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use std::collections::HashMap; use std::{cell::{RefCell}, rc::Rc}; use std::panic; use wasm_bindgen::closure::Closure; use crate::dom_types; use crate::dom_types::El; use crate::util; use crate::websys_bridge; pub struct Mailbox<Message: 'static> { func: Rc<Fn(Message)>, } impl<Ms: 'static> Mailbox<Ms> { pub fn new(func: impl Fn(Ms) + 'static) -> Self { Mailbox { func: Rc::new(func), } } pub fn send(&self, message: Ms) { (self.func)(message) } } impl<Ms> Clone for Mailbox<Ms> { fn clone(&self) -> Self { Mailbox { func: self.func.clone(), } } } // todo: Examine what needs to be ref cells, rcs etc type StoredPopstate = RefCell<Option<Closure<FnMut(web_sys::Event)>>>; /// Used as part of an interior-mutability pattern, ie Rc<RefCell<>> pub struct Data<Ms: Clone +'static , Mdl: 'static> { pub document: web_sys::Document, // todo take off pub if you no longer use it in init pub mount_point: web_sys::Element, // Model is in a RefCell here so we can replace it in self.update(). pub model: RefCell<Mdl>, pub update: fn(Ms, Mdl) -> Mdl, pub view: fn(App<Ms, Mdl>, Mdl) -> El<Ms>, pub main_el_vdom: RefCell<El<Ms>>, pub popstate_closure: StoredPopstate, routes: RefCell<Option<HashMap<String, Ms>>>, pub window_events: Option<fn(Mdl) -> Vec<dom_types::Listener<Ms>>>, window_listeners: RefCell<Vec<dom_types::Listener<Ms>>>, } pub struct App<Ms: Clone + 'static , Mdl: 'static> { pub data: Rc<Data<Ms, Mdl>> } /// We use a struct instead of series of functions, in order to avoid passing /// repetative sequences of parameters. impl<Ms: Clone + 'static, Mdl: Clone + 'static> App<Ms, Mdl> { fn new( model: Mdl, update: fn(Ms, Mdl) -> Mdl, view: fn(Self, Mdl) -> El<Ms>, // view: fn(Self, Mdl) -> DomEl<Ms>, parent_div_id: &str, routes: Option<HashMap<String, Ms>>, window_events: Option<fn(Mdl) -> Vec<dom_types::Listener<Ms>>>, ) -> Self { let window = util::window(); let document = window.document().expect("Can't find the window's document."); let mount_point = document.get_element_by_id(parent_div_id).unwrap(); Self { data: Rc::new(Data { document, mount_point, model: RefCell::new(model), update, view, main_el_vdom: RefCell::new(El::empty(dom_types::Tag::Div)), popstate_closure: RefCell::new(None), routes: RefCell::new(routes), window_events, window_listeners: RefCell::new(Vec::new()), }) } } /// This runs whenever the state is changed, ie the user-written update function is called. /// It updates the state, and any DOM elements affected by this change. /// todo this is where we need to compare against differences and only update nodes affected /// by the state change. /// /// We re-create the whole virtual dom each time (Is there a way around this? Probably not without /// knowing what vars the model holds ahead of time), but only edit the rendered, web_sys dom /// for things that have been changed. /// We re-render the virtual DOM on every change, but (attempt to) only change /// the actual DOM, via web_sys, when we need. /// The model storred in inner is the old model; updated_model is a newly-calculated one. pub fn update(&self, message: Ms) { // data.model is the old model; pass it to the update function created in the app, // which outputs an updated model. // We clone the model before running update, and again before passing it // to the view func, instead of using refs, to improve API syntax. // This approach may have performance impacts of unknown magnitude. let model_to_update = self.data.model.borrow().clone(); let updated_model = (self.data.update)(message, model_to_update); // Unlike in run, we clone model here anyway, so no need to change top_new_vdom // logic based on if we have window listeners. if let Some(window_events) = self.data.window_events { let mut new_listeners = (window_events)(updated_model.clone()); setup_window_listeners( &util::window(), &mut self.data.window_listeners.borrow_mut(), // &mut Vec::new(), &mut new_listeners, &self.mailbox() ); self.data.window_listeners.replace(new_listeners); } // Create a new vdom: The top element, and all its children. Does not yet // have ids, nest levels, or associated web_sys elements. // We accept cloning here, for the benefit of making data easier to work // with in the app. let mut topel_new_vdom = (self.data.view)(self.clone(), updated_model.clone()); // We're now done with this updated model; store it for use as the old // model for the next update. // Note: It appears that this step is why we need data.model to be in a RefCell. self.data.model.replace(updated_model); // We setup the vdom (which populates web_sys els through it, but don't // render them with attach_children; we try to do it cleverly via patch(). setup_els(&self.data.document, &mut topel_new_vdom, 0, 0); // Detach all old listeners before patching. We'll re-add them as required during patching. // We'll get a runtime panic if any are left un-removed. detach_listeners(&mut self.data.main_el_vdom.borrow_mut()); // We haven't updated data.main_el_vdom, so we use it as our old (previous) state. patch( &self.data.document, &mut self.data.main_el_vdom.borrow_mut(), &mut topel_new_vdom, &self.data.mount_point, &self.mailbox() ); // Now that we've re-rendered, replace our stored El with the new one; // it will be used as the old El next (. self.data.main_el_vdom.replace(topel_new_vdom); } fn mailbox(&self) -> Mailbox<Ms> { let cloned = self.clone(); Mailbox::new(move |message| { cloned.update(message); }) } } /// Populate the attached web_sys elements, ids, and nest-levels. Run this after creating a vdom, but before /// using it to process the web_sys dom. Does not attach children in the DOM. Run this on the top-level element. pub fn setup_els<Ms>(document: &web_sys::Document, el_vdom: &mut El<Ms>, active_level: u32, active_id: u32) // pub for tesets. where Ms: Clone +'static { // id iterates once per item; active-level once per nesting level. let mut id = active_id; el_vdom.id = Some(id); id += 1; // Raise the id after each element we process. el_vdom.nest_level = Some(active_level); // Create the web_sys element; add it to the working tree; store it in // its corresponding vdom El. let el_ws = websys_bridge::make_websys_el(el_vdom, document); el_vdom.el_ws = Some(el_ws); for child in &mut el_vdom.children { // Raise the active level once per recursion. setup_els(document, child, active_level + 1, id); id += 1; } } // trying this approach leads to lifetime problems. //fn mailbox<Ms, Mdl>(app: &'static App<Ms, Mdl>) -> Mailbox<Ms> // where Ms: Clone + 'static, Mdl: Clone + 'static { // Mailbox::new(move |message| { // app.clone().update(message); // }) // //} impl<Ms: Clone + 'static , Mdl: 'static> std::clone::Clone for App<Ms, Mdl> { fn clone(&self) -> Self { App { data: Rc::clone(&self.data), } } } // todo should this be here, or in a diff module? /// Recursively attach event-listeners. Run this at init. fn attach_listeners<Ms>(el: &mut dom_types::El<Ms>, mailbox: &Mailbox<Ms>) where Ms: Clone + 'static { let el_ws = el.el_ws.take().expect("Missing el_ws on attach_all_listeners"); for listener in &mut el.listeners { listener.attach(&el_ws, mailbox.clone()); } for child in &mut el.children { attach_listeners(child, mailbox) } el.el_ws.replace(el_ws); } // todo should this be here, or in a diff module? /// Recursively detach event-listeners. Run this before patching. fn detach_listeners<Ms>(el: &mut dom_types::El<Ms>) where Ms: Clone + 'static { let el_ws = el.el_ws.take().expect("Missing el_ws on detach_all_listeners"); for listener in &mut el.listeners { listener.detach(&el_ws); } for child in &mut el.children { detach_listeners(child) } el.el_ws.replace(el_ws); } /// We reattach all listeners, as with normal Els, since we have no /// way of diffing them. fn setup_window_listeners<Ms>( window: &web_sys::Window, old: &mut Vec<dom_types::Listener<Ms>>, new: &mut Vec<dom_types::Listener<Ms>>, mailbox: &Mailbox<Ms> ) where Ms: Clone + 'static { for listener in old { listener.detach(window); } for listener in new { listener.attach(window, mailbox.clone()); } } fn patch<Ms>(document: &web_sys::Document, old: &mut El<Ms>, new: &mut El<Ms>, parent: &web_sys::Element, mailbox: &Mailbox<Ms>) where Ms: Clone + 'static { // Old_el_ws is what we're patching, with items from the new vDOM el; or replacing. // Todo: Current sceme is that if the parent changes, redraw all children... // todo fix this later. // We make an assumption that most of the page is not dramatically changed // by each event, to optimize. // todo: There are a lot of ways you could make this more sophisticated. // Assume setup_vdom has been run on the new el, all listeners have been removed // from the old el_ws, and the only the old el vdom's elements are still attached. // take removes the interior value from the Option; otherwise we run into problems // about not being able to remove from borrowed content. // We remove it from the old el_vodom now, and at the end... add it to the new one. // We don't run attach_children() when patching, hence this approach. // if new.is_dummy() == true { return } let old_el_ws = old.el_ws.take().expect("No old elws"); if old != new { // Something about this element itself is different: patch it. // At this step, we already assume we have the right element - either // by entering this func directly for the top-level, or recursively after // analyzing children // If the tag's different, we must redraw the element and its children; there's // no way to patch one element type into another. // todo forcing a rerender for differnet listeners is potentially sloppy, // todo, but I'm not sure how to patch them, or deal with them. if old.tag != new.tag { // todo DRY here between this and later in func. if let Some(unmount_actions) = &mut old.will_unmount { unmount_actions(&old_el_ws) } parent.remove_child(&old_el_ws).expect("Problem removing an element"); websys_bridge::attach_els(new, parent); let mut new = new; attach_listeners(&mut new, &mailbox); // We've re-rendered this child and all children; we're done with this recursion. return } // Patch parts of the Element. websys_bridge::patch_el_details(old, new, &old_el_ws, document); } // Before running patch, assume we've removed all listeners from the old element. // Perform this attachment after we've verified we can patch this element, ie // it has the same tag - otherwise we'd have to detach after the parent.remove_child step. // Note that unlike the attach_listeners function, this only attaches for the currently // element. for listener in &mut new.listeners { listener.attach(&old_el_ws, mailbox.clone()); } // Now pair up children as best we can. // If there are the same number of children, assume there's a 1-to-1 mapping, // where we will not add or remove any; but patch as needed. // A more sophisticated approach would be to find the best match of every // combination of score of new vs old, then rank them somehow. (Eg even // if old id=2 is the best match for the first new, if it's only a marginal // winner, but a strong winner for the second, it makes sense to put it // in the second, but we are not allowing it this opporunity as-is. // One approach would be check all combinations, combine scores within each combo, and pick the one // with the highest total score, but this increases with the factorial of // child size! // todo: Look into this improvement sometime after the initial release. let avail_old_children = &mut old.children; for child_new in &mut new.children { if avail_old_children.is_empty() { // One or more new children has been added, or much content has // changed, or we've made a mistake: Attach new children. websys_bridge::attach_els(child_new, &old_el_ws); let mut child_new = child_new; attach_listeners(&mut child_new, &mailbox); } else { // We still have old children to pick a match from. If we pick // incorrectly, or there is no "good" match, we'll have some // patching and/or attaching (rendering) to do in subsequent recursions. let mut scores: Vec<(u32, f32)> = avail_old_children.iter() .map(|c| (c.id.unwrap(), match_score(c, child_new))).collect(); // should put highest score at the end. scores.sort_by(|b, a| b.1.partial_cmp(&a.1).unwrap()); // Sorting children vice picking the best one makes this easier to handle // without irking the borrow checker, despite appearing less counter-intuitive, // due to the convenient pop method. avail_old_children.sort_by(|b, a| { scores.iter().find(|s| s.0 == b.id.unwrap()).unwrap().1.partial_cmp( &scores.iter().find(|s| s.0 == a.id.unwrap()).unwrap().1 ).unwrap() }); let mut best_match = avail_old_children.pop().expect("Probably popping"); // todo do we really need to clone the mb again ehre? Keep this under control! patch(document, &mut best_match, child_new, &old_el_ws, &mailbox); // todo old vs new for par } } // Now purge any existing children; they're not part of the new model. for child in avail_old_children { let child_el_ws = child.el_ws.take().expect("Missing child el_ws"); // todo DRY here between this and earlier in func if let Some(unmount_actions) = &mut child.will_unmount { unmount_actions(&child_el_ws) } old_el_ws.remove_child(&child_el_ws).expect("Problem removing child"); child.el_ws.replace(child_el_ws); } new.el_ws = Some(old_el_ws); } /// Compare two elements. Rank based on how similar they are, using subjective criteria. fn match_score<Ms: Clone>(old: &El<Ms>, new: &El<Ms>) -> f32 { // children_to_eval is the number of children to look at on each nest level. // let children_to_eval = 3; // Don't weight children as heavily as the parent. This effect acculates the further down we go. // let child_score_significance = 0.6; let mut score = 0.; // Tags are not likely to change! Good indicator of it being the wrong element. if old.tag == new.tag { score += 0.3 } else { score -= 0.3 }; // Attrs are not likely to change. // todo: Compare attrs more directly. if old.attrs == new.attrs { score += 0.15 } else { score -= 0.15 }; // Style is likely to change. if old.style == new.style { score += 0.05 } else { score -= 0.05 }; // Text is likely to change, but may still be a good indicator. if old.text == new.text { score += 0.05 } else { score -= 0.05 }; // For children length, don't do it based on the difference, since children that actually change in // len may have very large changes. But having identical length is a sanity check. if old.children.len() == new.children.len() { score += 0.1 // } else if (old.children.len() as i16 - new.children.len() as i16).abs() == 1 { // // Perhaps we've added or removed a child. // score += 0.05 // todo non-even transaction } else { score -= 0.1 } // Same id implies it may have been added in the same order. if old.id.expect("Missing id") == new.id.expect("Missing id") { score += 0.15 } else { score -= 0.15 }; // For now, just look at the first child: Easier to code, and still helps. // Doing indefinite recursion of first child for now. Weight each child // subsequently-less. This is effective for some common HTML patterns. // for posit in 0..children_to_eval { // if let Some(child_old) = &old.children.get(posit) { // if let Some(child_new) = &old.children.get(posit) { // score += child_score_significance * match_score(child_old, child_new); // } // } // } score } /// App initialization: Collect its fundamental components, setup, and perform /// an initial render. pub fn run<Ms, Mdl>( model: Mdl, update: fn(Ms, Mdl) -> Mdl, view: fn(App<Ms, Mdl>, Mdl) -> dom_types::El<Ms>, mount_point_id: &str, routes: Option<HashMap<String, Ms>>, window_events: Option<fn(Mdl) -> Vec<dom_types::Listener<Ms>>>, ) where Ms: Clone + 'static, Mdl: Clone + 'static { let app = App::new(model.clone(), update, view, mount_point_id, routes.clone(), window_events); // Our initial render. Can't initialize in new due to mailbox() requiring self. // todo maybe have view take an update instead of whole app? // todo: There's a lot of DRY between here and update. // let mut topel_vdom = (app.data.view)(app.clone(), model.clone()); let window = util::window(); // Only clone model if we have window events. let mut topel_vdom; match app.data.window_events { Some(window_events) => { topel_vdom = (app.data.view)(app.clone(), model.clone()); setup_window_listeners( &util::window(), &mut Vec::new(), // todo: Fix this. Bug where if we try to add initial listeners, // todo we get many runtime panics. Workaround is to wait until // todo app.update, which means an event must be triggered // todo prior to window listeners working. &mut Vec::new(), // &mut (window_events)(model), &app.mailbox() ); }, None => { topel_vdom = (app.data.view)(app.clone(), model); } } let document = window.document().expect("Problem getting document"); setup_els(&document, &mut topel_vdom, 0, 0); attach_listeners(&mut topel_vdom, &app.mailbox()); // Attach all children: This is where our initial render occurs. websys_bridge::attach_els(&mut topel_vdom, &app.data.mount_point); app.data.main_el_vdom.replace(topel_vdom); // If a route map is inlcluded, update the state on page load, based // on the starting URL. Must be set up on the server as well. if let Some(routes_inner) = routes { let app2 = crate::routing::initial(app, routes_inner.clone()); crate::routing::update_popstate_listener(&app2, routes_inner); } // Allows panic messages to output to the browser console.error. panic::set_hook(Box::new(console_error_panic_hook::hook)); } pub trait Attrs: PartialEq + ToString { fn vals(self) -> HashMap<String, String>; } pub trait Style: PartialEq + ToString { fn vals(self) -> HashMap<String, String>; } pub trait Listener<Ms>: Sized { fn attach<T: AsRef<web_sys::EventTarget>>(&mut self, el_ws: &T, mailbox: Mailbox<Ms>); fn detach<T: AsRef<web_sys::EventTarget>>(&self, el_ws: &T); } /// WIP towards a modular VDOM /// Assumes dependency on web_sys. // todo: Do we need <Ms> ? pub trait DomEl<Ms>: Sized + PartialEq { type Tg: PartialEq + ToString; // todo tostring type At: Attrs; type St: Style; type Ls: Listener<Ms>; type Tx: PartialEq + ToString + Clone + Default; // Fields fn tag(self) -> Self::Tg; fn attrs(self) -> Self::At; fn style(self) -> Self::St; fn listeners(self) -> Vec<Self::Ls>; fn text(self) -> Option<Self::Tx>; fn children(self) -> Vec<Self>; fn did_mount(self) -> Option<Box<FnMut(&web_sys::Element)>>; fn did_update(self) -> Option<Box<FnMut(&web_sys::Element)>>; fn will_unmount(self) -> Option<Box<FnMut(&web_sys::Element)>>; fn websys_el(self) -> Option<web_sys::Element>; fn id(self) -> Option<u32>; fn raw_html(self) -> bool; // todo tying to dom_types is temp - defeats the urpose of the trait fn namespace(self) -> Option<crate::dom_types::Namespace>; // Methods fn empty(self) -> Self; // setters fn set_id(&mut self, id: Option<u32>); fn set_websys_el(&mut self, el: Option<web_sys::Element>); // fn make_websys_el(&self, document: &web_sys::Document) -> web_sys::Element; } #[cfg(test)] pub mod tests { use wasm_bindgen_test::wasm_bindgen_test_configure; wasm_bindgen_test_configure!(run_in_browser); use wasm_bindgen_test::*; use super::*; use crate as seed; // required for macros to work. use crate::prelude::*; use crate::{div,li}; #[derive(Clone)] enum Msg {} #[wasm_bindgen_test] fn el_added() { let old_vdom: El<Msg> = div![ "text", vec![ li![ "child1" ], ] ]; let new_vdom: El<Msg> = div![ "text", vec![ li![ "child1" ], li![ "child2" ] ] ]; let doc = util::document(); let old_ws = doc.create_element("div").unwrap(); let new_ws = doc.create_element("div").unwrap(); let child1 = doc.create_element("li").unwrap(); let child2 = doc.create_element("li").unwrap(); // todo make this match how you're setting text_content, eg could // todo be adding a text node. old_ws.set_text_content(Some("text")); child1.set_text_content(Some("child1")); child2.set_text_content(Some("child2")); old_ws.append_child(&child1).unwrap(); new_ws.append_child(&child1).unwrap(); new_ws.append_child(&child2).unwrap(); // let patched = patch(); assert_eq!(2 + 2, 4); } #[test] fn el_removed() { } #[test] fn el_changed() { } }