87 lines
2.2 KiB
JavaScript
87 lines
2.2 KiB
JavaScript
"use strict";
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// Returns "Type(value) is Object" in ES terminology.
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function isObject(value) {
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return typeof value === "object" && value !== null || typeof value === "function";
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}
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function getReferenceToBytes(bufferSource) {
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// Node.js' Buffer does not allow subclassing for now, so we can get away with a prototype object check for perf.
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if (Object.getPrototypeOf(bufferSource) === Buffer.prototype) {
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return bufferSource;
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}
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if (bufferSource instanceof ArrayBuffer) {
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return Buffer.from(bufferSource);
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}
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return Buffer.from(bufferSource.buffer, bufferSource.byteOffset, bufferSource.byteLength);
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}
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function getCopyToBytes(bufferSource) {
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return Buffer.from(getReferenceToBytes(bufferSource));
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}
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function mixin(target, source) {
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const keys = Object.getOwnPropertyNames(source);
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for (let i = 0; i < keys.length; ++i) {
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if (keys[i] in target) {
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continue;
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}
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Object.defineProperty(target, keys[i], Object.getOwnPropertyDescriptor(source, keys[i]));
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}
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}
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const wrapperSymbol = Symbol("wrapper");
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const implSymbol = Symbol("impl");
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const sameObjectCaches = Symbol("SameObject caches");
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function getSameObject(wrapper, prop, creator) {
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if (!wrapper[sameObjectCaches]) {
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wrapper[sameObjectCaches] = Object.create(null);
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}
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if (prop in wrapper[sameObjectCaches]) {
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return wrapper[sameObjectCaches][prop];
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}
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wrapper[sameObjectCaches][prop] = creator();
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return wrapper[sameObjectCaches][prop];
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}
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function wrapperForImpl(impl) {
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return impl ? impl[wrapperSymbol] : null;
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}
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function implForWrapper(wrapper) {
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return wrapper ? wrapper[implSymbol] : null;
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}
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function tryWrapperForImpl(impl) {
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const wrapper = wrapperForImpl(impl);
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return wrapper ? wrapper : impl;
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}
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function tryImplForWrapper(wrapper) {
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const impl = implForWrapper(wrapper);
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return impl ? impl : wrapper;
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}
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const iterInternalSymbol = Symbol("internal");
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const IteratorPrototype = Object.getPrototypeOf(Object.getPrototypeOf([][Symbol.iterator]()));
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module.exports = exports = {
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isObject,
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getReferenceToBytes,
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getCopyToBytes,
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mixin,
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wrapperSymbol,
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implSymbol,
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getSameObject,
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wrapperForImpl,
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implForWrapper,
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tryWrapperForImpl,
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tryImplForWrapper,
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iterInternalSymbol,
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IteratorPrototype
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};
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