dioxus/packages/core/src/nodes.rs
2022-01-16 15:13:31 -05:00

795 lines
24 KiB
Rust

//! Virtual Node Support
//!
//! VNodes represent lazily-constructed VDom trees that support diffing and event handlers. These VNodes should be *very*
//! cheap and *very* fast to construct - building a full tree should be quick.
use crate::{
innerlude::{Element, Properties, Scope, ScopeId, ScopeState},
lazynodes::LazyNodes,
AnyEvent, Component,
};
use bumpalo::{boxed::Box as BumpBox, Bump};
use std::{
cell::{Cell, RefCell},
fmt::{Arguments, Debug, Formatter},
};
/// A composable "VirtualNode" to declare a User Interface in the Dioxus VirtualDOM.
///
/// VNodes are designed to be lightweight and used with with a bump allocator. To create a VNode, you can use either of:
///
/// - the `rsx!` macro
/// - the [`NodeFactory`] API
pub enum VNode<'src> {
/// Text VNodes simply bump-allocated (or static) string slices
///
/// # Example
///
/// ```rust, ignore
/// let mut vdom = VirtualDom::new();
/// let node = vdom.render_vnode(rsx!( "hello" ));
///
/// if let VNode::Text(vtext) = node {
/// assert_eq!(vtext.text, "hello");
/// assert_eq!(vtext.dom_id.get(), None);
/// assert_eq!(vtext.is_static, true);
/// }
/// ```
Text(&'src VText<'src>),
/// Element VNodes are VNodes that may contain attributes, listeners, a key, a tag, and children.
///
/// # Example
///
/// ```rust, ignore
/// let mut vdom = VirtualDom::new();
///
/// let node = vdom.render_vnode(rsx!{
/// div {
/// key: "a",
/// onclick: |e| log::info!("clicked"),
/// hidden: "true",
/// style: { background_color: "red" },
/// "hello"
/// }
/// });
///
/// if let VNode::Element(velement) = node {
/// assert_eq!(velement.tag_name, "div");
/// assert_eq!(velement.namespace, None);
/// assert_eq!(velement.key, Some("a"));
/// }
/// ```
Element(&'src VElement<'src>),
/// Fragment nodes may contain many VNodes without a single root.
///
/// # Example
///
/// ```rust, ignore
/// rsx!{
/// a {}
/// link {}
/// style {}
/// "asd"
/// Example {}
/// }
/// ```
Fragment(&'src VFragment<'src>),
/// Component nodes represent a mounted component with props, children, and a key.
///
/// # Example
///
/// ```rust, ignore
/// fn Example(cx: Scope) -> Element {
/// ...
/// }
///
/// let mut vdom = VirtualDom::new();
///
/// let node = vdom.render_vnode(rsx!( Example {} ));
///
/// if let VNode::Component(vcomp) = node {
/// assert_eq!(vcomp.user_fc, Example as *const ());
/// }
/// ```
Component(&'src VComponent<'src>),
/// Placeholders are a type of placeholder VNode used when fragments don't contain any children.
///
/// Placeholders cannot be directly constructed via public APIs.
///
/// # Example
///
/// ```rust, ignore
/// let mut vdom = VirtualDom::new();
///
/// let node = vdom.render_vnode(rsx!( Fragment {} ));
///
/// if let VNode::Fragment(frag) = node {
/// let root = &frag.children[0];
/// assert_eq!(root, VNode::Anchor);
/// }
/// ```
Placeholder(&'src VPlaceholder),
}
impl<'src> VNode<'src> {
/// Get the VNode's "key" used in the keyed diffing algorithm.
pub fn key(&self) -> Option<&'src str> {
match &self {
VNode::Element(el) => el.key,
VNode::Component(c) => c.key,
VNode::Fragment(f) => f.key,
VNode::Text(_t) => None,
VNode::Placeholder(_f) => None,
}
}
/// Get the ElementID of the mounted VNode.
///
/// Panics if the mounted ID is None or if the VNode is not represented by a single Element.
pub fn mounted_id(&self) -> ElementId {
self.try_mounted_id().unwrap()
}
/// Try to get the ElementID of the mounted VNode.
///
/// Returns None if the VNode is not mounted, or if the VNode cannot be presented by a mounted ID (Fragment/Component)
pub fn try_mounted_id(&self) -> Option<ElementId> {
match &self {
VNode::Text(el) => el.id.get(),
VNode::Element(el) => el.id.get(),
VNode::Placeholder(el) => el.id.get(),
VNode::Fragment(_) => None,
VNode::Component(_) => None,
}
}
pub(crate) fn children(&self) -> &[VNode<'src>] {
match &self {
VNode::Fragment(f) => f.children,
_ => &[],
}
}
// Create an "owned" version of the vnode.
pub fn decouple(&self) -> VNode<'src> {
match *self {
VNode::Text(t) => VNode::Text(t),
VNode::Element(e) => VNode::Element(e),
VNode::Component(c) => VNode::Component(c),
VNode::Placeholder(a) => VNode::Placeholder(a),
VNode::Fragment(f) => VNode::Fragment(f),
}
}
}
impl Debug for VNode<'_> {
fn fmt(&self, s: &mut Formatter<'_>) -> std::result::Result<(), std::fmt::Error> {
match &self {
VNode::Element(el) => s
.debug_struct("VNode::VElement")
.field("name", &el.tag)
.field("key", &el.key)
.field("attrs", &el.attributes)
.field("children", &el.children)
.finish(),
VNode::Text(t) => write!(s, "VNode::VText {{ text: {} }}", t.text),
VNode::Placeholder(_) => write!(s, "VNode::VPlaceholder"),
VNode::Fragment(frag) => {
write!(s, "VNode::VFragment {{ children: {:?} }}", frag.children)
}
VNode::Component(comp) => write!(s, "VNode::VComponent {{ fc: {:?}}}", comp.user_fc),
}
}
}
/// An Element's unique identifier.
///
/// `ElementId` is a `usize` that is unique across the entire VirtualDOM - but not unique across time. If a component is
/// unmounted, then the `ElementId` will be reused for a new component.
#[derive(Copy, Clone, PartialEq, Eq, Hash, Debug)]
pub struct ElementId(pub usize);
impl std::fmt::Display for ElementId {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
write!(f, "{}", self.0)
}
}
impl ElementId {
pub fn as_u64(self) -> u64 {
self.0 as u64
}
}
fn empty_cell() -> Cell<Option<ElementId>> {
Cell::new(None)
}
/// A placeholder node only generated when Fragments don't have any children.
pub struct VPlaceholder {
pub id: Cell<Option<ElementId>>,
}
/// A bump-allocated string slice and metadata.
pub struct VText<'src> {
pub text: &'src str,
pub id: Cell<Option<ElementId>>,
pub is_static: bool,
}
/// A list of VNodes with no single root.
pub struct VFragment<'src> {
pub key: Option<&'src str>,
/// Fragments can never have zero children. Enforced by NodeFactory.
///
/// You *can* make a fragment with no children, but it's not a valid fragment and your VDom will panic.
pub children: &'src [VNode<'src>],
}
/// An element like a "div" with children, listeners, and attributes.
pub struct VElement<'a> {
pub tag: &'static str,
pub namespace: Option<&'static str>,
pub key: Option<&'a str>,
pub id: Cell<Option<ElementId>>,
pub parent: Cell<Option<ElementId>>,
pub listeners: &'a [Listener<'a>],
pub attributes: &'a [Attribute<'a>],
pub children: &'a [VNode<'a>],
}
impl Debug for VElement<'_> {
fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
f.debug_struct("VElement")
.field("tag_name", &self.tag)
.field("namespace", &self.namespace)
.field("key", &self.key)
.field("id", &self.id)
.field("parent", &self.parent)
.field("listeners", &self.listeners.len())
.field("attributes", &self.attributes)
.field("children", &self.children)
.finish()
}
}
/// A trait for any generic Dioxus Element.
///
/// This trait provides the ability to use custom elements in the `rsx!` macro.
///
/// ```rust, ignore
/// struct my_element;
///
/// impl DioxusElement for my_element {
/// const TAG_NAME: "my_element";
/// const NAME_SPACE: None;
/// }
///
/// let _ = rsx!{
/// my_element {}
/// };
/// ```
pub trait DioxusElement {
const TAG_NAME: &'static str;
const NAME_SPACE: Option<&'static str>;
#[inline]
fn tag_name(&self) -> &'static str {
Self::TAG_NAME
}
#[inline]
fn namespace(&self) -> Option<&'static str> {
Self::NAME_SPACE
}
}
/// An attribute on a DOM node, such as `id="my-thing"` or
/// `href="https://example.com"`.
#[derive(Clone, Debug)]
pub struct Attribute<'a> {
pub name: &'static str,
pub value: &'a str,
pub is_static: bool,
pub is_volatile: bool,
// Doesn't exist in the html spec.
// Used in Dioxus to denote "style" tags.
pub namespace: Option<&'static str>,
}
/// An event listener.
/// IE onclick, onkeydown, etc
pub struct Listener<'bump> {
/// The ID of the node that this listener is mounted to
/// Used to generate the event listener's ID on the DOM
pub mounted_node: Cell<Option<ElementId>>,
/// The type of event to listen for.
///
/// IE "click" - whatever the renderer needs to attach the listener by name.
pub event: &'static str,
/// The actual callback that the user specified
pub(crate) callback: InternalHandler<'bump>,
}
pub type InternalHandler<'bump> = &'bump RefCell<Option<InternalListenerCallback<'bump>>>;
type InternalListenerCallback<'bump> = BumpBox<'bump, dyn FnMut(AnyEvent) + 'bump>;
type ExternalListenerCallback<'bump, T> = BumpBox<'bump, dyn FnMut(T) + 'bump>;
/// The callback type generated by the `rsx!` macro when an `on` field is specified for components.
///
/// This makes it possible to pass `move |evt| {}` style closures into components as property fields.
///
///
/// # Example
///
/// ```rust, ignore
///
/// rsx!{
/// MyComponent { onclick: move |evt| log::info!("clicked"), }
/// }
///
/// #[derive(Props)]
/// struct MyProps<'a> {
/// onclick: EventHandler<'a, MouseEvent>,
/// }
///
/// fn MyComponent(cx: Scope<'a, MyProps<'a>>) -> Element {
/// cx.render(rsx!{
/// button {
/// onclick: move |evt| cx.props.onclick.call(evt),
/// }
/// })
/// }
///
/// ```
#[derive(Default)]
pub struct EventHandler<'bump, T = ()> {
pub callback: RefCell<Option<ExternalListenerCallback<'bump, T>>>,
}
impl<T> EventHandler<'_, T> {
/// Call this event handler with the appropriate event type
pub fn call(&self, event: T) {
if let Some(callback) = self.callback.borrow_mut().as_mut() {
callback(event);
}
}
/// Forcibly drop the internal handler callback, releasing memory
pub fn release(&self) {
self.callback.replace(None);
}
}
/// Virtual Components for custom user-defined components
/// Only supports the functional syntax
pub struct VComponent<'src> {
pub key: Option<&'src str>,
pub originator: ScopeId,
pub scope: Cell<Option<ScopeId>>,
pub can_memoize: bool,
pub user_fc: *const (),
pub props: RefCell<Option<Box<dyn AnyProps + 'src>>>,
}
pub(crate) struct VComponentProps<P> {
pub render_fn: Component<P>,
pub memo: unsafe fn(&P, &P) -> bool,
pub props: P,
}
pub trait AnyProps {
fn as_ptr(&self) -> *const ();
fn render<'a>(&'a self, bump: &'a ScopeState) -> Element<'a>;
unsafe fn memoize(&self, other: &dyn AnyProps) -> bool;
}
impl<P> AnyProps for VComponentProps<P> {
fn as_ptr(&self) -> *const () {
&self.props as *const _ as *const ()
}
// Safety:
// this will downcat the other ptr as our swallowed type!
// you *must* make this check *before* calling this method
// if your functions are not the same, then you will downcast a pointer into a different type (UB)
unsafe fn memoize(&self, other: &dyn AnyProps) -> bool {
let real_other: &P = &*(other.as_ptr() as *const _ as *const P);
let real_us: &P = &*(self.as_ptr() as *const _ as *const P);
(self.memo)(real_us, real_other)
}
fn render<'a>(&'a self, scope: &'a ScopeState) -> Element<'a> {
let props = unsafe { std::mem::transmute::<&P, &P>(&self.props) };
(self.render_fn)(Scope { scope, props })
}
}
/// This struct provides an ergonomic API to quickly build VNodes.
///
/// NodeFactory is used to build VNodes in the component's memory space.
/// This struct adds metadata to the final VNode about listeners, attributes, and children
#[derive(Copy, Clone)]
pub struct NodeFactory<'a> {
pub(crate) scope: &'a ScopeState,
pub(crate) bump: &'a Bump,
}
impl<'a> NodeFactory<'a> {
pub fn new(scope: &'a ScopeState) -> NodeFactory<'a> {
NodeFactory {
scope,
bump: &scope.wip_frame().bump,
}
}
#[inline]
pub fn bump(&self) -> &'a bumpalo::Bump {
self.bump
}
/// Directly pass in text blocks without the need to use the format_args macro.
pub fn static_text(&self, text: &'static str) -> VNode<'a> {
VNode::Text(self.bump.alloc(VText {
id: empty_cell(),
text,
is_static: true,
}))
}
/// Parses a lazy text Arguments and returns a string and a flag indicating if the text is 'static
///
/// Text that's static may be pointer compared, making it cheaper to diff
pub fn raw_text(&self, args: Arguments) -> (&'a str, bool) {
match args.as_str() {
Some(static_str) => (static_str, true),
None => {
use bumpalo::core_alloc::fmt::Write;
let mut str_buf = bumpalo::collections::String::new_in(self.bump);
str_buf.write_fmt(args).unwrap();
(str_buf.into_bump_str(), false)
}
}
}
/// Create some text that's allocated along with the other vnodes
///
pub fn text(&self, args: Arguments) -> VNode<'a> {
let (text, is_static) = self.raw_text(args);
VNode::Text(self.bump.alloc(VText {
text,
is_static,
id: empty_cell(),
}))
}
pub fn element(
&self,
el: impl DioxusElement,
listeners: &'a [Listener<'a>],
attributes: &'a [Attribute<'a>],
children: &'a [VNode<'a>],
key: Option<Arguments>,
) -> VNode<'a> {
self.raw_element(
el.tag_name(),
el.namespace(),
listeners,
attributes,
children,
key,
)
}
pub fn raw_element(
&self,
tag_name: &'static str,
namespace: Option<&'static str>,
listeners: &'a [Listener<'a>],
attributes: &'a [Attribute<'a>],
children: &'a [VNode<'a>],
key: Option<Arguments>,
) -> VNode<'a> {
let key = key.map(|f| self.raw_text(f).0);
let mut items = self.scope.items.borrow_mut();
for listener in listeners {
let long_listener = unsafe { std::mem::transmute(listener) };
items.listeners.push(long_listener);
}
VNode::Element(self.bump.alloc(VElement {
tag: tag_name,
key,
namespace,
listeners,
attributes,
children,
id: empty_cell(),
parent: empty_cell(),
}))
}
pub fn attr(
&self,
name: &'static str,
val: Arguments,
namespace: Option<&'static str>,
is_volatile: bool,
) -> Attribute<'a> {
let (value, is_static) = self.raw_text(val);
Attribute {
name,
value,
is_static,
namespace,
is_volatile,
}
}
pub fn component<P>(
&self,
component: fn(Scope<'a, P>) -> Element,
props: P,
key: Option<Arguments>,
) -> VNode<'a>
where
P: Properties + 'a,
{
let vcomp = self.bump.alloc(VComponent {
key: key.map(|f| self.raw_text(f).0),
scope: Default::default(),
can_memoize: P::IS_STATIC,
user_fc: component as *const (),
originator: self.scope.scope_id(),
props: RefCell::new(Some(Box::new(VComponentProps {
// local_props: RefCell::new(Some(props)),
// heap_props: RefCell::new(None),
props,
memo: P::memoize, // smuggle the memoization function across borders
// i'm sorry but I just need to bludgeon the lifetimes into place here
// this is safe because we're managing all lifetimes to originate from previous calls
// the intricacies of Rust's lifetime system make it difficult to properly express
// the transformation from this specific lifetime to the for<'a> lifetime
render_fn: unsafe { std::mem::transmute(component) },
}))),
});
if !P::IS_STATIC {
let vcomp = &*vcomp;
let vcomp = unsafe { std::mem::transmute(vcomp) };
self.scope.items.borrow_mut().borrowed_props.push(vcomp);
}
VNode::Component(vcomp)
}
pub fn listener(self, event: &'static str, callback: InternalHandler<'a>) -> Listener<'a> {
Listener {
event,
mounted_node: Cell::new(None),
callback,
}
}
pub fn fragment_root<'b, 'c>(
self,
node_iter: impl IntoIterator<Item = impl IntoVNode<'a> + 'c> + 'b,
) -> VNode<'a> {
let mut nodes = bumpalo::collections::Vec::new_in(self.bump);
for node in node_iter {
nodes.push(node.into_vnode(self));
}
if nodes.is_empty() {
VNode::Placeholder(self.bump.alloc(VPlaceholder { id: empty_cell() }))
} else {
VNode::Fragment(self.bump.alloc(VFragment {
children: nodes.into_bump_slice(),
key: None,
}))
}
}
pub fn fragment_from_iter<'b, 'c>(
self,
node_iter: impl IntoIterator<Item = impl IntoVNode<'a> + 'c> + 'b,
) -> VNode<'a> {
let mut nodes = bumpalo::collections::Vec::new_in(self.bump);
for node in node_iter {
nodes.push(node.into_vnode(self));
}
if nodes.is_empty() {
VNode::Placeholder(self.bump.alloc(VPlaceholder { id: empty_cell() }))
} else {
let children = nodes.into_bump_slice();
if cfg!(debug_assertions)
&& children.len() > 1
&& children.last().unwrap().key().is_none()
{
// todo: make the backtrace prettier or remove it altogether
log::error!(
r#"
Warning: Each child in an array or iterator should have a unique "key" prop.
Not providing a key will lead to poor performance with lists.
See docs.rs/dioxus for more information.
-------------
{:?}
"#,
backtrace::Backtrace::new()
);
}
VNode::Fragment(self.bump.alloc(VFragment {
children,
key: None,
}))
}
}
// this isn't quite feasible yet
// I think we need some form of interior mutability or state on nodefactory that stores which subtree was created
pub fn create_children(
self,
node_iter: impl IntoIterator<Item = impl IntoVNode<'a>>,
) -> Element<'a> {
let mut nodes = bumpalo::collections::Vec::new_in(self.bump);
for node in node_iter {
nodes.push(node.into_vnode(self));
}
if nodes.is_empty() {
Some(VNode::Placeholder(
self.bump.alloc(VPlaceholder { id: empty_cell() }),
))
} else {
let children = nodes.into_bump_slice();
Some(VNode::Fragment(self.bump.alloc(VFragment {
children,
key: None,
})))
}
}
pub fn event_handler<T>(self, f: impl FnMut(T) + 'a) -> EventHandler<'a, T> {
let handler: &mut dyn FnMut(T) = self.bump.alloc(f);
let caller = unsafe { BumpBox::from_raw(handler as *mut dyn FnMut(T)) };
let callback = RefCell::new(Some(caller));
EventHandler { callback }
}
}
impl Debug for NodeFactory<'_> {
fn fmt(&self, _: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
Ok(())
}
}
/// Trait implementations for use in the rsx! and html! macros.
///
/// ## Details
///
/// This section provides convenience methods and trait implementations for converting common structs into a format accepted
/// by the macros.
///
/// All dynamic content in the macros must flow in through `fragment_from_iter`. Everything else must be statically layed out.
/// We pipe basically everything through `fragment_from_iter`, so we expect a very specific type:
/// ```rust, ignore
/// impl IntoIterator<Item = impl IntoVNode<'a>>
/// ```
///
/// As such, all node creation must go through the factory, which is only available in the component context.
/// These strict requirements make it possible to manage lifetimes and state.
pub trait IntoVNode<'a> {
fn into_vnode(self, cx: NodeFactory<'a>) -> VNode<'a>;
}
// For the case where a rendered VNode is passed into the rsx! macro through curly braces
impl<'a> IntoIterator for VNode<'a> {
type Item = VNode<'a>;
type IntoIter = std::iter::Once<Self::Item>;
fn into_iter(self) -> Self::IntoIter {
std::iter::once(self)
}
}
// TODO: do we even need this? It almost seems better not to
// // For the case where a rendered VNode is passed into the rsx! macro through curly braces
impl<'a> IntoVNode<'a> for VNode<'a> {
fn into_vnode(self, _: NodeFactory<'a>) -> VNode<'a> {
self
}
}
// Conveniently, we also support "null" (nothing) passed in
impl IntoVNode<'_> for () {
fn into_vnode(self, cx: NodeFactory) -> VNode {
cx.fragment_from_iter(None as Option<VNode>)
}
}
// Conveniently, we also support "None"
impl IntoVNode<'_> for Option<()> {
fn into_vnode(self, cx: NodeFactory) -> VNode {
cx.fragment_from_iter(None as Option<VNode>)
}
}
impl<'a> IntoVNode<'a> for Option<VNode<'a>> {
fn into_vnode(self, cx: NodeFactory<'a>) -> VNode<'a> {
self.unwrap_or_else(|| cx.fragment_from_iter(None as Option<VNode>))
}
}
impl<'a> IntoVNode<'a> for Option<LazyNodes<'a, '_>> {
fn into_vnode(self, cx: NodeFactory<'a>) -> VNode<'a> {
match self {
Some(lazy) => lazy.call(cx),
None => VNode::Placeholder(cx.bump.alloc(VPlaceholder { id: empty_cell() })),
}
}
}
impl<'a, 'b> IntoIterator for LazyNodes<'a, 'b> {
type Item = LazyNodes<'a, 'b>;
type IntoIter = std::iter::Once<Self::Item>;
fn into_iter(self) -> Self::IntoIter {
std::iter::once(self)
}
}
impl<'a, 'b> IntoVNode<'a> for LazyNodes<'a, 'b> {
fn into_vnode(self, cx: NodeFactory<'a>) -> VNode<'a> {
self.call(cx)
}
}
impl<'b> IntoVNode<'_> for &'b str {
fn into_vnode(self, cx: NodeFactory) -> VNode {
cx.text(format_args!("{}", self))
}
}
impl IntoVNode<'_> for String {
fn into_vnode(self, cx: NodeFactory) -> VNode {
cx.text(format_args!("{}", self))
}
}
impl IntoVNode<'_> for Arguments<'_> {
fn into_vnode(self, cx: NodeFactory) -> VNode {
cx.text(self)
}
}
impl<'a> IntoVNode<'a> for &Option<VNode<'a>> {
fn into_vnode(self, cx: NodeFactory<'a>) -> VNode<'a> {
self.as_ref()
.map(|f| f.into_vnode(cx))
.unwrap_or_else(|| cx.fragment_from_iter(None as Option<VNode>))
}
}
impl<'a> IntoVNode<'a> for &VNode<'a> {
fn into_vnode(self, _cx: NodeFactory<'a>) -> VNode<'a> {
// borrowed nodes are strange
self.decouple()
}
}