TMapTextfile v.99/1
Class to handle text files as memory mapped files.
Including efficient methodes for access like sequentiell read
or random access read to text, high performance search routines
and many more.
{ ============================================================================== MapTextfiles - Release 99/1 14.03.1999 for Delphi 4, should also run with Delphi 3 ------------------------------------------------------------------------------ MapTextfiles is FREEWARE. Freeware means, that you can use this software without paying anything for it, but it is not public domain! This software is protected through the law of the Federal Republic of Germany, the European Union and other countries. (C)1999 by Peter Hellinger Software, All rights are reserved. Peter Hellinger Software, Zerzabelshofstrasse 41, D-90480 N黵nberg email: mail@helli.de homepage: http://www.helli.de ============================================================================== Installation: Copy MAPTEXTFILE.PAS into your library path. Use ist. 8-) ------------------------------------------------------------------------------ In Delphi you have many ways to manipulate text files. But all of these have a handicap: You must read the whole file (StringList) or you can only access data sequential (Assign/Readln). The Windows API provides the so called Memory Mapped Files. Windows self uses MMFs to load EXE or DLL. Therefore the mechanism is very efficient, but simple to handle. The only handicap is, that you must know the size of the file before you access it. This means for typical text files, that the operation is normally limited to read from the file or manipulate inside. The class TMapTextfile wraps the neccesary API calls and povides efficent functions for accessing the data. TMapTextfiles provides the following properties and methods: Methodes: ========= Create Creates an instace of the class Destroy Destroys the instance Open Opens a file as a memory mapped file. filename = name of the file mode = open mode: mmRead = Open only for read mmReadWrite = Open for read and wrie Returns INVALID_HANDLE_VALUE if the file not exist. If the result > 0 all is OK. NOTE: 1. The file must exist! 2. You cannot write behind the end of the file. Close Close the memory mapped file and frees all handles. EndOfFile Returns TRUE, if the End of the file is reached. GetSize Returns the Size of the file in Bytes GetPos Returns the actual file read/write position NOTE: Position 0 is the start of the file SetPos Sets the actual read/write position NOTE: Position 0 is the start of the file ReadChar Reads a character from the actual read/write position. The r/w position is incremented. ReadString Returns a string, starting at the actual r/w position. The string is delimited by characters < SPACE, but not by ESC (#27) and TAB. The r/w position moves to the end of the string, delimiter chararcters are skiped. ReadLn Same as ReadSring, but as a Procedure. ReadCharAt Reads a charater from an arbitray possition. The r/w position is NOT moved! pos = position to read from (0 = start of the file!) ReadChars Reads a line of charactes from the MMF. The r/w position is NOT moved! str = The buffer to read to pos = position to read from (0 = Start of the file!) len = number of characters to read. ReadStringAt Returns a string, starting at an arbitray possition. The string is delimited by characters < SPACE, but not by ESC (#27) and TAB. The r/w position is NOT moved. FindString Findes a substring in the MMF and Returns the position. str = rhe substring to search for pos = position to start the search (0 = start of the file) max = position to end the search. If this is 0 or less then 0 the end of the file is the limit. Returns the position of the substring or -1 if the substring is not found. FindWildCard Same as Findstring, but supports wildcard search. str = the substring to search for pos = position to start the search (0 = start of the file) max = position to end the search. If this is 0 or less then 0 the end of the file is the limit. wild = the character used as wildcard (i.e. "*") joker = the character used as joker (i.e. "?") Returns the position of the substring or -1 if the substring is not found. ReadBytes Reads a number of bytes to a anonymous variable. The r/w position is NOT moved! b = the anonymous variable pos = position to read from (0 = start of the file) len = number of bytes to read. WriteBytes Writes a number of bytes to the file. NOTE: You can not write behind the end of the file!!! b = the anonymous variable pos = position to write to (0 = start of the file) len = number of bytes to write ============================================================================== } unit uMapTextfile; interface uses Classes, Windows; type tMapMode = ( mmRead, mmReadWrite ); type TMapTextfile = class private f_file : THandle; f_MMF : THandle; f_size : INTEGER; f_view : PByte; f_data : PChar; f_pos : INTEGER; f_open : BOOLEAN; function CalcPos( pos : INTEGER ) : PChar; public constructor Create; destructor Destroy; override; function Open( const filename : string; mode : tMapMode ) : INTEGER; procedure Close; function ReadChar : CHAR; function ReadString : string; procedure ReadLn( var str : string ); function ReadCharAt( pos : LONGINT ) : CHAR; procedure ReadChars( str : PChar; pos, len : LONGINT ); function ReadStringAt( pos : LONGINT ) : string; function GetSize : LONGINT; function GetPos : LONGINT; procedure SetPos( pos : LONGINT ); function EndOfFile : BOOLEAN; function FindString( const str : string; pos, max : INTEGER ) : INTEGER; function FindWildCard( const str : string; pos, max : INTEGER; wild, joker : CHAR ) : INTEGER; procedure ReadBytes( var b; pos, len : LONGINT ); procedure WriteBytes( var b; pos, len : LONGINT ); end; implementation constructor TMapTextfile.Create; begin f_open := FALSE; end; function TMapTextfile.Open( const filename : string; mode : tMapMode ) : INTEGER; var m1, m2, m3 : CARDINAL; begin f_open := FALSE; if mode = mmRead then begin m1 := GENERIC_READ; m2 := PAGE_READONLY; m3 := FILE_MAP_READ; end else begin m1 := GENERIC_READ + GENERIC_WRITE; m2 := PAGE_READWRITE; m3 := FILE_MAP_WRITE; end; f_file := CreateFile( PChar( filename ), m1, FILE_SHARE_READ, nil, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, 0 ); if f_file = INVALID_HANDLE_VALUE then begin Result := INVALID_HANDLE_VALUE; EXIT; end; try f_size := GetFileSize( f_file, nil ); f_MMF := CreateFileMapping( f_file, nil, m2, 0, f_size, nil ); if f_MMF = 0 then begin Result := -1; EXIT; end; finally CloseHandle( f_file ); end; try f_view := MapViewOfFile( f_MMF, m3, 0, 0, f_size ); if f_view = nil then begin Result := -1; EXIT; end; finally CloseHandle( f_MMF ); end; f_data := PChar( f_view ); f_pos := 0; f_open := TRUE; Result := 0; end; destructor TMapTextfile.Destroy; begin if f_open then Close; inherited; end; procedure TMapTextfile.Close; begin if f_open then begin UnmapViewOfFile( f_view ); f_open := FALSE; end; end; function TMapTextfile.CalcPos( pos : INTEGER ) : PChar; begin Result := nil; if f_open then begin if pos < 0 then pos := 0; if pos > f_size then pos := f_size; Result := PChar( LONGINT( f_view ) + pos ); end; end; function TMapTextfile.ReadChar : CHAR; begin Result := #0; if f_open then begin f_data := PChar( LONGINT( f_view ) + f_pos ); Result := f_data^; INC( f_pos ); end; end; function TMapTextfile.ReadString : string; begin Result := ''; if f_open then begin f_data := PChar( LONGINT( f_view ) + f_pos ); while ( f_pos < f_size ) do begin case f_data^ of #0 .. #31 : case f_data^ of #9, #27 : Result := Result + f_data^; // Tab und Escape weiterreichen #10 : begin INC( f_pos ); EXIT; end; #13 : begin // Carriage Return terminiert INC( f_pos ); INC( f_data ); if f_data^ = #10 then INC( f_pos ); EXIT; end; end; else Result := Result + f_data^; end; INC( f_pos ); INC( f_data ); end; end; end; function TMapTextfile.ReadCharAt( pos : LONGINT ) : CHAR; begin if f_open then Result := CalcPos( pos )^ else Result := #0; end; procedure TMapTextfile.ReadChars( str : PChar; pos, len : LONGINT ); var i : INTEGER; p : PChar; begin if f_open then begin if len <= 0 then EXIT; i := 0; p := CalcPos( pos ); while ( i <= f_size ) and ( i <= len ) do begin str^ := p^; INC( str ); INC( p ); INC( i ); end; end; end; procedure TMapTextfile.ReadBytes( var b; pos, len : LONGINT ); var p : PChar; begin if f_open then begin p := CalcPos( pos ); Move( p^, b, len ); end; end; procedure TMapTextfile.WriteBytes( var b; pos, len : LONGINT ); var p : PChar; begin if f_open then begin p := CalcPos( pos ); Move( b, p^, len ); end; end; function TMapTextfile.ReadStringAt( pos : LONGINT ) : string; var i : INTEGER; p : PChar; begin Result := ''; if f_open then begin p := CalcPos( pos ); i := 0; while ( i <= f_size ) do begin case p^ of #0 .. #31 : case p^ of #9, #27 : Result := Result + p^; // Tabs und Escape weiterreichen #10, #13 : EXIT; // Linefeed and Carriage Return terminiert end; else Result := Result + p^; end; INC( p ); end; end; end; procedure TMapTextfile.ReadLn( var str : string ); begin str := ReadString; end; function TMapTextfile.GetSize : LONGINT; begin if f_open then Result := f_size else Result := -1; end; function TMapTextfile.GetPos : LONGINT; begin if f_open then Result := f_pos else Result := -1; end; procedure TMapTextfile.SetPos( pos : LONGINT ); begin if f_open then begin if pos < 0 then pos := 0; if pos > f_size then pos := f_size; f_pos := pos; end; end; function TMapTextfile.EndOfFile : BOOLEAN; begin if f_open then Result := f_pos >= f_size else Result := TRUE; end; function TMapTextfile.FindString( const str : string; pos, max : INTEGER ) : INTEGER; var s, l1, j : INTEGER; p, x : PChar; begin Result := -1; if f_open then begin if max <= 0 then max := f_size; if pos < 0 then pos := f_pos; if pos > max then EXIT; x := PChar( str ); p := PChar( f_view ); l1 := 0; while ( x[ l1 ] > #0 ) do INC( l1 ); if ( l1 > 0 ) then begin s := pos; repeat (* 1 *) j := 0; while ( s + j < max ) and ( j < l1 ) and ( x[ j ] = p[ s + j ] ) do begin INC( j ); if ( j = l1 ) then begin Result := s; EXIT; end; end; INC( s ); until s >= f_size; end; end; end; function TMapTextfile.FindWildCard( const str : string; pos, max : INTEGER; wild, joker : CHAR ) : INTEGER; var s, l1, j : INTEGER; p, x : PChar; begin Result := -1; if f_open then begin if max <= 0 then max := f_size; if pos < 0 then pos := f_pos; if pos > max then EXIT; x := PChar( str ); p := PChar( f_view ); l1 := 0; while ( x[ l1 ] > #0 ) do INC( l1 ); if ( l1 > 0 ) then begin s := pos; repeat (* 1 *) j := 0; while ( s + j < max ) and ( j < l1 ) and ( ( x[ j ] = p[ s + j ] ) or ( x[ j ] = joker ) ) do begin INC( j ); if ( x[ j ] = wild ) or ( j >= l1 ) then begin Result := s; EXIT; end; end; INC( s ); until s >= f_size; end; end; end; end.
