Enum Builtin 

pub enum Builtin {
    Container,
    Label,
    Button,
    Toggle,
    Slider,
    TextField,
    TextArea,
    Picker,
    Divider,
    Scroll,
    Image,
    Progress,
    Canvas,
    Nav,
    NavPage,
    NavMenu,
    List,
    ListCell,
    Tree,
    Cover,
    Inspector,
    InspectorPane,
    Split,
    SplitPane,
    ListItem,
}

Every piece kind Day itself defines (§5.3). Backends match on this exhaustively in realize; anything outside it is an extension piece resolved through the Registry by its string PieceKind.

Variants

Container

A dumb native panel (the column/row/stack backing).

Label

Button

Toggle

Slider

TextField

TextArea

A native multi-line text editor (docs/textarea.md). Built-in since 2026-07 (previously the satellite day-piece-textarea).

Picker

A native option picker with menu/segmented/inline stylings (docs/picker.md). Built-in since 2026-07 (previously the satellite day-piece-picker).

Divider

Scroll

Image

Progress

Progress indicator: determinate bar (fraction) or indeterminate spinner.

Canvas

Nav

Navigation host (docs/navigation.md): stack on mobile, split panes on desktop.

NavPage

One destination’s native container inside a NAV host.

NavMenu

Native navigation item list (docs/navigation.md): NSOutlineView source list / GtkListBox navigation-sidebar / QListWidget / UITableView rows with chevrons.

List

Native recycling list (docs/list.md): NSTableView / UITableView / RecyclerView / GtkListView / QListView. Owns scrolling + cell reuse; Day binds row content on demand.

ListCell

A recycled row’s content anchor inside a LIST; Day adopts the native cell as its handle. Adopted, never realized: Toolkit::adopt wraps the native cell, so backends’ realize never sees this kind.

Tree

Native hierarchical tree (docs/tree.md): NSOutlineView / sidebar collection list / GtkListView+TreeListModel / WinUI TreeView / ArkTS TreeView. Rows nest, disclose, and drag-to-reparent; Day binds row content on demand through Toolkit::attach_tree. Row cells are adopted (the same LIST_CELL anchor path as List).

Cover

A fullscreen cover (docs/cover.md): a modal surface presented over the whole window, edge-to-edge, driven by CoverPatch::{Present,Dismiss}. The handle is the cover’s content container; its frame is native-owned while presented (the backend sizes it to the safe area and reports it via Event::FrameChanged).

Inspector

Content beside a trailing inspector pane (docs/inspector.md): the native split whose second pane is a show/hidable properties panel. Exactly two INSPECTOR_PANE children: the content, then the panel (InspectorPaneProps::panel). Only realized where Cap::Inspector answers Native; everywhere else the inspector piece composes the pane from plain containers and this kind never reaches the backend.

InspectorPane

One pane’s container inside an INSPECTOR host: the NAV_PAGE of the inspector split. Its frame is native-owned (the splitter/dock sizes it), reported via Event::FrameChanged on this node; Day lays the pane’s content out inside it.

Split

Two panes with a divider the user drags (docs/split.md): the toolkit’s own splitter, side by side or stacked (SplitProps::axis), the first pane’s share bound to the app (SplitProps::fraction, reported back as Event::ValueChanged). Exactly two SPLIT_PANE children, first then second. Only realized where Cap::Split answers Native; everywhere else the split piece composes the panes and draws the divider itself, and this kind never reaches the backend.

SplitPane

One pane’s container inside a SPLIT host: native-owned frame (the splitter sizes it), reported via Event::FrameChanged on this node, like an INSPECTOR_PANE.

ListItem

A list row’s standard content (docs/list.md “List items”): a leading icon, a title, an optional subtitle and trailing detail, and a check mark, drawn the way the platform draws its own list rows: a UIListContentView with the cell’s default content configuration, a Material list item, an NSTableCellView’s image and text, a GTK row box. Only realized where Cap::ListItem answers Native; everywhere else the list_item piece composes the same content and this kind never reaches the backend.

Implementations

impl Builtin

pub const ALL: &'static [Builtin]

Every built-in, in declaration order (conformance tests iterate it).

pub const fn key(self) -> PieceKind

This kind’s wire key: the same string as the matching kinds::* constant.

pub fn from_key(kind: PieceKind) -> Option<Builtin>

The built-in this key names, or None for an extension piece’s kind.

Trait Implementations

impl Clone for Builtin

fn clone(&self) -> Self

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for Builtin

impl Debug for Builtin

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

Formats the value using the given formatter.

impl Eq for Builtin

impl Hash for Builtin

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl PartialEq for Builtin

fn eq(&self, other: &Self) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl StructuralPartialEq for Builtin