74 lines
1.8 KiB
JavaScript
74 lines
1.8 KiB
JavaScript
import { declare } from "@babel/helper-plugin-utils";
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import { types as t } from "@babel/core";
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export default declare(api => {
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api.assertVersion(7);
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return {
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name: "transform-new-target",
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visitor: {
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MetaProperty(path) {
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const meta = path.get("meta");
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const property = path.get("property");
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const { scope } = path;
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if (
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meta.isIdentifier({ name: "new" }) &&
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property.isIdentifier({ name: "target" })
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) {
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const func = path.findParent(path => {
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if (path.isClass()) return true;
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if (path.isFunction() && !path.isArrowFunctionExpression()) {
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if (path.isClassMethod({ kind: "constructor" })) {
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return false;
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}
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return true;
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}
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return false;
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});
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if (!func) {
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throw path.buildCodeFrameError(
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"new.target must be under a (non-arrow) function or a class.",
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);
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}
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const { node } = func;
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if (!node.id) {
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if (func.isMethod()) {
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path.replaceWith(scope.buildUndefinedNode());
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return;
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}
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node.id = scope.generateUidIdentifier("target");
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}
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const constructor = t.memberExpression(
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t.thisExpression(),
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t.identifier("constructor"),
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);
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if (func.isClass()) {
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path.replaceWith(constructor);
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return;
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}
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path.replaceWith(
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t.conditionalExpression(
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t.binaryExpression(
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"instanceof",
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t.thisExpression(),
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t.cloneNode(node.id),
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),
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constructor,
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scope.buildUndefinedNode(),
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),
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);
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}
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},
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},
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};
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});
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