mirror of
https://github.com/DioxusLabs/dioxus
synced 2024-12-22 10:33:07 +00:00
1302 lines
51 KiB
Rust
1302 lines
51 KiB
Rust
//! This module contains the stateful DiffState and all methods to diff VNodes, their properties, and their children.
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//!
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//! The [`DiffState`] calculates the diffs between the old and new frames, updates the new nodes, and generates a set
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//! of mutations for the RealDom to apply.
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//!
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//! ## Notice:
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//!
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//! The inspiration and code for this module was originally taken from Dodrio (@fitzgen) and then modified to support
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//! Components, Fragments, Suspense, SubTree memoization, incremental diffing, cancellation, NodeRefs, pausing, priority
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//! scheduling, and additional batching operations.
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//!
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//! ## Implementation Details:
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//!
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//! ### IDs for elements
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//! --------------------
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//! All nodes are addressed by their IDs. The RealDom provides an imperative interface for making changes to these nodes.
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//! We don't necessarily require that DOM changes happen instantly during the diffing process, so the implementor may choose
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//! to batch nodes if it is more performant for their application. The element IDs are indices into the internal element
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//! array. The expectation is that implementors will use the ID as an index into a Vec of real nodes, allowing for passive
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//! garbage collection as the VirtualDOM replaces old nodes.
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//!
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//! When new vnodes are created through `cx.render`, they won't know which real node they correspond to. During diffing,
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//! we always make sure to copy over the ID. If we don't do this properly, the ElementId will be populated incorrectly
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//! and brick the user's page.
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//!
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//! ### Fragment Support
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//! --------------------
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//! Fragments (nodes without a parent) are supported through a combination of "replace with" and anchor vnodes. Fragments
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//! can be particularly challenging when they are empty, so the anchor node lets us "reserve" a spot for the empty
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//! fragment to be replaced with when it is no longer empty. This is guaranteed by logic in the NodeFactory - it is
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//! impossible to craft a fragment with 0 elements - they must always have at least a single placeholder element. Adding
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//! "dummy" nodes _is_ inefficient, but it makes our diffing algorithm faster and the implementation is completely up to
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//! the platform.
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//!
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//! Other implementations either don't support fragments or use a "child + sibling" pattern to represent them. Our code is
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//! vastly simpler and more performant when we can just create a placeholder element while the fragment has no children.
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//!
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//! ### Suspense
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//! ------------
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//! Dioxus implements Suspense slightly differently than React. In React, each fiber is manually progressed until it runs
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//! into a promise-like value. React will then work on the next "ready" fiber, checking back on the previous fiber once
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//! it has finished its new work. In Dioxus, we use a similar approach, but try to completely render the tree before
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//! switching sub-fibers. Instead, each future is submitted into a futures-queue and the node is manually loaded later on.
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//! Due to the frequent calls to "yield_now" we can get the pure "fetch-as-you-render" behavior of React Fiber.
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//!
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//! We're able to use this approach because we use placeholder nodes - futures that aren't ready still get submitted to
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//! DOM, but as a placeholder.
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//!
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//! Right now, the "suspense" queue is intertwined with hooks. In the future, we should allow any future to drive attributes
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//! and contents, without the need for the "use_suspense" hook. In the interim, this is the quickest way to get Suspense working.
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//!
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//! ## Subtree Memoization
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//! -----------------------
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//! We also employ "subtree memoization" which saves us from having to check trees which hold no dynamic content. We can
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//! detect if a subtree is "static" by checking if its children are "static". Since we dive into the tree depth-first, the
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//! calls to "create" propagate this information upwards. Structures like the one below are entirely static:
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//! ```rust, ignore
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//! rsx!( div { class: "hello world", "this node is entirely static" } )
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//! ```
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//! Because the subtrees won't be diffed, their "real node" data will be stale (invalid), so it's up to the reconciler to
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//! track nodes created in a scope and clean up all relevant data. Support for this is currently WIP and depends on comp-time
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//! hashing of the subtree from the rsx! macro. We do a very limited form of static analysis via static string pointers as
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//! a way of short-circuiting the most expensive checks.
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//!
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//! ## Bloom Filter and Heuristics
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//! ------------------------------
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//! For all components, we employ some basic heuristics to speed up allocations and pre-size bump arenas. The heuristics are
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//! currently very rough, but will get better as time goes on. The information currently tracked includes the size of a
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//! bump arena after first render, the number of hooks, and the number of nodes in the tree.
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//!
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//! ## Garbage Collection
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//! ---------------------
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//! Dioxus uses a passive garbage collection system to clean up old nodes once the work has been completed. This garbage
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//! collection is done internally once the main diffing work is complete. After the "garbage" is collected, Dioxus will then
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//! start to re-use old keys for new nodes. This results in a passive memory management system that is very efficient.
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//!
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//! The IDs used by the key/map are just an index into a Vec. This means that Dioxus will drive the key allocation strategy
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//! so the client only needs to maintain a simple list of nodes. By default, Dioxus will not manually clean up old nodes
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//! for the client. As new nodes are created, old nodes will be over-written.
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//!
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//! ## Further Reading and Thoughts
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//! ----------------------------
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//! There are more ways of increasing diff performance here that are currently not implemented.
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//! - Strong memoization of subtrees.
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//! - Guided diffing.
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//! - Certain web-dom-specific optimizations.
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//!
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//! More info on how to improve this diffing algorithm:
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//! - <https://hacks.mozilla.org/2019/03/fast-bump-allocated-virtual-doms-with-rust-and-wasm/>
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use crate::innerlude::*;
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use fxhash::{FxHashMap, FxHashSet};
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use smallvec::{smallvec, SmallVec};
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use DomEdit::*;
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/// Our DiffState is an iterative tree differ.
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///
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/// It uses techniques of a stack machine to allow pausing and restarting of the diff algorithm. This
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/// was originally implemented using recursive techniques, but Rust lacks the ability to call async functions recursively,
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/// meaning we could not "pause" the original diffing algorithm.
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///
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/// Instead, we use a traditional stack machine approach to diff and create new nodes. The diff algorithm periodically
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/// calls "yield_now" which allows the machine to pause and return control to the caller. The caller can then wait for
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/// the next period of idle time, preventing our diff algorithm from blocking the main thread.
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///
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/// Funnily enough, this stack machine's entire job is to create instructions for another stack machine to execute. It's
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/// stack machines all the way down!
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pub(crate) struct DiffState<'bump> {
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pub(crate) scopes: &'bump ScopeArena,
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pub(crate) mutations: Mutations<'bump>,
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pub(crate) stack: DiffStack<'bump>,
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pub(crate) force_diff: bool,
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}
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impl<'bump> DiffState<'bump> {
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pub(crate) fn new(scopes: &'bump ScopeArena) -> Self {
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Self {
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scopes,
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mutations: Mutations::new(),
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stack: DiffStack::new(),
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force_diff: false,
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}
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}
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}
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/// The stack instructions we use to diff and create new nodes.
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#[derive(Debug)]
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pub(crate) enum DiffInstruction<'a> {
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Diff {
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old: &'a VNode<'a>,
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new: &'a VNode<'a>,
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},
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Create {
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node: &'a VNode<'a>,
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},
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/// pushes the node elements onto the stack for use in mount
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PrepareMove {
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node: &'a VNode<'a>,
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},
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Mount {
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and: MountType<'a>,
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},
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PopScope,
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PopElement,
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}
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#[derive(Debug, Clone, Copy)]
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pub(crate) enum MountType<'a> {
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Absorb,
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Append,
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Replace { old: &'a VNode<'a> },
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InsertAfter { other_node: &'a VNode<'a> },
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InsertBefore { other_node: &'a VNode<'a> },
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}
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pub(crate) struct DiffStack<'bump> {
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pub(crate) instructions: Vec<DiffInstruction<'bump>>,
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pub(crate) nodes_created_stack: SmallVec<[usize; 10]>,
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pub(crate) scope_stack: SmallVec<[ScopeId; 5]>,
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pub(crate) element_stack: SmallVec<[ElementId; 10]>,
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}
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impl<'bump> DiffStack<'bump> {
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fn new() -> Self {
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Self {
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instructions: Vec::with_capacity(1000),
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nodes_created_stack: smallvec![],
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scope_stack: smallvec![],
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element_stack: smallvec![],
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}
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}
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fn pop(&mut self) -> Option<DiffInstruction<'bump>> {
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self.instructions.pop()
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}
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fn pop_off_scope(&mut self) {
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self.scope_stack.pop();
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}
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pub(crate) fn push(&mut self, instruction: DiffInstruction<'bump>) {
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self.instructions.push(instruction)
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}
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fn create_children(&mut self, children: &'bump [VNode<'bump>], and: MountType<'bump>) {
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self.nodes_created_stack.push(0);
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self.instructions.push(DiffInstruction::Mount { and });
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for child in children.iter().rev() {
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self.instructions
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.push(DiffInstruction::Create { node: child });
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}
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}
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// todo: subtrees
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// fn push_subtree(&mut self) {
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// self.nodes_created_stack.push(0);
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// self.instructions.push(DiffInstruction::Mount {
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// and: MountType::Append,
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// });
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// }
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fn push_nodes_created(&mut self, count: usize) {
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self.nodes_created_stack.push(count);
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}
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pub(crate) fn create_node(&mut self, node: &'bump VNode<'bump>, and: MountType<'bump>) {
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self.nodes_created_stack.push(0);
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self.instructions.push(DiffInstruction::Mount { and });
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self.instructions.push(DiffInstruction::Create { node });
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}
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fn add_child_count(&mut self, count: usize) {
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*self.nodes_created_stack.last_mut().unwrap() += count;
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}
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fn pop_nodes_created(&mut self) -> usize {
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self.nodes_created_stack.pop().unwrap()
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}
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fn current_scope(&self) -> Option<ScopeId> {
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self.scope_stack.last().copied()
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}
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fn create_component(&mut self, idx: ScopeId, node: &'bump VNode<'bump>) {
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// Push the new scope onto the stack
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self.scope_stack.push(idx);
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self.instructions.push(DiffInstruction::PopScope);
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// Run the creation algorithm with this scope on the stack
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// ?? I think we treat components as fragments??
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self.instructions.push(DiffInstruction::Create { node });
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}
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}
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impl<'bump> DiffState<'bump> {
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/// Progress the diffing for this "fiber"
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///
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/// This method implements a depth-first iterative tree traversal.
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///
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/// We do depth-first to maintain high cache locality (nodes were originally generated recursively).
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///
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/// Returns a `bool` indicating that the work completed properly.
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pub fn work(&mut self, mut deadline_expired: impl FnMut() -> bool) -> bool {
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while let Some(instruction) = self.stack.pop() {
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match instruction {
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DiffInstruction::Diff { old, new } => self.diff_node(old, new),
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DiffInstruction::Create { node } => self.create_node(node),
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DiffInstruction::Mount { and } => self.mount(and),
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DiffInstruction::PrepareMove { node } => {
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let num_on_stack = self.push_all_nodes(node);
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self.stack.add_child_count(num_on_stack);
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}
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DiffInstruction::PopScope => self.stack.pop_off_scope(),
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DiffInstruction::PopElement => {
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self.stack.element_stack.pop();
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}
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};
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if deadline_expired() {
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log::debug!("Deadline expired before we could finish!");
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return false;
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}
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}
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true
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}
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// recursively push all the nodes of a tree onto the stack and return how many are there
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fn push_all_nodes(&mut self, node: &'bump VNode<'bump>) -> usize {
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match node {
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VNode::Text(_) | VNode::Placeholder(_) => {
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self.mutations.push_root(node.mounted_id());
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1
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}
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VNode::Fragment(_) | VNode::Component(_) => {
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//
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let mut added = 0;
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for child in node.children() {
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added += self.push_all_nodes(child);
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}
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added
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}
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VNode::Element(el) => {
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let mut num_on_stack = 0;
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for child in el.children.iter() {
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num_on_stack += self.push_all_nodes(child);
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}
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self.mutations.push_root(el.id.get().unwrap());
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num_on_stack + 1
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}
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}
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}
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fn mount(&mut self, and: MountType<'bump>) {
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let nodes_created = self.stack.pop_nodes_created();
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match and {
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// add the nodes from this virtual list to the parent
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// used by fragments and components
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MountType::Absorb => {
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self.stack.add_child_count(nodes_created);
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}
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MountType::Replace { old } => {
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self.replace_node(old, nodes_created);
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}
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MountType::Append => {
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self.mutations.edits.push(AppendChildren {
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many: nodes_created as u32,
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});
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}
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MountType::InsertAfter { other_node } => {
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let root = self.find_last_element(other_node).unwrap();
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self.mutations.insert_after(root, nodes_created as u32);
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}
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MountType::InsertBefore { other_node } => {
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let root = self.find_first_element_id(other_node).unwrap();
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self.mutations.insert_before(root, nodes_created as u32);
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}
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}
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}
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// =================================
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// Tools for creating new nodes
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// =================================
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fn create_node(&mut self, node: &'bump VNode<'bump>) {
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match node {
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VNode::Text(vtext) => self.create_text_node(vtext, node),
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VNode::Placeholder(anchor) => self.create_anchor_node(anchor, node),
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VNode::Element(element) => self.create_element_node(element, node),
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VNode::Fragment(frag) => self.create_fragment_node(frag),
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VNode::Component(component) => self.create_component_node(*component),
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}
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}
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fn create_text_node(&mut self, vtext: &'bump VText<'bump>, node: &'bump VNode<'bump>) {
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let real_id = self.scopes.reserve_node(node);
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self.mutations.create_text_node(vtext.text, real_id);
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vtext.id.set(Some(real_id));
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self.stack.add_child_count(1);
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}
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fn create_anchor_node(&mut self, anchor: &'bump VPlaceholder, node: &'bump VNode<'bump>) {
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let real_id = self.scopes.reserve_node(node);
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self.mutations.create_placeholder(real_id);
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anchor.id.set(Some(real_id));
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self.stack.add_child_count(1);
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}
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fn create_element_node(&mut self, element: &'bump VElement<'bump>, node: &'bump VNode<'bump>) {
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let VElement {
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tag: tag_name,
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listeners,
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attributes,
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children,
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namespace,
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id: dom_id,
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parent: parent_id,
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..
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} = element;
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// set the parent ID for event bubbling
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self.stack.instructions.push(DiffInstruction::PopElement);
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let parent = self.stack.element_stack.last().unwrap();
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parent_id.set(Some(*parent));
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// set the id of the element
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let real_id = self.scopes.reserve_node(node);
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self.stack.element_stack.push(real_id);
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dom_id.set(Some(real_id));
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self.mutations.create_element(tag_name, *namespace, real_id);
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self.stack.add_child_count(1);
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if let Some(cur_scope_id) = self.stack.current_scope() {
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let scope = self.scopes.get_scope(cur_scope_id).unwrap();
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for listener in *listeners {
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self.attach_listener_to_scope(listener, scope);
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listener.mounted_node.set(Some(real_id));
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self.mutations.new_event_listener(listener, cur_scope_id);
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}
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} else {
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log::warn!("create element called with no scope on the stack - this is an error for a live dom");
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}
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for attr in *attributes {
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self.mutations.set_attribute(attr, real_id.as_u64());
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}
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// todo: the settext optimization
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//
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// if children.len() == 1 {
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// if let VNode::Text(vtext) = children[0] {
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// self.mutations.set_text(vtext.text, real_id.as_u64());
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// return;
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// }
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// }
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if !children.is_empty() {
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self.stack.create_children(children, MountType::Append);
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}
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}
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fn create_fragment_node(&mut self, frag: &'bump VFragment<'bump>) {
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self.stack.create_children(frag.children, MountType::Absorb);
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}
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fn create_component_node(&mut self, vcomponent: &'bump VComponent<'bump>) {
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let parent_idx = self.stack.current_scope().unwrap();
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// Insert a new scope into our component list
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let props: Box<dyn AnyProps + 'bump> = vcomponent.props.borrow_mut().take().unwrap();
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let props: Box<dyn AnyProps + 'static> = unsafe { std::mem::transmute(props) };
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let new_idx = self.scopes.new_with_key(
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vcomponent.user_fc,
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props,
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Some(parent_idx),
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self.stack.element_stack.last().copied().unwrap(),
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0,
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);
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// Actually initialize the caller's slot with the right address
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vcomponent.scope.set(Some(new_idx));
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match vcomponent.can_memoize {
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true => {
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// todo: implement promotion logic. save us from boxing props that we don't need
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}
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false => {
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// track this component internally so we know the right drop order
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let cur_scope = self.scopes.get_scope(parent_idx).unwrap();
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let extended = unsafe { std::mem::transmute(vcomponent) };
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cur_scope.items.borrow_mut().borrowed_props.push(extended);
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}
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}
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// Run the scope for one iteration to initialize it
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self.scopes.run_scope(new_idx);
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// Take the node that was just generated from running the component
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let nextnode = self.scopes.fin_head(new_idx);
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self.stack.create_component(new_idx, nextnode);
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// Finally, insert this scope as a seen node.
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self.mutations.dirty_scopes.insert(new_idx);
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}
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// =================================
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// Tools for diffing nodes
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// =================================
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pub fn diff_node(&mut self, old_node: &'bump VNode<'bump>, new_node: &'bump VNode<'bump>) {
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use VNode::*;
|
|
match (old_node, new_node) {
|
|
// Check the most common cases first
|
|
// these are *actual* elements, not wrappers around lists
|
|
(Text(old), Text(new)) => {
|
|
if let Some(root) = old.id.get() {
|
|
if old.text != new.text {
|
|
self.mutations.set_text(new.text, root.as_u64());
|
|
}
|
|
self.scopes.update_node(new_node, root);
|
|
|
|
new.id.set(Some(root));
|
|
}
|
|
}
|
|
|
|
(Placeholder(old), Placeholder(new)) => {
|
|
if let Some(root) = old.id.get() {
|
|
self.scopes.update_node(new_node, root);
|
|
new.id.set(Some(root))
|
|
}
|
|
}
|
|
|
|
(Element(old), Element(new)) => self.diff_element_nodes(old, new, old_node, new_node),
|
|
|
|
// These two sets are pointers to nodes but are not actually nodes themselves
|
|
(Component(old), Component(new)) => {
|
|
self.diff_component_nodes(old_node, new_node, *old, *new)
|
|
}
|
|
|
|
(Fragment(old), Fragment(new)) => self.diff_fragment_nodes(old, new),
|
|
|
|
// The normal pathway still works, but generates slightly weird instructions
|
|
// This pathway ensures uses the ReplaceAll, not the InsertAfter and remove
|
|
(Placeholder(_), Fragment(new)) => {
|
|
self.stack
|
|
.create_children(new.children, MountType::Replace { old: old_node });
|
|
}
|
|
|
|
// Anything else is just a basic replace and create
|
|
(
|
|
Component(_) | Fragment(_) | Text(_) | Element(_) | Placeholder(_),
|
|
Component(_) | Fragment(_) | Text(_) | Element(_) | Placeholder(_),
|
|
) => self
|
|
.stack
|
|
.create_node(new_node, MountType::Replace { old: old_node }),
|
|
}
|
|
}
|
|
|
|
fn diff_element_nodes(
|
|
&mut self,
|
|
old: &'bump VElement<'bump>,
|
|
new: &'bump VElement<'bump>,
|
|
old_node: &'bump VNode<'bump>,
|
|
new_node: &'bump VNode<'bump>,
|
|
) {
|
|
let root = old.id.get().unwrap();
|
|
|
|
// If the element type is completely different, the element needs to be re-rendered completely
|
|
// This is an optimization React makes due to how users structure their code
|
|
//
|
|
// This case is rather rare (typically only in non-keyed lists)
|
|
if new.tag != old.tag || new.namespace != old.namespace {
|
|
// maybe make this an instruction?
|
|
// issue is that we need the "vnode" but this method only has the velement
|
|
self.stack.push_nodes_created(0);
|
|
self.stack.push(DiffInstruction::Mount {
|
|
and: MountType::Replace { old: old_node },
|
|
});
|
|
self.create_element_node(new, new_node);
|
|
return;
|
|
}
|
|
|
|
self.scopes.update_node(new_node, root);
|
|
|
|
new.id.set(Some(root));
|
|
new.parent.set(old.parent.get());
|
|
|
|
// todo: attributes currently rely on the element on top of the stack, but in theory, we only need the id of the
|
|
// element to modify its attributes.
|
|
// it would result in fewer instructions if we just set the id directly.
|
|
// it would also clean up this code some, but that's not very important anyways
|
|
|
|
// Diff Attributes
|
|
//
|
|
// It's extraordinarily rare to have the number/order of attributes change
|
|
// In these cases, we just completely erase the old set and make a new set
|
|
//
|
|
// TODO: take a more efficient path than this
|
|
if old.attributes.len() == new.attributes.len() {
|
|
for (old_attr, new_attr) in old.attributes.iter().zip(new.attributes.iter()) {
|
|
if old_attr.value != new_attr.value || new_attr.is_volatile {
|
|
self.mutations.set_attribute(new_attr, root.as_u64());
|
|
}
|
|
}
|
|
} else {
|
|
for attribute in old.attributes {
|
|
self.mutations.remove_attribute(attribute, root.as_u64());
|
|
}
|
|
for attribute in new.attributes {
|
|
self.mutations.set_attribute(attribute, root.as_u64())
|
|
}
|
|
}
|
|
|
|
// Diff listeners
|
|
//
|
|
// It's extraordinarily rare to have the number/order of listeners change
|
|
// In the cases where the listeners change, we completely wipe the data attributes and add new ones
|
|
//
|
|
// We also need to make sure that all listeners are properly attached to the parent scope (fix_listener)
|
|
//
|
|
// TODO: take a more efficient path than this
|
|
if let Some(cur_scope_id) = self.stack.current_scope() {
|
|
let scope = self.scopes.get_scope(cur_scope_id).unwrap();
|
|
|
|
if old.listeners.len() == new.listeners.len() {
|
|
for (old_l, new_l) in old.listeners.iter().zip(new.listeners.iter()) {
|
|
if old_l.event != new_l.event {
|
|
self.mutations
|
|
.remove_event_listener(old_l.event, root.as_u64());
|
|
self.mutations.new_event_listener(new_l, cur_scope_id);
|
|
}
|
|
new_l.mounted_node.set(old_l.mounted_node.get());
|
|
self.attach_listener_to_scope(new_l, scope);
|
|
}
|
|
} else {
|
|
for listener in old.listeners {
|
|
self.mutations
|
|
.remove_event_listener(listener.event, root.as_u64());
|
|
}
|
|
for listener in new.listeners {
|
|
listener.mounted_node.set(Some(root));
|
|
self.mutations.new_event_listener(listener, cur_scope_id);
|
|
self.attach_listener_to_scope(listener, scope);
|
|
}
|
|
}
|
|
}
|
|
|
|
if old.children.is_empty() && !new.children.is_empty() {
|
|
self.mutations.edits.push(PushRoot {
|
|
root: root.as_u64(),
|
|
});
|
|
self.stack.element_stack.push(root);
|
|
self.stack.instructions.push(DiffInstruction::PopElement);
|
|
self.stack.create_children(new.children, MountType::Append);
|
|
} else {
|
|
self.stack.element_stack.push(root);
|
|
self.stack.instructions.push(DiffInstruction::PopElement);
|
|
self.diff_children(old.children, new.children);
|
|
}
|
|
|
|
// todo: this is for the "settext" optimization
|
|
// it works, but i'm not sure if it's the direction we want to take right away
|
|
// I haven't benchmarked the performance imporvemenet yet. Perhaps
|
|
// we can make it a config?
|
|
|
|
// match (old.children.len(), new.children.len()) {
|
|
// (0, 0) => {}
|
|
// (1, 1) => {
|
|
// let old1 = &old.children[0];
|
|
// let new1 = &new.children[0];
|
|
|
|
// match (old1, new1) {
|
|
// (VNode::Text(old_text), VNode::Text(new_text)) => {
|
|
// if old_text.text != new_text.text {
|
|
// self.mutations.set_text(new_text.text, root.as_u64());
|
|
// }
|
|
// }
|
|
// (VNode::Text(_old_text), _) => {
|
|
// self.stack.element_stack.push(root);
|
|
// self.stack.instructions.push(DiffInstruction::PopElement);
|
|
// self.stack.create_node(new1, MountType::Append);
|
|
// }
|
|
// (_, VNode::Text(new_text)) => {
|
|
// self.remove_nodes([old1], false);
|
|
// self.mutations.set_text(new_text.text, root.as_u64());
|
|
// }
|
|
// _ => {
|
|
// self.stack.element_stack.push(root);
|
|
// self.stack.instructions.push(DiffInstruction::PopElement);
|
|
// self.diff_children(old.children, new.children);
|
|
// }
|
|
// }
|
|
// }
|
|
// (0, 1) => {
|
|
// if let VNode::Text(text) = &new.children[0] {
|
|
// self.mutations.set_text(text.text, root.as_u64());
|
|
// } else {
|
|
// self.stack.element_stack.push(root);
|
|
// self.stack.instructions.push(DiffInstruction::PopElement);
|
|
// }
|
|
// }
|
|
// (0, _) => {
|
|
// self.mutations.edits.push(PushRoot {
|
|
// root: root.as_u64(),
|
|
// });
|
|
// self.stack.element_stack.push(root);
|
|
// self.stack.instructions.push(DiffInstruction::PopElement);
|
|
// self.stack.create_children(new.children, MountType::Append);
|
|
// }
|
|
// (_, 0) => {
|
|
// self.remove_nodes(old.children, false);
|
|
// self.mutations.set_text("", root.as_u64());
|
|
// }
|
|
// (_, _) => {
|
|
// self.stack.element_stack.push(root);
|
|
// self.stack.instructions.push(DiffInstruction::PopElement);
|
|
// self.diff_children(old.children, new.children);
|
|
// }
|
|
// }
|
|
}
|
|
|
|
fn diff_component_nodes(
|
|
&mut self,
|
|
old_node: &'bump VNode<'bump>,
|
|
new_node: &'bump VNode<'bump>,
|
|
old: &'bump VComponent<'bump>,
|
|
new: &'bump VComponent<'bump>,
|
|
) {
|
|
let scope_addr = old.scope.get().unwrap();
|
|
|
|
// Make sure we're dealing with the same component (by function pointer)
|
|
if old.user_fc == new.user_fc {
|
|
self.stack.scope_stack.push(scope_addr);
|
|
|
|
// Make sure the new component vnode is referencing the right scope id
|
|
new.scope.set(Some(scope_addr));
|
|
|
|
// make sure the component's caller function is up to date
|
|
let scope = self
|
|
.scopes
|
|
.get_scope(scope_addr)
|
|
.unwrap_or_else(|| panic!("could not find {:?}", scope_addr));
|
|
|
|
// take the new props out regardless
|
|
// when memoizing, push to the existing scope if memoization happens
|
|
let new_props = new.props.borrow_mut().take().unwrap();
|
|
|
|
let should_run = {
|
|
if old.can_memoize {
|
|
let props_are_the_same = unsafe {
|
|
scope
|
|
.props
|
|
.borrow()
|
|
.as_ref()
|
|
.unwrap()
|
|
.memoize(new_props.as_ref())
|
|
};
|
|
!props_are_the_same || self.force_diff
|
|
} else {
|
|
true
|
|
}
|
|
};
|
|
|
|
if should_run {
|
|
let _old_props = scope
|
|
.props
|
|
.replace(unsafe { std::mem::transmute(Some(new_props)) });
|
|
|
|
// this should auto drop the previous props
|
|
self.scopes.run_scope(scope_addr);
|
|
self.diff_node(
|
|
self.scopes.wip_head(scope_addr),
|
|
self.scopes.fin_head(scope_addr),
|
|
);
|
|
} else {
|
|
// memoization has taken place
|
|
drop(new_props);
|
|
};
|
|
|
|
self.stack.scope_stack.pop();
|
|
} else {
|
|
self.stack
|
|
.create_node(new_node, MountType::Replace { old: old_node });
|
|
}
|
|
}
|
|
|
|
fn diff_fragment_nodes(&mut self, old: &'bump VFragment<'bump>, new: &'bump VFragment<'bump>) {
|
|
// This is the case where options or direct vnodes might be used.
|
|
// In this case, it's faster to just skip ahead to their diff
|
|
if old.children.len() == 1 && new.children.len() == 1 {
|
|
self.diff_node(&old.children[0], &new.children[0]);
|
|
return;
|
|
}
|
|
|
|
debug_assert!(!old.children.is_empty());
|
|
debug_assert!(!new.children.is_empty());
|
|
|
|
self.diff_children(old.children, new.children);
|
|
}
|
|
|
|
// =============================================
|
|
// Utilities for creating new diff instructions
|
|
// =============================================
|
|
|
|
// Diff the given set of old and new children.
|
|
//
|
|
// The parent must be on top of the change list stack when this function is
|
|
// entered:
|
|
//
|
|
// [... parent]
|
|
//
|
|
// the change list stack is in the same state when this function returns.
|
|
//
|
|
// If old no anchors are provided, then it's assumed that we can freely append to the parent.
|
|
//
|
|
// Remember, non-empty lists does not mean that there are real elements, just that there are virtual elements.
|
|
//
|
|
// Fragment nodes cannot generate empty children lists, so we can assume that when a list is empty, it belongs only
|
|
// to an element, and appending makes sense.
|
|
fn diff_children(&mut self, old: &'bump [VNode<'bump>], new: &'bump [VNode<'bump>]) {
|
|
// Remember, fragments can never be empty (they always have a single child)
|
|
match (old, new) {
|
|
([], []) => {}
|
|
([], _) => self.stack.create_children(new, MountType::Append),
|
|
(_, []) => self.remove_nodes(old, true),
|
|
_ => {
|
|
let new_is_keyed = new[0].key().is_some();
|
|
let old_is_keyed = old[0].key().is_some();
|
|
|
|
debug_assert!(
|
|
new.iter().all(|n| n.key().is_some() == new_is_keyed),
|
|
"all siblings must be keyed or all siblings must be non-keyed"
|
|
);
|
|
debug_assert!(
|
|
old.iter().all(|o| o.key().is_some() == old_is_keyed),
|
|
"all siblings must be keyed or all siblings must be non-keyed"
|
|
);
|
|
|
|
if new_is_keyed && old_is_keyed {
|
|
self.diff_keyed_children(old, new);
|
|
} else {
|
|
self.diff_non_keyed_children(old, new);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
// Diff children that are not keyed.
|
|
//
|
|
// The parent must be on the top of the change list stack when entering this
|
|
// function:
|
|
//
|
|
// [... parent]
|
|
//
|
|
// the change list stack is in the same state when this function returns.
|
|
fn diff_non_keyed_children(&mut self, old: &'bump [VNode<'bump>], new: &'bump [VNode<'bump>]) {
|
|
// Handled these cases in `diff_children` before calling this function.
|
|
debug_assert!(!new.is_empty());
|
|
debug_assert!(!old.is_empty());
|
|
|
|
for (new, old) in new.iter().zip(old.iter()).rev() {
|
|
self.stack.push(DiffInstruction::Diff { new, old });
|
|
}
|
|
|
|
use std::cmp::Ordering;
|
|
match old.len().cmp(&new.len()) {
|
|
Ordering::Greater => self.remove_nodes(&old[new.len()..], true),
|
|
Ordering::Less => {
|
|
self.stack.create_children(
|
|
&new[old.len()..],
|
|
MountType::InsertAfter {
|
|
other_node: old.last().unwrap(),
|
|
},
|
|
);
|
|
}
|
|
Ordering::Equal => {
|
|
// nothing - they're the same size
|
|
}
|
|
}
|
|
}
|
|
|
|
// Diffing "keyed" children.
|
|
//
|
|
// With keyed children, we care about whether we delete, move, or create nodes
|
|
// versus mutate existing nodes in place. Presumably there is some sort of CSS
|
|
// transition animation that makes the virtual DOM diffing algorithm
|
|
// observable. By specifying keys for nodes, we know which virtual DOM nodes
|
|
// must reuse (or not reuse) the same physical DOM nodes.
|
|
//
|
|
// This is loosely based on Inferno's keyed patching implementation. However, we
|
|
// have to modify the algorithm since we are compiling the diff down into change
|
|
// list instructions that will be executed later, rather than applying the
|
|
// changes to the DOM directly as we compare virtual DOMs.
|
|
//
|
|
// https://github.com/infernojs/inferno/blob/36fd96/packages/inferno/src/DOM/patching.ts#L530-L739
|
|
//
|
|
// The stack is empty upon entry.
|
|
fn diff_keyed_children(&mut self, old: &'bump [VNode<'bump>], new: &'bump [VNode<'bump>]) {
|
|
if cfg!(debug_assertions) {
|
|
let mut keys = fxhash::FxHashSet::default();
|
|
let mut assert_unique_keys = |children: &'bump [VNode<'bump>]| {
|
|
keys.clear();
|
|
for child in children {
|
|
let key = child.key();
|
|
debug_assert!(
|
|
key.is_some(),
|
|
"if any sibling is keyed, all siblings must be keyed"
|
|
);
|
|
keys.insert(key);
|
|
}
|
|
debug_assert_eq!(
|
|
children.len(),
|
|
keys.len(),
|
|
"keyed siblings must each have a unique key"
|
|
);
|
|
};
|
|
assert_unique_keys(old);
|
|
assert_unique_keys(new);
|
|
}
|
|
|
|
// First up, we diff all the nodes with the same key at the beginning of the
|
|
// children.
|
|
//
|
|
// `shared_prefix_count` is the count of how many nodes at the start of
|
|
// `new` and `old` share the same keys.
|
|
let (left_offset, right_offset) = match self.diff_keyed_ends(old, new) {
|
|
Some(count) => count,
|
|
None => return,
|
|
};
|
|
|
|
// Ok, we now hopefully have a smaller range of children in the middle
|
|
// within which to re-order nodes with the same keys, remove old nodes with
|
|
// now-unused keys, and create new nodes with fresh keys.
|
|
|
|
let old_middle = &old[left_offset..(old.len() - right_offset)];
|
|
let new_middle = &new[left_offset..(new.len() - right_offset)];
|
|
|
|
debug_assert!(
|
|
!((old_middle.len() == new_middle.len()) && old_middle.is_empty()),
|
|
"keyed children must have the same number of children"
|
|
);
|
|
if new_middle.is_empty() {
|
|
// remove the old elements
|
|
self.remove_nodes(old_middle, true);
|
|
} else if old_middle.is_empty() {
|
|
// there were no old elements, so just create the new elements
|
|
// we need to find the right "foothold" though - we shouldn't use the "append" at all
|
|
if left_offset == 0 {
|
|
// insert at the beginning of the old list
|
|
let foothold = &old[old.len() - right_offset];
|
|
self.stack.create_children(
|
|
new_middle,
|
|
MountType::InsertBefore {
|
|
other_node: foothold,
|
|
},
|
|
);
|
|
} else if right_offset == 0 {
|
|
// insert at the end the old list
|
|
let foothold = old.last().unwrap();
|
|
self.stack.create_children(
|
|
new_middle,
|
|
MountType::InsertAfter {
|
|
other_node: foothold,
|
|
},
|
|
);
|
|
} else {
|
|
// inserting in the middle
|
|
let foothold = &old[left_offset - 1];
|
|
self.stack.create_children(
|
|
new_middle,
|
|
MountType::InsertAfter {
|
|
other_node: foothold,
|
|
},
|
|
);
|
|
}
|
|
} else {
|
|
self.diff_keyed_middle(old_middle, new_middle);
|
|
}
|
|
}
|
|
|
|
/// Diff both ends of the children that share keys.
|
|
///
|
|
/// Returns a left offset and right offset of that indicates a smaller section to pass onto the middle diffing.
|
|
///
|
|
/// If there is no offset, then this function returns None and the diffing is complete.
|
|
fn diff_keyed_ends(
|
|
&mut self,
|
|
|
|
old: &'bump [VNode<'bump>],
|
|
new: &'bump [VNode<'bump>],
|
|
) -> Option<(usize, usize)> {
|
|
let mut left_offset = 0;
|
|
|
|
for (old, new) in old.iter().zip(new.iter()) {
|
|
// abort early if we finally run into nodes with different keys
|
|
if old.key() != new.key() {
|
|
break;
|
|
}
|
|
self.stack.push(DiffInstruction::Diff { old, new });
|
|
left_offset += 1;
|
|
}
|
|
|
|
// If that was all of the old children, then create and append the remaining
|
|
// new children and we're finished.
|
|
if left_offset == old.len() {
|
|
self.stack.create_children(
|
|
&new[left_offset..],
|
|
MountType::InsertAfter {
|
|
other_node: old.last().unwrap(),
|
|
},
|
|
);
|
|
return None;
|
|
}
|
|
|
|
// And if that was all of the new children, then remove all of the remaining
|
|
// old children and we're finished.
|
|
if left_offset == new.len() {
|
|
self.remove_nodes(&old[left_offset..], true);
|
|
return None;
|
|
}
|
|
|
|
// if the shared prefix is less than either length, then we need to walk backwards
|
|
let mut right_offset = 0;
|
|
for (old, new) in old.iter().rev().zip(new.iter().rev()) {
|
|
// abort early if we finally run into nodes with different keys
|
|
if old.key() != new.key() {
|
|
break;
|
|
}
|
|
self.diff_node(old, new);
|
|
right_offset += 1;
|
|
}
|
|
|
|
Some((left_offset, right_offset))
|
|
}
|
|
|
|
// The most-general, expensive code path for keyed children diffing.
|
|
//
|
|
// We find the longest subsequence within `old` of children that are relatively
|
|
// ordered the same way in `new` (via finding a longest-increasing-subsequence
|
|
// of the old child's index within `new`). The children that are elements of
|
|
// this subsequence will remain in place, minimizing the number of DOM moves we
|
|
// will have to do.
|
|
//
|
|
// Upon entry to this function, the change list stack must be empty.
|
|
//
|
|
// This function will load the appropriate nodes onto the stack and do diffing in place.
|
|
//
|
|
// Upon exit from this function, it will be restored to that same self.
|
|
fn diff_keyed_middle(&mut self, old: &'bump [VNode<'bump>], new: &'bump [VNode<'bump>]) {
|
|
/*
|
|
1. Map the old keys into a numerical ordering based on indices.
|
|
2. Create a map of old key to its index
|
|
3. Map each new key to the old key, carrying over the old index.
|
|
- IE if we have ABCD becomes BACD, our sequence would be 1,0,2,3
|
|
- if we have ABCD to ABDE, our sequence would be 0,1,3,MAX because E doesn't exist
|
|
|
|
now, we should have a list of integers that indicates where in the old list the new items map to.
|
|
|
|
4. Compute the LIS of this list
|
|
- this indicates the longest list of new children that won't need to be moved.
|
|
|
|
5. Identify which nodes need to be removed
|
|
6. Identify which nodes will need to be diffed
|
|
|
|
7. Going along each item in the new list, create it and insert it before the next closest item in the LIS.
|
|
- if the item already existed, just move it to the right place.
|
|
|
|
8. Finally, generate instructions to remove any old children.
|
|
9. Generate instructions to finally diff children that are the same between both
|
|
*/
|
|
|
|
// 0. Debug sanity checks
|
|
// Should have already diffed the shared-key prefixes and suffixes.
|
|
debug_assert_ne!(new.first().map(|n| n.key()), old.first().map(|o| o.key()));
|
|
debug_assert_ne!(new.last().map(|n| n.key()), old.last().map(|o| o.key()));
|
|
|
|
// 1. Map the old keys into a numerical ordering based on indices.
|
|
// 2. Create a map of old key to its index
|
|
// IE if the keys were A B C, then we would have (A, 1) (B, 2) (C, 3).
|
|
let old_key_to_old_index = old
|
|
.iter()
|
|
.enumerate()
|
|
.map(|(i, o)| (o.key().unwrap(), i))
|
|
.collect::<FxHashMap<_, _>>();
|
|
|
|
let mut shared_keys = FxHashSet::default();
|
|
|
|
// 3. Map each new key to the old key, carrying over the old index.
|
|
let new_index_to_old_index = new
|
|
.iter()
|
|
.map(|node| {
|
|
let key = node.key().unwrap();
|
|
if let Some(&index) = old_key_to_old_index.get(&key) {
|
|
shared_keys.insert(key);
|
|
index
|
|
} else {
|
|
u32::MAX as usize
|
|
}
|
|
})
|
|
.collect::<Vec<_>>();
|
|
|
|
// If none of the old keys are reused by the new children, then we remove all the remaining old children and
|
|
// create the new children afresh.
|
|
if shared_keys.is_empty() {
|
|
if let Some(first_old) = old.get(0) {
|
|
self.remove_nodes(&old[1..], true);
|
|
self.stack
|
|
.create_children(new, MountType::Replace { old: first_old })
|
|
} else {
|
|
self.stack.create_children(new, MountType::Append {});
|
|
}
|
|
return;
|
|
}
|
|
|
|
// 4. Compute the LIS of this list
|
|
let mut lis_sequence = Vec::default();
|
|
lis_sequence.reserve(new_index_to_old_index.len());
|
|
|
|
let mut predecessors = vec![0; new_index_to_old_index.len()];
|
|
let mut starts = vec![0; new_index_to_old_index.len()];
|
|
|
|
longest_increasing_subsequence::lis_with(
|
|
&new_index_to_old_index,
|
|
&mut lis_sequence,
|
|
|a, b| a < b,
|
|
&mut predecessors,
|
|
&mut starts,
|
|
);
|
|
|
|
// the lis comes out backwards, I think. can't quite tell.
|
|
lis_sequence.sort_unstable();
|
|
|
|
// if a new node gets u32 max and is at the end, then it might be part of our LIS (because u32 max is a valid LIS)
|
|
if lis_sequence.last().map(|f| new_index_to_old_index[*f]) == Some(u32::MAX as usize) {
|
|
lis_sequence.pop();
|
|
}
|
|
|
|
let apply = |new_idx, new_node: &'bump VNode<'bump>, stack: &mut DiffStack<'bump>| {
|
|
let old_index = new_index_to_old_index[new_idx];
|
|
if old_index == u32::MAX as usize {
|
|
stack.create_node(new_node, MountType::Absorb);
|
|
} else {
|
|
// this function should never take LIS indices
|
|
stack.push(DiffInstruction::PrepareMove { node: new_node });
|
|
stack.push(DiffInstruction::Diff {
|
|
new: new_node,
|
|
old: &old[old_index],
|
|
});
|
|
}
|
|
};
|
|
|
|
// add mount instruction for the last items not covered by the lis
|
|
let first_lis = *lis_sequence.first().unwrap();
|
|
if first_lis > 0 {
|
|
self.stack.push_nodes_created(0);
|
|
self.stack.push(DiffInstruction::Mount {
|
|
and: MountType::InsertBefore {
|
|
other_node: &new[first_lis],
|
|
},
|
|
});
|
|
|
|
for (idx, new_node) in new[..first_lis].iter().enumerate().rev() {
|
|
apply(idx, new_node, &mut self.stack);
|
|
}
|
|
}
|
|
|
|
// for each spacing, generate a mount instruction
|
|
let mut lis_iter = lis_sequence.iter().rev();
|
|
let mut last = *lis_iter.next().unwrap();
|
|
for next in lis_iter {
|
|
if last - next > 1 {
|
|
self.stack.push_nodes_created(0);
|
|
self.stack.push(DiffInstruction::Mount {
|
|
and: MountType::InsertBefore {
|
|
other_node: &new[last],
|
|
},
|
|
});
|
|
for (idx, new_node) in new[(next + 1)..last].iter().enumerate().rev() {
|
|
apply(idx + next + 1, new_node, &mut self.stack);
|
|
}
|
|
}
|
|
last = *next;
|
|
}
|
|
|
|
// add mount instruction for the first items not covered by the lis
|
|
let last = *lis_sequence.last().unwrap();
|
|
if last < (new.len() - 1) {
|
|
self.stack.push_nodes_created(0);
|
|
self.stack.push(DiffInstruction::Mount {
|
|
and: MountType::InsertAfter {
|
|
other_node: &new[last],
|
|
},
|
|
});
|
|
for (idx, new_node) in new[(last + 1)..].iter().enumerate().rev() {
|
|
apply(idx + last + 1, new_node, &mut self.stack);
|
|
}
|
|
}
|
|
|
|
for idx in lis_sequence.iter().rev() {
|
|
self.stack.push(DiffInstruction::Diff {
|
|
new: &new[*idx],
|
|
old: &old[new_index_to_old_index[*idx]],
|
|
});
|
|
}
|
|
}
|
|
|
|
// =====================
|
|
// Utilities
|
|
// =====================
|
|
|
|
fn find_last_element(&mut self, vnode: &'bump VNode<'bump>) -> Option<ElementId> {
|
|
let mut search_node = Some(vnode);
|
|
|
|
loop {
|
|
match &search_node.take().unwrap() {
|
|
VNode::Text(t) => break t.id.get(),
|
|
VNode::Element(t) => break t.id.get(),
|
|
VNode::Placeholder(t) => break t.id.get(),
|
|
VNode::Fragment(frag) => {
|
|
search_node = frag.children.last();
|
|
}
|
|
VNode::Component(el) => {
|
|
let scope_id = el.scope.get().unwrap();
|
|
search_node = Some(self.scopes.root_node(scope_id));
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
fn find_first_element_id(&mut self, vnode: &'bump VNode<'bump>) -> Option<ElementId> {
|
|
let mut search_node = Some(vnode);
|
|
|
|
loop {
|
|
match &search_node.take().unwrap() {
|
|
// the ones that have a direct id
|
|
VNode::Fragment(frag) => {
|
|
search_node = Some(&frag.children[0]);
|
|
}
|
|
VNode::Component(el) => {
|
|
let scope_id = el.scope.get().unwrap();
|
|
search_node = Some(self.scopes.root_node(scope_id));
|
|
}
|
|
VNode::Text(t) => break t.id.get(),
|
|
VNode::Element(t) => break t.id.get(),
|
|
VNode::Placeholder(t) => break t.id.get(),
|
|
}
|
|
}
|
|
}
|
|
|
|
fn replace_node(&mut self, old: &'bump VNode<'bump>, nodes_created: usize) {
|
|
match old {
|
|
VNode::Element(el) => {
|
|
let id = old
|
|
.try_mounted_id()
|
|
.unwrap_or_else(|| panic!("broke on {:?}", old));
|
|
|
|
self.mutations.replace_with(id, nodes_created as u32);
|
|
self.remove_nodes(el.children, false);
|
|
}
|
|
|
|
VNode::Text(_) | VNode::Placeholder(_) => {
|
|
let id = old
|
|
.try_mounted_id()
|
|
.unwrap_or_else(|| panic!("broke on {:?}", old));
|
|
|
|
self.mutations.replace_with(id, nodes_created as u32);
|
|
}
|
|
|
|
VNode::Fragment(f) => {
|
|
self.replace_node(&f.children[0], nodes_created);
|
|
self.remove_nodes(f.children.iter().skip(1), true);
|
|
}
|
|
|
|
VNode::Component(c) => {
|
|
let node = self.scopes.fin_head(c.scope.get().unwrap());
|
|
self.replace_node(node, nodes_created);
|
|
|
|
let scope_id = c.scope.get().unwrap();
|
|
|
|
self.scopes.try_remove(scope_id).unwrap();
|
|
}
|
|
}
|
|
}
|
|
|
|
/// schedules nodes for garbage collection and pushes "remove" to the mutation stack
|
|
/// remove can happen whenever
|
|
pub(crate) fn remove_nodes(
|
|
&mut self,
|
|
nodes: impl IntoIterator<Item = &'bump VNode<'bump>>,
|
|
gen_muts: bool,
|
|
) {
|
|
// or cache the vec on the diff machine
|
|
for node in nodes {
|
|
match node {
|
|
VNode::Text(t) => {
|
|
// this check exists because our null node will be removed but does not have an ID
|
|
if let Some(id) = t.id.get() {
|
|
self.scopes.collect_garbage(id);
|
|
|
|
if gen_muts {
|
|
self.mutations.remove(id.as_u64());
|
|
}
|
|
}
|
|
}
|
|
VNode::Placeholder(a) => {
|
|
let id = a.id.get().unwrap();
|
|
self.scopes.collect_garbage(id);
|
|
|
|
if gen_muts {
|
|
self.mutations.remove(id.as_u64());
|
|
}
|
|
}
|
|
VNode::Element(e) => {
|
|
let id = e.id.get().unwrap();
|
|
|
|
if gen_muts {
|
|
self.mutations.remove(id.as_u64());
|
|
}
|
|
|
|
self.remove_nodes(e.children, false);
|
|
}
|
|
|
|
VNode::Fragment(f) => {
|
|
self.remove_nodes(f.children, gen_muts);
|
|
}
|
|
|
|
VNode::Component(c) => {
|
|
let scope_id = c.scope.get().unwrap();
|
|
let root = self.scopes.root_node(scope_id);
|
|
self.remove_nodes(Some(root), gen_muts);
|
|
self.scopes.try_remove(scope_id).unwrap();
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
/// Adds a listener closure to a scope during diff.
|
|
fn attach_listener_to_scope(&mut self, listener: &'bump Listener<'bump>, scope: &ScopeState) {
|
|
let long_listener = unsafe { std::mem::transmute(listener) };
|
|
scope.items.borrow_mut().listeners.push(long_listener)
|
|
}
|
|
}
|