kbmmemtable.pas

内存表控件 kbmMemTable

unit kbmMemTable;

interface

{$include kbmMemTable.inc}

uses
  SysUtils,
  Classes,
  DB,
  DBCommon
{$IFDEF LINUX}
  ,Types
  ,Libc
{$ELSE}
  ,Windows
{$ENDIF}
{$IFDEF LEVEL5}
  ,SyncObjs
  ,Masks
{$ENDIF}
{$IFDEF LEVEL6}
  ,variants
  ,fmtbcd
  ,SqlTimSt
{$ENDIF};

{$B-}    // Enable short circuit evaluation.

// kbmMemTable v. 3.07
const COMPONENT_VERSION = '3.07';
// =========================================================================
// An inmemory temporary table.
// Can be used as a demonstration of how to create descendents of TDataSet,
// or as in my case, to allow a program to generate temporary data that can
// be used directly by all data aware controls.
//
// Copyright 1999,2000,2001 Kim Bo Madsen/Components4Developers DK
// All rights reserved.
//
// LICENSE AGREEMENT
// PLEASE NOTE THAT THE LICENSE AGREEMENT HAS CHANGED!!! 16. Feb. 2000
//
// You are allowed to use this component in any project for free.
// You are NOT allowed to claim that you have created this component or to
// copy its code into your own component and claim that it was your idea.
//
// -----------------------------------------------------------------------------------
// IM OFFERING THIS FOR FREE FOR YOUR CONVINIENCE, BUT
// YOU ARE REQUIRED TO SEND AN E-MAIL ABOUT WHAT PROJECT THIS COMPONENT (OR DERIVED VERSIONS)
// IS USED FOR !
// -----------------------------------------------------------------------------------
//
// -----------------------------------------------------------------------------------
// PLEASE NOTE THE FOLLOWING ADDITION TO THE LICENSE AGREEMENT:
// If you choose to use this component for generating middleware libraries (with similar
// functionality as dbOvernet, Midas, Asta etc.), those libraries MUST be released as
// Open Source and Freeware!
// -----------------------------------------------------------------------------------
//
// You dont need to state my name in your software, although it would be
// appreciated if you do.
//
// If you find bugs or alter the component (f.ex. see suggested enhancements
// further down), please DONT just send the corrected/new code out on the internet,
// but instead send it to me, so I can put it into the official version. You will
// be acredited if you do so.
//
//
// DISCLAIMER
// By using this component or parts theirof you are accepting the full
// responsibility of the use. You are understanding that the author cant be
// made responsible in any way for any problems occuring using this component.
// You also recognize the author as the creator of this component and agrees
// not to claim otherwize!
//
// Please forward corrected versions (source code ONLY!), comments,
// and emails saying you are using it for this or that project to:
//            [e-mail]
//
// Latest version can be found at:
//            http://www.components4developers.com
//
// Suggestions for future enhancements:
//
//      - IDE designer for adding static data to the memtable.
//      - Optimized sorting. Combosort, many way mergesort or the like for large datasets.
//      - Swap functionality for storing parts of an active table on disk for
//        preserving memory.
//
// History:
//
//1.00:	The first release. Was created due to a need for a component like this.
//                                                                    (15. Jan. 99)
//1.01:	The first update. Release 1.00 contained some bugs related to the ordering
//	    of records inserted and to bookmarks. Problems fixed.         (21. Jan. 99)

//1.02:	Fixed handling of NULL values. Added SaveToStream, SaveToFile,
//	    LoadFromStream and LoadFromFile. SaveToStream and SaveToFile is controlled
//	    by a flag telling if to save data, contents of calculated fields,
//	    contents of lookupfields and contents of non visible fields.
//	    Added an example application with Delphi 3 source code.       (26. Jan. 99)
//
//1.03: Claude Rieth from Computer Team sarl ([e-mail]) came up with an
//      implementation of CommaText and made a validation check in _InternalInsert.
//      Because I allready have implemented the saveto.... functions, I decided
//      to implement Claude's idea using my own saveto.... functions. (27. Jan. 99)
//      I have decided to rename the component, because Claude let me know that
//      the RX library have a component with the same name as this.
//      Thus in the future the component will be named TkbmMemTable.
//      SaveToStream and LoadFromStream now set up date and decimal separator
//      temporary to make sure that the data saved can be loaded on another
//      installation with different date and decimal separator setups.
//      Added EmptyTable method to clear the contents of the memory table.
//
//1.04: Wagner ADP ([e-mail]) found a bug in the _internalinsert
//      procedure which he came up with a fix for.                     (4. Feb. 99)
//      Added support for the TDataset protected function findrecord.
//      Added support for CreateTable, DeleteTable.
//
//1.05: Charlie McKeegan from Task Software Limited ([e-mail]) found
//      a minor bug (and came up with a fix) in SetRecNo which mostly is
//      noticeable in a grid where the grid wont refresh when the record slider
//      is moved to the end of the recordset.                          (5. Feb. 99)
//      Changed SaveToStream to use the displayname of the field as the header
//      instead of the fieldname.
//
//1.06: Introduced a persistence switch and a reference to a file. If the
//      persistence switch is set, the file will be read aut. on table open,
//      and the contents of the table will be saved in the table on table close.
//
//1.07: Changed calculation of fieldofsets in InternalOpen to follow the fielddefs
//      instead of fields. It has importance when rearranging fields.
//      Because of this change the calculation of fieldoffsets into the buffer
//      has been changed too. These corrections was found to be needed to
//      support the new components tkbmPooledQuery and tkbmPooledStoredProc
//      (found in the package tkbmPooledConn)
//      which in turn handles pooled connections to a database. Very usefull
//      in f.ex a WWW application as they also makes the BDE function threadsafe,
//      and limits the concurrent connections to a database.
//
//1.08: Changed buffer algorithm in GetLine since the old one was faulty.
//      Problem was pointed out by: Markus [e-mail]
//