scummvm/common/hashmap.cpp

/* 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 3 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, see <http://www.gnu.org/licenses/>.
 *
 */

// The hash map (associative array) implementation in this file is
// based on the PyDict implementation of CPython. The erase() method
// is based on example code in the Wikipedia article on Hash tables.

#include "common/hashmap.h"

namespace Common {

// Hash function for strings, taken from CPython.
uint hashit(const char *p) {
	uint hash = *p << 7;
	byte c;
	int size = 0;
	while ((c = *p++)) {
		hash = (1000003 * hash) ^ c;
		size++;
	}
	return hash ^ size;
}

// Like hashit, but converts every char to lowercase before hashing.
uint hashit_lower(const char *p) {
	uint hash = tolower(*p) << 7;
	byte c;
	int size = 0;
	while ((c = *p++)) {
		hash = (1000003 * hash) ^ tolower(c);
		size++;
	}
	return hash ^ size;
}


template<> void unknownKeyError(::Common::String key) {
	error("Unknown key \"%s\"", key.c_str());
}

template<> void unknownKeyError(signed char key) {
	error("Unknown key \"%hhi\"", key);
}

template<> void unknownKeyError(unsigned char key) {
	error("Unknown key \"%hhu\"", key);
}

template<> void unknownKeyError(short signed key) {
	error("Unknown key \"%hi\"", key);
}

template<> void unknownKeyError(short unsigned key) {
	error("Unknown key \"%hu\"", key);
}

template<> void unknownKeyError(long signed key) {
	error("Unknown key \"%li\"", key);
}

template<> void unknownKeyError(long unsigned key) {
	error("Unknown key \"%lu\"", key);
}

template<>
void unknownKeyError(signed int key) {
	error("Unknown key \"%i\"", key);
}

template<>
void unknownKeyError(unsigned int key) {
	error("Unknown key \"%u\"", key);
}

template<> void unknownKeyError(long long signed key) {
	error("Unknown key \"%lli\"", key);
}

template<> void unknownKeyError(long long unsigned key) {
	error("Unknown key \"%llu\"", key);
}

template<> void unknownKeyError(void *key) {
	error("Unknown key \"%p\"", key);
}

template<> void unknownKeyError(const char *key) {
	error("Unknown key \"%s\"", key);
}

#ifdef DEBUG_HASH_COLLISIONS
static double
	g_collisions = 0,
	g_dummyHits = 0,
	g_lookups = 0,
	g_collPerLook = 0,
	g_capacity = 0,
	g_size = 0;
static int g_max_capacity = 0, g_max_size = 0;
static int g_totalHashmaps = 0;
static int g_stats[4] = {0,0,0,0};

void updateHashCollisionStats(int collisions, int dummyHits, int lookups, int arrsize, int nele) {
	g_collisions += collisions;
	g_lookups += lookups;
	g_dummyHits += dummyHits;
	if (lookups)
		g_collPerLook += (double)collisions / (double)lookups;
	g_capacity += arrsize;
	g_size += nele;
	g_totalHashmaps++;

	if (3*nele <= 2*8)
		g_stats[0]++;
	if (3*nele <= 2*16)
		g_stats[1]++;
	if (3*nele <= 2*32)
		g_stats[2]++;
	if (3*nele <= 2*64)
		g_stats[3]++;

	g_max_capacity = MAX(g_max_capacity, arrsize);
	g_max_size = MAX(g_max_size, nele);

	debug("%d hashmaps: colls %.1f; dummies hit %.1f, lookups %.1f; ratio %.3f%%; size %f (max: %d); capacity %f (max: %d)",
		g_totalHashmaps,
		g_collisions / g_totalHashmaps,
		g_dummyHits / g_totalHashmaps,
		g_lookups / g_totalHashmaps,
		100 * g_collPerLook / g_totalHashmaps,
		g_size / g_totalHashmaps, g_max_size,
		g_capacity / g_totalHashmaps, g_max_capacity);
	debug("  %d less than %d; %d less than %d; %d less than %d; %d less than %d",
		g_stats[0], 2 *  8 / 3,
		g_stats[1], 2 * 16 / 3,
		g_stats[2], 2 * 32 / 3,
		g_stats[3], 2 * 64 / 3);

	// TODO:
	// * Should record the maximal size of the map during its lifetime, not that at its death
	// * Should do some statistics: how many maps are less than 2/3*8, 2/3*16, 2/3*32, ...
}
#endif

} // End of namespace Common