1 files changed, 108 insertions, 0 deletions

diff --git a/source/btree.h b/source/btree.h
new file mode 100644
index 0000000..42c8e21
--- /dev/null
+++ b/source/btree.h
@@ -0,0 +1,108 @@
+#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 */