Fast Pascal String

function Wee(str: string): string;
var
  h, i: Integer;
  s, r: string;
begin
  if (Length(str) > 1) then
  begin
    s := '0'#0 'a'#7 'b'#8 't'#9 'n'#10 'f'#12 'r'#13 'e'#27;
    h := (Length(s) div 2);
    r := #0'[R%B%S]'#0;
    Result := Replace(str, '\\', r, [rfReplaceAll]);
    for i := 1 to h do
      Result := Replace(Result, ('\' + s[((i * 2) - 1)]), s[(i * 2)], [rfReplaceAll]);
    Result := Replace(Result, r, '\', [rfReplaceAll]);
  end;
end;

function Wee2(str: string): string;
var
  b, h, i, l, p, c, q: Integer;
  s, r, t, z: string;
begin
  Result := '';
  if (Length(str) > 1) then
  begin
    s := '0abtnfre'#0#7#8#9#10#12#13#27;
    h := (Length(s) div 2);
    r := #0'[R%B%S]'#0;
    c := 0;
    p := 0;
    b := 1;
    z := Replace(str, '\\', r, [rfReplaceAll]);
    l := (Length(z) - 1);
    repeat
      p := (p + 1);
      if (z[p] = '\') then
      begin
        q := (p + 1);
        for i := 1 to h do
          if (z[q] = s[i]) then
          begin
            if (c > 0) then
              Result := (Result + Copy(z, b, c));
            Result := (Result + s[(i + h)]);
            p := q;
            b := (p + 1);
            c := -1;
            Break;
          end;
      end;
      c := (c + 1);
    until (p >= l);
    Result := (Result + Copy(z, b, (c + 1)));
    Result := Replace(Result, r, '\', [rfReplaceAll]);
  end;
end;


function Wee3(Str: string): String;
var
  hi,i,j,k,hipat: Integer;
  ptrn, repl: TCharArray;
  prev,next: Char;
  DidRep: Boolean;
begin
  Result := '';
  if (Length(str) > 1) then
  begin
    ptrn := ['0','a','b','t','n','f','r','e'];
    repl := [#0, #7, #8, #9, #10,#12,#13,#27];
    hipat := High(ptrn);
    Hi := Length(Str);
    SetLength(Result, (Hi+1));
    prev := ' ';
    k := 1;
    i := 1;
    repeat
      DidRep := False;
      if (Str[i] = '\') then
        if (Prev = '\') then
          Inc(i)
        else begin
          next := Str[i+1];
          for j := 0 to HiPat do
            if (next = ptrn[j]) then
            begin
              Result[k] := repl[j];
              Inc(k);
              DidRep := True;
              i := i+2;
              break;
            end;
          if DidRep then Continue;
        end;
      Result[k] := Str[i];
      prev := Str[i];
      Inc(k);
      Inc(i);
    until (i > Hi);
    SetLength(Result, k-1);
  end else
    Result := Str[1];
end;

var
  t: Integer;
  str, data: string;

begin
  data := 'Test \r\n Wtf \\n Wee\r\n';
  for t := 0 to 13 do
    data := (data + data);
  WriteLn(Length(data));
  t := GetSystemTime;
  str := Wee2(data);
  WriteLn('Wee2 - ' + IntToStr(Length(str)) + ': ' + IntToStr(GetSystemTime - t) + ' ms. [' + MD5(str) + ']');
  str := '';
  t := GetSystemTime;
  str := Wee(data);
  WriteLn('Wee - ' + IntToStr(Length(str)) + ': ' + IntToStr(GetSystemTime - t) + ' ms. [' + MD5(str) + ']');
  t := GetSystemTime;
  str := Wee3(data);
  WriteLn('Wee3 - ' + IntToStr(Length(str)) + ': ' + IntToStr(GetSystemTime - t) + ' ms. [' + MD5(str) + ']');
end.