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#ifndef BTREE_H
#define BTREE_H
// maximum height of the tree the lower the lower the lower amount
// of disk reads which translates into faster?
#define B_TREE_ORDER 4
typedef struct b_tree_node b_tree_node;
struct b_tree_node
{
// store the values
string8 keys[B_TREE_ORDER - 1];
csv_row *rows[B_TREE_ORDER - 1];
b_tree_node *parent;
// handle to store children faster than linked list
// because now we can iteratate over the nodes instead of having cache misses
// when jumping through linked nodes
b_tree_node *children[B_TREE_ORDER];
// NOTE(nasr): reference count ::: check how many leaves are using this node
// also not needed for now because we don't free individual node because of arena allocator
// s32 *refc;
s32 key_count;
b32 leaf;
};
typedef struct b_tree b_tree;
struct b_tree
{
// NOTE(nasr): make sure this always stays in memory
// so that initial fetch never requires a disk read
b_tree_node *root;
};
// TODO(nasr): 1. splitting the tree when getting too big? (horizontally) 2. joining trees?
internal b_tree_node *
node_alloc(mem_arena *arena)
{
b_tree_node *node = PushStructZero(arena, type);
node->leaf = 1;
return node;
}
// NOTE(nasr): @return the index of of the found element
internal s32
node_find_pos(mem_arena *arena, string8 value)
{
s32 i = 0;
while (i < n->key_count && str8_cmp(n->keys[i], k) < 0)
{
++i;
}
return i;
}
interal void
b_tree_create(mem_arena *arena, b_tree *tree)
{
tree->root = node_alloc(arena);
tree->root->leaf = 1;
tree->root->key_count = 0;
}
// NOTE(nasr): nodes that get passed as parameters should've already been loaded into memory
internal void
b_tree_search(b_tree_node *node, string8 key)
{
s32 found_index = node_find_pos(node, key);
if (found_index < n->key_count && string_compare(n->keys[i], key) == 0)
{
return n->rows[i];
}
if (n->leaf)
{
return NULL;
}
return b_tree_search(n->children[i], key);
}
internal void
b_tree_insert()
{
}
internal void
b_tree_write()
{
// TODO(nasr): write the b_tree to disk
}
#endif /* BTREE_H */
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