unit UCS4Helper;
{$mode objfpc}{$H+}{$modeswitch typehelpers}
// Unit UCS4Helper by Jorg3000, Version 1.0 from 2023-12-24
interface
type
{ TUCS4Helper }
TUCS4Helper = type helper for UCS4String
function GetLength: SizeInt;
procedure SetLength(NewLen: SizeInt);
procedure SetStr(const s: String); overload;
procedure SetStr(const ws: WideString); inline;
procedure SetStr(const ws: UnicodeString); inline;
procedure Add(const s: String); overload;
procedure Add(const us: UCS4String);
function CharAsUtf8(i: SizeInt): String;
procedure SetChar(i: SizeInt; const s: String);
function toUtf8: String;
function toUtf16: UnicodeString; inline;
function Copy(Index, Len: SizeInt): UCS4String;
function CopyAsUtf8(Index, Len: SizeInt): String;
procedure Delete(Index, Len: SizeInt);
procedure Insert(const Source: String; Index: SizeInt); overload;
procedure Insert(const Source: UCS4String; Index: SizeInt);
function Pos(const s: String; Offset: SizeInt=1): SizeInt; overload;
function Pos(const us: UCS4String; Offset: SizeInt=1): SizeInt;
property Length: SizeInt read GetLength write SetLength;
property Chars[i: SizeInt]: String read CharAsUtf8 write SetChar; // "default" funzt nicht weil UCS4String = Array
end;
implementation
{ TUCS4Helper }
function TUCS4Helper.GetLength: SizeInt;
begin
Result:=System.Length(self);
if Result>0 then dec(Result);
end;
procedure TUCS4Helper.SetLength(NewLen: SizeInt);
var OldLen: SizeInt;
begin
if NewLen<=0 then begin self:=nil; Exit; end;
OldLen:=self.GetLength;
if OldLen=NewLen then Exit;
System.SetLength(self,NewLen+1);
self[NewLen]:=0;
end;
procedure TUCS4Helper.SetStr(const s: String);
begin
if s='' then self:=nil
else self:=WideStringToUCS4String(WideString(s));
end;
procedure TUCS4Helper.SetStr(const ws: WideString);
begin
self:=WideStringToUCS4String(ws);
end;
procedure TUCS4Helper.SetStr(const ws: UnicodeString);
begin
self:=UnicodeStringToUCS4String(ws);
end;
procedure TUCS4Helper.Add(const s: String);
begin
self.Add( WideStringToUCS4String(WideString(s)) );
end;
procedure TUCS4Helper.Add(const us: UCS4String);
var Len1, Len2: SizeInt;
begin
Len2:=System.Length(us)-1;
if Len2<=0 then Exit;
Len1:=System.Length(self)-1;
if Len1<=0 then begin self:=us; Exit; end;
System.SetLength(self,Len1+Len2+1);
Move( us[0], self[Len1], (Len2+1)*SizeOf(UCS4Char) );
end;
procedure decodeUCS4Char(c4: UCS4Char; out w1, w2: WideChar); // ähnlich wie in ustrings.inc:UCS4Decode()
begin
w2:=#0; // default for 1 UTF16 codepoint only
if c4<=$ffff then begin w1:=WideChar(Lo(c4)); Exit; end;
if DWord(c4)>$10ffff then begin w1:='?'; Exit; end; // invalid codepoint
w1:=WideChar(c4 shr 10 + $d7c0);
w2:=WideChar(c4 and $3ff + $dc00);
end;
function TUCS4Helper.CharAsUtf8(i: SizeInt): String;
var c4: UCS4Char;
w1, w2: WideChar;
ws: WideString;
begin
c4:=self[i-1];
if c4<128 then begin System.SetLength(Result,1); Result[1]:=Char(c4); Exit; end; // shortcut for ASCII
decodeUCS4Char(c4,{out}w1,w2);
if w2=#0 then begin System.SetLength(ws,1); ws[1]:=w1; end
else begin System.SetLength(ws,2); ws[1]:=w1; ws[2]:=w2; end;
Result:=UTF8Encode(ws);
end;
procedure TUCS4Helper.SetChar(i: SizeInt; const s: String);
var us: UCS4String;
Len2: SizeInt;
begin
us:=WideStringToUCS4String(WideString(s));
Len2:=System.Length(us)-1;
if Len2<=0 then Exit;
self[i-1]:=us[0];
end;
function TUCS4Helper.toUtf8: String;
begin
Result:=UTF8Encode(UCS4StringToWideString(self));
end;
function TUCS4Helper.toUtf16: UnicodeString; inline;
begin
Result:=UCS4StringToUnicodeString(self);
end;
function TUCS4Helper.Copy(Index, Len: SizeInt): UCS4String;
var Len1, Len2: SizeInt;
begin
if (Index<=0) or (Len<=0) then Exit;
Len1:=self.GetLength;
Len2:=Len1+1-Index; // maximal mögliche Länge ab Index
if Len2<=0 then Exit;
if Len<Len2 then Len2:=Len;
System.SetLength(Result,Len2+1);
Move( self[Index-1], Result[0], Len2*SizeOf(UCS4Char) );
Result[Len2]:=0;
end;
function TUCS4Helper.CopyAsUtf8(Index, Len: SizeInt): String;
begin
Result:=UTF8Encode(UCS4StringToWideString( self.Copy(Index,Len) ));
end;
procedure TUCS4Helper.Delete(Index, Len: SizeInt);
var Len1, Len2: SizeInt;
begin
if (Index<=0) or (Len<=0) then Exit;
Len1:=self.GetLength;
if (Len1<=0) or (Index>Len1) then Exit;
Len2:=Len1+1-Index; // maximal mögliche Länge ab Index
if Len2<=0 then Exit;
if Len<Len2 then Len2:=Len;
System.Delete(self,Index-1,Len2);
// Move( self[Index+Len2-1], self[Index-1], (Len2+1)*SizeOf(UCS4Char) );
// System.SetLength(self,Index+Len2);
end;
procedure TUCS4Helper.Insert(const Source: String; Index: SizeInt);
begin
self.Insert( WideStringToUCS4String(WideString(Source)), Index);
end;
procedure TUCS4Helper.Insert(const Source: UCS4String; Index: SizeInt);
var Len2: SizeInt;
begin
if Index<=0 then Exit;
Len2:=Source.GetLength;
if Len2<=0 then Exit;
System.Insert(Source,{var}self,Index-1);
System.Delete({var}self,Index-1+Len2,1); // remove the terminating zero of Source
end;
function TUCS4Helper.Pos(const s: String; Offset: SizeInt=1): SizeInt;
begin
Result:=self.Pos( WideStringToUCS4String(WideString(s)), Offset );
end;
function TUCS4Helper.Pos(const us: UCS4String; Offset: SizeInt=1): SizeInt;
var i, Len1, Len2, Len2Bytes: SizeInt;
begin
Result:=0;
Len1:=System.Length(self)-1;
if Len1<=0 then Exit{0};
Len2:=System.Length(us)-1;
if Len2<=0 then Exit{0};
if Offset<1 then Offset:=1;
dec(Offset);
if Len2>Len1-Offset then Exit{0};
Len2Bytes:=Len2*SizeOf(UCS4Char);
// note "dec(Offset)" see above => e.g. Offset=0
for i:=Offset to Len1-Len2 do
if CompareByte(us[0],self[i],Len2Bytes)=0 then Exit(i+1);
end;
end.
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