */
void kcmapappend(KCMAP* map, const char* kbuf, size_t ksiz, const char* vbuf, size_t vsiz);


/**
 * Remove a record.
 * @param map the map object.
 * @param kbuf the pointer to the key region.
 * @param ksiz the size of the key region.
 * @return true on success, or false on failure.
 * @note If no record corresponds to the key, false is returned.
 */
int32_t kcmapremove(KCMAP* map, const char* kbuf, size_t ksiz);


/**
 * Retrieve the value of a record.
 * @param map the map object.
 * @param kbuf the pointer to the key region.
 * @param ksiz the size of the key region.
 * @param sp the pointer to the variable into which the size of the region of the return
 * value is assigned.
 * @return the pointer to the value region of the corresponding record, or NULL on failure.
 */
const char* kcmapget(KCMAP* map, const char* kbuf, size_t ksiz, size_t* sp);


/**
 * Remove all records.
 * @param map the map object.
 */
void kcmapclear(KCMAP* map);


/**
 * Get the number of records.
 * @param map the map object.
 * @return the number of records.
 */
size_t kcmapcount(KCMAP* map);


/**
 * Create a string hash map iterator object.
 * @param map a map object.
 * @return the return value is the created iterator object.
 * @note The object of the return value should be released with the kcmapiterdel function when
 * it is no longer in use.
 * @note This object will not be invalidated even when the map object is updated once.
 * However, phantom records may be retrieved if they are removed after creation of each iterator.
 */
KCMAPITER* kcmapiterator(KCMAP* map);


/**
 * Destroy an iterator object.
 * @param iter the iterator object.
 */
void kcmapiterdel(KCMAPITER* iter);


/**
 * Get the key of the current record.
 * @param iter the iterator object.
 * @param sp the pointer to the variable into which the size of the region of the return
 * value is assigned.
 * @return the pointer to the key region of the current record, or NULL on failure.
 */
const char* kcmapitergetkey(KCMAPITER* iter, size_t* sp);


/**
 * Get the value of the current record.
 * @param iter the iterator object.
 * @param sp the pointer to the variable into which the size of the region of the return
 * value is assigned.
 * @return the pointer to the value region of the current record, or NULL on failure.
 */
const char* kcmapitergetvalue(KCMAPITER* iter, size_t* sp);


/**
 * Get a pair of the key and the value of the current record.
 * @param iter the iterator object.
 * @param ksp the pointer to the variable into which the size of the region of the return
 * value is assigned.
 * @param vbp the pointer to the variable into which the pointer to the value region is
 * assigned.
 * @param vsp the pointer to the variable into which the size of the value region is
 * assigned.
 * @return the pointer to the key region, or NULL on failure.
 */
const char* kcmapiterget(KCMAPITER* iter, size_t* ksp, const char** vbp, size_t* vsp);


/**
 * Step the cursor to the next record.
 * @param iter the iterator object.
 */
void kcmapiterstep(KCMAPITER* iter);


/**
 * Create a string hash map sorter object.
 * @param map a map object.
 * @return the return value is the created sorter object.
 * @note The object of the return value should be released with the kcmapsortdel function when
 * it is no longer in use.
 * @note This object will not be invalidated even when the map object is updated once.
 * However, phantom records may be retrieved if they are removed after creation of each sorter.
 */
KCMAPSORT* kcmapsorter(KCMAP* map);


/**
 * Destroy an sorter object.
 * @param sort the sorter object.
 */
void kcmapsortdel(KCMAPSORT* sort);


/**
 * Get the key of the current record.
 * @param sort the sorter object.
 * @param sp the pointer to the variable into which the size of the region of the return
 * value is assigned.
 * @return the pointer to the key region of the current record, or NULL on failure.
 */
const char* kcmapsortgetkey(KCMAPSORT* sort, size_t* sp);


/**
 * Get the value of the current record.
 * @param sort the sorter object.
 * @param sp the pointer to the variable into which the size of the region of the return
 * value is assigned.
 * @return the pointer to the value region of the current record, or NULL on failure.
 */
const char* kcmapsortgetvalue(KCMAPSORT* sort, size_t* sp);


/**
 * Get a pair of the key and the value of the current record.
 * @param sort the sorter object.
 * @param ksp the pointer to the variable into which the size of the region of the return
 * value is assigned.
 * @param vbp the pointer to the variable into which the pointer to the value region is
 * assigned.
 * @param vsp the pointer to the variable into which the size of the value region is
 * assigned.
 * @return the pointer to the key region, or NULL on failure.
 */
const char* kcmapsortget(KCMAPSORT* sort, size_t* ksp, const char** vbp, size_t* vsp);


/**
 * Step the cursor to the next record.
 * @param sort the sorter object.
 */
void kcmapsortstep(KCMAPSORT* sort);


/**
 * C wrapper of memory-saving string hash map.
 */
typedef struct {
  void* list;                            /**< dummy member */
} KCLIST;


/**
 * Create a string array list object.
 * @return the created list object.
 * @note The object of the return value should be released with the kclistdel function when it is
 * no longer in use.
 */
KCLIST* kclistnew();


/**
 * Destroy a list object.
 * @param list the list object.
 */
void kclistdel(KCLIST* list);


/**
 * Insert a record at the bottom of the list.
 * @param list the list object.
 * @param buf the pointer to the record region.
 * @param size the size of the record region.
 */
void kclistpush(KCLIST* list, const char* buf, size_t size);


/**
 * Remove a record at the bottom of the list.
 * @param list the list object.
 * @return true if the operation success, or false if there is no record in the list.
 */
int32_t kclistpop(KCLIST* list);


/**
 * Insert a record at the top of the list.
 * @param list the list object.
 * @param buf the pointer to the record region.
 * @param size the size of the record region.
 */
void kclistunshift(KCLIST* list, const char* buf, size_t size);


/**
 * Remove a record at the top of the list.
 * @param list the list object.
 * @return true if the operation success, or false if there is no record in the list.
 */
int32_t kclistshift(KCLIST* list);


/**
 * Insert a record at the position of the given index of the list.
 * @param list the list object.
 * @param buf the pointer to the record region.
 * @param size the size of the record region.
 * @param idx the index of the position.  It must be equal to or less than the number of
 * records.
 */
void kclistinsert(KCLIST* list, const char* buf, size_t size, size_t idx);


/**
 * Remove a record at the position of the given index of the list.
 * @param list the list object.
 * @param idx the index of the position.  It must be less than the number of records.
 */
void kclistremove(KCLIST* list, size_t idx);


/**
 * Retrieve a record at the position of the given index of the list.
 * @param list the list object.
 * @param idx the index of the position.  It must be less than the number of records.
 * @param sp the pointer to the variable into which the size of the region of the return
 * value is assigned.
 * @return the pointer to the region of the retrieved record.
 */
const char* kclistget(KCLIST* list, size_t idx, size_t* sp);


/**
 * Remove all records.
 * @param list the list object.
 */
void kclistclear(KCLIST* list);


/**
 * Get the number of records.
 * @param list the list object.
 * @return the number of records.
 */
size_t kclistcount(KCLIST* list);


#if defined(__cplusplus)
}
#endif

#endif                                   /* duplication check */

/* END OF FILE */