Enum Mutation 

#[non_exhaustive]
pub enum Mutation {
    AttributeChanged {
        id: NodeId,
        name: String,
        old: Option<String>,
        new: Option<String>,
    },
    ClassChanged {
        id: NodeId,
        added: Vec<String>,
        removed: Vec<String>,
    },
    ChildListChanged {
        parent: NodeId,
        added: Vec<NodeId>,
        removed: Vec<NodeId>,
    },
    CharacterDataChanged {
        id: NodeId,
        old: String,
        new: String,
    },
    InteractionChanged {
        prev: Option<NodeId>,
        next: Option<NodeId>,
        kind: InteractionKind,
    },
    SelectionChanged {
        prev: Option<Selection>,
        next: Option<Selection>,
    },
    PreDetach {
        detached_root: NodeId,
        focused: Option<NodeId>,
        hovered: Option<NodeId>,
    },
}

One DOM mutation notification.

Variants (Non-exhaustive)

Non-exhaustive enums could have additional variants added in future. Therefore, when matching against variants of non-exhaustive enums, an extra wildcard arm must be added to account for any future variants.

AttributeChanged

set_attribute / remove_attribute / toggle_attribute. old == None && new.is_some() → attribute added. old.is_some() && new == None → attribute removed. Both Some → value changed.

Fields

id: NodeId

name: String

old: Option<String>

new: Option<String>

ClassChanged

One class was added or removed. add_class / remove_class / toggle_class each fire a single record with one entry in either added or removed; replace_class fires once with both populated.

Fields

id: NodeId

added: Vec<String>

removed: Vec<String>

ChildListChanged

A parent’s child list was mutated. Fires once per top-level operation — e.g. append_child(parent, frag) where frag has three children fires three records, one per unwrapped child.

Fields

parent: NodeId

added: Vec<NodeId>

removed: Vec<NodeId>

CharacterDataChanged

Text or Comment node data changed.

Fields

id: NodeId

old: String

new: String

InteractionChanged

Hovered or focused node changed. Both prev and next may be Some (re-pointed), either may be None (cleared or set-from- nothing). The cascade dirty-tracker uses this to invalidate both sides’ subtrees for :hover / :focus re-matching.

Fields

prev: Option<NodeId>

next: Option<NodeId>

kind: InteractionKind

SelectionChanged

Document selection changed via Dom::set_selection. Either prev or next may be None; cleared selections fire next: None. Paint observers use this to invalidate the ::selection overlay on the nodes whose range changed.

Fields

prev: Option<Selection>

next: Option<Selection>

PreDetach

About to detach — fired in detach_from_parent BEFORE the structural unlink, so observers can dispatch implicit blur / focusout / mouseleave / mouseout events while the tree is still intact (the focused/hovered node’s parent_node() still walks the live ancestor chain).

focused is Some(id) iff dom.focused() was inside the subtree rooted at detached_root at the moment of detach. hovered likewise for hover. If neither is set, no PreDetach record is emitted (the structurally-cheap short-circuit path in purge_interaction_state_for_subtree also gates this record’s emission).

The subsequent InteractionChanged { next: None, kind } records still fire from the purge step — observers that only care about the post-detach state can listen to those. PreDetach is for observers that need to dispatch real DOM events with bubbling intact.

Fields

detached_root: NodeId

Subtree root being detached.

focused: Option<NodeId>

Pre-detach focused node, if it was inside the subtree.

hovered: Option<NodeId>

Pre-detach hovered node, if it was inside the subtree.

Trait Implementations

impl Clone for Mutation

fn clone(&self) -> Self

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Mutation

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.