Hi,
On the topic of markers, attached is what I did when a year back when
I was still interested in Go....
I am not at all saying that this is the best way to do it (there is a
bit of overhead), but it is a cute trick that should bring a smile or
two.
Joel
On Thu, Oct 30, 2008 at 9:40 PM, Mark Boon <[EMAIL PROTECTED]> wrote:
>
> On 30-okt-08, at 00:20, Christoph Birk wrote:
>
>> On Wed, 29 Oct 2008, Mark Boon wrote:
>>>
>>> the implementation with one that clears the array instead of increasing
>>> the marker. And I'll only have to make changes in one place instead of
>>> dozens, or more. Not that I had this in mind when I designed it, it's just
>>> the beneficial side-effect of OO design in general.
>>
>> [troll on]
>> What's that todo with OO design?
>> You can do the same by writing a function (eg. in 'C').
>> [troll off]
>>
>
> Because then in C you have only one of them. It has everything to do with OO
> design.
>
> Mark
>
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>
#ifndef __POINTSET_HPP__
#define __POINTSET_HPP__
#include "goanna.hpp"
/*
Bounded Range Unique Integer Storage Entity
M is the maximum number of elements in the container
[0,N-1] is the range of values that the container can hold
O(1) exists
O(1) insert
O(1) delete
O(1) initialise
using only O(N + M) memory.
*/
template<unsigned int N, unsigned int M>
class Bruise {
public:
// construct an empty container
Bruise<N, M>(void) : m_element_c(0) { }
// copy constructor that only copies the necessary parts
Bruise<N, M>(const Bruise<N, M> ©) {
assignFrom(copy);
}
// assignment operator that only copies necessary parts
Bruise<N, M> &operator=(const Bruise<N, M> &rhs) {
if (this == &rhs) return *this;
assignFrom(rhs);
return *this;
}
// retrieve an item from the container
bool exists(unsigned int n) const {
if (n >= N) return false;
return m_hash[n] < m_element_c && n ==
m_element[m_hash[n]];
}
// insert an item into container, false on failure
bool insert(unsigned int n) {
if (m_element_c >= M) return false;
if (exists(n)) return false;
m_hash[n] = m_element_c;
m_element[m_element_c++] = n;
return true;
}
// remove an item from the container, false on failure
bool remove(unsigned int n) {
if (!exists(n)) return false;
m_element[m_hash[n]] = m_element[m_element_c-1];
m_hash[m_element[m_element_c-1]] = m_hash[n];
m_element_c--;
return true;
}
// grab the n'th element with no bounds checking
unsigned int operator[](size_t n) const {
return m_element[n];
}
// determine the size of the container
size_t size(void) const {
return m_element_c;
}
// reset the point set
void clear(void) {
m_element_c = 0;
}
private:
// fast copying for sparsely populated pointsets
void assignFrom(const Bruise<N,M> ©) {
m_element_c = copy.m_element_c;
for (uint i=0; i < m_element_c; i++) {
unsigned int elem = copy.m_element[i];
m_element[i] = elem;
m_hash[elem] = i;
}
}
unsigned int m_element_c;
unsigned int m_element[M];
unsigned int m_hash[N];
};
typedef Bruise<MAX_POINTS, MAX_POINTS> PointSet;
#endif // __POINTSET_HPP__
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