94 lines
2.4 KiB
JavaScript
94 lines
2.4 KiB
JavaScript
import * as t from "babel-types";
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function getTDZStatus(refPath, bindingPath) {
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let executionStatus = bindingPath._guessExecutionStatusRelativeTo(refPath);
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if (executionStatus === "before") {
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return "inside";
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} else if (executionStatus === "after") {
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return "outside";
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} else {
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return "maybe";
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}
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}
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function buildTDZAssert(node, file) {
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return t.callExpression(
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file.addHelper("temporalRef"),
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[node, t.stringLiteral(node.name), file.addHelper("temporalUndefined")]
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);
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}
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function isReference(node, scope, state) {
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let declared = state.letReferences[node.name];
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if (!declared) return false;
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// declared node is different in this scope
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return scope.getBindingIdentifier(node.name) === declared;
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}
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export let visitor = {
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ReferencedIdentifier(path, state) {
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if (!this.file.opts.tdz) return;
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let { node, parent, scope } = path;
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if (path.parentPath.isFor({ left: node })) return;
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if (!isReference(node, scope, state)) return;
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let bindingPath = scope.getBinding(node.name).path;
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let status = getTDZStatus(path, bindingPath);
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if (status === "inside") return;
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if (status === "maybe") {
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let assert = buildTDZAssert(node, state.file);
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// add tdzThis to parent variable declarator so it's exploded
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bindingPath.parent._tdzThis = true;
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path.skip();
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if (path.parentPath.isUpdateExpression()) {
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if (parent._ignoreBlockScopingTDZ) return;
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path.parentPath.replaceWith(t.sequenceExpression([assert, parent]));
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} else {
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path.replaceWith(assert);
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}
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} else if (status === "outside") {
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path.replaceWith(t.throwStatement(t.inherits(
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t.newExpression(t.identifier("ReferenceError"), [
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t.stringLiteral(`${node.name} is not defined - temporal dead zone`)
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]),
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node
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)));
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}
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},
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AssignmentExpression: {
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exit(path, state) {
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if (!this.file.opts.tdz) return;
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let { node } = path;
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if (node._ignoreBlockScopingTDZ) return;
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let nodes = [];
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let ids = path.getBindingIdentifiers();
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for (let name in ids) {
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let id = ids[name];
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if (isReference(id, path.scope, state)) {
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nodes.push(buildTDZAssert(id, state.file));
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}
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}
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if (nodes.length) {
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node._ignoreBlockScopingTDZ = true;
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nodes.push(node);
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path.replaceWithMultiple(nodes.map(t.expressionStatement));
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}
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}
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}
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};
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