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109 lines
3.3 KiB
C++
109 lines
3.3 KiB
C++
/* ScummVM - Graphic Adventure Engine
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*
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* ScummVM is the legal property of its developers, whose names
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* are too numerous to list here. Please refer to the COPYRIGHT
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* file distributed with this source distribution.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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*
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* $URL$
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* $Id$
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*
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*/
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#ifndef SCI_ENGINE_INTMAP_H
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#define SCI_ENGINE_INTMAP_H
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#include "common/scummsys.h"
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#include "common/serializer.h"
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namespace Sci {
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// Assumes that the ints are relatively evenly distributed
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enum {
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DCS_INT_HASH_MAX = 256
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};
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/**
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* Defines a map from arbitrary integers to "small" integers, useable as index
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* into small arrays. This class is somewhat like a hashmap, but not quite:
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* Unlike a hashmap, it generates the values associated to each key. It does
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* not try to be very clever about it, either, e.g. using a linked list of
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* values to keep track of what is mapped where.
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* Another important feature is that it reclaims unused values when they
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* are removed.
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*
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* All in all, this implementation is not very elegant, and wastes memory.
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* But it does the job. Any rewrite of this class would have to provide a
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* way to load the old savegames made using the current implementation.
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*
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* One approach to implement a replacement: Combine a Common::HashMap<int,int>
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* with a bitfield which track which low-value integers are in use.
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* That way, lookup just invokes the hashmap, and insertion (which requires
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* finding an unmapped low-value integer) can still be implemented efficiently.
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*/
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struct IntMapper : public Common::Serializable {
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struct Node {
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int key;
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int idx;
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Node *next;
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};
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int base_value; // Starts at zero, counts upwards
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Node *nodes[DCS_INT_HASH_MAX];
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Node *holes; /* List of freed entries to minimize
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** memory operations and modifications
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** to base_value */
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void free_node_recursive(Node *node);
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protected:
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void insert(int key, int idx); // For loading only
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public:
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IntMapper();
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~IntMapper();
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virtual void saveLoadWithSerializer(Common::Serializer &ser);
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void clear();
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/**
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* Checks whether a key is in the map, adds it if neccessary.
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* @param value The key to check for/add
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* @param add Whether to add the key if it's not in there
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* @param was_added Set to non-zero if and only if the key is new, ignored if NULL.
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* @return The new (or old) index, or -1 if add was zero and
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* the key couldn't be found
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*/
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int checkKey(int key, bool add, bool *wasAdded = 0);
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int lookupKey(int key) const;
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/**
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* Removes a key from the map.
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* @param key The key to remove
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* @return The index of the key, or -1 if it wasn't present
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*/
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int removeKey(int key);
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};
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} // End of namespace Sci
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#endif // SCI_ENGINE_INTMAP_H
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