scummvm/common/algorithm.h

/* ScummVM - Graphic Adventure Engine
 *
 * ScummVM is the legal property of its developers, whose names
 * are too numerous to list here. Please refer to the COPYRIGHT
 * file distributed with this source distribution.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 *
 * $URL$
 * $Id$
 */

#ifndef COMMON_ALGORITHM_H
#define COMMON_ALGORITHM_H

#include "common/scummsys.h"

namespace Common {

/**
 * Copies data from the range [first, last) to [dst, dst + (last - first)).
 * It requires the range [dst, dst + (last - first)) to be valid.
 * It also requires dst not to be in the range [first, last).
 */
template<class In, class Out>
Out copy(In first, In last, Out dst) {
	while (first != last)
		*dst++ = *first++;
	return dst;
}

/**
 * Copies data from the range [first, last) to [dst - (last - first), dst).
 * It requires the range [dst - (last - first), dst) to be valid.
 * It also requires dst not to be in the range [first, last).
 * 
 * Unlike copy copy_backward copies the data from the end to the beginning.
 */
template<class In, class Out>
Out copy_backward(In first, In last, Out dst) {
	while (first != last)
		*--dst = *--last;
	return dst;
}

/**
 * Copies data from the range [first, last) to [dst, dst + (last - first)).
 * It requires the range [dst, dst + (last - first)) to be valid.
 * It also requires dst not to be in the range [first, last).
 *
 * Unlike copy or copy_backward it does not copy all data. It only copies
 * a data element when operator() of the op parameter returns true for the
 * passed data element.
 */
template<class In, class Out, class Op>
Out copy_if(In first, In last, Out dst, Op op) {
	while (first != last) {
		if (op(*first))
			*dst++ = *first;
		++first;
	}
	return dst;
}

// Our 'specialized' 'set_to' template for char, signed char and unsigned char arrays.
// Since C++ doesn't support partial specialized template functions (currently) we
// are going this way...
// With this we assure the usage of memset for those, which should be
// faster than a simple loop like for the generic 'set_to'.
template<class Value>
signed char *set_to(signed char *first, signed char *last, Value val) {
	memset(first, (val & 0xFF), last - first);
	return last;
}

template<class Value>
unsigned char *set_to(unsigned char *first, unsigned char *last, Value val) {
	memset(first, (val & 0xFF), last - first);
	return last;
}

template<class Value>
char *set_to(char *first, char *last, Value val) {
	memset(first, (val & 0xFF), last - first);
	return last;
}

/**
 * Sets all elements in the range [first, last) to val.
 */
template<class In, class Value>
In set_to(In first, In last, Value val) {
	while (first != last)
		*first++ = val;
	return first;
}

/**
 * Finds the first data value in the range [first, last) matching v.
 * For data comperance it uses operator == of the data elements.
 */
template<class In, class T>
In find(In first, In last, const T &v) {
	while (first != last) {
		if (*first == v)
			return first;
		++first;
	}
	return last;
}

/**
 * Finds the first data value in the range [first, last) for which
 * the specified predicate p returns true.
 */
template<class In, class Pred>
In find_if(In first, In last, Pred p) {
	while (first != last) {
		if (p(*first))
			return first;
		++first;
	}
	return last;
}

/**
 * Applies the function f on all elements of the range [first, last).
 * The processing order is from beginning to end.
 */
template<class In, class Op>
Op for_each(In first, In last, Op f) {
	while (first != last) f(*first++);
	return f;
}

/**
 * Simple sort function, modeled after std::sort.
 * Use it like this: sort(container.begin(), container.end()).
 * Also works on plain old i.e. int arrays etc. For comperance
 * operator < is used.
 */
template<class T>
void sort(T first, T last) {
	if (first == last)
		return;

	// Simple selection sort
	T i(first);
	for (; i != last; ++i) {
		T minElem(i);
		T j(i);
		++j;
		for (; j != last; ++j)
			if (*j < *minElem)
				minElem = j;
		if (minElem != i)
			SWAP(*minElem, *i);
	}
}

/**
 * Simple sort function, modeled after std::sort.
 * It compares data with the given comparator object comp.
 *
 * Note: Using this with: Common::Less from common/func.h
 * will give the same results as the plain sort function.
 */
template<class T, class StrictWeakOrdering>
void sort(T first, T last, StrictWeakOrdering comp) {
	if (first == last)
		return;

	// Simple selection sort
	T i(first);
	for (; i != last; ++i) {
		T minElem(i);
		T j(i);
		++j;
		for (; j != last; ++j)
			if (comp(*j, *minElem))
				minElem = j;
		if (minElem != i)
			SWAP(*minElem, *i);
	}
}

} // end of namespace Common
#endif