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extern crate rand; extern crate serde_json; extern crate uuid; use std::fmt::Debug; use std::collections::HashMap; use std::collections::hash_map::DefaultHasher; use std::hash::{Hash, Hasher}; use std::iter::FromIterator; use std::rc::Rc; use std::cell::{Cell, RefCell}; use rand::{OsRng, RngCore}; use uuid::Uuid; pub use serde_json::Value as HandlerArg; type Attributes = Vec<(String, AttributeValue)>; fn diff_attributes(a: &mut Attributes, b: &Attributes) -> 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, (u64, String)); type Handlers = Vec<Handler>; fn diff_handlers(a: &mut Handlers, b: &Handlers) -> Vec<Diff> { let mut result = vec![]; let mut old_map = HashMap::<String, (u64, String)>::from_iter(a.drain(..)); for &(ref new_key, (ref new_hash, ref new_id)) in b { match old_map.remove(new_key) { Some((old_hash, _)) => { if &old_hash != new_hash { result.push(Diff::SetHandler(new_key.clone(), new_id.clone())) } } None => 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)) => Element::diff(a, b, &i), (&mut Node::Text(ref mut text_a), &Node::Text(ref text_b)) => { if text_a == text_b { return None; } Some(Diff::ReplaceChild(i.clone(), b.clone())) } (&mut Node::Null, &Node::Null) => None, (&mut Node::Null, _) => Some(Diff::AddChild(i.clone(), b.clone())), (_, &Node::Null) => { let j = i.clone(); *i -= 1; Some(Diff::RemoveChild(j)) } _ => Some(Diff::ReplaceChild(i.clone(), b.clone())), } } } #[derive(Clone, Debug)] pub struct Element { pub name: String, pub attributes: Attributes, pub handlers: Handlers, pub children: Vec<Node>, } impl Element { pub fn new( name: String, attributes: Attributes, handlers: Handlers, children: Vec<Node>, ) -> Element { Element { name, attributes, handlers, children, } } pub fn diff(a: &mut Element, b: &Element, j: &usize) -> Option<Diff> { if a.name != b.name { return Some(Diff::ReplaceChild(j.clone(), 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)); let mut i = 0; a.children.reverse(); for new_child in &b.children { match a.children.pop() { None => { result.push(Diff::AddChild(i, new_child.clone())); i += 1; } Some(mut old_child) => { if let Some(d) = Node::diff(&mut old_child, new_child, &mut i) { result.push(d); } } } i += 1; } for _ in &a.children { result.push(Diff::RemoveChild(i)); } if result.is_empty() { return None; } Some(Diff::PatchChild(j.clone(), result)) } } #[derive(Debug)] 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>, } impl<A> View<A> { pub fn new( name: String, attributes: Attributes, handlers: Vec<(String, (u64, String, HandlerFunction<A>))>, children: Vec<View<A>>, ) -> View<A> { let mut handler_map = HashMap::new(); let handlers = handlers .into_iter() .map(|(kind, (hash, id, f))| { let handler = (kind, (hash, id.clone())); handler_map.insert(id, f); handler }) .collect(); let children = children .into_iter() .map(|child| { handler_map.extend(child.handler_map); child.node }) .collect(); View { node: Node::Element(Element::new(name, attributes, handlers, children)), 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 { type State: Clone + Debug + PartialEq + 'static; type Action: Clone + Debug + 'static; fn reducer(state: Self::State, action: Self::Action) -> Self::State; fn view(state: Self::State) -> View<Self::Action>; } pub fn handler<A, H, F>(hash: H, f: F) -> (u64, String, HandlerFunction<A>) where H: Hash, F: Fn(HandlerArg) -> Option<A> + 'static, { let mut hasher = DefaultHasher::new(); let mut rng = OsRng::new().unwrap(); hash.hash(&mut hasher); let mut bytes = [0; 16]; rng.fill_bytes(&mut bytes); let id = Uuid::from_random_bytes(bytes).to_string(); (hasher.finish(), id, Box::new(f)) } #[derive(Clone)] pub struct Env<A: App> { 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 { 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 debug<T: Debug + 'static>(v: T); fn run(&self) { let env = self.get_env(); env.scheduled.set(false); let mut old_node = env.get_node(); let view = A::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) -> bool>> { let handler = match self.get_env().pop_handler(id) { Some(h) => h, None => return None, }; let this = self.clone(); let f = move |arg: HandlerArg| { let action = match handler(arg) { Some(a) => a, None => return false, }; let env = this.get_env(); let old_state = env.get_state(); let new_state = A::reducer(old_state.clone(), action); if old_state == new_state { return false; } env.set_state(new_state); if env.scheduled.get() { return false; } env.scheduled.set(true); this.schedule_render(); true }; Some(Box::new(f)) } }