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extern crate rand; extern crate serde_json; extern crate uuid; use rand::prelude::*; use std::cell::{Cell, RefCell}; use std::collections::{HashMap, HashSet}; use std::fmt::Debug; use std::iter::FromIterator; use std::rc::Rc; use uuid::Uuid; thread_local! { static RNG: RefCell<SmallRng> = RefCell::new(SmallRng::from_entropy()); } pub use serde_json::Value as HandlerArg; type Attribute = (String, AttributeValue); fn diff_attributes(a: &mut Vec<Attribute>, b: &[Attribute]) -> Vec<Diff> { let mut result = vec![]; let mut old_map = HashMap::<String, AttributeValue>::from_iter(a.drain(..)); for &(ref new_key, ref new_val) in b { match old_map.remove(new_key) { Some(old_val) => { if &old_val != new_val { result.push(Diff::SetAttribute(new_key.clone(), new_val.clone())) } } None => result.push(Diff::SetAttribute(new_key.clone(), new_val.clone())), } } for (old_key, _) in old_map.drain() { result.push(Diff::RemoveAttribute(old_key)); } result } type HandlerFunction<A> = Box<Fn(HandlerArg) -> Option<A>>; type Handler = (String, String); fn diff_handlers(a: &mut Vec<Handler>, b: &[Handler]) -> Vec<Diff> { let mut result = vec![]; let mut old_map = HashMap::<String, String>::from_iter(a.drain(..)); for &(ref new_key, ref new_id) in b { old_map.remove(new_key); result.push(Diff::SetHandler(new_key.clone(), new_id.clone())); } for (old_key, old_id) in old_map.drain() { result.push(Diff::RemoveHandler(old_key, old_id)); } result } #[derive(Clone, Debug)] pub enum Node { Text(String), Element(Element), Null, } impl Node { fn diff(a: &mut Node, b: &Node, i: &mut usize) -> Option<Diff> { match (a, b) { (&mut Node::Element(ref mut a), &Node::Element(ref b)) => { match Element::diff(a, b, *i) { Some(diff) => Some(diff), None => None, } } (&mut Node::Text(ref mut text_a), &Node::Text(ref text_b)) => { if text_a == text_b { return None; } Some(Diff::ReplaceChild(*i, b.clone())) } (&mut Node::Null, &Node::Null) => None, (&mut Node::Null, _) => Some(Diff::AddChild(*i, b.clone())), (_, &Node::Null) => Some(Diff::RemoveChild(*i)), _ => Some(Diff::ReplaceChild(*i, b.clone())), } } fn get_key(&self) -> Option<String> { match self { Node::Element(ref el) => el.get_key(), _ => None, } } } fn get_nodelist_key_set(nodelist: &[Node]) -> HashSet<String> { HashSet::from_iter(nodelist.iter().filter_map(|c| c.get_key())) } fn diff_children(a: &mut Vec<Node>, b: &[Node], i: &mut usize) -> Vec<Diff> { let mut result = vec![]; let b_key_set = get_nodelist_key_set(b); let survived = a .drain(..) .filter(|c| match c.get_key() { Some(k) => { let is_survived = b_key_set.contains(&k); if !is_survived { result.push(Diff::RemoveChild(*i)); return false; } *i += 1; true } None => { *i += 1; true } }) .collect(); *a = survived; let mut i = 0; a.reverse(); for new_child in b.iter() { match a.pop() { None => { result.push(Diff::AddChild(i, new_child.clone())); i += 1; } Some(mut old_child) => { if let Some(diff) = Node::diff(&mut old_child, new_child, &mut i) { result.push(diff.clone()); if let Diff::RemoveChild(_) = diff { continue; } } } } i += 1; } for _ in a.iter() { result.push(Diff::RemoveChild(i)); } result } #[derive(Clone, Debug)] pub struct Element { name: String, attributes: Vec<Attribute>, handlers: Vec<Handler>, children: Vec<Node>, } impl Element { fn new( name: String, attributes: Vec<Attribute>, handlers: Vec<Handler>, children: Vec<Node>, ) -> Element { Element { name, attributes, handlers, children, } } pub fn name(&self) -> &str { &self.name } pub fn attributes(&self) -> &[Attribute] { &self.attributes } pub fn handlers(&self) -> &[Handler] { &self.handlers } pub fn children(&self) -> &[Node] { &self.children } fn diff(a: &mut Element, b: &Element, i: usize) -> Option<Diff> { if let (Some(a_key), Some(b_key)) = (a.get_key(), b.get_key()) { if a_key != b_key { return Some(Diff::ReplaceChild(i, Node::Element(b.clone()))); } } if a.name != b.name { return Some(Diff::ReplaceChild(i, Node::Element(b.clone()))); } let mut result = vec![]; result.append(&mut diff_attributes(&mut a.attributes, &b.attributes)); result.append(&mut diff_handlers(&mut a.handlers, &b.handlers)); result.append(&mut diff_children(&mut a.children, &b.children, &mut 0)); if result.is_empty() { return None; } Some(Diff::PatchChild(i, result)) } fn get_key(&self) -> Option<String> { self.attributes .iter() .find(|&&(ref k, _)| k == "key") .and_then(|&(_, ref v)| match v { AttributeValue::String(ref s) => Some(s.clone()), AttributeValue::Bool(_) => None, }) } } #[derive(Debug, Clone)] pub enum Diff { SetAttribute(String, AttributeValue), RemoveAttribute(String), AddChild(usize, Node), ReplaceChild(usize, Node), RemoveChild(usize), PatchChild(usize, Vec<Diff>), SetHandler(String, String), RemoveHandler(String, String), } #[derive(Clone, Debug, PartialEq)] pub enum AttributeValue { String(String), Bool(bool), } impl From<String> for AttributeValue { fn from(s: String) -> AttributeValue { AttributeValue::String(s) } } impl<'a> From<&'a str> for AttributeValue { fn from(s: &'a str) -> AttributeValue { AttributeValue::String(s.to_string()) } } impl From<bool> for AttributeValue { fn from(b: bool) -> AttributeValue { AttributeValue::Bool(b) } } type HandlerMap<A> = HashMap<String, HandlerFunction<A>>; pub struct View<A> { node: Node, handler_map: HandlerMap<A>, } pub enum Child<A> { View(View<A>), ViewList(Vec<View<A>>), } impl<A, T> From<T> for Child<A> where T: Into<View<A>> + Sized, { fn from(v: T) -> Child<A> { Child::View(v.into()) } } impl<A> FromIterator<View<A>> for Child<A> { fn from_iter<I>(iter: I) -> Child<A> where I: IntoIterator<Item = View<A>>, { Child::ViewList(iter.into_iter().collect()) } } impl<A> View<A> { pub fn new( name: String, attributes: Vec<Attribute>, handlers: Vec<(String, (String, HandlerFunction<A>))>, children: Vec<Child<A>>, ) -> View<A> { let mut handler_map = HashMap::new(); let handlers = handlers .into_iter() .map(|(kind, (id, f))| { let handler = (kind, id.clone()); handler_map.insert(id, f); handler }) .collect(); let mut children_vec = vec![]; for child in children { match child { Child::View(v) => { handler_map.extend(v.handler_map); children_vec.push(v.node); } Child::ViewList(child_vec) => { for v in child_vec { handler_map.extend(v.handler_map); children_vec.push(v.node); } } } } View { node: Node::Element(Element::new(name, attributes, handlers, children_vec)), handler_map, } } pub fn text(s: String) -> View<A> { View { node: Node::Text(s), handler_map: HashMap::new(), } } pub fn null() -> View<A> { View { node: Node::Null, handler_map: HashMap::new(), } } } impl<A> From<()> for View<A> { fn from(_: ()) -> View<A> { View::null() } } impl<A> From<String> for View<A> { fn from(s: String) -> View<A> { View::text(s) } } impl<'a, A> From<&'a str> for View<A> { fn from(s: &'a str) -> View<A> { View::text(s.to_string()) } } impl<A, T> From<Option<T>> for View<A> where T: Into<View<A>>, { fn from(option: Option<T>) -> View<A> { option.map_or_else(View::null, |v| v.into()) } } pub trait App: 'static + Clone + Default { type State: Clone + Debug + PartialEq + 'static; type Action: Clone + Debug + 'static; fn reducer(&self, state: Self::State, action: Self::Action) -> Self::State; fn view(&self, state: Self::State) -> View<Self::Action>; } pub fn handler<A, F>(f: F) -> (String, HandlerFunction<A>) where F: Fn(HandlerArg) -> Option<A> + 'static, { (uuid(), Box::new(f)) } #[derive(Clone)] pub struct Env<A: App> { app: A, state: Rc<RefCell<A::State>>, node: Rc<RefCell<Node>>, handler_map: Rc<RefCell<HandlerMap<A::Action>>>, scheduled: Rc<Cell<bool>>, } impl<A: App> Env<A> { pub fn new(state: A::State) -> Env<A> { Env { app: A::default(), state: Rc::new(RefCell::new(state)), node: Rc::new(RefCell::new(Node::Null)), handler_map: Rc::new(RefCell::new(HashMap::new())), scheduled: Rc::new(Cell::new(false)), } } fn get_state(&self) -> A::State { self.state.borrow().clone() } fn set_state(&self, state: A::State) { *self.state.borrow_mut() = state; } fn get_node(&self) -> Node { self.node.borrow().clone() } fn set_node(&self, node: Node) { *self.node.borrow_mut() = node; } fn pop_handler(&self, id: &str) -> Option<HandlerFunction<A::Action>> { self.handler_map.borrow_mut().remove(id) } } pub trait Runtime<A: App>: Clone + 'static { fn get_env<'a>(&'a self) -> &'a Env<A>; fn handle_diff(&self, diff: Diff); fn schedule_render(&self); fn run(&self) { let env = self.get_env(); env.scheduled.set(false); let mut old_node = env.get_node(); let view = env.app.view(env.get_state()); *env.handler_map.borrow_mut() = view.handler_map; if let Some(diff) = Node::diff(&mut old_node, &view.node, &mut 0) { env.set_node(view.node); self.handle_diff(diff); } } fn pop_handler(&self, id: &str) -> Option<Box<Fn(HandlerArg)>> { let env = self.get_env(); let handler = env.pop_handler(id)?; let app = env.app.clone(); let this = self.clone(); let f = move |arg: HandlerArg| { let action = match handler(arg) { Some(a) => a, None => return, }; let env = this.get_env(); let old_state = env.get_state(); let new_state = app.reducer(old_state.clone(), action); if old_state == new_state { return; } env.set_state(new_state); if env.scheduled.get() { return; } env.scheduled.set(true); this.schedule_render(); }; Some(Box::new(f)) } } pub fn uuid() -> String { RNG.with(|rng| Uuid::from_random_bytes(rng.borrow_mut().gen())) .to_string() }