365 lines
18 KiB
JavaScript
365 lines
18 KiB
JavaScript
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/**
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* Utility function that works like `Object.apply`, but copies getters and setters properly as well. Additionally gives
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* the option to exclude properties by name.
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*/
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const copyProps = (dest, src, exclude = []) => {
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const props = Object.getOwnPropertyDescriptors(src);
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for (let prop of exclude)
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delete props[prop];
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Object.defineProperties(dest, props);
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};
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/**
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* Returns the full chain of prototypes up until Object.prototype given a starting object. The order of prototypes will
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* be closest to farthest in the chain.
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*/
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const protoChain = (obj, currentChain = [obj]) => {
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const proto = Object.getPrototypeOf(obj);
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if (proto === null)
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return currentChain;
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return protoChain(proto, [...currentChain, proto]);
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};
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/**
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* Identifies the nearest ancestor common to all the given objects in their prototype chains. For most unrelated
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* objects, this function should return Object.prototype.
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*/
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const nearestCommonProto = (...objs) => {
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if (objs.length === 0)
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return undefined;
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let commonProto = undefined;
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const protoChains = objs.map(obj => protoChain(obj));
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while (protoChains.every(protoChain => protoChain.length > 0)) {
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const protos = protoChains.map(protoChain => protoChain.pop());
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const potentialCommonProto = protos[0];
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if (protos.every(proto => proto === potentialCommonProto))
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commonProto = potentialCommonProto;
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else
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break;
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}
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return commonProto;
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};
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/**
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* Creates a new prototype object that is a mixture of the given prototypes. The mixing is achieved by first
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* identifying the nearest common ancestor and using it as the prototype for a new object. Then all properties/methods
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* downstream of this prototype (ONLY downstream) are copied into the new object.
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*
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* The resulting prototype is more performant than softMixProtos(...), as well as ES5 compatible. However, it's not as
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* flexible as updates to the source prototypes aren't captured by the mixed result. See softMixProtos for why you may
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* want to use that instead.
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*/
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const hardMixProtos = (ingredients, constructor, exclude = []) => {
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var _a;
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const base = (_a = nearestCommonProto(...ingredients)) !== null && _a !== void 0 ? _a : Object.prototype;
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const mixedProto = Object.create(base);
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// Keeps track of prototypes we've already visited to avoid copying the same properties multiple times. We init the
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// list with the proto chain below the nearest common ancestor because we don't want any of those methods mixed in
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// when they will already be accessible via prototype access.
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const visitedProtos = protoChain(base);
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for (let prototype of ingredients) {
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let protos = protoChain(prototype);
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// Apply the prototype chain in reverse order so that old methods don't override newer ones.
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for (let i = protos.length - 1; i >= 0; i--) {
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let newProto = protos[i];
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if (visitedProtos.indexOf(newProto) === -1) {
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copyProps(mixedProto, newProto, ['constructor', ...exclude]);
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visitedProtos.push(newProto);
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}
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}
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}
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mixedProto.constructor = constructor;
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return mixedProto;
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};
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const unique = (arr) => arr.filter((e, i) => arr.indexOf(e) == i);
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/**
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* Finds the ingredient with the given prop, searching in reverse order and breadth-first if searching ingredient
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* prototypes is required.
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*/
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const getIngredientWithProp = (prop, ingredients) => {
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const protoChains = ingredients.map(ingredient => protoChain(ingredient));
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// since we search breadth-first, we need to keep track of our depth in the prototype chains
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let protoDepth = 0;
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// not all prototype chains are the same depth, so this remains true as long as at least one of the ingredients'
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// prototype chains has an object at this depth
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let protosAreLeftToSearch = true;
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while (protosAreLeftToSearch) {
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// with the start of each horizontal slice, we assume this is the one that's deeper than any of the proto chains
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protosAreLeftToSearch = false;
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// scan through the ingredients right to left
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for (let i = ingredients.length - 1; i >= 0; i--) {
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const searchTarget = protoChains[i][protoDepth];
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if (searchTarget !== undefined && searchTarget !== null) {
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// if we find something, this is proof that this horizontal slice potentially more objects to search
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protosAreLeftToSearch = true;
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// eureka, we found it
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if (Object.getOwnPropertyDescriptor(searchTarget, prop) != undefined) {
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return protoChains[i][0];
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}
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}
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}
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protoDepth++;
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}
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return undefined;
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};
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/**
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* "Mixes" ingredients by wrapping them in a Proxy. The optional prototype argument allows the mixed object to sit
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* downstream of an existing prototype chain. Note that "properties" cannot be added, deleted, or modified.
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*/
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const proxyMix = (ingredients, prototype = Object.prototype) => new Proxy({}, {
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getPrototypeOf() {
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return prototype;
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},
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setPrototypeOf() {
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throw Error('Cannot set prototype of Proxies created by ts-mixer');
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},
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getOwnPropertyDescriptor(_, prop) {
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return Object.getOwnPropertyDescriptor(getIngredientWithProp(prop, ingredients) || {}, prop);
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},
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defineProperty() {
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throw new Error('Cannot define new properties on Proxies created by ts-mixer');
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},
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has(_, prop) {
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return getIngredientWithProp(prop, ingredients) !== undefined || prototype[prop] !== undefined;
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},
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get(_, prop) {
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return (getIngredientWithProp(prop, ingredients) || prototype)[prop];
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},
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set(_, prop, val) {
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const ingredientWithProp = getIngredientWithProp(prop, ingredients);
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if (ingredientWithProp === undefined)
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throw new Error('Cannot set new properties on Proxies created by ts-mixer');
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ingredientWithProp[prop] = val;
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return true;
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},
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deleteProperty() {
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throw new Error('Cannot delete properties on Proxies created by ts-mixer');
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},
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ownKeys() {
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return ingredients
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.map(Object.getOwnPropertyNames)
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.reduce((prev, curr) => curr.concat(prev.filter(key => curr.indexOf(key) < 0)));
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},
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});
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/**
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* Creates a new proxy-prototype object that is a "soft" mixture of the given prototypes. The mixing is achieved by
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* proxying all property access to the ingredients. This is not ES5 compatible and less performant. However, any
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* changes made to the source prototypes will be reflected in the proxy-prototype, which may be desirable.
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*/
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const softMixProtos = (ingredients, constructor) => proxyMix([...ingredients, { constructor }]);
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const settings = {
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initFunction: null,
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staticsStrategy: 'copy',
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prototypeStrategy: 'copy',
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decoratorInheritance: 'deep',
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};
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// Keeps track of constituent classes for every mixin class created by ts-mixer.
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const mixins = new Map();
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const getMixinsForClass = (clazz) => mixins.get(clazz);
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const registerMixins = (mixedClass, constituents) => mixins.set(mixedClass, constituents);
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const hasMixin = (instance, mixin) => {
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if (instance instanceof mixin)
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return true;
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const constructor = instance.constructor;
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const visited = new Set();
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let frontier = new Set();
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frontier.add(constructor);
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while (frontier.size > 0) {
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// check if the frontier has the mixin we're looking for. if not, we can say we visited every item in the frontier
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if (frontier.has(mixin))
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return true;
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frontier.forEach(item => visited.add(item));
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// build a new frontier based on the associated mixin classes and prototype chains of each frontier item
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const newFrontier = new Set();
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frontier.forEach(item => {
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var _a;
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const itemConstituents = (_a = mixins.get(item)) !== null && _a !== void 0 ? _a : protoChain(item.prototype).map(proto => proto.constructor).filter(item => item !== null);
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if (itemConstituents)
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itemConstituents.forEach(constituent => {
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if (!visited.has(constituent) && !frontier.has(constituent))
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newFrontier.add(constituent);
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});
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});
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// we have a new frontier, now search again
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frontier = newFrontier;
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}
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// if we get here, we couldn't find the mixin anywhere in the prototype chain or associated mixin classes
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return false;
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};
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const mergeObjectsOfDecorators = (o1, o2) => {
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var _a, _b;
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const allKeys = unique([...Object.getOwnPropertyNames(o1), ...Object.getOwnPropertyNames(o2)]);
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const mergedObject = {};
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for (let key of allKeys)
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mergedObject[key] = unique([...((_a = o1 === null || o1 === void 0 ? void 0 : o1[key]) !== null && _a !== void 0 ? _a : []), ...((_b = o2 === null || o2 === void 0 ? void 0 : o2[key]) !== null && _b !== void 0 ? _b : [])]);
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return mergedObject;
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};
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const mergePropertyAndMethodDecorators = (d1, d2) => {
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var _a, _b, _c, _d;
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return ({
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property: mergeObjectsOfDecorators((_a = d1 === null || d1 === void 0 ? void 0 : d1.property) !== null && _a !== void 0 ? _a : {}, (_b = d2 === null || d2 === void 0 ? void 0 : d2.property) !== null && _b !== void 0 ? _b : {}),
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method: mergeObjectsOfDecorators((_c = d1 === null || d1 === void 0 ? void 0 : d1.method) !== null && _c !== void 0 ? _c : {}, (_d = d2 === null || d2 === void 0 ? void 0 : d2.method) !== null && _d !== void 0 ? _d : {}),
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});
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};
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const mergeDecorators = (d1, d2) => {
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var _a, _b, _c, _d, _e, _f;
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return ({
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class: unique([...(_a = d1 === null || d1 === void 0 ? void 0 : d1.class) !== null && _a !== void 0 ? _a : [], ...(_b = d2 === null || d2 === void 0 ? void 0 : d2.class) !== null && _b !== void 0 ? _b : []]),
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static: mergePropertyAndMethodDecorators((_c = d1 === null || d1 === void 0 ? void 0 : d1.static) !== null && _c !== void 0 ? _c : {}, (_d = d2 === null || d2 === void 0 ? void 0 : d2.static) !== null && _d !== void 0 ? _d : {}),
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instance: mergePropertyAndMethodDecorators((_e = d1 === null || d1 === void 0 ? void 0 : d1.instance) !== null && _e !== void 0 ? _e : {}, (_f = d2 === null || d2 === void 0 ? void 0 : d2.instance) !== null && _f !== void 0 ? _f : {}),
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});
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};
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const decorators = new Map();
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const findAllConstituentClasses = (...classes) => {
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var _a;
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const allClasses = new Set();
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const frontier = new Set([...classes]);
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while (frontier.size > 0) {
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for (let clazz of frontier) {
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const protoChainClasses = protoChain(clazz.prototype).map(proto => proto.constructor);
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const mixinClasses = (_a = getMixinsForClass(clazz)) !== null && _a !== void 0 ? _a : [];
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const potentiallyNewClasses = [...protoChainClasses, ...mixinClasses];
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const newClasses = potentiallyNewClasses.filter(c => !allClasses.has(c));
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for (let newClass of newClasses)
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frontier.add(newClass);
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allClasses.add(clazz);
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frontier.delete(clazz);
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}
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}
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return [...allClasses];
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};
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const deepDecoratorSearch = (...classes) => {
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const decoratorsForClassChain = findAllConstituentClasses(...classes)
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.map(clazz => decorators.get(clazz))
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.filter(decorators => !!decorators);
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if (decoratorsForClassChain.length == 0)
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return {};
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if (decoratorsForClassChain.length == 1)
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return decoratorsForClassChain[0];
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return decoratorsForClassChain.reduce((d1, d2) => mergeDecorators(d1, d2));
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};
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const directDecoratorSearch = (...classes) => {
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const classDecorators = classes.map(clazz => getDecoratorsForClass(clazz));
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if (classDecorators.length === 0)
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return {};
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if (classDecorators.length === 1)
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return classDecorators[0];
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return classDecorators.reduce((d1, d2) => mergeDecorators(d1, d2));
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};
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const getDecoratorsForClass = (clazz) => {
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let decoratorsForClass = decorators.get(clazz);
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if (!decoratorsForClass) {
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decoratorsForClass = {};
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decorators.set(clazz, decoratorsForClass);
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}
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return decoratorsForClass;
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};
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const decorateClass = (decorator) => ((clazz) => {
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const decoratorsForClass = getDecoratorsForClass(clazz);
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let classDecorators = decoratorsForClass.class;
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if (!classDecorators) {
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classDecorators = [];
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decoratorsForClass.class = classDecorators;
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}
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classDecorators.push(decorator);
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return decorator(clazz);
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});
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const decorateMember = (decorator) => ((object, key, ...otherArgs) => {
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var _a, _b, _c;
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const decoratorTargetType = typeof object === 'function' ? 'static' : 'instance';
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const decoratorType = typeof object[key] === 'function' ? 'method' : 'property';
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const clazz = decoratorTargetType === 'static' ? object : object.constructor;
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const decoratorsForClass = getDecoratorsForClass(clazz);
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const decoratorsForTargetType = (_a = decoratorsForClass === null || decoratorsForClass === void 0 ? void 0 : decoratorsForClass[decoratorTargetType]) !== null && _a !== void 0 ? _a : {};
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decoratorsForClass[decoratorTargetType] = decoratorsForTargetType;
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let decoratorsForType = (_b = decoratorsForTargetType === null || decoratorsForTargetType === void 0 ? void 0 : decoratorsForTargetType[decoratorType]) !== null && _b !== void 0 ? _b : {};
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decoratorsForTargetType[decoratorType] = decoratorsForType;
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let decoratorsForKey = (_c = decoratorsForType === null || decoratorsForType === void 0 ? void 0 : decoratorsForType[key]) !== null && _c !== void 0 ? _c : [];
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decoratorsForType[key] = decoratorsForKey;
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// @ts-ignore: array is type `A[] | B[]` and item is type `A | B`, so technically a type error, but it's fine
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decoratorsForKey.push(decorator);
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// @ts-ignore
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return decorator(object, key, ...otherArgs);
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});
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const decorate = (decorator) => ((...args) => {
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if (args.length === 1)
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return decorateClass(decorator)(args[0]);
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return decorateMember(decorator)(...args);
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});
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function Mixin(...constructors) {
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var _a, _b, _c;
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const prototypes = constructors.map(constructor => constructor.prototype);
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// Here we gather up the init functions of the ingredient prototypes, combine them into one init function, and
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// attach it to the mixed class prototype. The reason we do this is because we want the init functions to mix
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// similarly to constructors -- not methods, which simply override each other.
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const initFunctionName = settings.initFunction;
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if (initFunctionName !== null) {
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const initFunctions = prototypes
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.map(proto => proto[initFunctionName])
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.filter(func => typeof func === 'function');
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const combinedInitFunction = function (...args) {
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for (let initFunction of initFunctions)
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initFunction.apply(this, args);
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};
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const extraProto = { [initFunctionName]: combinedInitFunction };
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prototypes.push(extraProto);
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}
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function MixedClass(...args) {
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for (const constructor of constructors)
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// @ts-ignore: potentially abstract class
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copyProps(this, new constructor(...args));
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if (initFunctionName !== null && typeof this[initFunctionName] === 'function')
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this[initFunctionName].apply(this, args);
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}
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MixedClass.prototype = settings.prototypeStrategy === 'copy'
|
||
|
|
? hardMixProtos(prototypes, MixedClass)
|
||
|
|
: softMixProtos(prototypes, MixedClass);
|
||
|
|
Object.setPrototypeOf(MixedClass, settings.staticsStrategy === 'copy'
|
||
|
|
? hardMixProtos(constructors, null, ['prototype'])
|
||
|
|
: proxyMix(constructors, Function.prototype));
|
||
|
|
let DecoratedMixedClass = MixedClass;
|
||
|
|
if (settings.decoratorInheritance !== 'none') {
|
||
|
|
const classDecorators = settings.decoratorInheritance === 'deep'
|
||
|
|
? deepDecoratorSearch(...constructors)
|
||
|
|
: directDecoratorSearch(...constructors);
|
||
|
|
for (let decorator of (_a = classDecorators === null || classDecorators === void 0 ? void 0 : classDecorators.class) !== null && _a !== void 0 ? _a : []) {
|
||
|
|
const result = decorator(DecoratedMixedClass);
|
||
|
|
if (result) {
|
||
|
|
DecoratedMixedClass = result;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
applyPropAndMethodDecorators((_b = classDecorators === null || classDecorators === void 0 ? void 0 : classDecorators.static) !== null && _b !== void 0 ? _b : {}, DecoratedMixedClass);
|
||
|
|
applyPropAndMethodDecorators((_c = classDecorators === null || classDecorators === void 0 ? void 0 : classDecorators.instance) !== null && _c !== void 0 ? _c : {}, DecoratedMixedClass.prototype);
|
||
|
|
}
|
||
|
|
registerMixins(DecoratedMixedClass, constructors);
|
||
|
|
return DecoratedMixedClass;
|
||
|
|
}
|
||
|
|
const applyPropAndMethodDecorators = (propAndMethodDecorators, target) => {
|
||
|
|
const propDecorators = propAndMethodDecorators.property;
|
||
|
|
const methodDecorators = propAndMethodDecorators.method;
|
||
|
|
if (propDecorators)
|
||
|
|
for (let key in propDecorators)
|
||
|
|
for (let decorator of propDecorators[key])
|
||
|
|
decorator(target, key);
|
||
|
|
if (methodDecorators)
|
||
|
|
for (let key in methodDecorators)
|
||
|
|
for (let decorator of methodDecorators[key])
|
||
|
|
decorator(target, key, Object.getOwnPropertyDescriptor(target, key));
|
||
|
|
};
|
||
|
|
/**
|
||
|
|
* A decorator version of the `Mixin` function. You'll want to use this instead of `Mixin` for mixing generic classes.
|
||
|
|
*/
|
||
|
|
const mix = (...ingredients) => decoratedClass => {
|
||
|
|
// @ts-ignore
|
||
|
|
const mixedClass = Mixin(...ingredients.concat([decoratedClass]));
|
||
|
|
Object.defineProperty(mixedClass, 'name', {
|
||
|
|
value: decoratedClass.name,
|
||
|
|
writable: false,
|
||
|
|
});
|
||
|
|
return mixedClass;
|
||
|
|
};
|
||
|
|
|
||
|
|
export { Mixin, decorate, hasMixin, mix, settings };
|