react-magic-state/dist/core/observer.js

React state management without the hassle.

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
const symbols = require("./symbols");
class Observer {
    constructor(wrappedFunction) {
        this._observations = new WeakMap();
        this._reactions = new Set();
        this._wrappedFunction = wrappedFunction;
        Observer._all.add(this);
    }
    static get all() {
        return this._all;
    }
    static get active() {
        return this._activeObserver;
    }
    addReaction(reaction) {
        this._reactions.add(reaction);
    }
    beginObservationPhase() {
        if (Observer._activeObserver) {
            if (Observer._activeObserver === this) {
                //TODO: Write test
                throw new Error("beginObservationPhase() called twice for the same observer.");
            }
            Observer._observerStack.push(Observer._activeObserver);
        }
        // Remove old observations
        //TODO: Write test
        this._observations = new WeakMap();
        Observer._activeObserver = this;
    }
    createWrapper() {
        const self = this;
        const target = this._wrappedFunction;
        const wrapper = function () {
            self.beginObservationPhase();
            try {
                return Reflect.apply(target, this, arguments);
            }
            finally {
                self.endObservationPhase();
            }
        };
        return wrapper;
    }
    destroy() {
        const wrapped = this._wrappedFunction;
        const self = this;
        Observer.all.delete(this);
        delete self._observations;
        delete self._reactions;
        delete self._wrappedFunction;
        delete wrapped[symbols.observer];
        return wrapped;
    }
    endObservationPhase() {
        if (Observer._activeObserver !== this) {
            throw new Error("Unmatched beingObservationPhase()/endObservationPhase() calls.");
        }
        Observer._activeObserver = Observer._observerStack.pop();
    }
    getReactionsForChange(target, propKey) {
        const observation = this._observations.get(target);
        if (observation) {
            if (observation.has(propKey)) {
                return this._reactions;
            }
        }
        return null;
    }
    hasReaction(reaction) {
        return this._reactions.has(reaction);
    }
    registerAccess(target, propKey) {
        if (!this._observations.has(target)) {
            this._observations.set(target, new Set());
        }
        this._observations.get(target).add(propKey);
    }
}
exports.Observer = Observer;
Observer._observerStack = new Array();
Observer._all = new Set();