bullet3/examples/Experiments/ImplicitCloth/stan/array.h

//
//  Typical template dynamic array container class.
//  By S Melax 1998
// 
// anyone is free to use, inspect, learn from, or ignore
// the code here as they see fit.  
//
// A very simple template array class.
// Its easiest to understand this array
// class by seeing how it is used in code.
//
// For example:
//     for(i=0;i<myarray.count;i++) 
//         myarray[i] = somefunction(i);
// 
// When the array runs out of room, it 
// reallocates memory and doubles the size of its
// storage buffer.  The reason for *doubleing* the amount of
// memory is so the order of any algorithm using this class
// is the same as it would be had you used a regular C array.
// The penalty for reallocating and copying 
// For example consider adding n elements to a list.
// Lets sum the number of times elements are "copied".
// The worst case occurs when n=2^k+1 where k is integer.
// In this case we do a big reallocation when we add the last element.  
// n elements are copied once, n/2 elements are copied twice,
// n/4 elements are copied 3 times, and so on ...
//    total == n* (1+1/2 + 1/4 + 1/8 + ...) == n * 2
// So we do n*2 copies.  Therefore adding n 
// elements to an Array is still O(n).
// The memory usage is also of the same order as if a C array was used.
// An Array uses less than double the minimum needed space.  Again, we 
// see that we are within a small constant multiple.
// 
// Why no "realloc" to avoid the copy when reallocating memory?  
// You have a choice to either use malloc/free and friends 
// or to use new/delete.  Its bad mojo to mix these.  new/delete was
// chosen to be C++ish and have the array elements constructors/destructors 
// invoked as expected.
//
//

#ifndef SM_ARRAY_H
#define SM_ARRAY_H

#include <assert.h>
#include <stdio.h>

template <class Type> class Array {
  public:
				Array(int s=0);
				Array(Array<Type> &array);
				~Array();
	void		allocate(int s);
	void		SetSize(int s);
	void		Pack();
	Type&		Add(Type);
	void		AddUnique(Type);
	int 		Contains(Type);
	void		Insert(Type,int);
	int			IndexOf(Type);
	void		Remove(Type);
	void		DelIndex(int i);
	Type&		DelIndexWithLast(int i);
	Type *		element;
	int			count;
	int			array_size;
	const Type	&operator[](int i) const { assert(i>=0 && i<count);  return element[i]; }
	Type		&operator[](int i)  { assert(i>=0 && i<count);  return element[i]; }
	Type		&Pop() { assert(count); count--;  return element[count]; }
	Array<Type> &copy(const Array<Type> &array);
	Array<Type> &operator=(Array<Type> &array);
};


template <class Type> Array<Type>::Array(int s)
{
	if(s==-1) return;
	count=0;
	array_size = 0;
	element = NULL;
	if(s) 
    {
		allocate(s);
	}
}


template <class Type> Array<Type>::Array(Array<Type> &array)
{
	count=0;
	array_size = 0;
	element = NULL;
	*this = array;
}




template <class Type> Array<Type> &Array<Type>::copy(const Array<Type> &array)
{
	assert(array.array_size>=0);
	count=0;
	for(int i=0;i<array.count;i++) 
    {
		Add(array[i]);
	}
	return *this;
}
template <class Type> Array<Type> &Array<Type>::operator=(  Array<Type> &array)
{
	if(array.array_size<0)  //  negative number means steal the data buffer instead of copying
	{
        delete[] element;
		element = array.element;
		array_size = -array.array_size;
		count = array.count;
		array.count =array.array_size = 0;
		array.element = NULL;
		return *this;
	}
	count=0;
	for(int i=0;i<array.count;i++) 
    {
		Add(array[i]);
	}
	return *this;
}

template <class Type> Array<Type>::~Array()
{
    if (element != NULL && array_size!=0)
    {
        delete[] element;
    }
	count=0;array_size=0;element=NULL;
}

template <class Type> void Array<Type>::allocate(int s)
{
	assert(s>0);
	assert(s>=count);
	if(s==array_size) return;
	Type *old = element;
	array_size =s;
	element = new Type[array_size];
	assert(element);
	for(int i=0;i<count;i++)
    {
		element[i]=old[i];
	}
	if(old) delete[] old;
}

template <class Type> void Array<Type>::SetSize(int s)
{
	if(s==0) 
    { 
        if(element) 
        {
            delete[] element;
            element = NULL;
        }
		array_size = s;
    }
	else 
    {	
        allocate(s); 
    }
	count=s;
}

template <class Type> void Array<Type>::Pack()
{
	allocate(count);
}

template <class Type> Type& Array<Type>::Add(Type t)
{
	assert(count<=array_size);
	if(count==array_size) 
    {
		allocate((array_size)?array_size *2:16);
	}
	//int i;
	//for(i=0;i<count;i++) {
		// dissallow duplicates
	//	assert(element[i] != t);
	//}
	element[count++] = t;
	return element[count-1];
}

template <class Type> int Array<Type>::Contains(Type t)
{
	int i;
	int found=0;
	for(i=0;i<count;i++) 
    {
		if(element[i] == t) found++;
	}
	return found;
}

template <class Type> void Array<Type>::AddUnique(Type t)
{
	if(!Contains(t)) Add(t);
}


template <class Type> void Array<Type>::DelIndex(int i)
{
	assert(i<count);
	count--;
	while(i<count)
    {
		element[i] = element[i+1];
		i++;
	}
}

template <class Type> Type& Array<Type>::DelIndexWithLast(int i)
{
	assert(i<count);
	count--;
	if(i<count)
    {
		Type r=element[i];
		element[i] = element[count];
		element[count]=r;
	}
	return element[count];
}

template <class Type> void Array<Type>::Remove(Type t)
{
	int i;
	for(i=0;i<count;i++) 
    {
		if(element[i] == t) 
        {
			break;
		}
	}
	assert(i<count); // assert object t is in the array.
	DelIndex(i);
	for(i=0;i<count;i++) 
    {
		assert(element[i] != t);
	}
}

template <class Type> void Array<Type>::Insert(Type t,int k)
{
	int i=count;
	Add(t); // to allocate space
	while(i>k) 
    {
		element[i]=element[i-1];
		i--;
	}
	assert(i==k);
	element[k]=t;
}


template <class Type> int Array<Type>::IndexOf(Type t)
{
	int i;
	for(i=0;i<count;i++) 
    {
		if(element[i] == t) 
        {
			return i;
		}
	}
	assert(0);
	return -1;
}




#endif