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unit dbf_idxcur;
interface
{$I dbf_common.inc}
uses
SysUtils,
Classes,
db,
dbf_cursor,
dbf_idxfile,
dbf_prsdef,
{$ifndef WINDOWS}
dbf_wtil,
{$endif}
dbf_common;
type
//====================================================================
//=== Index support
//====================================================================
TIndexCursor = class(TVirtualCursor)
private
FIndexFile: TIndexFile;
protected
function GetPhysicalRecNo: Integer; override;
function GetSequentialRecNo: Integer; override;
function GetSequentialRecordCount: Integer; override;
procedure SetPhysicalRecNo(RecNo: Integer); override;
procedure SetSequentialRecNo(RecNo: Integer); override;
procedure VariantStrToBuffer(Key: Variant; ABuffer: TRecordBuffer);
public
constructor Create(DbfIndexFile: TIndexFile);
destructor Destroy; override;
function Next: Boolean; override;
function Prev: Boolean; override;
procedure First; override;
procedure Last; override;
procedure Insert(RecNo: Integer; Buffer: TRecordBuffer);
procedure Update(RecNo: Integer; PrevBuffer, NewBuffer: TRecordBuffer);
{$ifdef SUPPORT_VARIANTS}
function VariantToBuffer(Key: Variant; ABuffer: TRecordBuffer): TExpressionType;
{$endif}
function CheckUserKey(Key: PChar; StringBuf: PChar): PChar;
property IndexFile: TIndexFile read FIndexFile;
end;
//====================================================================
// TIndexCursor = class;
//====================================================================
PIndexPosInfo = ^TIndexPage;
//====================================================================
implementation
{$ifdef WINDOWS}
uses
Windows;
{$endif}
//==========================================================
//============ TIndexCursor
//==========================================================
constructor TIndexCursor.Create(DbfIndexFile: TIndexFile);
begin
inherited Create(DbfIndexFile);
FIndexFile := DbfIndexFile;
end;
destructor TIndexCursor.Destroy; {override;}
begin
inherited Destroy;
end;
procedure TIndexCursor.Insert(RecNo: Integer; Buffer: TRecordBuffer);
begin
TIndexFile(PagedFile).Insert(RecNo,Buffer);
// TODO SET RecNo and Key
end;
procedure TIndexCursor.Update(RecNo: Integer; PrevBuffer, NewBuffer: TRecordBuffer);
begin
TIndexFile(PagedFile).Update(RecNo, PrevBuffer, NewBuffer);
end;
procedure TIndexCursor.First;
begin
TIndexFile(PagedFile).First;
end;
procedure TIndexCursor.Last;
begin
TIndexFile(PagedFile).Last;
end;
function TIndexCursor.Prev: Boolean;
begin
Result := TIndexFile(PagedFile).Prev;
end;
function TIndexCursor.Next: Boolean;
begin
Result := TIndexFile(PagedFile).Next;
end;
function TIndexCursor.GetPhysicalRecNo: Integer;
begin
Result := TIndexFile(PagedFile).PhysicalRecNo;
end;
procedure TIndexCursor.SetPhysicalRecNo(RecNo: Integer);
begin
TIndexFile(PagedFile).PhysicalRecNo := RecNo;
end;
function TIndexCursor.GetSequentialRecordCount: Integer;
begin
Result := TIndexFile(PagedFile).SequentialRecordCount;
end;
function TIndexCursor.GetSequentialRecNo: Integer;
begin
Result := TIndexFile(PagedFile).SequentialRecNo;
end;
procedure TIndexCursor.SetSequentialRecNo(RecNo: Integer);
begin
TIndexFile(PagedFile).SequentialRecNo := RecNo;
end;
{$ifdef SUPPORT_VARIANTS}
procedure TIndexCursor.VariantStrToBuffer(Key: Variant; ABuffer: TRecordBuffer);
var
currLen: Integer;
StrKey: string;
begin
StrKey := Key;
currLen := TranslateString(GetACP, FIndexFile.CodePage, PAnsiChar(StrKey), PAnsiChar(ABuffer), -1);
// we have null-terminated string, pad with spaces if string too short
FillChar(ABuffer[currLen], TIndexFile(PagedFile).KeyLen-currLen, ' ');
end;
function TIndexCursor.VariantToBuffer(Key: Variant; ABuffer: TRecordBuffer): TExpressionType;
// assumes ABuffer is large enough ie. at least max key size
begin
if (TIndexFile(PagedFile).KeyType='N') then
begin
PDouble(ABuffer)^ := Key;
if (TIndexFile(PagedFile).IndexVersion <> xBaseIII) then
begin
// make copy of userbcd to buffer
Move(TIndexFile(PagedFile).PrepareKey(ABuffer, etFloat)[0], ABuffer[0], 11);
end;
Result := etInteger;
end else begin
VariantStrToBuffer(Key, ABuffer);
Result := etString;
end;
end;
{$endif}
function TIndexCursor.CheckUserKey(Key: PChar; StringBuf: PChar): PChar;
var
keyLen, userLen: Integer;
begin
// default is to use key
Result := Key;
// if key is double, then no check
if (TIndexFile(PagedFile).KeyType = 'N') then
begin
// nothing needs to be done
end else begin
// check if string long enough then no copying needed
userLen := StrLen(Key);
keyLen := TIndexFile(PagedFile).KeyLen;
if userLen < keyLen then
begin
// copy string
Move(Key^, StringBuf[0], userLen);
// add spaces to searchstring
FillChar(StringBuf[userLen], keyLen - userLen, ' ');
// set buffer to temporary buffer
Result := StringBuf;
end;
end;
end;
end.
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