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https://github.com/jaandrle/deka-dom-el
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💥 rename signals to observables
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261
src/observables-lib.js
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261
src/observables-lib.js
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@@ -0,0 +1,261 @@
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export const mark= Symbol.for("observable");
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export function isObservable(candidate){
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try{ return Reflect.has(candidate, mark); }
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catch(e){ return false; }
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}
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/** @type {function[]} */
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const stack_watch= [];
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/**
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* ### `WeakMap<function, Set<ddeObservable<any, any>>>`
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* The `Set` is in the form of `[ source, ...depended observables (DSs) ]`.
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* When the DS is cleaned (`S.clear`) it is removed from DSs,
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* if remains only one (`source`) it is cleared too.
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* ### `WeakMap<object, function>`
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* This is used for revesed deps, the `function` is also key for `deps`.
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* @type {WeakMap<function|object,Set<ddeObservable<any, any>>|function>}
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* */
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const deps= new WeakMap();
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export function observable(value, actions){
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if(typeof value!=="function")
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return create(value, actions);
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if(isObservable(value)) return value;
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const out= create();
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const contextReWatch= function(){
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const [ origin, ...deps_old ]= deps.get(contextReWatch);
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deps.set(contextReWatch, new Set([ origin ]));
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stack_watch.push(contextReWatch);
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out(value());
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stack_watch.pop();
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if(!deps_old.length) return;
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const deps_curr= deps.get(contextReWatch);
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for (const dep_observable of deps_old){
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if(deps_curr.has(dep_observable)) continue;
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removeObservableListener(dep_observable, contextReWatch);
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}
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};
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deps.set(out[mark], contextReWatch);
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deps.set(contextReWatch, new Set([ out ]));
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contextReWatch();
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return out;
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}
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export { observable as O };
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observable.action= function(observable, name, ...a){
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const s= observable[mark], { actions }= s;
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if(!actions || !Reflect.has(actions, name))
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throw new Error(`'${observable}' has no action with name '${name}'!`);
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actions[name].apply(s, a);
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if(s.skip) return Reflect.deleteProperty(s, "skip");
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s.listeners.forEach(l=> l(s.value));
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};
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observable.on= function on(observables, listener, options= {}){
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const { observable: as }= options;
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if(as && as.aborted) return;
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if(Array.isArray(observables)) return observables.forEach(s=> on(s, listener, options));
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addObservableListener(observables, listener);
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if(as) as.addEventListener("abort", ()=> removeObservableListener(observables, listener));
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//TODO cleanup when observable removed
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};
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observable.symbols= {
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observable: mark,
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onclear: Symbol.for("Observable.onclear")
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};
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observable.clear= function(...observables){
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for(const observable of observables){
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Reflect.deleteProperty(observable, "toJSON");
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const s= observable[mark];
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s.onclear.forEach(f=> f.call(s));
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clearListDeps(observable, s);
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Reflect.deleteProperty(observable, mark);
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}
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function clearListDeps(observable, s){
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s.listeners.forEach(l=> {
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s.listeners.delete(l);
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if(!deps.has(l)) return;
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const ls= deps.get(l);
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ls.delete(observable);
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if(ls.size>1) return;
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observable.clear(...ls);
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deps.delete(l);
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});
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}
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};
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const key_reactive= "__dde_reactive";
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import { el, elementAttribute } from "./dom.js";
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import { scope } from "./dom.js";
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observable.el= function(observable, map){
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const mark_start= el.mark({ type: "reactive" }, false);
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const mark_end= mark_start.end;
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const out= document.createDocumentFragment();
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out.append(mark_start, mark_end);
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const { current }= scope;
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const reRenderReactiveElement= v=> {
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if(!mark_start.parentNode || !mark_end.parentNode)
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return removeObservableListener(observable, reRenderReactiveElement);
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scope.push(current);
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let els= map(v);
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scope.pop();
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if(!Array.isArray(els))
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els= [ els ];
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let el_r= mark_start;
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while(( el_r= mark_start.nextSibling ) !== mark_end)
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el_r.remove();
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mark_start.after(...els);
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};
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addObservableListener(observable, reRenderReactiveElement);
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removeObservablesFromElements(observable, reRenderReactiveElement, mark_start, map);
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reRenderReactiveElement(observable());
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return out;
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};
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import { on } from "./events.js";
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const key_attributes= "__dde_attributes";
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observable.attribute= function(name, initial= null){
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//TODO host=element & reuse existing
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const out= observable(initial);
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let element;
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scope.host(el=> {
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element= el;
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if(elementAttribute(element, "has", name)) out(elementAttribute(element, "get", name));
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else if(initial!==null) elementAttribute(element, "set", name, initial);
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if(el[key_attributes]){
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el[key_attributes][name]= out;
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return;
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}
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element[key_attributes]= { [name]: out };
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on.attributeChanged(function attributeChangeToObservable({ detail }){
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/*! This maps attributes to observables (`S.attribute`).
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* Investigate `__dde_attributes` key of the element.*/
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const [ name, value ]= detail;
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const curr= element[key_attributes][name];
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if(curr) return curr(value);
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})(element);
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on.disconnected(function(){
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/*! This removes all observables mapped to attributes (`S.attribute`).
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* Investigate `__dde_attributes` key of the element.*/
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observable.clear(...Object.values(element[key_attributes]));
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})(element);
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});
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return new Proxy(out, {
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apply(target, _, args){
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if(!args.length) return target();
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const value= args[0];
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return elementAttribute(element, "set", name, value);
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}
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});
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};
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import { typeOf } from './helpers.js';
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export const observables_config= {
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isObservable,
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processReactiveAttribute(element, key, attrs, set){
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if(!isObservable(attrs)) return attrs;
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const l= attr=> set(key, attr);
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addObservableListener(attrs, l);
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removeObservablesFromElements(attrs, l, element, key);
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return attrs();
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}
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};
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function removeObservablesFromElements(observable, listener, ...notes){
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const { current }= scope;
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if(current.prevent) return;
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current.host(function(element){
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if(!element[key_reactive]){
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element[key_reactive]= [];
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on.disconnected(()=>
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/*!
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* Clears all Observables listeners added in the current scope/host (`S.el`, `assign`, …?).
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* You can investigate the `__dde_reactive` key of the element.
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* */
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element[key_reactive].forEach(([ [ observable, listener ] ])=>
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removeObservableListener(observable, listener, observable[mark]?.host() === element))
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)(element);
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}
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element[key_reactive].push([ [ observable, listener ], ...notes ]);
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});
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}
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function create(value, actions){
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const observable= (...value)=>
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value.length ? write(observable, ...value) : read(observable);
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return toObservable(observable, value, actions);
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}
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const protoSigal= Object.assign(Object.create(null), {
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stopPropagation(){
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this.skip= true;
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}
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});
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class ObservableDefined extends Error{
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constructor(){
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super();
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const [ curr, ...rest ]= this.stack.split("\n");
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const curr_file= curr.slice(curr.indexOf("@"), curr.indexOf(".js:")+4);
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this.stack= rest.find(l=> !l.includes(curr_file));
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}
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}
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function toObservable(observable, value, actions){
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const onclear= [];
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if(typeOf(actions)!=="[object Object]")
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actions= {};
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const { onclear: ocs }= observable.symbols;
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if(actions[ocs]){
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onclear.push(actions[ocs]);
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Reflect.deleteProperty(actions, ocs);
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}
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const { host }= scope;
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Reflect.defineProperty(observable, mark, {
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value: {
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value, actions, onclear, host,
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listeners: new Set(),
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defined: new ObservableDefined()
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},
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enumerable: false,
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writable: false,
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configurable: true
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});
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observable.toJSON= ()=> observable();
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Object.setPrototypeOf(observable[mark], protoSigal);
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return observable;
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}
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function currentContext(){
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return stack_watch[stack_watch.length - 1];
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}
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function read(observable){
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if(!observable[mark]) return;
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const { value, listeners }= observable[mark];
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const context= currentContext();
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if(context) listeners.add(context);
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if(deps.has(context)) deps.get(context).add(observable);
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return value;
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}
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function write(observable, value, force){
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if(!observable[mark]) return;
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const s= observable[mark];
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if(!force && s.value===value) return;
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s.value= value;
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s.listeners.forEach(l=> l(value));
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return value;
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}
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function addObservableListener(observable, listener){
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if(!observable[mark]) return;
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return observable[mark].listeners.add(listener);
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}
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function removeObservableListener(observable, listener, clear_when_empty){
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const s= observable[mark];
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if(!s) return;
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const out= s.listeners.delete(listener);
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if(clear_when_empty && !s.listeners.size){
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observable.clear(observable);
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if(!deps.has(s)) return out;
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const c= deps.get(s);
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if(!deps.has(c)) return out;
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deps.get(c).forEach(sig=> removeObservableListener(sig, c, true));
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}
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return out;
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}
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