Discussion:
Composite Pattern, Iterators, STL and C++ Standard Library
(too old to reply)
k***@gmail.com
2013-12-26 16:32:55 UTC
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How can access be provided to the containers methods begin() & end()
without providing access to the container itself?
See the code for external stl-compliant composite iteration at https://github.com/kkruecke/composite-iterator

The composite in the about referenced code is a Directory which can contain other Directories of File leaf nodes. Both Directory and File derive from a base Node class, the analogue of the Component class in the Composite Pattern
Wenwei Peng
2015-04-22 07:48:41 UTC
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在 1997年2月3日星期一 UTC+8下午4:00:00,Kevin Holland写道:
The design pattern Composite as presented in Design Patterns, Gamma et el,
uses an iterator
Class CompositeEquipment : public Equipment {
...
virtual Iterator<Equipment*>* CreateIterator();
...
List<Equipment*> _equipment;
}
The Iterator template includes methods not just for increment the iterator,
Iterator<Equipment*>* i = CreateIterator();
for (i->First(); !i->IsDone(); i->Next())
...
This style of iterators is at odds with the STL or C++ Standard Library
style of iterators. STL containers have the methods begin() and end().
Using the standard library within Visual C++, I have modified the
CompositeEquipment class to
Class CompositeEquipment : public Equipment {
...
vector<Equipment*> _equipment;
}
CComponent equip;
....
for (vector<Equipment*>::iterator i = equip.begin(); i != equip.end(); i++)
....
which violates about every rule known about encapsulation!
How can access be provided to the containers methods begin() & end()
without providing access to the container itself?
Can "Traits" be used to remove the explicate reference to vector so the
type of internal container can be optimized without changing external use
of the iterator?
Any help would be appreciated!
kevin-hollandflowcode.com
Title: The core of the core of the big data solutions -- Map
Author: pengwenwei
Email:
Language: c++
Platform: Windows, linux
Technology: Perfect hash algorithm
Level: Advanced
Description: Map algorithm with high performance
Section MFC c++ map stl
SubSection c++ algorithm
License: (GPLv3)

Download demo project - 1070 Kb
Download source - 1070 Kb

Introduction:
For the c++ program, map is used everywhere.And bottleneck of program performance is often the performance of map.Especially in the case of large data,and the business association closely and unable to realize the data distribution and parallel processing condition.So the performance of map becomes the key technology.

In the work experience with telecommunications industry and the information security industry, I was dealing with the big bottom data,especially the most complex information security industry data,all can’t do without map.

For example, IP table, MAC table, telephone number list, domain name resolution table, ID number table query, the Trojan horse virus characteristic code of cloud killing etc..

The map of STL library using binary chop, its has the worst performance.Google Hash map has the optimal performance and memory at present, but it has repeated collision probability.Now the big data rarely use a collision probability map,especially relating to fees, can’t be wrong.

Now I put my algorithms out here,there are three kinds of map,after the build is Hash map.We can test the comparison,my algorithm has the zero probability of collision,but its performance is also better than the hash algorithm, even its ordinary performance has no much difference with Google.

My algorithm is perfect hash algorithm,its key index and the principle of compression algorithm is out of the ordinary,the most important is a completely different structure,so the key index compression is fundamentally different.The most direct benefit for program is that for the original map need ten servers for solutions but now I only need one server.
Declare: the code can not be used for commercial purposes, if for commercial applications,you can contact me with QQ 75293192.
Download:
https://sourceforge.net/projects/pwwhashmap/files

Applications:
First,modern warfare can’t be without the mass of information query, if the query of enemy target information slows down a second, it could lead to the delaying fighter, leading to failure of the entire war. Information retrieval is inseparable from the map, if military products use pwwhashMap instead of the traditional map,you must be the winner.

Scond,the performance of the router determines the surfing speed, just replace open source router code map for pwwHashMap, its speed can increase ten times.
There are many tables to query and set in the router DHCP ptotocol,such as IP,Mac ,and all these are completed by map.But until now,all map are using STL liabrary,its performance is very low,and using the Hash map has error probability,so it can only use multi router packet dispersion treatment.If using pwwHashMap, you can save at least ten sets of equipment.

Third,Hadoop is recognized as the big data solutions at present,and its most fundamental thing is super heavy use of the map,instead of SQL and table.Hadoop assumes the huge amounts of data so that the data is completely unable to move, people must carry on the data analysis in the local.But as long as the open source Hadoop code of the map changes into pwwHashMap, the performance will increase hundredfold without any problems.


Background to this article that may be useful such as an introduction to the basic ideas presented:
http://blog.csdn.net/chixinmuzi/article/details/1727195

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