53 lines
1.8 KiB
JavaScript
53 lines
1.8 KiB
JavaScript
var uncurryThis = require('../internals/function-uncurry-this');
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var fails = require('../internals/fails');
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var isCallable = require('../internals/is-callable');
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var classof = require('../internals/classof');
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var getBuiltIn = require('../internals/get-built-in');
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var inspectSource = require('../internals/inspect-source');
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var noop = function () { /* empty */ };
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var empty = [];
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var construct = getBuiltIn('Reflect', 'construct');
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var constructorRegExp = /^\s*(?:class|function)\b/;
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var exec = uncurryThis(constructorRegExp.exec);
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var INCORRECT_TO_STRING = !constructorRegExp.exec(noop);
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var isConstructorModern = function isConstructor(argument) {
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if (!isCallable(argument)) return false;
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try {
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construct(noop, empty, argument);
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return true;
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} catch (error) {
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return false;
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}
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};
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var isConstructorLegacy = function isConstructor(argument) {
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if (!isCallable(argument)) return false;
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switch (classof(argument)) {
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case 'AsyncFunction':
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case 'GeneratorFunction':
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case 'AsyncGeneratorFunction': return false;
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}
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try {
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// we can't check .prototype since constructors produced by .bind haven't it
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// `Function#toString` throws on some built-it function in some legacy engines
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// (for example, `DOMQuad` and similar in FF41-)
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return INCORRECT_TO_STRING || !!exec(constructorRegExp, inspectSource(argument));
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} catch (error) {
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return true;
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}
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};
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isConstructorLegacy.sham = true;
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// `IsConstructor` abstract operation
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// https://tc39.es/ecma262/#sec-isconstructor
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module.exports = !construct || fails(function () {
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var called;
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return isConstructorModern(isConstructorModern.call)
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|| !isConstructorModern(Object)
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|| !isConstructorModern(function () { called = true; })
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|| called;
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}) ? isConstructorLegacy : isConstructorModern;
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