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{
Some handly UTF8 function copied from the Lazarus LCL. Comes from the LCLProc
unit.Surely we can move this into FPC?
}
unit gfx_UTF8utils;
{$mode objfpc}{$H+}
interface
uses
Classes, SysUtils;
function UTF8Pos(const SearchForText, SearchInText: string): integer;
function UTF8Copy(const s: string; StartCharIndex, CharCount: integer): string;
function UTF8Length(const s: string): integer;
function UTF8Length(p: PChar; ByteCount: integer): integer;
function UTF8CharStart(UTF8Str: PChar; Len, Index: integer): PChar;
function UTF8CharacterLength(p: PChar): integer;
procedure UTF8Insert(const Source: string; var S: string; Index: integer);
procedure UTF8Delete(var S: string; Index, Size: integer);
implementation
// returns the character index, where the SearchForText starts in SearchInText
function UTF8Pos(const SearchForText, SearchInText: string): integer;
var
p: LongInt;
begin
p := System.Pos(SearchForText, SearchInText);
if p > 0 then
Result := UTF8Length(PChar(SearchInText), p-1) + 1
else
Result := 0;
end;
// returns substring
function UTF8Copy(const s: string; StartCharIndex, CharCount: integer): string;
var
StartBytePos: PChar;
EndBytePos: PChar;
MaxBytes: PtrInt;
begin
StartBytePos := UTF8CharStart(PChar(s),length(s),StartCharIndex-1);
if StartBytePos = nil then
Result := ''
else
begin
MaxBytes := PtrInt(PChar(s)+length(s)-StartBytePos);
EndBytePos := UTF8CharStart(StartBytePos,MaxBytes,CharCount);
if EndBytePos = nil then
Result := copy(s,StartBytePos-PChar(s)+1,MaxBytes)
else
Result := copy(s,StartBytePos-PChar(s)+1,EndBytePos-StartBytePos);
end;
end;
function UTF8Length(const s: string): integer;
begin
Result := UTF8Length(PChar(s),length(s));
end;
function UTF8Length(p: PChar; ByteCount: integer): integer;
var
CharLen: LongInt;
begin
Result := 0;
while (ByteCount > 0) do
begin
inc(Result);
CharLen := UTF8CharacterLength(p);
inc(p, CharLen);
dec(ByteCount, CharLen);
end;
end;
function UTF8CharStart(UTF8Str: PChar; Len, Index: integer): PChar;
var
CharLen: LongInt;
begin
Result := UTF8Str;
if Result <> nil then
begin
while (Index > 0) and (Len > 0) do
begin
CharLen := UTF8CharacterLength(Result);
dec(Len, CharLen);
dec(Index);
inc(Result, CharLen);
end;
if (Index > 0) or (Len < 0) then
Result := nil;
end;
end;
function UTF8CharacterLength(p: PChar): integer;
begin
if p <> nil then
begin
if ord(p^) < %11000000 then
begin
// regular single byte character (#0 is a character, this is pascal ;)
Result:=1;
end
else if ((ord(p^) and %11100000) = %11000000) then
begin
// could be 2 byte character
if (ord(p[1]) and %11000000) = %10000000 then
Result := 2
else
Result := 1;
end
else if ((ord(p^) and %11110000) = %11100000) then
begin
// could be 3 byte character
if ((ord(p[1]) and %11000000) = %10000000)
and ((ord(p[2]) and %11000000) = %10000000) then
Result:=3
else
Result:=1;
end
else if ((ord(p^) and %11111000) = %11110000) then
begin
// could be 4 byte character
if ((ord(p[1]) and %11000000) = %10000000)
and ((ord(p[2]) and %11000000) = %10000000)
and ((ord(p[3]) and %11000000) = %10000000) then
Result:=4
else
Result:=1;
end
else
Result:=1;
end
else
Result:=0;
end;
procedure UTF8Insert(const Source: string; var S: string; Index: integer);
var
b: string;
e: string;
begin
if UTF8Length(Source) = 0 then
Exit; //==>
b := UTF8Copy(S, 1, Index-1); // beginning string
e := UTF8Copy(S, Index, UTF8Length(S)-Index+1); // ending string
S := b + Source + e;
end;
procedure UTF8Delete(var S: string; Index, Size: integer);
var
ls: integer;
b: string;
e: string;
begin
ls := UTF8Length(S);
if (Index > ls) or (Index <= 0) or (Size <= 0) then
Exit; //==>
b := UTF8Copy(S, 1, Index-1); // beginning string
e := UTF8Copy(S, Index+Size, UTF8Length(S)-(Index+Size-1)); // ending string
S := b + e;
end;
end.
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