dioxus/packages/core/old/patch.rs
2021-03-03 02:27:26 -05:00

80 lines
2.9 KiB
Rust

use fxhash::FxHashMap;
use crate::innerlude::{VNode, VText};
/// A Patch encodes an operation that modifies a real DOM element.
///
/// To update the real DOM that a user sees you'll want to first diff your
/// old virtual dom and new virtual dom.
///
/// This diff operation will generate `Vec<Patch>` with zero or more patches that, when
/// applied to your real DOM, will make your real DOM look like your new virtual dom.
///
/// Each Patch has a u32 node index that helps us identify the real DOM node that it applies to.
///
/// Our old virtual dom's nodes are indexed depth first, as shown in this illustration
/// (0 being the root node, 1 being it's first child, 2 being it's first child's first child).
///
/// ```text
/// .─.
/// ( 0 )
/// `┬'
/// ┌────┴──────┐
/// │ │
/// ▼ ▼
/// .─. .─.
/// ( 1 ) ( 4 )
/// `┬' `─'
/// ┌────┴───┐ ├─────┬─────┐
/// │ │ │ │ │
/// ▼ ▼ ▼ ▼ ▼
/// .─. .─. .─. .─. .─.
/// ( 2 ) ( 3 ) ( 5 ) ( 6 ) ( 7 )
/// `─' `─' `─' `─' `─'
/// ```
///
/// The patching process is tested in a real browser in crates/virtual-dom-rs/tests/diff_patch.rs
// #[derive(serde::Serialize, serde::Deserialize)]
pub enum Patch<'a> {
/// Append a vector of child nodes to a parent node id.
AppendChildren(NodeIdx, Vec<&'a VNode<'a>>),
/// For a `node_i32`, remove all children besides the first `len`
TruncateChildren(NodeIdx, usize),
/// Replace a node with another node. This typically happens when a node's tag changes.
/// ex: <div> becomes <span>
Replace(NodeIdx, &'a VNode<'a>),
/// Add attributes that the new node has that the old node does not
AddAttributes(NodeIdx, FxHashMap<&'a str, &'a str>),
/// Remove attributes that the old node had that the new node doesn't
RemoveAttributes(NodeIdx, Vec<&'a str>),
/// Change the text of a Text node.
ChangeText(NodeIdx, &'a VText<'a>),
}
type NodeIdx = usize;
impl<'a> Patch<'a> {
/// Every Patch is meant to be applied to a specific node within the DOM. Get the
/// index of the DOM node that this patch should apply to. DOM nodes are indexed
/// depth first with the root node in the tree having index 0.
pub fn node_idx(&self) -> usize {
match self {
Patch::AppendChildren(node_idx, _) => *node_idx,
Patch::TruncateChildren(node_idx, _) => *node_idx,
Patch::Replace(node_idx, _) => *node_idx,
Patch::AddAttributes(node_idx, _) => *node_idx,
Patch::RemoveAttributes(node_idx, _) => *node_idx,
Patch::ChangeText(node_idx, _) => *node_idx,
}
}
}
pub struct PatchList<'a> {
patches: Vec<Patch<'a>>,
}