Reworked RD-Tree to behave more consistently. The construction of the tree did not allow specifying what index to insert a child at under a parent.

Traverser orders were also broken, which is now fixed.

gdb/fennec/containers.py

@@ -171,6 +171,7 @@ class RDTreePrinter:
             nprev  = self.tree[node]['prev']
             nprevc = self.tree[nprev]['child'] if nprev != 18446744073709551615 else 18446744073709551615
             child  = self.tree[node]['child']
+            n_chld = self.tree[node]['num_children']
 
             index = '⠀' * depth * 2 # Uses Braille Space, otherwise it would get eaten as whitespace by parsers
 
@@ -188,7 +189,7 @@ class RDTreePrinter:
                 index += '└'
 
             index += '─'
-            index += '[{}, {}]'.format(i, node)
+            index += '[{}, {}, {}, {}]'.format(i, node, depth, n_chld)
             print(index)
             if value is None:
                 return index, '{ empty }'

include/fennec/containers/rdtree.h

@@ -44,28 +44,26 @@ public:
 	static constexpr size_t root = 0;
 	static constexpr size_t npos = -1;
 
-	enum control_ : uint8_t {
-		control_continue = 0,
-		control_jump_over,
-		control_break
-	};
-
 protected:
 	struct node {
 		optional<TypeT> value;
 		size_t parent, child, prev, next;
+		size_t depth, num_children;
 
 		template<typename...ArgsT>
-		constexpr node(size_t p, size_t c, size_t v, size_t n, ArgsT&&...args)
+		constexpr node(size_t p, size_t c, size_t v, size_t n, size_t d, ArgsT&&...args)
 			: value(fennec::forward<ArgsT>(args)...)
-			, parent(p), child(c), prev(v), next(n) {
+			, parent(p), child(c), prev(v), next(n)
+			, depth(d), num_children(0) {
 		}
 
 		constexpr ~node() {
-			parent = npos;
+			parent       = npos;
-			child  = npos;
+			child        = npos;
-			prev   = npos;
+			prev         = npos;
-			next   = npos;
+			next         = npos;
+			depth        = npos;
+			num_children = 0;
 		}
 	};
 
@@ -77,7 +75,7 @@ public:
 	explicit constexpr rdtree(ArgsT&&...args)
 		: _table(), _freed(), _size(1) {
 		_table.callocate(8);
-		fennec::construct(&_table[0], npos, npos, npos, npos, fennec::forward<ArgsT>(args)...);
+		fennec::construct(&_table[0], npos, npos, npos, npos, 0, fennec::forward<ArgsT>(args)...);
 	}
 
 	constexpr rdtree(const rdtree& tree)
@@ -133,34 +131,74 @@ public:
 	/// \param i The id of the node to check
 	/// \returns The id of the parent node
 	constexpr size_t parent(size_t i) const {
+		if (i >= _table.capacity()) return npos;
 		return i == npos ? npos : _table[i].parent;
 	}
 
 	///
 	/// \param i The id of the node to check
 	/// \returns The id of the child node
-	constexpr size_t child(size_t i) const {
+	constexpr size_t child(size_t i, size_t n = 0) const {
-		return i == npos ? npos : _table[i].child;
+		if (i >= _table.capacity()) return npos;
+		size_t c = i == npos ? npos : _table[i].child;
+		if (n != 0)
+			return next(c, n == npos ? npos : n - 1);
+		return c;
 	}
 
 	///
 	/// \param i The id of the node to check
 	/// \returns The id of the next node
-	constexpr size_t next(size_t i) const {
+	constexpr size_t next(size_t i, size_t n = 0) const {
-		return i == npos ? npos : _table[i].next;
+		if (i >= _table.capacity()) return npos;
+		if (i == npos) {
+			return npos;
+		}
+
+		size_t org = i;
+		size_t nxt = _table[i].next;
+		while (nxt != npos) {
+			i = nxt;
+			nxt = _table[i].next;
+			if (n != npos) {
+				if (n-- == 0) {
+					break;
+				}
+			}
+		}
+
+		return i == org && n != npos ? npos : i;
 	}
 
 	///
 	/// \param i The id of the node to check
 	/// \returns The id of the previous node
-	constexpr size_t prev(size_t i) const {
+	constexpr size_t prev(size_t i, size_t n = 0) const {
-		return i == npos ? npos : _table[i].prev;
+		if (i >= _table.capacity()) return npos;
+		if (i == npos) {
+			return npos;
+		}
+
+		size_t org = i;
+		size_t prv = _table[i].prev;
+		while (prv != npos) {
+			i = prv;
+			prv = _table[i].prev;
+			if (n != npos) {
+				if (n-- == 0) {
+					break;
+				}
+			}
+		}
+
+		return i == org && n != npos ? npos : i;
 	}
 
 	///
 	/// \param i the node to start at
 	/// \returns the left-most child of node `i`
 	constexpr size_t left_most(size_t i) const {
+		if (i >= _table.capacity()) return npos;
 		size_t n = i;
 		if ((n = child(n)) == npos) {
 			return i;
@@ -177,6 +215,7 @@ public:
 	/// \param i the node to start at
 	/// \returns the right-most child of node `i`
 	constexpr size_t right_most(size_t i) const {
+		if (i >= _table.capacity()) return npos;
 		if ((i = child(i)) == npos) {
 			return npos;
 		}
@@ -192,18 +231,54 @@ public:
 		}
 	}
 
+	///
+	/// \param i The id of the node to check
+	/// \returns The depth of the node
+	constexpr size_t depth(size_t i) const {
+		if (i >= _table.capacity()) return npos;
+		return i == npos ? npos : _table[i].depth;
+	}
+
+	///
+	/// \param i The id of the node to check
+	/// \returns The number of children the node has
+	constexpr size_t num_children(size_t i) const {
+		if (i >= _table.capacity()) return 0;
+		return i == npos ? 0 : _table[i].num_children;
+	}
+
+	///
+	/// \returns The next node id were `insert` or `emplace` to be called
+	constexpr size_t next_free() const {
+		size_t i = _size;
+		if (not _freed.empty()) {
+			i = _freed.front();
+		}
+		return i;
+	}
+
 	///
 	/// \param i The id of the node to access
 	/// \returns A reference to the value of the node wrapped in an optional
-	constexpr optional<value_t>& operator[](size_t i) {
+	constexpr value_t* operator[](size_t i) {
-		return _table[i].value;
+		auto& it = _table[i].value;
+		if (it) {
+			return &*_table[i].value;
+		} else {
+			return nullptr;
+		}
 	}
 
 	///
 	/// \param i The id of the node to access
 	/// \returns A const-qualified reference to the value of the node wrapped in an optional
-	constexpr const optional<value_t>& operator[](size_t i) const {
+	constexpr const value_t* operator[](size_t i) const {
-		return _table[i].value;
+		const auto& it = _table[i].value;
+		if (it) {
+			return &*_table[i].value;
+		} else {
+			return nullptr;
+		}
 	}
 
 
@@ -212,21 +287,49 @@ public:
 	///
 	/// \brief Insertion, creates a node in the tree with parent `parent`
 	/// \param parent the parent node, if `npos` sets the value of the root node
+	/// \param next the next node, as an index relative to the parent
 	/// \param val the value to insert
 	/// \returns the index of the created node
-	constexpr size_t insert(size_t parent, const value_t& val) {
+	constexpr size_t insert(size_t parent, size_t next, const value_t& val) {
-		return this->_insert(parent, val);
+		return this->_insert(parent, next, val);
 	}
 
 	///
 	/// \brief Insertion, creates a node in the tree with parent `parent`
 	/// \param parent the parent node, if `npos` sets the value of the root node
+	/// \param next the next node, as an index relative to the parent
 	/// \param val the value to insert
 	/// \returns the index of the created node
-	constexpr size_t insert(size_t parent, value_t&& val) {
+	constexpr size_t insert(size_t parent, size_t next, value_t&& val) {
-		return this->_insert(parent, fennec::forward<value_t>(val));
+		return this->_insert(parent, next, fennec::forward<value_t>(val));
 	}
 
+	///
+	/// \brief Insertion, creates a node in the tree with parent `parent`
+	/// \param parent the parent node, if `npos` sets the value of the root node
+	/// \param next the next node, as an index relative to the parent
+	/// \param args the args to construct the value to insert
+	/// \returns the index of the created node
+	template<typename...ArgsT>
+	constexpr size_t emplace(size_t parent, size_t next, ArgsT&&...args) {
+		return this->_insert(parent, next, fennec::forward<ArgsT>(args)...);
+	}
+
+	///
+	/// \brief Swap two nodes
+	/// \param i0 The id of the first node
+	/// \param i1 The id of the second node
+	constexpr void swap(size_t i0, size_t i1) {
+		size_t p0 = parent(i0);
+		size_t p1 = parent(i1);
+
+		fennec::swap(_table[i0], _table[i1]);
+
+		if (child(p0) == i0) _table[p0].child = i1;
+		if (child(p1) == i1) _table[p1].child = i0;
+	}
+
+
 	///
 	/// \brief Erase a node in the tree and all of it's children
 	/// \param i the index of the node
@@ -332,7 +435,7 @@ public:
 		OrderT order;
 		i = order(*this, i);
 		while (i != npos) {
-			uint8_t mode = visit(*_table[i].value);
+			uint8_t mode = visit(*_table[i].value, i);
 			if (mode == traversal_control_break) {
 				break;
 			}
@@ -353,8 +456,8 @@ protected:
 	size_t _next_free() {
 		size_t next = _size;
 		if (not _freed.empty()) {
-			next = _freed.back();
+			next = _freed.front();
-			_freed.pop_back();
+			_freed.pop_front();
 		}
 		if (_size >= capacity()) {
 			_expand();
@@ -364,9 +467,9 @@ protected:
 	}
 
 	template<typename...ArgsT>
-	constexpr size_t _insert(size_t p, ArgsT&&...args) {
+	constexpr size_t _insert(size_t p, size_t n, ArgsT&&...args) {
 		if (_size == 0) {
-			fennec::construct(&_table[root], npos, npos, npos, npos, fennec::forward<ArgsT>(args)...);
+			fennec::construct(&_table[root], npos, npos, npos, npos, 0, fennec::forward<ArgsT>(args)...);
 			_size = 1;
 			return root;
 		}
@@ -377,17 +480,34 @@ protected:
 			return root;
 		}
 
-		size_t i = _next_free();
+		size_t idx = _next_free();
-		size_t n = child(p);
+		size_t nxt = child(p, n);
-		_table[p].child = i;
+		size_t prv = n == npos ? npos : prev(n);
-		if (n != npos) _table[n].prev  = i;
+
-		fennec::construct(&_table[i], p, npos, npos, n, fennec::forward<ArgsT>(args)...);
+		++_table[p].num_children;
-		return i;
+		if ((nxt == child(p) && n != npos) || nxt == npos) {
+			_table[p].child = idx;
+		}
+
+		if (n == npos) {
+			if (nxt != npos) {
+				_table[nxt].next = idx;
+			}
+			fennec::construct(&_table[idx], p, npos, nxt, npos, depth(p) + 1, fennec::forward<ArgsT>(args)...);
+		} else {
+			if (nxt != npos) {
+				_table[nxt].prev = idx;
+			}
+			if (prv != npos) {
+				_table[prv].next = idx;
+			}
+			fennec::construct(&_table[idx], p, npos, prv, nxt, depth(p) + 1, fennec::forward<ArgsT>(args)...);
+		}
+		return idx;
 	}
 
 	constexpr void _erase(size_t i) {
 		list<size_t> queue;
-		size_t j = 0;
 		queue.push_back(child(i));
 		while (queue.empty() == false) {
 			size_t n = queue.front(); queue.pop_front();
@@ -397,7 +517,6 @@ protected:
 			fennec::destruct(&_table[n]);
 			_freed.push_back(n);
 			--_size;
-			++j;
 		}
 
 		fennec::destruct(&_table[i]);

test/tests/containers/test_rdtree.h

@@ -45,7 +45,7 @@ inline void fennec_test_containers_rdtree() {
 		const size_t prev   = rdtree<size_t>::npos;
 		const size_t next   = test.child(parent);
 		size_t l;
-		assertf((l = test.insert(parent, i)) == i + 1, "Tree Construct Test Failed.");
+		assertf((l = test.insert(parent, 0, i)) == i + 1, "Tree Construct Test Failed.");
 		assertf(test.parent(l) == parent, "Tree Construct Test Failed.");
 		assertf(test.child(l)  == child, "Tree Construct Test Failed.");
 		assertf(test.prev(l)   == prev, "Tree Construct Test Failed.");
@@ -55,12 +55,12 @@ inline void fennec_test_containers_rdtree() {
 
 	test.erase(0);
 
-	size_t n1 = test.insert(npos, 1);
+	size_t n1 = test.insert(npos, 0, 1);
-	size_t n3 = test.insert(n1, 3);
+	size_t n2 = test.insert(n1, 0, 2);
-	size_t n2 = test.insert(n1, 2);
+	size_t n3 = test.insert(n1, npos, 3);
-	size_t n5 = test.insert(n2, 5);
+	size_t n4 = test.insert(n2, 0, 4);
-	size_t n4 = test.insert(n2, 4);
+	size_t n5 = test.insert(n2, npos, 5);
-	size_t n6 = test.insert(n3, 6);
+	size_t n6 = test.insert(n3, 0, 6);
 	fennec_test_run(n1 != npos, true);
 	fennec_test_run(n2 != npos, true);
 	fennec_test_run(n3 != npos, true);
@@ -73,7 +73,7 @@ inline void fennec_test_containers_rdtree() {
 	size_t i;
 
 	i = 0;
-	test.traverse<tree_t::pre_order>([&](size_t x) -> uint8_t {
+	test.traverse<tree_t::pre_order>([&](size_t x, size_t) -> uint8_t {
 		fennec_test_run(x, pre_order[i++]);
 		return traversal_control_continue;
 	});
@@ -81,7 +81,7 @@ inline void fennec_test_containers_rdtree() {
 	fennec_test_spacer(1);
 
 	i = 0;
-	test.traverse<tree_t::in_order>([&](size_t x) -> uint8_t {
+	test.traverse<tree_t::in_order>([&](size_t x, size_t) -> uint8_t {
 		fennec_test_run(x, in_order[i++]);
 		return traversal_control_continue;
 	});
@@ -89,7 +89,7 @@ inline void fennec_test_containers_rdtree() {
 	fennec_test_spacer(1);
 
 	i = 0;
-	test.traverse<tree_t::post_order>([&](size_t x) -> uint8_t {
+	test.traverse<tree_t::post_order>([&](size_t x, size_t) -> uint8_t {
 		fennec_test_run(x, post_order[i++]);
 		return traversal_control_continue;
 	});