yew/html/component/children.rs
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//! Component children module
use std::fmt;
use std::rc::Rc;
use crate::html::Html;
use crate::virtual_dom::{VChild, VComp, VList, VNode};
use crate::{BaseComponent, Properties};
/// A type used for accepting children elements in Component::Properties.
///
/// # Example
/// **`model.rs`**
///
/// In this example, the `Wrapper` component is used to wrap other elements.
/// ```
/// # use yew::{Children, Html, Properties, Component, Context, html};
/// # #[derive(Clone, Properties, PartialEq)]
/// # struct WrapperProps {
/// # children: Children,
/// # }
/// # struct Wrapper;
/// # impl Component for Wrapper {
/// # type Message = ();
/// # type Properties = WrapperProps;
/// # fn create(ctx: &Context<Self>) -> Self { Self }
/// # fn view(&self, ctx: &Context<Self>) -> Html {
/// html! {
/// <Wrapper>
/// <h4>{ "Hi" }</h4>
/// <div>{ "Hello" }</div>
/// </Wrapper>
/// }
/// # }
/// # }
/// ```
///
/// **`wrapper.rs`**
///
/// The Wrapper component must define a `children` property in order to wrap other elements. The
/// children property can be used to render the wrapped elements.
/// ```
/// # use yew::{Children, Html, Properties, Component, Context, html};
/// #[derive(Clone, Properties, PartialEq)]
/// struct WrapperProps {
/// children: Children,
/// }
///
/// # struct Wrapper;
/// impl Component for Wrapper {
/// // ...
/// # type Message = ();
/// # type Properties = WrapperProps;
/// # fn create(ctx: &Context<Self>) -> Self { Self }
/// fn view(&self, ctx: &Context<Self>) -> Html {
/// html! {
/// <div id="container">
/// { ctx.props().children.clone() }
/// </div>
/// }
/// }
/// }
/// ```
pub type Children = ChildrenRenderer<Html>;
/// A type used for accepting children elements in Component::Properties and accessing their props.
///
/// # Example
/// **`model.rs`**
///
/// In this example, the `List` component can wrap `ListItem` components.
/// ```
/// # use yew::{html, Component, Html, Context, ChildrenWithProps, Properties};
/// #
/// # #[derive(Clone, Properties, PartialEq)]
/// # struct ListProps {
/// # children: ChildrenWithProps<ListItem>,
/// # }
/// # struct List;
/// # impl Component for List {
/// # type Message = ();
/// # type Properties = ListProps;
/// # fn create(ctx: &Context<Self>) -> Self { Self }
/// # fn view(&self, ctx: &Context<Self>) -> Html { unimplemented!() }
/// # }
/// # #[derive(Clone, Properties, PartialEq)]
/// # struct ListItemProps {
/// # value: String
/// # }
/// # struct ListItem;
/// # impl Component for ListItem {
/// # type Message = ();
/// # type Properties = ListItemProps;
/// # fn create(ctx: &Context<Self>) -> Self { Self }
/// # fn view(&self, ctx: &Context<Self>) -> Html { unimplemented!() }
/// # }
/// # fn view() -> Html {
/// html! {
/// <List>
/// <ListItem value="a" />
/// <ListItem value="b" />
/// <ListItem value="c" />
/// </List>
/// }
/// # }
/// ```
///
/// **`list.rs`**
///
/// The `List` component must define a `children` property in order to wrap the list items. The
/// `children` property can be used to filter, mutate, and render the items.
/// ```
/// # use yew::{html, Component, Html, ChildrenWithProps, Context, Properties};
/// # use std::rc::Rc;
/// #
/// #[derive(Clone, Properties, PartialEq)]
/// struct ListProps {
/// children: ChildrenWithProps<ListItem>,
/// }
///
/// # struct List;
/// impl Component for List {
/// # type Message = ();
/// # type Properties = ListProps;
/// # fn create(ctx: &Context<Self>) -> Self { Self }
/// # fn view(&self, ctx: &Context<Self>) -> Html {
/// html!{{
/// for ctx.props().children.iter().map(|mut item| {
/// let mut props = Rc::make_mut(&mut item.props);
/// props.value = format!("item-{}", props.value);
/// item
/// })
/// }}
/// }
/// }
/// #
/// # #[derive(Clone, Properties, PartialEq)]
/// # struct ListItemProps {
/// # #[prop_or_default]
/// # value: String
/// # }
/// #
/// # struct ListItem;
/// # impl Component for ListItem {
/// # type Message = ();
/// # type Properties = ListItemProps;
/// # fn create(ctx: &Context<Self>) -> Self { Self }
/// # fn view(&self, ctx: &Context<Self>) -> Html { unimplemented!() }
/// # }
/// ```
pub type ChildrenWithProps<CHILD> = ChildrenRenderer<VChild<CHILD>>;
/// A type used for rendering children html.
#[derive(Clone)]
pub struct ChildrenRenderer<T> {
pub(crate) children: Vec<T>,
}
impl<T: PartialEq> PartialEq for ChildrenRenderer<T> {
fn eq(&self, other: &Self) -> bool {
self.children == other.children
}
}
impl<T> ChildrenRenderer<T>
where
T: Clone,
{
/// Create children
pub fn new(children: Vec<T>) -> Self {
Self { children }
}
/// Children list is empty
pub fn is_empty(&self) -> bool {
self.children.is_empty()
}
/// Number of children elements
pub fn len(&self) -> usize {
self.children.len()
}
/// Render children components and return `Iterator`
pub fn iter(&self) -> impl Iterator<Item = T> + '_ {
// clone each child lazily.
// This way `self.iter().next()` only has to clone a single node.
self.children.iter().cloned()
}
/// Convert the children elements to another object (if there are any).
///
/// ```
/// # let children = Children::new(Vec::new());
/// # use yew::{classes, html, Children};
/// # let _ =
/// children.map(|children| {
/// html! {
/// <div class={classes!("container")}>
/// {children.clone()}
/// </div>
/// }
/// })
/// # ;
/// ```
pub fn map<OUT: Default>(&self, closure: impl FnOnce(&Self) -> OUT) -> OUT {
if self.is_empty() {
Default::default()
} else {
closure(self)
}
}
}
impl<T> Default for ChildrenRenderer<T> {
fn default() -> Self {
Self {
children: Vec::new(),
}
}
}
impl<T> fmt::Debug for ChildrenRenderer<T> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.write_str("ChildrenRenderer<_>")
}
}
impl<T> IntoIterator for ChildrenRenderer<T> {
type IntoIter = std::vec::IntoIter<Self::Item>;
type Item = T;
fn into_iter(self) -> Self::IntoIter {
self.children.into_iter()
}
}
impl From<ChildrenRenderer<Html>> for Html {
fn from(mut val: ChildrenRenderer<Html>) -> Self {
if val.children.len() == 1 {
if let Some(m) = val.children.pop() {
return m;
}
}
Html::VList(Rc::new(val.into()))
}
}
impl From<ChildrenRenderer<Html>> for VList {
fn from(val: ChildrenRenderer<Html>) -> Self {
if val.is_empty() {
return VList::new();
}
VList::with_children(val.children, None)
}
}
impl<COMP> From<ChildrenRenderer<VChild<COMP>>> for ChildrenRenderer<Html>
where
COMP: BaseComponent,
{
fn from(value: ChildrenRenderer<VChild<COMP>>) -> Self {
Self::new(
value
.into_iter()
.map(VComp::from)
.map(VNode::from)
.collect(),
)
}
}
/// A [Properties] type with Children being the only property.
#[derive(Debug, Properties, PartialEq)]
pub struct ChildrenProps {
/// The Children of a Component.
#[prop_or_default]
pub children: Html,
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn children_map() {
let children = Children::new(vec![]);
let res = children.map(|children| Some(children.clone()));
assert!(res.is_none());
let children = Children::new(vec![Default::default()]);
let res = children.map(|children| Some(children.clone()));
assert!(res.is_some());
}
}