godot/core/list.h

/*************************************************************************/
/*  list.h                                                               */
/*************************************************************************/
/*                       This file is part of:                           */
/*                           GODOT ENGINE                                */
/*                    http://www.godotengine.org                         */
/*************************************************************************/
/* Copyright (c) 2007-2016 Juan Linietsky, Ariel Manzur.                 */
/*                                                                       */
/* Permission is hereby granted, free of charge, to any person obtaining */
/* a copy of this software and associated documentation files (the       */
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/* the following conditions:                                             */
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/*                                                                       */
/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,       */
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/*************************************************************************/
#ifndef GLOBALS_LIST_H
#define GLOBALS_LIST_H

#include "os/memory.h"
#include "sort.h"

/**
 * Generic Templatized Linked List Implementation.
 * The implementation differs from the STL one because
 * a compatible preallocated linked list can be written
 * using the same API, or features such as erasing an element
 * from the iterator.
 */

template <class T,class A=DefaultAllocator>
class List {
	struct _Data;
public:


	class Element {

	private:
		friend class List<T,A>;

		T value;
		Element* next_ptr;
		Element* prev_ptr;
		_Data *data;
	public:

		/**
		 * Get NEXT Element iterator, for constant lists.
		 */
		_FORCE_INLINE_ const Element* next() const {

			return next_ptr;
		};
		/**
		 * Get NEXT Element iterator,
		 */
		_FORCE_INLINE_ Element* next() {

			return next_ptr;
		};

		/**
		 * Get PREV Element iterator, for constant lists.
		 */
		_FORCE_INLINE_ const Element* prev() const {

			return prev_ptr;
		};
		/**
		 * Get PREV Element iterator,
		 */
		_FORCE_INLINE_ Element* prev() {

			return prev_ptr;
		};

		/**
		 * * operator, for using as *iterator, when iterators are defined on stack.
		 */
		_FORCE_INLINE_ const T& operator *() const {
			return value;
		};
		/**
		 * operator->, for using as iterator->, when iterators are defined on stack, for constant lists.
		 */
		_FORCE_INLINE_ const T* operator->() const {

			return &value;
		};
		/**
		 * * operator, for using as *iterator, when iterators are defined on stack,
		 */
		_FORCE_INLINE_ T& operator *() {
			return value;
		};
		/**
		 * operator->, for using as iterator->, when iterators are defined on stack, for constant lists.
		 */
		_FORCE_INLINE_ T* operator->() {
			return &value;
		};

		/**
		 * get the value stored in this element.
		 */
		_FORCE_INLINE_ T& get() {
			return value;
		};
		/**
		 * get the value stored in this element, for constant lists
		 */
		_FORCE_INLINE_ const T& get() const {
			return value;
		};
		/**
		 * set the value stored in this element.
		 */
		_FORCE_INLINE_ void set(const T& p_value) {
			value = (T&)p_value;
 		};

		void erase() {

			data->erase(this);
		}

		_FORCE_INLINE_ Element() {
			next_ptr = 0;
			prev_ptr = 0;
			data=NULL;
		};
	};

private:

	struct _Data {

		Element* first;
		Element* last;
		int size_cache;


		bool erase(const Element* p_I) {

			ERR_FAIL_COND_V(!p_I,false);
			ERR_FAIL_COND_V(p_I->data!=this,false);

			if (first==p_I) {
				first=p_I->next_ptr;
			};

			if (last==p_I)
				last=p_I->prev_ptr;

			if (p_I->prev_ptr)
				p_I->prev_ptr->next_ptr=p_I->next_ptr;

			if (p_I->next_ptr)
				p_I->next_ptr->prev_ptr=p_I->prev_ptr;

			memdelete_allocator<Element,A>( const_cast<Element*>(p_I) );
			size_cache--;

			return true;
		}
	};

	_Data *_data;


public:

	/**
 	* return an const iterator to the begining of the list.
	*/
	_FORCE_INLINE_ const Element* front() const {

		return _data?_data->first:0;
	};

	/**
 	* return an iterator to the begining of the list.
	*/
	_FORCE_INLINE_ Element* front() {
		return _data?_data->first:0;
	};

	/**
 	* return an const iterator to the last member of the list.
	*/
	_FORCE_INLINE_ const Element* back() const {

		return _data?_data->last:0;
	};

	/**
 	* return an iterator to the last member of the list.
	*/
	_FORCE_INLINE_ Element* back() {

		return _data?_data->last:0;
	};

	/**
	 * store a new element at the end of the list
	 */
	Element* push_back(const T& value) {

		if (!_data) {

			_data=memnew_allocator(_Data,A);
			_data->first=NULL;
			_data->last=NULL;
			_data->size_cache=0;
		}

		Element* n = memnew_allocator(Element,A);
		n->value = (T&)value;

		n->prev_ptr=_data->last;
		n->next_ptr=0;
		n->data=_data;

		if (_data->last) {

			_data->last->next_ptr=n;
		}

		_data->last = n;

		if (!_data->first)
			_data->first=n;

		_data->size_cache++;
		
		return n;
	};

	void pop_back() {

		if (_data && _data->last)
			erase(_data->last);
	}

	/**
	 * store a new element at the begining of the list
	 */
	Element* push_front(const T& value) {

		if (!_data) {

			_data=memnew_allocator(_Data,A);
			_data->first=NULL;
			_data->last=NULL;
			_data->size_cache=0;
		}

		Element* n = memnew_allocator(Element,A);
		n->value = (T&)value;
		n->prev_ptr = 0;
		n->next_ptr = _data->first;
		n->data=_data;

		if (_data->first) {

			_data->first->prev_ptr=n;
		}

		_data->first = n;

		if (!_data->last)
			_data->last=n;

		_data->size_cache++;
		
		return n;
	};

	void pop_front() {

		if (_data && _data->first)
			erase(_data->first);
	}

	/**
	 * find an element in the list,
	 */
	template<class T_v>
	Element* find(const T_v& p_val) {

		Element* it = front();
		while (it) {
			if (it->value == p_val) return it;
			it = it->next();
		};

		return NULL;
	};

	/**
	 * erase an element in the list, by iterator pointing to it. Return true if it was found/erased.
	 */
	bool erase(const Element* p_I) {

		if (_data) {
			bool ret =  _data->erase(p_I);

			if (_data->size_cache==0) {
				memdelete_allocator<_Data,A>(_data);
				_data=NULL;
			}

			return ret;
		}

		return false;
	};

	/**
	 * erase the first element in the list, that contains value
	 */
	bool erase(const T& value) {

		Element* I = find(value);
		return erase(I);
	};

	/**
	 * return wether the list is empty
	 */
	_FORCE_INLINE_ bool empty() const {

		return (!_data || !_data->size_cache);
	}

	/**
	 * clear the list
	 */
	void clear() {

		while (front()) {
			erase(front());
		};
	};

	_FORCE_INLINE_ int size() const {

		return _data?_data->size_cache:0;

	}

	void swap(Element* p_A, Element *p_B) {
		
		ERR_FAIL_COND(!p_A || !p_B);
		ERR_FAIL_COND(p_A->data!=_data);
		ERR_FAIL_COND(p_B->data!=_data);
		
		Element* A_prev=p_A->prev_ptr;
		Element* A_next=p_A->next_ptr;
		
		p_A->next_ptr=p_B->next_ptr;
		p_A->prev_ptr=p_B->prev_ptr;
		
		p_B->next_ptr=A_next;
		p_B->prev_ptr=A_prev;	
		
		if (p_A->prev_ptr)
			p_A->prev_ptr->next_ptr=p_A;
		if (p_A->next_ptr)
			p_A->next_ptr->prev_ptr=p_A;		
		
		if (p_B->prev_ptr)
			p_B->prev_ptr->next_ptr=p_B;
		if (p_B->next_ptr)
			p_B->next_ptr->prev_ptr=p_B;		
		
	}
	/**
	 * copy the list
	 */
	void operator=(const List& p_list) {

		clear();
		const Element *it=p_list.front();
		while (it) {

			push_back( it->get() );
			it=it->next();
		}

	}

	T& operator[](int p_index) {

		if (p_index<0 || p_index>=size()) {
			T& aux=*((T*)0); //nullreturn
			ERR_FAIL_COND_V(p_index<0 || p_index>=size(),aux);
		}

		Element *I=front();
		int c=0;
		while(I) {

			if (c==p_index) {

				return I->get();
			}
			I=I->next();
			c++;
		}

		ERR_FAIL_V( *((T*)0) );	// bug!!
	}

	const T& operator[](int p_index) const {

		if (p_index<0 || p_index>=size()) {
			T& aux=*((T*)0); //nullreturn
			ERR_FAIL_COND_V(p_index<0 || p_index>=size(),aux);
		}

		const Element *I=front();
		int c=0;
		while(I) {

			if (c==p_index) {

				return I->get();
			}
			I=I->next();
			c++;
		}

		ERR_FAIL_V( *((T*)0) );	 // bug!
	}


	void move_to_back(Element* p_I) {

		ERR_FAIL_COND(p_I->data!=_data);
		if (!p_I->next_ptr)
			return;

		if (_data->first==p_I) {
			_data->first=p_I->next_ptr;
		};

		if (_data->last==p_I)
			_data->last=p_I->prev_ptr;

		if (p_I->prev_ptr)
			p_I->prev_ptr->next_ptr=p_I->next_ptr;

		if (p_I->next_ptr)
			p_I->next_ptr->prev_ptr=p_I->prev_ptr;


		_data->last->next_ptr=p_I;
		p_I->prev_ptr=_data->last;
		p_I->next_ptr=NULL;
		_data->last=p_I;

	}

	void invert() {

		int s = size() / 2;
		Element *F = front();
		Element *B = back();
		for(int i=0;i<s;i++) {

			SWAP( F->value, B->value );
			F=F->next();
			B=B->prev();
		}
	}

	void move_to_front(Element* p_I) {

		ERR_FAIL_COND(p_I->data!=_data);
		if (!p_I->prev_ptr)
			return;

		if (_data->first==p_I) {
			_data->first=p_I->next_ptr;
		};

		if (_data->last==p_I)
			_data->last=p_I->prev_ptr;

		if (p_I->prev_ptr)
			p_I->prev_ptr->next_ptr=p_I->next_ptr;

		if (p_I->next_ptr)
			p_I->next_ptr->prev_ptr=p_I->prev_ptr;

		_data->first->prev_ptr=p_I;
		p_I->next_ptr=_data->first;
		p_I->prev_ptr=NULL;
		_data->first=p_I;

	}

	void move_before(Element* value, Element* where) {

		if (value->prev_ptr) {
			value->prev_ptr->next_ptr = value->next_ptr;
		}
		else {
			_data->first = value->next_ptr;
		}
		if (value->next_ptr) {
			value->next_ptr->prev_ptr = value->prev_ptr;
		}
		else {
			_data->last = value->prev_ptr;
		}

		value->next_ptr = where;
		if (!where) {
			value->prev_ptr = _data->last;
			_data->last = value;
			return;
		};

		value->prev_ptr = where->prev_ptr;

		if (where->prev_ptr) {
			where->prev_ptr->next_ptr = value;
		} else {
			_data->first = value;
		};

		where->prev_ptr = value;
	};

	/**
	 * simple insertion sort
	 */

	void sort() {
		
		sort_custom< Comparator<T> >();
	}
			
	template<class C>
	void sort_custom_inplace() {

		if(size()<2)
			return;

		Element *from=front();
		Element *current=from;
		Element *to=from;
		
		while(current) {
			
			Element *next=current->next_ptr;
			
			//disconnect
			current->next_ptr=NULL;
			
			if (from!=current) {
				
				current->prev_ptr=NULL;
				current->next_ptr=from;
				
				Element *find=from;
				C less;
				while( find && less(find->value,current->value) ) {
				
					current->prev_ptr=find;
					current->next_ptr=find->next_ptr;
					find=find->next_ptr;
				}
								
				if (current->prev_ptr)
					current->prev_ptr->next_ptr=current;
				else
					from=current;
				
				if (current->next_ptr)
					current->next_ptr->prev_ptr=current;
				else
					to=current;
			} else {
				
				current->prev_ptr=NULL;
				current->next_ptr=NULL;
				
			}
			
			current=next;
		}
		_data->first=from;
		_data->last=to;
	}

	template<class C>
	struct AuxiliaryComparator {

		C compare;
		_FORCE_INLINE_ bool operator()(const Element *a,const Element* b) const {

			return compare(a->value,b->value);
		}
	};

	template<class C>
	void sort_custom() {

		//this version uses auxiliary memory for speed.
		//if you don't want to use auxiliary memory, use the in_place version

		int s = size();
		if(s<2)
			return;


		Element **aux_buffer = memnew_arr(Element*,s);

		int idx=0;
		for(Element *E=front();E;E=E->next_ptr) {

			aux_buffer[idx]=E;
			idx++;
		}

		SortArray<Element*,AuxiliaryComparator<C> > sort;
		sort.sort(aux_buffer,s);

		_data->first=aux_buffer[0];
		aux_buffer[0]->prev_ptr=NULL;
		aux_buffer[0]->next_ptr=aux_buffer[1];

		_data->last=aux_buffer[s-1];
		aux_buffer[s-1]->prev_ptr=aux_buffer[s-2];
		aux_buffer[s-1]->next_ptr=NULL;

		for(int i=1;i<s-1;i++) {

			aux_buffer[i]->prev_ptr=aux_buffer[i-1];
			aux_buffer[i]->next_ptr=aux_buffer[i+1];

		}

		memdelete_arr(aux_buffer);
	}


	/**
	 * copy constructor for the list
	 */
	List(const List& p_list) {

		_data=NULL;
		const Element *it=p_list.front();
		while (it) {

			push_back( it->get() );
			it=it->next();
		}

	}

	List() {
		_data=NULL;
	};
	~List() {
		clear();
		if (_data) {

			ERR_FAIL_COND(_data->size_cache);
			memdelete_allocator<_Data,A>(_data);
		}
	};
};

#endif