86 lines
3.8 KiB
JavaScript
86 lines
3.8 KiB
JavaScript
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"use strict";
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Object.defineProperty(exports, "__esModule", { value: true });
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exports.flatten = exports.unique = exports.hardMixProtos = exports.nearestCommonProto = exports.protoChain = exports.copyProps = void 0;
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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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exports.copyProps = copyProps;
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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 (0, exports.protoChain)(proto, [...currentChain, proto]);
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};
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exports.protoChain = protoChain;
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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 => (0, exports.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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exports.nearestCommonProto = nearestCommonProto;
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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 = (0, exports.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 = (0, exports.protoChain)(base);
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for (let prototype of ingredients) {
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let protos = (0, exports.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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(0, exports.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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exports.hardMixProtos = hardMixProtos;
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const unique = (arr) => arr.filter((e, i) => arr.indexOf(e) == i);
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exports.unique = unique;
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const flatten = (arr) => arr.length === 0
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? []
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: arr.length === 1
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? arr[0]
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: arr.reduce((a1, a2) => [...a1, ...a2]);
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exports.flatten = flatten;
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