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use std::cell::RefCell;
use wasm_bindgen::prelude::*;
use web_sys::{js_sys::Function, HtmlElement};
#[wasm_bindgen]
extern "C" {
fn _create_custom_element_js(name: String, renderer: BaseComponent);
}
enum HandlerVal {
#[allow(dead_code)]
Value(RefCell<Box<dyn Component>>),
None,
}
/// A trait that provides the necessary methods for a custom element lifecycle
///
/// # Basic example
///
/// ```
/// use rs_web_component::{define_component, Component};
/// use wasm_bindgen::prelude::*;
/// use web_sys::{HtmlElement, ShadowRoot, ShadowRootInit, ShadowRootMode};
/// pub enum ThisVal {
/// Value(HtmlElement),
/// None,
/// }
/// pub enum RootVal {
/// Value(ShadowRoot),
/// None,
/// }
/// struct MyComponent {
/// root: RootVal,
/// this: ThisVal,
/// }
/// impl Component for MyComponent {
/// fn init(&mut self, this: HtmlElement) {
/// self.this = ThisVal::Value(this);
/// }
/// fn observed_attributes(&self) -> Vec<String> {
/// return vec!["test".to_string()];
/// }
/// fn attribute_changed_callback(&self, _name: String, _old_value: JsValue, _new_value: JsValue) {
/// if _old_value != _new_value {
/// self.get_root().set_inner_html(self.render().as_str())
/// }
/// }
/// fn connected_callback(&mut self) {
/// self.root = RootVal::Value(
/// self.get_this()
/// .attach_shadow(&ShadowRootInit::new(ShadowRootMode::Open))
/// .unwrap(),
/// );
/// self.get_root().set_inner_html(self.render().as_str())
/// }
/// fn disconnected_callback(&self) {}
/// }
/// impl MyComponent {
/// fn render(&self) -> String {
/// "<div><span>Hello from Rust</span></div>".to_string()
/// }
/// fn get_root(&self) -> &ShadowRoot {
/// return match &self.root {
/// RootVal::Value(root) => &root,
/// RootVal::None => panic!("not a root!"),
/// };
/// }
/// fn get_this(&self) -> &HtmlElement {
/// match &self.this {
/// ThisVal::Value(val) => val,
/// ThisVal::None => panic!("not an HtmlElement"),
/// }
/// }
/// }
/// #[wasm_bindgen(start)]
/// fn run() {
/// define_component("test-component".to_string(), || -> Box<dyn Component> {
/// Box::new(MyComponent {
/// root: RootVal::None,
/// this: ThisVal::None,
/// })
/// });
/// }
/// ```
///
/// # An Example with a button and an event handler
///
/// ```
/// use rs_web_component::{define_element, Component};
/// use wasm_bindgen::prelude::*;
/// use web_sys::{
/// CustomEvent, CustomEventInit, Event, HtmlElement, ShadowRoot, ShadowRootInit, ShadowRootMode,
/// };
/// const BUTTON_EVENT_NAME: &str = "buttonClicked";
/// pub enum ThisVal {
/// Value(HtmlElement),
/// None,
/// }
/// pub enum RootVal {
/// Value(ShadowRoot),
/// None,
/// }
/// pub enum CallbackVal {
/// Value(Closure<dyn FnMut(Event) + 'static>),
/// None,
/// }
/// struct MyComponent {
/// root: RootVal,
/// this: ThisVal,
/// callback: CallbackVal,
/// }
/// impl Component for MyComponent {
/// fn init(&mut self, this: HtmlElement) {
/// self.this = ThisVal::Value(this);
/// }
///
/// fn observed_attributes(&self) -> Vec<String> {
/// return vec!["test".to_string()];
/// }
///
/// fn attribute_changed_callback(&self, _name: String, _old_value: JsValue, _new_value: JsValue) {}
///
/// fn connected_callback(&mut self) {
/// self.root = RootVal::Value(
/// self.get_this()
/// .attach_shadow(&ShadowRootInit::new(ShadowRootMode::Open))
/// .unwrap(),
/// );
///
/// self.get_root().set_inner_html(self.render().as_str());
/// self.attach_event_handler();
/// }
///
/// fn disconnected_callback(&self) {
/// self.detach_event_handler();
/// }
/// }
/// impl MyComponent {
/// fn render(&self) -> String {
/// "<div><button>Click me</button></div>".to_string()
/// }
///
/// fn attach_event_handler(&mut self) {
/// let btn = self.get_root().query_selector("button").unwrap().unwrap();
/// let closure = Closure::<dyn FnMut(Event) + 'static>::new(move |e: Event| {
/// let evt = CustomEvent::new_with_event_init_dict(
/// BUTTON_EVENT_NAME,
/// CustomEventInit::new().composed(true).bubbles(true),
/// )
/// .unwrap();
/// let _ = btn.dispatch_event(&evt);
/// });
/// self.callback = CallbackVal::Value(closure);
/// let btn = self.get_root().query_selector("button").unwrap().unwrap();
/// let _ = btn.add_event_listener_with_callback(
/// "click",
/// self.get_callback().as_ref().unchecked_ref(),
/// );
/// }
///
/// fn detach_event_handler(&self) {
/// let btn = self.get_this().query_selector("button").unwrap().unwrap();
/// let _ = btn.remove_event_listener_with_callback(
/// "click",
/// self.get_callback().as_ref().unchecked_ref(),
/// );
/// }
///
/// fn get_callback(&self) -> &Closure<dyn FnMut(Event) + 'static> {
/// return match &self.callback {
/// CallbackVal::Value(callback) => callback,
/// &CallbackVal::None => panic!("not a callback!"),
/// };
/// }
///
/// fn get_root(&self) -> &ShadowRoot {
/// return match &self.root {
/// RootVal::Value(root) => &root,
/// RootVal::None => panic!("not a root!"),
/// };
/// }
///
/// fn get_this(&self) -> &HtmlElement {
/// match &self.this {
/// ThisVal::Value(val) => val,
/// ThisVal::None => panic!("not an HtmlElement"),
/// }
/// }
/// }
///
/// #[wasm_bindgen(start)]
/// fn run() {
/// define_element("test-component".to_string(), || -> Box<dyn Component> {
/// Box::new(MyComponent {
/// root: RootVal::None,
/// this: ThisVal::None,
/// callback: CallbackVal::None,
/// })
/// });
/// }
/// ```
fn create_global_func() {
let _ = create_custom_element().call0(&JsValue::default());
}
pub trait Component {
/// Gives access to a web_sys::HtmlElement
/// # Arguments
///
/// * `this` - A structure that holds an HtmlElement
fn init(&mut self, this: HtmlElement);
/// Returns list of observed attributes
fn observed_attributes(&self) -> Vec<String> {
vec![]
}
/// Invoked when one of the custom element's attributes is added, removed, or changed.
/// # Arguments
///
/// * `_name` - A name of an attribute
/// * `_old_value` - A previous value of an attribute
/// * `_old_value` - A new value of an attribute
fn attribute_changed_callback(&self, _name: String, _old_value: JsValue, _new_value: JsValue);
/// Invoked when the custom element is first connected to the document's DOM.
fn connected_callback(&mut self);
/// Invoked when the custom element is disconnected from the document's DOM.
fn disconnected_callback(&self);
/// Invoked when the custom element is moved to a new document.
fn adopted_callback(&self) {}
/// Can be invoked to pass state to a custom element
fn set_data(&mut self, _data: JsValue) {}
}
#[wasm_bindgen]
struct BaseComponent {
#[allow(dead_code)]
handler: RefCell<HandlerVal>,
#[allow(dead_code)]
component_constructor: fn() -> Box<(dyn Component + 'static)>,
}
#[wasm_bindgen]
impl BaseComponent {
#[allow(dead_code)]
pub fn init(&mut self, this: HtmlElement) {
let is_empty = match &(*self.handler.borrow()) {
HandlerVal::None => true,
HandlerVal::Value(_val) => false,
};
if is_empty {
self.handler = RefCell::new(HandlerVal::Value(RefCell::new((self
.component_constructor)(
))));
}
self.get_handler().get_mut().init(this);
}
#[allow(dead_code)]
pub fn observed_attributes(&mut self) -> Vec<String> {
let is_empty = match &(*self.handler.borrow()) {
HandlerVal::None => true,
HandlerVal::Value(_val) => false,
};
if is_empty {
self.handler = RefCell::new(HandlerVal::Value(RefCell::new((self
.component_constructor)(
))));
}
return self.get_handler().get_mut().observed_attributes();
}
#[allow(dead_code)]
pub fn attribute_changed_callback(
&mut self,
_name: String,
_old_value: JsValue,
_new_value: JsValue,
) {
self.get_handler()
.get_mut()
.attribute_changed_callback(_name, _old_value, _new_value);
}
#[allow(dead_code)]
pub fn connected_callback(&mut self) {
self.get_handler().get_mut().connected_callback();
}
#[allow(dead_code)]
pub fn disconnected_callback(&mut self) {
self.get_handler().get_mut().disconnected_callback();
}
#[allow(dead_code)]
pub fn adopted_callback(&mut self) {
self.get_handler().get_mut().adopted_callback();
}
#[allow(dead_code)]
pub fn set_data(&mut self, _data: JsValue) {
self.get_handler().get_mut().set_data(_data);
}
fn get_handler(&mut self) -> &mut RefCell<Box<dyn Component>> {
match self.handler.get_mut() {
HandlerVal::Value(val) => val,
HandlerVal::None => panic!("not a component"),
}
}
}
/// Defines a new custom element
/// # Arguments
///
/// * `name` - A name of a new custom element
/// * `constructor` - Function/Closure which creates an instance of a custom element
pub fn define_element(name: String, constructor: fn() -> Box<dyn Component>) {
create_global_func();
let renderer: BaseComponent = BaseComponent {
handler: RefCell::new(HandlerVal::None),
component_constructor: constructor,
};
_create_custom_element_js(name, renderer);
}
/**
* Creates a template element with the specified content
* # Arguments
*
* * `template_id` - An id of a template
* * `template_content` - A string representation of a content without the Template tag.
* Can be validated/sanitized with some great libs <https://crates.io/search?q=sanitize%20html>
*/
pub fn add_template(template_id: String, template_content: String) {
let window = if let Some(window) = web_sys::window() {
window
} else {
panic!("could not get a window");
};
let document = if let Some(document) = window.document() {
document
} else {
panic!("could not get a document");
};
let template = if let Ok(template) = document.create_element("template") {
template
} else {
panic!("could not create template element");
};
template.set_id(&template_id);
template.set_inner_html(&template_content);
let body = if let Some(body) = document.body() {
body
} else {
panic!("could not get a body element");
};
if let Err(_) = body.append_child(&template) {
panic!("could not add a template to the body element");
};
}
fn create_custom_element() -> Function {
Function::new_no_args(
"
if(window._create_custom_element_js) {
return;
}
window._create_custom_element_js = function(
name,
component
) {
class CustomElement extends HTMLElement {
constructor() {
super();
component.init(this);
}
static get observedAttributes() {
return component.observed_attributes();
}
setData(data = []) {
component.set_data(data);
}
attributeChangedCallback(name, oldValue, newValue) {
component.attribute_changed_callback(name, oldValue ?? undefined, newValue);
}
connectedCallback() {
component.connected_callback();
}
disconnectedCallback() {
component.disconnected_callback();
}
adoptedCallback() {
component.adopted_callback();
}
};
customElements.define(name, CustomElement);
}
",
)
}