Any TStringBuilder class implementation?

[Thaddy]

Did you all miss:
https://www.freepascal.org/docs-html/rtl/sysutils/tstringbuilder.html
https://www.freepascal.org/daily/doc/rtl/sysutils/tunicodestringbuilder.html
https://www.freepascal.org/daily/doc/rtl/sysutils/tansistringbuilder.html

I hope Micheal does it not take too seriously that you did read the official documentation?

This has already been solved over 12 years ago.
If there are still things missing, the way to go is a feature request.

[bytebites]

Stringbuilder.append(char) is slower than naive string concatenation.

[BeniBela]

Stringbuilder.append(char) is slower than naive string concatenation.

that is why I wrote my own string builder

[Thaddy]

Stringbuilder.append(char) is slower than naive string concatenation.

Even if the capacity is properly set? I did not notice that yet.

[bytebites]

Stringbuilder.append(char) is slower than naive string concatenation.

Even if the capacity is properly set? I did not notice that yet.

It is not relevant.

[Thaddy]

It is not relevant.

Really? Setting the capacity is really relevant for the performance of all Tstringbuilders, even on Delphi, where it is even documented as such.
It avoids re-allocations and that is where the perceived speed loss comes from.
The default capacity is rather low / non-existent.
Note I did not test it thoroughly yet, but it seems there is a considerable performance gain compared to the default when I set it to about 1024 even for longer strings (because the growth factor relies on the initial value).

If you think it is not relevant, please give an example?

[bytebites]

It is not relevant.

Really? Setting the capacity is really relevant for the performance of all Tstringbuilders, even on Delphi, where it is even documented as such.
It avoids re-allocations and that is where the perceived speed loss comes from.
The default capacity is rather low / non-existent.
Note I did not test it thoroughly yet, but it seems there is a considerable performance gain compared to the default when I set it to about 1024 even for longer strings (because the growth factor relies on the initial value).

If you think it is not relevant, please give an example?

Since the problem is poor algorithm for char type.

[Thaddy]

Since the problem is poor algorithm for char type.

Examine the sourcecode: it is not poor, it relies on the buffersize. As it should.
I asked for an example.

[ALLIGATOR]

Code: Pascal  [Select][+][-]

1. program app;
2. {$mode objfpc}{$h+}
3.  
4. uses SysUtils, DateUtils;
5.  
6. const
7.   mem = 4*1024*1024;
8.  
9. var
10.   sb: TStringBuilder;
11.   t: TDateTime;
12.   i, j: Integer;
13.   r, s: AnsiString;
14.  
15. begin
16.   t:=Now;
17.   for i:=1 to 100 do
18.   begin
19.     r:='';
20.     s:=StringOfChar('*', i);
21.     for j:=1 to mem div i do
22.       r:=r+s;
23.   end;
24.   WriteLn('concat: ', MilliSecondsBetween(Now, t));
25.  
26.   t:=Now;
27.   sb:=TStringBuilder.Create;
28.   for i:=1 to 100 do
29.   begin
30.     sb.Length:=1;
31.     sb.Capacity:=1;
32.     s:=StringOfChar('*', i);
33.     for j:=1 to mem div i do
34.       sb.Append(s);
35.   end;
36.   r:=sb.ToString;
37.   sb.Free;
38.   WriteLn('sb: ', MilliSecondsBetween(Now, t));
39.  
40.   ReadLn;
41. end.

Code: Pascal  [Select][+][-]

1. concat: 3206
2. sb: 382

[bytebites]

Test program for a person, who unable to test thoroughly.

Code: Pascal  [Select][+][-]

1. program app;
2. {$mode objfpc}{$h+}
3.  
4. uses SysUtils, DateUtils;
5.  
6. const
7.   c = 10000000;
8.  
9. var
10.   sb: TStringBuilder;
11.   t: TDateTime;
12.   i: Integer;
13.   r: AnsiString;
14.  
15. begin
16.   t:=Now;
17.   r:='';
18.   for i:=1 to c do
19.       r:=r+'e';
20.  
21.   WriteLn('concat: ', MilliSecondsBetween(Now, t));
22.  
23.   t:=Now;
24.   sb:=TStringBuilder.Create;
25.   //sb:=TStringBuilder.Create(c);
26.   for i:=1 to c do
27.       sb.Append('e');
28.   WriteLn('sb: ', MilliSecondsBetween(Now, t));
29.   sb.Free;
30.  
31. end.

[Thaddy]

Please write correct code and start timing correctly:

Code: Pascal  [Select][+][-]

1. program app;
2. {$mode objfpc}{$h+}
3.  
4. uses SysUtils, DateUtils;
5.  
6. const
7.   c = 10000000;
8.  
9. var
10.   sb: TStringBuilder;
11.   t: TDateTime;
12.   i: Integer;
13.   r: AnsiString;
14.  
15. begin
16.   r:='';
17.   t:=Now;
18.   for i:=1 to c do
19.       r:=r+'e';
20.  
21.   WriteLn('concat: ', MilliSecondsBetween(Now, t));
22.  
23.   sb:=TStringBuilder.Create; // default capacity used
24.   t:=Now;
25.   for i:=1 to c do
26.       sb.Append('e');
27.   WriteLn('sb: ', MilliSecondsBetween(Now, t));
28.   sb.Free;
29.  
30. end.

Sb is faster.

[bytebites]

Code: Pascal  [Select][+][-]

1. program app;
2. {$mode objfpc}{$h+}
3.  
4. uses SysUtils, DateUtils;
5.  
6. const
7.   c = 10000000;
8.  
9. var
10.   sb: TStringBuilder;
11.   t: TDateTime;
12.   i: Integer;
13.   r: AnsiString;
14.  
15. begin
16.   t:=Now;
17.   r:='';
18.   for i:=1 to c do
19.       r:=r+'e';
20.  
21.   WriteLn('concat: ', MilliSecondsBetween(Now, t));
22.  
23.   t:=Now;
24.   sb:=TStringBuilder.Create; // default capacity used
25.   for i:=1 to c do
26.       sb.Append('e');
27.   WriteLn('sb default: ', MilliSecondsBetween(Now, t));
28.   sb.Free;
29.  
30.   t:=Now;
31.   sb:=TStringBuilder.Create(c);
32.   for i:=1 to c do
33.       sb.Append('e');
34.   WriteLn('sb: no realloc ', MilliSecondsBetween(Now, t));
35.   sb.Free;
36.  
37. end.

concat: 130
sb default: 352
sb: no realloc 347

How is with the capacity issue?

[Thaddy]

Well, try 
Whatever the tries: there is no difference or SB wins in most cases.

[bytebites]

Well, try 
Whatever the tries: there is no difference or SB wins in most cases.

Didn't you see the results? You claimed that there is some difference due capacity.

Sb should win always.

[ALLIGATOR]

Sb should win always.

Code: Pascal  [Select][+][-]

1. program app;
2. {$mode objfpc}{$h+}
3.  
4. uses SysUtils, DateUtils;
5.  
6. const
7.   c = 10000000;
8.  
9. var
10.   sb: TStringBuilder;
11.   t: TDateTime;
12.   i: Integer;
13.   r: AnsiString;
14.  
15. begin
16.   t:=Now;
17.   r:='';
18.   for i:=1 to c do
19.       r:=r+AnsiString('e');
20.  
21.   WriteLn('concat: ', MilliSecondsBetween(Now, t));
22.  
23.   t:=Now;
24.   sb:=TStringBuilder.Create; // default capacity used
25.   for i:=1 to c do
26.       sb.Append(AnsiString('e'));
27.   WriteLn('sb default: ', MilliSecondsBetween(Now, t));
28.   sb.Free;
29.  
30.   t:=Now;
31.   sb:=TStringBuilder.Create(c);
32.   for i:=1 to c do
33.       sb.Append(AnsiString('e'));
34.   WriteLn('sb: no realloc ', MilliSecondsBetween(Now, t));
35.   sb.Free;
36. end.

And that's how it is )

Code: Pascal  [Select][+][-]

1. concat: 406
2. sb default: 118
3. sb: no realloc 112