contrib/irrXML/irrArray.h

// Copyright (C) 2002-2005 Nikolaus Gebhardt
// This file is part of the "Irrlicht Engine" and the "irrXML" project.
// For conditions of distribution and use, see copyright notice in irrlicht.h and irrXML.h

#ifndef __IRR_ARRAY_H_INCLUDED__
#define __IRR_ARRAY_H_INCLUDED__

#include "irrTypes.h"
#include "heapsort.h"

namespace irr
{
namespace core
{

//!	Self reallocating template array (like stl vector) with additional features.
/** Some features are: Heap sorting, binary search methods, easier debugging.
*/
template <class T>
class array
{

public:

	array()
		: data(0), allocated(0), used(0),
			free_when_destroyed(true), is_sorted(true)
	{
	}

	//! Constructs a array and allocates an initial chunk of memory.
	//! \param start_count: Amount of elements to allocate.
	array(u32 start_count)
		: data(0), allocated(0), used(0),
			free_when_destroyed(true),	is_sorted(true)
	{
		reallocate(start_count);
	}


	//! Copy constructor
	array(const array<T>& other)
		: data(0)
	{
		*this = other;
	}


	//! Destructor. Frees allocated memory, if set_free_when_destroyed
	//! was not set to false by the user before.
	~array()
	{
		if (free_when_destroyed)
			delete [] data;
	}


	//! Reallocates the array, make it bigger or smaller.
	//! \param new_size: New size of array.
	void reallocate(u32 new_size)
	{
		T* old_data = data;

		data = new T[new_size];
		allocated = new_size;

		s32 end = used < new_size ? used : new_size;
		for (s32 i=0; i<end; ++i)
			data[i] = old_data[i];

		if (allocated < used)
			used = allocated;

		delete [] old_data;
	}

	//! Adds an element at back of array. If the array is to small to
	//! add this new element, the array is made bigger.
	//! \param element: Element to add at the back of the array.
	void push_back(const T& element)
	{
		if (used + 1 > allocated)
		{
			// reallocate(used * 2 +1);
			// this doesn't work if the element is in the same array. So
			// we'll copy the element first to be sure we'll get no data
			// corruption

			T e;
			e = element;           // copy element
			reallocate(used * 2 +1); // increase data block
			data[used++] = e;        // push_back
			is_sorted = false;
			return;
		}

		data[used++] = element;
		is_sorted = false;
	}


	//! Adds an element at the front of the array. If the array is to small to
	//! add this new element, the array is made bigger. Please note that this
	//! is slow, because the whole array needs to be copied for this.
	//! \param element: Element to add at the back of the array.
	void push_front(const T& element)
	{
		if (used + 1 > allocated)
			reallocate(used * 2 +1);

		for (int i=(int)used; i>0; --i)
			data[i] = data[i-1];

		data[0] = element;
		is_sorted = false;
		++used;
	}


	//! Insert item into array at specified position. Please use this
	//! only if you know what you are doing (possible performance loss).
	//! The preferred method of adding elements should be push_back().
	//! \param element: Element to be inserted
	//! \param index: Where position to insert the new element.
	void insert(const T& element, u32 index=0)
	{
		_IRR_DEBUG_BREAK_IF(index>used) // access violation

		if (used + 1 > allocated)
			reallocate(used * 2 +1);

		for (u32 i=used++; i>index; i--)
			data[i] = data[i-1];

		data[index] = element;
		is_sorted = false;
	}


	//! Clears the array and deletes all allocated memory.
	void clear()
	{
		delete [] data;
		data = 0;
		used = 0;
		allocated = 0;
		is_sorted = true;
	}


	//! Sets pointer to new array, using this as new workspace.
	//! \param newPointer: Pointer to new array of elements.
	//! \param size: Size of the new array.
	void set_pointer(T* newPointer, u32 size)
	{
		delete [] data;
		data = newPointer;
		allocated = size;
		used = size;
		is_sorted = false;
	}


	//! Sets if the array should delete the memory it used.
	//! \param f: If true, the array frees the allocated memory in its
	//! destructor, otherwise not. The default is true.
	void set_free_when_destroyed(bool f)
	{
		free_when_destroyed = f;
	}


	//! Sets the size of the array.
	//! \param usedNow: Amount of elements now used.
	void set_used(u32 usedNow)
	{
		if (allocated < usedNow)
			reallocate(usedNow);

		used = usedNow;
	}


	//! Assignement operator
	void operator=(const array<T>& other)
	{
		if (data)
			delete [] data;

		//if (allocated < other.allocated)
		if (other.allocated == 0)
			data = 0;
		else
			data = new T[other.allocated];

		used = other.used;
		free_when_destroyed = other.free_when_destroyed;
		is_sorted = other.is_sorted;
		allocated = other.allocated;

		for (u32 i=0; i<other.used; ++i)
			data[i] = other.data[i];
	}


	//! Direct access operator
	T& operator [](u32 index)
	{
		_IRR_DEBUG_BREAK_IF(index>=used) // access violation

		return data[index];
	}


	//! Direct access operator
	const T& operator [](u32 index) const
	{
		_IRR_DEBUG_BREAK_IF(index>=used) // access violation

		return data[index];
	}

    //! Gets last frame
	const T& getLast() const
	{
		_IRR_DEBUG_BREAK_IF(!used) // access violation

		return data[used-1];
	}

    //! Gets last frame
	T& getLast()
	{
		_IRR_DEBUG_BREAK_IF(!used) // access violation

		return data[used-1];
	}


	//! Returns a pointer to the array.
	//! \return Pointer to the array.
	T* pointer()
	{
		return data;
	}


	//! Returns a const pointer to the array.
	//! \return Pointer to the array.
	const T* const_pointer() const
	{
		return data;
	}


	//! Returns size of used array.
	//! \return Size of elements in the array.
	u32 size() const
	{
		return used;
	}


	//! Returns amount memory allocated.
	//! \return Returns amount of memory allocated. The amount of bytes
	//! allocated would  be allocated_size() * sizeof(ElementsUsed);
	u32 allocated_size() const
	{
		return allocated;
	}


	//! Returns true if array is empty
	//! \return True if the array is empty, false if not.
	bool empty() const
	{
		return used == 0;
	}


	//! Sorts the array using heapsort. There is no additional memory waste and
	//! the algorithm performs (O) n log n in worst case.
	void sort()
	{
		if (is_sorted || used<2)
			return;

		heapsort(data, used);
		is_sorted = true;
	}


	//! Performs a binary search for an element, returns -1 if not found.
	//! The array will be sorted before the binary search if it is not
	//! already sorted.
	//! \param element: Element to search for.
	//! \return Returns position of the searched element if it was found,
	//! otherwise -1 is returned.
	s32 binary_search(const T& element)
	{
		return binary_search(element, 0, used-1);
	}


	//! Performs a binary search for an element, returns -1 if not found.
	//! The array will be sorted before the binary search if it is not
	//! already sorted.
	//! \param element: Element to search for.
	//! \param left: First left index
	//! \param right: Last right index.
	//! \return Returns position of the searched element if it was found,
	//! otherwise -1 is returned.
	s32 binary_search(const T& element, s32 left, s32 right)
	{
		if (!used)
			return -1;

		sort();

		s32 m;

		do
		{
			m = (left+right)>>1;

			if (element < data[m])
				right = m - 1;
			else
				left = m + 1;

		} while((element < data[m] || data[m] < element) && left<=right);

		// this last line equals to:
		// " while((element != array[m]) && left<=right);"
		// but we only want to use the '<' operator.
		// the same in next line, it is "(element == array[m])"

		if (!(element < data[m]) && !(data[m] < element))
			return m;

		return -1;
	}


	//! Finds an element in linear time, which is very slow. Use
	//! binary_search for faster finding. Only works if =operator is implemented.
	//! \param element: Element to search for.
	//! \return Returns position of the searched element if it was found,
	//! otherwise -1 is returned.
	s32 linear_search(T& element)
	{
		for (u32 i=0; i<used; ++i)
			if (!(element < data[i]) && !(data[i] < element))
				return (s32)i;

		return -1;
	}


	//! Finds an element in linear time, which is very slow. Use
	//! binary_search for faster finding. Only works if =operator is implemented.
	//! \param element: Element to search for.
	//! \return Returns position of the searched element if it was found,
	//! otherwise -1 is returned.
	s32 linear_reverse_search(T& element)
	{
		for (s32 i=used-1; i>=0; --i)
			if (data[i] == element)
				return (s32)i;

		return -1;
	}


	//! Erases an element from the array. May be slow, because all elements
	//! following after the erased element have to be copied.
	//! \param index: Index of element to be erased.
	void erase(u32 index)
	{
		_IRR_DEBUG_BREAK_IF(index>=used || index<0) // access violation

		for (u32 i=index+1; i<used; ++i)
			data[i-1] = data[i];

		--used;
	}


	//! Erases some elements from the array. may be slow, because all elements
	//! following after the erased element have to be copied.
	//! \param index: Index of the first element to be erased.
	//! \param count: Amount of elements to be erased.
	void erase(u32 index, s32 count)
	{
		_IRR_DEBUG_BREAK_IF(index>=used || index<0 || count<1 || index+count>used) // access violation

		for (u32 i=index+count; i<used; ++i)
			data[i-count] = data[i];

		used-= count;
	}


	//! Sets if the array is sorted
	void set_sorted(bool _is_sorted)
	{
		is_sorted = _is_sorted;
	}


	private:

		T* data;
		u32 allocated;
		u32 used;
		bool free_when_destroyed;
		bool is_sorted;
};


} // end namespace core
} // end namespace irr


#endif