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substring find [message #769]

Wed, 01 February 2006 15:10

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.

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Re: substring find [message #774 is a reply to message #769]

Wed, 01 February 2006 17:57

mirek
Messages: 14105
Registered: November 2005

Ultimate Member

Yes it is missing. Adding to ToDo... (there will huge String refactoring soon anyway...)

Mirek

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Re: substring find [message #783 is a reply to message #774]

Thu, 02 February 2006 13:08

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.

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Re: substring find [message #786 is a reply to message #783]

Thu, 02 February 2006 20:28

mirek
Messages: 14105
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

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Re: substring find [message #859 is a reply to message #786]

Mon, 06 February 2006 08:20

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.

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Re: substring find [message #861 is a reply to message #859]

Mon, 06 February 2006 11:28

mirek
Messages: 14105
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

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Re: substring find [message #862 is a reply to message #859]

Mon, 06 February 2006 11:30

mirek
Messages: 14105
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

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Re: substring find [message #866 is a reply to message #861]

Mon, 06 February 2006 11:37

hojtsy
Messages: 241
Registered: January 2006
Location: Budapest, Hungary

Experienced Member

luzr wrote on Mon, 06 February 2006 05:28

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.

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Re: substring find [message #867 is a reply to message #866]

Mon, 06 February 2006 11:39

mirek
Messages: 14105
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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