1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256
//! Tree data structure.
//!
//! # Concepts
//!
//! ## Tree
//!
//! Tree consists of one or more nodes. Empty tree cannot exist since a tree
//! must have just one root node.
//!
//! ## Reference counting
//!
//! Lifetime of a tree is managed by references to a tree and its nodes.
//! An object of [`Tree`] type refers to a tree and makes the tree live longer
//! than the reference.
//! Objects of node types ([`Node`], [`FrozenNode`], and [`HotNode`] types)
//! refer to nodes. They make the node (and the tree it belongs to) live longer
//! than the references.
//!
//! These four types are similar to trees created by node types and
//! [`Rc`][`alloc::rc::Rc`], but this crate neither leaks the nodes nor releases
//! the nodes if they are connected to other nodes referred by the user.
//! See examples below for detail.
//!
//! ```
//! use dendron::Node;
//!
//! let root = Node::new_tree("root");
//! let grant = root.tree().grant_hierarchy_edit().unwrap();
//! let child0 = root.create_as_last_child(&grant, "child0");
//! let child1 = root.create_as_last_child(&grant, "child1");
//! let child1_0 = child1.create_as_last_child(&grant, "child1_0");
//! // root
//! // |-- child0
//! // `-- child1
//! // `-- child1_0
//!
//! drop(grant);
//! drop(root);
//! drop(child0);
//! drop(child1);
//! // Now only `child1_0` is alive.
//!
//! // `child1_0` makes the entire tree and belonging nodes alive,
//! // so `root` is still alive.
//! assert_eq!(*child1_0.root().borrow_data(), "root");
//!
//! let tree = child1_0.tree();
//! drop(child1_0);
//! // Now all node references are dropped and only `tree` is alive.
//!
//! // `tree` makes the entire tree and belonging nodes alive,
//! // so `child0` is still alive.
//! assert_eq!(
//! *tree.root().first_child().unwrap().borrow_data(),
//! "child0"
//! );
//!
//! drop(tree);
//! // Now all tree references and node references are dropped, so all objects
//! // in the tree is released. No memory leaks!
//! ```
//!
//! ## Hierarchy edit prohibitions and grants
//!
//! Sometimes users may wish tree hierarchy to be preserved, especially when
//! they are iterating nodes.
//!
//! ```
//! use dendron::tree_node;
//!
//! let root = tree_node! {
//! "root", [
//! "0",
//! "1",
//! "2",
//! ]
//! };
//! let grant = root.tree().grant_hierarchy_edit().unwrap();
//! let mut children = root.children();
//! // Detach the first child from `root`.
//! root.first_child().unwrap().detach_subtree(&grant);
//!
//! // Next node is... not "1"! This is because `children` have a cache of
//! // "next node" at the creation of the iterator.
//! assert_eq!(children.next().map(|node| *node.borrow_data()), Some("0"));
//! assert_eq!(children.next(), None);
//! ```
//!
//! To enable "freezing" hierarchy, this crate requires users to have a "grant"
//! to edit hierarchy, and also provides capability to "prohibit" hierarchy
//! editing (for arbitrary duration).
//!
//! ```should_panic
//! use dendron::tree;
//!
//! let tree = tree! { "root" };
//!
//! // This "prohibition" prohibits tree hierarchy editing
//! // (and grant acquisition).
//! let freezer = tree.prohibit_hierarchy_edit().unwrap();
//!
//! // This `grant_hierarchy_edit()` fails, so you can ensure
//! // the hierarchy is stable until `freezer` is dropped!
//! let grant = tree.grant_hierarchy_edit().unwrap();
//! ```
//!
//! "Grant" ([`HierarchyEditGrant`]) and "prohibition" ([`HierarchyEditProhibition`])
//! works in ways similar to [`MutexGuard`][`std::sync::MutexGuard`].
//! The grants and prohibitions work like scoped locks; trees are editable or
//! non-editable during grants or prohibitions exist, and once they are dropped,
//! trees become neutral.
//!
//! Note that grants and prohibitions are mutually exclusive, but only multiple
//! grants or only multiple prohibitions can coexist for a tree, like reader
//! locks. In other words, you can have multiple grants for a tree, and also
//! can have multiple prohibitions for a tree, but not both at the same time.
//!
//! ```
//! use dendron::tree;
//!
//! let tree = tree! { "root" };
//!
//! let freezer1 = tree.prohibit_hierarchy_edit().unwrap();
//! // You can have multiple prohibitions at the same time.
//! let freezer2 = tree.prohibit_hierarchy_edit().unwrap();
//! let freezer3 = tree.prohibit_hierarchy_edit().unwrap();
//!
//! // But not both prohibitions and grants.
//! assert!(tree.grant_hierarchy_edit().is_err());
//!
//! // Release the locks.
//! drop(freezer1);
//! drop(freezer2);
//! drop(freezer3);
//!
//! // Now the tree is neutral. You can re-prohibit or grant hierarchy edit.
//! let grant = tree.grant_hierarchy_edit().unwrap();
//!
//! // Again, prohibitions and grants cannot coexist for the same tree.
//! assert!(tree.prohibit_hierarchy_edit().is_err());
//! ```
//!
//! ## Nodes
//!
//! The crate provides three node types: [`Node`], [`FrozenNode`], and
//! [`HotNode`]. They all have shared ownerships of the tree they belong to.
//!
//! [`Node`] is the basic neutral plain node. It can be turned into `FrozenNode`
//! or `HotNode` by generating or bundling a prohibition or a grant to edit
//! hierarchy.
//!
//! [`FrozenNode`] is a `Node` with a hierarchy edit prohibition bundled. This
//! exposes some extra methods to create tree traversal iterators, for example
//! [`FrozenNode::children_stable`] and
//! [`FrozenNode::allocating_breadth_first_traverse_stable`].
//!
//! [`HotNode`] is a `Node` with a hierarchy edit grant bundled. This exposes
//! some extra methods to edit tree hierarchy without passing grants as
//! arguments, for example [`HotNode::detach_subtree`] and
//! [`HotNode::try_create_node_as`].
//!
//! # Usage
//!
//! To create tree directly, use [`tree_node!`] or [`tree!`].
//!
//! ```
//! use dendron::{tree, tree_node};
//!
//! let root1 = tree_node! {
//! "root", [
//! "0",
//! /("1", [
//! /("1-0", [
//! "1-0-0"
//! ]),
//! "1-1",
//! ]),
//! ]
//! };
//! let tree1 = root1.tree();
//!
//! let tree2 = tree! {
//! "root", [
//! "0",
//! /("1", [
//! /("1-0", [
//! "1-0-0"
//! ]),
//! "1-1",
//! ]),
//! ]
//! };
//! let root2 = tree2.root();
//!
//! assert_eq!(root1, root2);
//! assert_eq!(tree1, tree2);
//! ```
//!
//! To create a new orphan (root) node, use [`Node::new_tree`] or
//! [`HotNode::new_tree`].
//!
//! ```
//! use dendron::Node;
//!
//! let root = Node::new_tree("root");
//! ```
//!
//! For other operations (creating a node that is connected to other nodes,
//! moving nodes to other places, iterating nodes, getting and setting data,
//! etc.), see methods of node types ([`Node`], [`FrozenNode`], and [`HotNode`]).
#![forbid(unsafe_code)]
//#![forbid(unsafe_op_in_unsafe_fn)]
//#![forbid(clippy::undocumented_unsafe_blocks)]
#![warn(rust_2018_idioms)]
// `clippy::missing_docs_in_private_items` implies `missing_docs`.
#![warn(clippy::missing_docs_in_private_items)]
#![warn(clippy::must_use_candidate)]
#![warn(clippy::unwrap_used)]
#![cfg_attr(not(feature = "std"), no_std)]
extern crate alloc;
#[macro_use]
mod macros;
mod anchor;
mod membership;
pub mod node;
pub mod serial;
pub mod traverse;
pub mod tree;
pub use self::anchor::{AdoptAs, InsertAs};
pub use self::node::{FrozenNode, HierarchyError, HotNode, Node, NodeWeak};
pub use self::tree::{HierarchyEditGrant, HierarchyEditProhibition, Tree, TreeWeak};
/// Deprecated re-export of [`node::DebugPrettyPrint`].
// `#[deprecated] cannot be used for `use` statement. See
// <https://github.com/rust-lang/rust/issues/30827>.
#[deprecated(since = "0.1.1", note = "use `node::DebugPrettyPrint` instead")]
pub type DebugPrettyPrint<'a, T> = self::node::DebugPrettyPrint<'a, T>;
/// Deprecated re-export of [`tree::HierarchyEditGrantError`].
// `#[deprecated] cannot be used for `use` statement. See
// <https://github.com/rust-lang/rust/issues/30827>.
#[deprecated(since = "0.1.1", note = "use `tree::HierarchyEditGrantError` instead")]
pub type HierarchyEditGrantError = self::tree::HierarchyEditGrantError;
/// Deprecated re-export of [`tree::HierarchyEditProhibitionError`].
// `#[deprecated] cannot be used for `use` statement. See
// <https://github.com/rust-lang/rust/issues/30827>.
#[deprecated(
since = "0.1.1",
note = "use `tree::HierarchyEditProhibitionError` instead"
)]
pub type HierarchyEditProhibitionError = self::tree::HierarchyEditProhibitionError;