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insertonlymap.h
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insertonlymap.h
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/* InsertOnlyMap Copyright (C) 2016 Frans Faase
Simple class for a insert-only map.
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., 675 Mass Ave, Cambridge, MA 02139, USA.
GNU General Public License:
http://www.iwriteiam.nl/GNU.txt
Details:
http://www.iwriteiam.nl/D1604.html#24
*/
template <class Key, class Value>
class InsertOnlyMap
{
public:
InsertOnlyMap() : _root(0) {}
~InsertOnlyMap() { delete _root; }
Value *findOrCreate(const Key& key)
{
Value *value = 0;
_find_or_create(key, _root, 0, value);
return value;
}
private:
struct tree_t
{
tree_t(Key n_key) : key(n_key), value(n_key), left(0), right(0), depth(0) {}
~tree_t() { delete left; delete right; }
void calc_depth()
{
if (left == 0)
depth = right == 0 ? 0 : right->depth + 1;
else if (right == 0)
depth = left->depth + 1;
else
depth = (left->depth > right->depth ? left->depth : right->depth) + 1;
}
Key key;
Value value;
tree_t* left;
tree_t* right;
tree_t* parent; // used by iterator class
int depth;
};
public:
class iterator
{
public:
iterator(const InsertOnlyMap& map)
{
_cur = map._root;
if (_cur == 0)
return;
_cur->parent = 0;
while (_cur->left != 0)
{
_cur->left->parent = _cur;
_cur = _cur->left;
}
}
bool more() const { return _cur != 0; }
void next()
{
if (_cur->right != 0)
{
_cur->right->parent = _cur;
_cur = _cur->right;
while (_cur->left != 0)
{
_cur->left->parent = _cur;
_cur = _cur->left;
}
}
else
{
for(;;)
{
tree_t* prev = _cur;
_cur = _cur->parent;
if (_cur == 0 || _cur->left == prev)
break;
}
}
}
const Key& key() const { return _cur->key; }
Value& value() const { return _cur->value; }
private:
tree_t* _cur;
};
tree_t* _root;
private:
bool _find_or_create(const Key& key, tree_t *&tree, tree_t* parent, Value *&value)
{
if (tree == 0)
{
tree = new tree_t(key);
value = &tree->value;
if (parent != 0)
parent->calc_depth();
return true;
}
int c = key.compare(tree->key);
if (c == 0)
value = &tree->value;
else if (c < 0)
{
if (_find_or_create(key, tree->left, tree, value))
{
if (tree->left->depth > (tree->right == 0 ? 1 : tree->right->depth+1))
{
tree_t *old_tree = tree;
tree = tree->left;
tree_t *middle_tree = tree->right;
tree->right = old_tree;
old_tree->left = middle_tree;
old_tree->calc_depth();
}
tree->calc_depth();
return true;
}
}
else
{
if (_find_or_create(key, tree->right, tree, value))
{
if (tree->right->depth > (tree->left == 0 ? 1 : tree->left->depth+1))
{
tree_t *old_tree = tree;
tree = tree->right;
tree_t *middle_tree = tree->left;
tree->left = old_tree;
old_tree->right = middle_tree;
old_tree->calc_depth();
}
tree->calc_depth();
return true;
}
}
return false;
}
public:
bool contains(const Key& key) const
{
tree_t* tree = _root;
while (tree != 0)
{
int c = key.compare(tree->key);
if (c == 0)
return true;
tree = c < 0 ? tree->left : tree->right;
}
return false;
}
Value *find(const Key& key)
{
tree_t* tree = _root;
while (tree != 0)
{
int c = key.compare(tree->key);
if (c == 0)
return &tree->value;
tree = c < 0 ? tree->left : tree->right;
}
return 0;
}
};