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Home » U++ Library support » U++ Core » substring find
substring find [message #769] Wed, 01 February 2006 15:10 Go to next message
hojtsy is currently offline  hojtsy
Messages: 241
Registered: January 2006
Location: Budapest, Hungary
Experienced Member
I can not seem to find any String::Find(String) method. Is it possible that this is missing? Then please add it to the wishlist.
Re: substring find [message #774 is a reply to message #769] Wed, 01 February 2006 17:57 Go to previous messageGo to next message
mirek is currently offline  mirek
Messages: 13975
Registered: November 2005
Ultimate Member
Yes it is missing. Adding to ToDo... (there will huge String refactoring soon anyway...)

Mirek
Re: substring find [message #783 is a reply to message #774] Thu, 02 February 2006 13:08 Go to previous messageGo to next message
hojtsy is currently offline  hojtsy
Messages: 241
Registered: January 2006
Location: Budapest, Hungary
Experienced Member
What needs to be refactored in String? (Well except adding the substring and regexp find features, which doesn't seem to me as refactoring) Maybe I can help in it.
Re: substring find [message #786 is a reply to message #783] Thu, 02 February 2006 20:28 Go to previous messageGo to next message
mirek is currently offline  mirek
Messages: 13975
Registered: November 2005
Ultimate Member
Implementation.

Right now, we have pure reference counted string. Not bad, but I now see better performing implementations that can save quite a lot of memory as well (small string optimization).

BTW, it would be interesting to combine substring search with character filter...

Mirek
Re: substring find [message #859 is a reply to message #786] Mon, 06 February 2006 08:20 Go to previous messageGo to next message
hojtsy is currently offline  hojtsy
Messages: 241
Registered: January 2006
Location: Budapest, Hungary
Experienced Member
luzr wrote on Thu, 02 February 2006 14:28

Right now, we have pure reference counted string. Not bad, but I now see better performing implementations that can save quite a lot of memory as well (small string optimization).

Is that small string optimization similar to what the Mitor class does? By the way where is the "Mitor" name coming from? I can't seem to find anything with this name on google.
Re: substring find [message #861 is a reply to message #859] Mon, 06 February 2006 11:28 Go to previous messageGo to next message
mirek is currently offline  mirek
Messages: 13975
Registered: November 2005
Ultimate Member
No, small string optimization means that for small strings, you keep data inside String object, something like:

String {
struct Large {
const char *ptr;
....
}
union {
char data[16]
Large large_string;
}
};

If you think about the issue, unshared reference counted string (and per my research, most reference counted strings are unshared) has 16 bytes overhead (4 bytes for pointer in String, 4 bytes reference count, 4 bytes length of string, 4 bytes allocation length). Then 70% of Strings has len < 15. Means, in 70% cases SSO will store the String "for free" when compared to current implementation. In remaining 30%, SSO will just use those 16 bytes to store pointer/length/alloc previously stored in shared string (storing there just reference count). Also, you will avoid alloc/free, interlocked increment/decrement etc...

Mirek
Re: substring find [message #862 is a reply to message #859] Mon, 06 February 2006 11:30 Go to previous messageGo to next message
mirek is currently offline  mirek
Messages: 13975
Registered: November 2005
Ultimate Member
Mitor - Mi[niVec]tor Smile

Not being native English speaker, I am sometimes too creative with words Smile

The motivation: Most of Ctrls have just single Frame, but some have more than one. Speed of Mitor is less of concern there.

Mirek
Re: substring find [message #866 is a reply to message #861] Mon, 06 February 2006 11:37 Go to previous messageGo to next message
hojtsy is currently offline  hojtsy
Messages: 241
Registered: January 2006
Location: Budapest, Hungary
Experienced Member
luzr wrote on Mon, 06 February 2006 05:28

No, small string optimization means that for small strings, you keep data inside String object, something like:

String {
struct Large {
const char *ptr;
....
}
union {
char data[16]
Large large_string;
}
};
Yes, that was what I thought. And it's similar to how the Mitor works - storing element data in the memory area of the container object itself.
Re: substring find [message #867 is a reply to message #866] Mon, 06 February 2006 11:39 Go to previous message
mirek is currently offline  mirek
Messages: 13975
Registered: November 2005
Ultimate Member
Well, you are right. It was just that final performance characteristics are completely different, anyway, it is true that basic idea is the same.

Mirek
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