harbour-core/harbour/doc/en/hashes.txt

/*
 * $Id$
 */

/*
 * Harbour Project source code:
 * Hash table type and functions
 *
 * Copyright 2009 April White <april@users.sourceforge.net>
 * www - http://harbour-project.org
 *
 * Based on the content of hashfunc.c and hashes.c
 * Copyright 2007 Przemyslaw Czerpak <druzus / at / priv.onet.pl>
 *
 * 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 2, or (at your option)
 * 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 software; see the file COPYING.  If not, write to
 * the Free Software Foundation, Inc., 59 Temple Place, Suite 330,
 * Boston, MA 02111-1307 USA (or visit the web site http://www.gnu.org/).
 *
 * As a special exception, the Harbour Project gives permission for
 * additional uses of the text contained in its release of Harbour.
 *
 * The exception is that, if you link the Harbour libraries with other
 * files to produce an executable, this does not by itself cause the
 * resulting executable to be covered by the GNU General Public License.
 * Your use of that executable is in no way restricted on account of
 * linking the Harbour library code into it.
 *
 * This exception does not however invalidate any other reasons why
 * the executable file might be covered by the GNU General Public License.
 *
 * This exception applies only to the code released by the Harbour
 * Project under the name Harbour.  If you copy code from other
 * Harbour Project or Free Software Foundation releases into a copy of
 * Harbour, as the General Public License permits, the exception does
 * not apply to the code that you add in this way.  To avoid misleading
 * anyone as to the status of such modified files, you must delete
 * this exception notice from them.
 *
 * If you write modifications of your own for Harbour, it is your choice
 * whether to permit this exception to apply to your modifications.
 * If you do not wish that, delete this exception notice.
 *
 */

/*  $DOC$
 *  $TEMPLATE$
 *       Function
 *  $NAME$
 *       HB_HASH()
 *  $CATEGORY$
 *       API
 *  $SUBCATEGORY$
 *       Hash table
 *  $ONELINER$
 *       Returns a hash table
 *  $SYNTAX$
 *       HB_HASH( [ <Key1>, <Value1> ], [ <KeyN>, <ValueN> ], ... ) -> hsTable
 *  $ARGUMENTS$
 *       <Key1> entry key;
 *       can be of type: number, date, datetime, string, pointer
 *
 *       <Value1> entry value; can be of type: block, string, numeric, date/datetime, logical, nil, pointer, array, hash table
 *  $RETURNS$
 *       A hash table built from the initial key/value pairs
 *  $DESCRIPTION$
 *
 *  $EXAMPLES$
 *
 *  $TESTS$
 *
 *  $STATUS$
 *      R
 *  $COMPLIANCE$
 *      H
 *  $PLATFORMS$
 *
 *  $FILES$
 *
 *  $SEEALSO$
 *
 *  $END$
 */

/*  $DOC$
 *  $TEMPLATE$
 *       Function
 *  $NAME$
 *       HB_HHASKEY()
 *  $CATEGORY$
 *       API
 *  $SUBCATEGORY$
 *       Hash table
 *  $ONELINER$
 *       Determines whether a hash table has an entry with a give key
 *  $SYNTAX$
 *       HB_HHASKEY( <hsTable>, <Key> ) -> lExists
 *  $ARGUMENTS$
 *       <hsTable> a hash table, created by HB_HASH()
 *
 *       <Key> a key value to be queried for;
 *       can be of type: number, date, datetime, string, pointer
 *  $RETURNS$
 *       A logical value indicating whether the key exists within the hash table
 *  $DESCRIPTION$
 *
 *  $EXAMPLES$
 *
 *  $TESTS$
 *
 *  $STATUS$
 *      R
 *  $COMPLIANCE$
 *      H
 *  $PLATFORMS$
 *
 *  $FILES$
 *
 *  $SEEALSO$
 *
 *  $END$
 */

/*  $DOC$
 *  $TEMPLATE$
 *       Function
 *  $NAME$
 *       HB_HPOS()
 *  $CATEGORY$
 *       API
 *  $SUBCATEGORY$
 *       Hash table
 *  $ONELINER$
 *       Locates the index of a key within a hash table
 *  $SYNTAX$
 *       HB_HPOS( <hsTable>, <Key> ) -> nPosition
 *  $ARGUMENTS$
 *       <hsTable> a hash table, created by HB_HASH()
 *
 *       <Key> key for which its position is to be determined;
 *       can be of type: number, date, datetime, string, pointer
 *  $RETURNS$
 *       A integer number being the index position of the key within the hash table.
 *
 *      TODO: what is the return value if the key does not exist?  zero (0)?  RTE?
 *  $DESCRIPTION$
 *
 *  $EXAMPLES$
 *
 *  $TESTS$
 *
 *  $STATUS$
 *      R
 *  $COMPLIANCE$
 *      H
 *  $PLATFORMS$
 *
 *  $FILES$
 *
 *  $SEEALSO$
 *
 *  $END$
 */

/*  $DOC$
 *  $TEMPLATE$
 *       Function
 *  $NAME$
 *       HB_HGET()
 *  $CATEGORY$
 *       API
 *  $SUBCATEGORY$
 *       Hash table
 *  $ONELINER$
 *       Returns a hash value
 *  $SYNTAX$
 *       HB_HGET( <hsTable>, <Key> ) -> <Value>
 *  $ARGUMENTS$
 *       <hsTable> a hash table, created by HB_HASH()
 *
 *       <Key> key to be retrieve from the hash table;
 *       can be of type: number, date, datetime, string, pointer
 *  $RETURNS$
 *       Either the value within the hash table for the given key.
 *
 *       An array access error occurs of the key is not found
 *  $DESCRIPTION$
 *
 *  $EXAMPLES$
 *
 *  $TESTS$
 *
 *  $STATUS$
 *      R
 *  $COMPLIANCE$
 *      H
 *  $PLATFORMS$
 *
 *  $FILES$
 *
 *  $SEEALSO$
 *
 *  $END$
 */

/*  $DOC$
 *  $TEMPLATE$
 *       Function
 *  $NAME$
 *       HB_HGETDEF()
 *  $CATEGORY$
 *       API
 *  $SUBCATEGORY$
 *       Hash table
 *  $ONELINER$
 *       Returns a hash value, or a default value if the key is not present
 *  $SYNTAX$
 *       HB_HGETDEF( <hsTable>, <Key>, [<DefaultValue>] ) -> <Value>
 *  $ARGUMENTS$
 *       <hsTable> a hash table, created by HB_HASH()
 *
 *       <Key> key to be retrieve from the hash table;
 *       can be of type: number, date, datetime, string, pointer
 *
 *       <DefaultValue> a default value to be returned if the
 *       hash table does not contain the key
 *  $RETURNS$
 *       Either the value within the hash table for the given key,
 *       or the default value.
 *  $DESCRIPTION$
 *
 *  $EXAMPLES$
 *
 *  $TESTS$
 *
 *  $STATUS$
 *      R
 *  $COMPLIANCE$
 *      H
 *  $PLATFORMS$
 *
 *  $FILES$
 *
 *  $SEEALSO$
 *
 *  $END$
 */

/*  $DOC$
 *  $TEMPLATE$
 *       Function
 *  $NAME$
 *       HB_HSET()
 *  $CATEGORY$
 *       API
 *  $SUBCATEGORY$
 *       Hash table
 *  $ONELINER$
 *       Sets a hash value
 *  $SYNTAX$
 *       HB_HSET( <hsTable>, <Key>, <Value> ) -> <hsTable>
 *  $ARGUMENTS$
 *       <hsTable> a hash table, created by HB_HASH()
 *
 *       <Key> the key of the entry to be set;
 *       can be of type: number, date, datetime, string, pointer
 *
 *       <Value> the entry value
 *  $RETURNS$
 *       The hash table
 *  $DESCRIPTION$
 *
 *  $EXAMPLES$
 *
 *  $TESTS$
 *
 *  $STATUS$
 *      R
 *  $COMPLIANCE$
 *      H
 *  $PLATFORMS$
 *
 *  $FILES$
 *
 *  $SEEALSO$
 *
 *  $END$
 */

/*  $DOC$
 *  $TEMPLATE$
 *       Function
 *  $NAME$
 *       HB_HDEL()
 *  $CATEGORY$
 *       API
 *  $SUBCATEGORY$
 *       Hash table
 *  $ONELINER$
 *        Removes a key/value pair from a hash table
 *  $SYNTAX$
 *       HB_HDEL( <hsTable>, <Key> ) -> <hsTable>
 *  $ARGUMENTS$
 *       <hsTable> a hash table, created by HB_HASH()
 *
 *       <Key> key to be removed from the hash table;
 *       can be of type: number, date, datetime, string, pointer
 *  $RETURNS$
 *       The hash table
 *  $DESCRIPTION$
 *
 *  $EXAMPLES$
 *
 *  $TESTS$
 *
 *  $STATUS$
 *      R
 *  $COMPLIANCE$
 *      H
 *  $PLATFORMS$
 *
 *  $FILES$
 *
 *  $SEEALSO$
 *
 *  $END$
 */

/*  $DOC$
 *  $TEMPLATE$
 *       Function
 *  $NAME$
 *       HB_HKEYAT()
 *  $CATEGORY$
 *       API
 *  $SUBCATEGORY$
 *       Hash table
 *  $ONELINER$
 *       Gets a hash table key at a given position
 *  $SYNTAX$
 *       HB_HKEYAT( <hsTable>, <nPosition> ) -> <Key>
 *  $ARGUMENTS$
 *       <hsTable> a hash table, created by HB_HASH()
 *
 *       <nPosition> the position of an entry within the hash table that will
 *       be returned
 *  $RETURNS$
 *       The key at the given position of the hash table;
 *       the type will be one: number, date, datetime, string, pointer
 *  $DESCRIPTION$
 *
 *  $EXAMPLES$
 *
 *  $TESTS$
 *
 *  $STATUS$
 *      R
 *  $COMPLIANCE$
 *      H
 *  $PLATFORMS$
 *
 *  $FILES$
 *
 *  $SEEALSO$
 *
 *  $END$
 */

/*  $DOC$
 *  $TEMPLATE$
 *       Function
 *  $NAME$
 *       HB_HVALUEAT()
 *  $CATEGORY$
 *       API
 *  $SUBCATEGORY$
 *       Hash table
 *  $ONELINER$
 *       Gets/sets a hash value at a given position
 *  $SYNTAX$
 *       HB_HVALUEAT( <hsTable>, <nPosition>, [<NewValue>] ) -> <Value>
 *  $ARGUMENTS$
 *       <hsTable> a hash table, created by HB_HASH()
 *
 *       <nPosition> the position of an entry within the hash table that will
 *       be returned
 *
 *       <NewValue> a new value to be assigned to the hash table at the given
 *       position
 *  $RETURNS$
 *       The existing value, or the new value if it is given
 *  $DESCRIPTION$
 *
 *  $EXAMPLES$
 *
 *  $TESTS$
 *
 *  $STATUS$
 *      R
 *  $COMPLIANCE$
 *      H
 *  $PLATFORMS$
 *
 *  $FILES$
 *
 *  $SEEALSO$
 *
 *  $END$
 */

/*  $DOC$
 *  $TEMPLATE$
 *       Function
 *  $NAME$
 *       HB_HPAIRAT()
 *  $CATEGORY$
 *       API
 *  $SUBCATEGORY$
 *       Hash table
 *  $ONELINER$
 *       Returns a two-dimensional array of a hash table entry key/value pair
 *  $SYNTAX$
 *       HB_HPAIRAT( <hsTable>, <nPosition> ) -> <aKeyValue>
 *  $ARGUMENTS$
 *       <hsTable> a hash table, created by HB_HASH()
 *
 *       <nPosition> the position of an entry within the hash table that will
 *       be returned
 *  $RETURNS$
 *       A two-dimensional array of the key/value pair entry of the hash table
 *  $DESCRIPTION$
 *
 *  $EXAMPLES$
 *
 *  $TESTS$
 *
 *  $STATUS$
 *      R
 *  $COMPLIANCE$
 *      H
 *  $PLATFORMS$
 *
 *  $FILES$
 *
 *  $SEEALSO$
 *
 *  $END$
 */

/*  $DOC$
 *  $TEMPLATE$
 *       Function
 *  $NAME$
 *       HB_HDELAT()
 *  $CATEGORY$
 *       API
 *  $SUBCATEGORY$
 *       Hash table
 *  $ONELINER$
 *       Removes an entry from a hash table based on its index position
 *  $SYNTAX$
 *       HB_HDELAT( <hsTable>, <nPosition> ) -> <hsTable>
 *  $ARGUMENTS$
 *       <hsTable> a hash table, created by HB_HASH()
 *
 *       <nPosition> the position of an entry within the hash table that will
 *       be deleted
 *  $RETURNS$
 *       The hash table
 *  $DESCRIPTION$
 *
 *  $EXAMPLES$
 *
 *  $TESTS$
 *
 *  $STATUS$
 *      R
 *  $COMPLIANCE$
 *      H
 *  $PLATFORMS$
 *
 *  $FILES$
 *
 *  $SEEALSO$
 *
 *  $END$
 */

/*  $DOC$
 *  $TEMPLATE$
 *       Function
 *  $NAME$
 *       HB_HKEYS()
 *  $CATEGORY$
 *       API
 *  $SUBCATEGORY$
 *       Hash table
 *  $ONELINER$
 *       Returns an array of the keys of a hash table
 *  $SYNTAX$
 *       HB_HKEYS( <hsTable> ) -> <aKeys>
 *  $ARGUMENTS$
 *       <hsTable> a hash table, created by HB_HASH()
 *  $RETURNS$
 *       An array of all the hash table keys
 *  $DESCRIPTION$
 *
 *  $EXAMPLES$
 *
 *  $TESTS$
 *
 *  $STATUS$
 *      R
 *  $COMPLIANCE$
 *      H
 *  $PLATFORMS$
 *
 *  $FILES$
 *
 *  $SEEALSO$
 *
 *  $END$
 */

/*  $DOC$
 *  $TEMPLATE$
 *       Function
 *  $NAME$
 *       HB_HVALUES()
 *  $CATEGORY$
 *       API
 *  $SUBCATEGORY$
 *       Hash table
 *  $ONELINER$
 *       Returns an array of the values of a hash table
 *  $SYNTAX$
 *       HB_HVALUES( <hsTable> ) -> <aValues>
 *  $ARGUMENTS$
 *       <hsTable> a hash table, created by HB_HASH()
 *  $RETURNS$
 *       An array of all the hash values
 *  $DESCRIPTION$
 *
 *  $EXAMPLES$
 *
 *  $TESTS$
 *
 *  $STATUS$
 *      R
 *  $COMPLIANCE$
 *      H
 *  $PLATFORMS$
 *
 *  $FILES$
 *
 *  $SEEALSO$
 *
 *  $END$
 */

/*  $DOC$
 *  $TEMPLATE$
 *       Function
 *  $NAME$
 *       HB_HFILL()
 *  $CATEGORY$
 *       API
 *  $SUBCATEGORY$
 *       Hash table
 *  $ONELINER$
 *       Fills a hash table with a value
 *  $SYNTAX$
 *       HB_HFILL( <hsTable>, <Value> ) -> <hsTable>
 *  $ARGUMENTS$
 *       <hsTable> a hash table, created by HB_HASH()
 *
 *       <Value> fill value; can be of type: block, string, numeric, date/datetime, logical, nil, pointer, array, hash table
 *  $RETURNS$
 *       The hash table
 *  $DESCRIPTION$
 *
 *  $EXAMPLES$
 *
 *  $TESTS$
 *
 *  $STATUS$
 *      R
 *  $COMPLIANCE$
 *      H
 *  $PLATFORMS$
 *
 *  $FILES$
 *
 *  $SEEALSO$
 *
 *  $END$
 */

/*  $DOC$
 *  $TEMPLATE$
 *       Function
 *  $NAME$
 *       HB_HCLONE()
 *  $CATEGORY$
 *       API
 *  $SUBCATEGORY$
 *       Hash table
 *  $ONELINER$
 *       Creates a copy of a hash table
 *  $SYNTAX$
 *       HB_HCLONE( <hsTable> ) -> <hsDestination>
 *  $ARGUMENTS$
 *       <hsTable> a hash table, created by HB_HASH()
 *  $RETURNS$
 *       A cloned copy of the hash table
 *  $DESCRIPTION$
 *
 *  $EXAMPLES$
 *
 *  $TESTS$
 *
 *  $STATUS$
 *      R
 *  $COMPLIANCE$
 *      H
 *  $PLATFORMS$
 *
 *  $FILES$
 *
 *  $SEEALSO$
 *
 *  $END$
 */

/*  $DOC$
 *  $TEMPLATE$
 *       Function
 *  $NAME$
 *       HB_HCOPY()
 *  $CATEGORY$
 *       API
 *  $SUBCATEGORY$
 *       Hash table
 *  $ONELINER$
 *       Adds entries from the source hash table to the destination hash table
 *  $SYNTAX$
 *       HB_HCOPY( <hsDestination>, <hsSource>, [<nStart>], [<nCount>] ) -> <hsDestination>
 *  $ARGUMENTS$
 *       <hsDestination> a destination hash table, created by HB_HASH()
 *
 *       <hsSource> a source hash table, created by HB_HASH()
 *
 *       <nStart> starting index, defaults to 1 if omitted
 *
 *       <nCount> counter, defaults to (length) - <nStart> is omitted
 *  $RETURNS$
 *       The destination hash table
 *  $DESCRIPTION$
 *
 *  $EXAMPLES$
 *
 *  $TESTS$
 *
 *  $STATUS$
 *      R
 *  $COMPLIANCE$
 *      H
 *  $PLATFORMS$
 *
 *  $FILES$
 *
 *  $SEEALSO$
 *
 *  $END$
 */

/*  $DOC$
 *  $TEMPLATE$
 *       Function
 *  $NAME$
 *       HB_HMERGE()
 *  $CATEGORY$
 *       API
 *  $SUBCATEGORY$
 *       Hash table
 *  $ONELINER$
 *       Merges a source hash table into a destination hash table
 *  $SYNTAX$
 *       HB_HMERGE( <hsDestination>, <hsSource>, <bBlock>|<nPosition> ) -> <hsDestination>
 *  $ARGUMENTS$
 *       <hsDestination> a destination hash table, created by HB_HASH()
 *
 *       <hsSource> a source hash table, created by HB_HASH()
 *
 *       <bBlock> a code block that will be evaluated for each entry within the
 *       source hash table; the code block will be passed the entry key, value and
 *       position; if the code block returns a true value, the entry will be added to
 *       the destination hash table
 *
 *       <nPosition> the position of an entry within the source hash table that will
 *       be appended to the destination hash table
 *
 *       TODO: the source code passes either a number or HB_HASH_UNION; research this
 *  $RETURNS$
 *       The destination hash table with the contents of the source hash table merged
 *  $DESCRIPTION$
 *
 *  $EXAMPLES$
 *
 *  $TESTS$
 *
 *  $STATUS$
 *      R
 *  $COMPLIANCE$
 *      H
 *  $PLATFORMS$
 *
 *  $FILES$
 *
 *  $SEEALSO$
 *
 *  $END$
 */

/*  $DOC$
 *  $TEMPLATE$
 *       Function
 *  $NAME$
 *       HB_HEVAL()
 *  $CATEGORY$
 *       API
 *  $SUBCATEGORY$
 *       Hash table
 *  $ONELINER$
 *       Evaluate a code block across the contents of a hash table
 *  $SYNTAX$
 *       HB_HEVAL( <hsTable>, <bBlock>, [<nStart>], [<nCount>] ) -> <hsTable>
 *  $ARGUMENTS$
 *       <hsTable> a hash table, created by HB_HASH()
 *
 *       <bBlock> code block to be evaluated
 *
 *       <nStart> starting index, defaults to 1 if omitted
 *
 *       <nCount> counter, defaults to (length) - <nStart> is omitted
 *  $RETURNS$
 *       The hash table
 *  $DESCRIPTION$
 *       The code block is evaluated for every hash table entry starting at
 *       <nStart> for <nCount> items.
 *
 *       The code block is passed the entry key, value, and numeric position
 *  $EXAMPLES$
 *
 *  $TESTS$
 *
 *  $STATUS$
 *      R
 *  $COMPLIANCE$
 *      H
 *  $PLATFORMS$
 *
 *  $FILES$
 *
 *  $SEEALSO$
 *
 *  $END$
 */

/*  $DOC$
 *  $TEMPLATE$
 *       Function
 *  $NAME$
 *       HB_HSCAN()
 *  $CATEGORY$
 *       API
 *  $SUBCATEGORY$
 *       Hash table
 *  $ONELINER$
 *       Scans a hash table
 *  $SYNTAX$
 *       HB_HSCAN( <hsTable>, <Value>, [<nStart>], [<nCount>, [<lExact>] ) -> nPosition
 *  $ARGUMENTS$
 *       <hsTable> a hash table, created by HB_HASH()
 *
 *       <Value> to be located within the hash table
 *
 *       <nStart> starting index, defaults to 1 if omitted
 *
 *       <nCount> counter, defaults to (length) - <nStart> is omitted
 *
 *       <lExact> logical valuye indicating whether the comparision
 *       is to be be exact or not
 *  $RETURNS$
 *       The position of the located value within the hash table, or zero (0) if not found.
 *  $DESCRIPTION$
 *
 *  $EXAMPLES$
 *
 *  $TESTS$
 *
 *  $STATUS$
 *      R
 *  $COMPLIANCE$
 *      H
 *  $PLATFORMS$
 *
 *  $FILES$
 *
 *  $SEEALSO$
 *
 *  $END$
 */

/*  $DOC$
 *  $TEMPLATE$
 *       Function
 *  $NAME$
 *       HB_HSORT()
 *  $CATEGORY$
 *       API
 *  $SUBCATEGORY$
 *       Hash table
 *  $ONELINER$
 *       Reorganizes the internal list of the hash table to be sorted
 *  $SYNTAX$
 *       HB_HSORT( <hsTable> ) -> <hsSortedTable>
 *  $ARGUMENTS$
 *       <hsTable> a hash table, created by HB_HASH()
 *  $RETURNS$
 *       The hash table sorted
 *
 *       TODO: is the original table altered?
 *  $DESCRIPTION$
 *
 *  $EXAMPLES$
 *
 *  $TESTS$
 *
 *  $STATUS$
 *      R
 *  $COMPLIANCE$
 *      H
 *  $PLATFORMS$
 *
 *  $FILES$
 *
 *  $SEEALSO$
 *
 *  $END$
 */

/*  $DOC$
 *  $TEMPLATE$
 *       Function
 *  $NAME$
 *       HB_HCASEMATCH()
 *  $CATEGORY$
 *       API
 *  $SUBCATEGORY$
 *       Hash table
 *  $ONELINER$
 *       Sets the 'case match' flag for the hash table
 *  $SYNTAX$
 *       HB_HCASEMATCH( <hsTable>, [<lFlag>] ) -> <lPreviousFlag>
 *  $ARGUMENTS$
 *       <hsTable> a hash table, created by HB_HASH()
 *
 *       <lFlag> a logical value indicating to turn on or off
 *       the 'case match' flag of the hash table
 *  $RETURNS$
 *       The previous value of the 'case match' flag
 *  $DESCRIPTION$
 *       This function is equivalent to HB_HSETCASEMATCH() but it returns
 *       the old flag value rather than the hash table
 *  $EXAMPLES$
 *       LOCAL hsTable, lFlag
 *       hsTable := HB_HASH( "one", 1, "two", 2 )
 *       // turn 'case match' on for a new hash table, storing ol flag
 *       lFlag := HB_HCASEMATCH( hsTable, .T. )
 *  $TESTS$
 *
 *  $STATUS$
 *      R
 *  $COMPLIANCE$
 *      H
 *  $PLATFORMS$
 *
 *  $FILES$
 *
 *  $SEEALSO$
 *      HB_HSETCASEMATCH()
 *  $END$
  */

/*  $DOC$
 *  $TEMPLATE$
 *       Function
 *  $NAME$
 *       HB_HBINARY()
 *  $CATEGORY$
 *       API
 *  $SUBCATEGORY$
 *       Hash table
 *  $ONELINER$
 *       Sets the 'binary' flag for the hash table
 *  $SYNTAX$
 *       HB_HBINARY( <hsTable>, [<lFlag>] ) -> <lPreviousFlag>
 *  $ARGUMENTS$
 *       <hsTable> a hash table, created by HB_HASH()
 *
 *       <lFlag> a logical value indicating to turn on or off
 *       the 'binary' flag of the hash table
 *  $RETURNS$
 *       The previous value of the 'binary' flag
 *  $DESCRIPTION$
 *       This function is equivalent to HB_HBINARY() but it returns
 *       the old flag value rather than the hash table
 *  $EXAMPLES$
 *       LOCAL hsTable, lFlag
 *       hsTable := HB_HASH( "one", 1, "two", 2 )
 *       // turn 'binary' on for a new hash table, storing ol flag
 *       lFlag := HB_HBINARY( hsTable, .T. )
 *  $TESTS$
 *
 *  $STATUS$
 *      R
 *  $COMPLIANCE$
 *      H
 *  $PLATFORMS$
 *
 *  $FILES$
 *
 *  $SEEALSO$
 *      HB_HSETBINARY()
 *  $END$
 */

/*  $DOC$
 *  $TEMPLATE$
 *       Function
 *  $NAME$
 *       HB_HAUTOADD()
 *  $CATEGORY$
 *       API
 *  $SUBCATEGORY$
 *       Hash table
 *  $ONELINER$
 *       Sets the 'auto add' flag for the hash table
 *  $SYNTAX$
 *       HB_HAUTOADD( <hsTable>, [<lFlag>] ) -> <lPreviousFlag>
 *  $ARGUMENTS$
 *       <hsTable> a hash table, created by HB_HASH()
 *
 *       <lFlag> a logical value indicating to turn on or off
 *       the 'auto add' flag of the hash table
 *  $RETURNS$
 *       The previous value of the 'auto add' flag
 *  $DESCRIPTION$
 *       This function is equivalent to HB_HAUTOADD() but it returns
 *       the old flag value rather than the hash table
 *  $EXAMPLES$
 *       LOCAL hsTable, lFlag
 *       hsTable := HB_HASH( "one", 1, "two", 2 )
 *       // turn 'auto add' on for a new hash table, storing ol flag
 *       lFlag := HB_HAUTOADD( hsTable, .T. )
 *  $TESTS$
 *
 *  $STATUS$
 *      R
 *  $COMPLIANCE$
 *      H
 *  $PLATFORMS$
 *
 *  $FILES$
 *
 *  $SEEALSO$
 *      HB_HSETAUTOADD()
 *  $END$
 */

/*  $DOC$
 *  $TEMPLATE$
 *       Procedure
 *  $NAME$
 *       HB_HALLOCATE()
 *  $CATEGORY$
 *       API
 *  $SUBCATEGORY$
 *       Hash table
 *  $ONELINER$
 *       Preallocates a hash table
 *  $SYNTAX$
 *       HB_HALLOCATE( <hsTable>, <nItems> )
 *  $ARGUMENTS$
 *       <hsTable> a hash table, created by HB_HASH()
 *
 *       <nItems> number of items to preallocate in the hash table
 *  $DESCRIPTION$
 *
 *  $EXAMPLES$
 *
 *  $TESTS$
 *
 *  $STATUS$
 *      R
 *  $COMPLIANCE$
 *      H
 *  $PLATFORMS$
 *
 *  $FILES$
 *
 *  $SEEALSO$
 *
 *  $END$
 */

/*  $DOC$
 *  $TEMPLATE$
 *       Function
 *  $NAME$
 *       HB_HDEFAULT()
 *  $CATEGORY$
 *       API
 *  $SUBCATEGORY$
 *       Hash table
 *  $ONELINER$
 *       Returns/sets a default value for a hash table.
 *  $SYNTAX$
 *       HB_HDEFAULT( <hsTable>, <DefaultValue> ) -> <OldDefaultValye>
 *  $ARGUMENTS$
 *       <hsTable> a hash table, created by HB_HASH()
 *
 *       <DefaultValue>
 *  $RETURNS$
 *       The previous default value assigned to the hash table
 *  $DESCRIPTION$
 *
 *  $EXAMPLES$
 *
 *  $TESTS$
 *
 *  $STATUS$
 *      R
 *  $COMPLIANCE$
 *      H
 *  $PLATFORMS$
 *
 *  $FILES$
 *
 *  $SEEALSO$
 *      TODO: locate and list those methods that use this feature
 *  $END$
 */

/*  $DOC$
 *  $TEMPLATE$
 *       Function
 *  $NAME$
 *       HB_HSETAUTOADD()
 *  $CATEGORY$
 *       API
 *  $SUBCATEGORY$
 *       Hash table
 *  $ONELINER$
 *       Sets the 'auto add' flag for the hash table
 *  $SYNTAX$
 *       HB_HSETAUTOADD( <hsTable>, [<lFlag>] ) -> <hsTable>
 *  $ARGUMENTS$
 *       <hsTable> a hash table, created by HB_HASH()
 *
 *       <lFlag> a logical value indicating to turn on or off
 *       the 'auto add' flag of the hash table
 *  $RETURNS$
 *       The hash table
 *  $DESCRIPTION$
 *       This function is equivalent to HB_HAUTOADD() but it returns
 *       the passed hash table rather than the old flag value
 *  $EXAMPLES$
 *       LOCAL hsTable
 *       // turn 'auto add' on for a new hash table
 *       hsTable := HB_HSETAUTOADD( HB_HASH( "one", 1, "two", 2 ), .T. )
 *  $TESTS$
 *
 *  $STATUS$
 *      R
 *  $COMPLIANCE$
 *      H
 *  $PLATFORMS$
 *
 *  $FILES$
 *
 *  $SEEALSO$
 *      HB_HAUTOADD(),HB_HSETBINARY(),HB_HSETCASEMATCH()
 *  $END$
 */

/*  $DOC$
 *  $TEMPLATE$
 *       Function
 *  $NAME$
 *       HB_HSETCASEMATCH()
 *  $CATEGORY$
 *       API
 *  $SUBCATEGORY$
 *       Hash table
 *  $ONELINER$
 *       Sets the 'case match' flag for the hash table
 *  $SYNTAX$
 *       HB_HSETCASEMATCH( <hsTable>, [<lFlag>] ) -> <hsTable>
 *  $ARGUMENTS$
 *       <hsTable> a hash table, created by HB_HASH()
 *
 *       <lFlag> a logical value indicating to turn on or off
 *       the 'case match' flag of the hash table
 *  $RETURNS$
 *       The hash table
 *  $DESCRIPTION$
 *       This function is equivalent to HB_HCASEMATCH() but it returns
 *       the passed hash table rather than the old flag value
 *  $EXAMPLES$
 *       LOCAL hsTable
 *       // turn 'case match' on for a new hash table
 *       hsTable := HB_HSETCASEMATCH( HB_HASH( "one", 1, "two", 2 ), .T. )
 *  $TESTS$
 *
 *  $STATUS$
 *      R
 *  $COMPLIANCE$
 *      H
 *  $PLATFORMS$
 *
 *  $FILES$
 *
 *  $SEEALSO$
 *      HB_HCASEMATCH(),HB_HSETAUTOADD(),HB_HSETBINARY
 *  $END$
 */

/*  $DOC$
 *  $TEMPLATE$
 *       Function
 *  $NAME$
 *       HB_HSETBINARY()
 *  $CATEGORY$
 *       API
 *  $SUBCATEGORY$
 *       Hash table
 *  $ONELINER$
 *       Sets the 'binary' flag for the hash table
 *  $SYNTAX$
 *       HB_HSETBINARY( <hsTable>, [<lFlag>] ) -> <hsTable>
 *  $ARGUMENTS$
 *       <hsTable> a hash table, created by HB_HASH()
 *
 *       <lFlag> a logical value indicating to turn on or off
 *       the 'binary' flag of the hash table
 *  $RETURNS$
 *       The hash table
 *  $DESCRIPTION$
 *       This function is equivalent to HB_HBINARY() but it returns
 *       the passed hash table rather than the old flag value
 *  $EXAMPLES$
 *       LOCAL hsTable
 *       // turn 'binary' on for a new hash table
 *       hsTable := HB_HSETBINARY( HB_HASH( "one", 1, "two", 2 ), .T. )
 *  $TESTS$
 *
 *  $STATUS$
 *      R
 *  $COMPLIANCE$
 *      H
 *  $PLATFORMS$
 *
 *  $FILES$
 *
 *  $SEEALSO$
 *      HB_HBINARY(),HB_HSETAUTOADD(),HB_HSETCASEMATCH
 *  $END$
 */