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JavaScript

'use strict';
let fastProto = null;
// Creates an object with permanently fast properties in V8. See Toon Verwaest's
// post https://medium.com/@tverwaes/setting-up-prototypes-in-v8-ec9c9491dfe2#5f62
// for more details. Use %HasFastProperties(object) and the Node.js flag
// --allow-natives-syntax to check whether an object has fast properties.
function FastObject(o) {
// A prototype object will have "fast properties" enabled once it is checked
// against the inline property cache of a function, e.g. fastProto.property:
// https://github.com/v8/v8/blob/6.0.122/test/mjsunit/fast-prototype.js#L48-L63
if (fastProto !== null && typeof fastProto.property) {
const result = fastProto;
fastProto = FastObject.prototype = null;
return result;
}
fastProto = FastObject.prototype = o == null ? Object.create(null) : o;
return new FastObject;
}
// Initialize the inline property cache of FastObject
FastObject();
module.exports = function toFastproperties(o) {
return FastObject(o);
};