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node_modules/@babel/plugin-transform-block-scoping/lib/tdz.js

@@ -0,0 +1,97 @@
+"use strict";
+
+Object.defineProperty(exports, "__esModule", {
+  value: true
+});
+exports.visitor = void 0;
+
+var _core = require("@babel/core");
+
+function getTDZStatus(refPath, bindingPath) {
+  const executionStatus = bindingPath._guessExecutionStatusRelativeTo(refPath);
+
+  if (executionStatus === "before") {
+    return "outside";
+  } else if (executionStatus === "after") {
+    return "inside";
+  } else {
+    return "maybe";
+  }
+}
+
+function buildTDZAssert(node, state) {
+  return _core.types.callExpression(state.addHelper("temporalRef"), [node, _core.types.stringLiteral(node.name)]);
+}
+
+function isReference(node, scope, state) {
+  const declared = state.letReferences.get(node.name);
+  if (!declared) return false;
+  return scope.getBindingIdentifier(node.name) === declared;
+}
+
+const visitedMaybeTDZNodes = new WeakSet();
+const visitor = {
+  ReferencedIdentifier(path, state) {
+    if (!state.tdzEnabled) return;
+    const {
+      node,
+      parent,
+      scope
+    } = path;
+    if (path.parentPath.isFor({
+      left: node
+    })) return;
+    if (!isReference(node, scope, state)) return;
+    const bindingPath = scope.getBinding(node.name).path;
+    if (bindingPath.isFunctionDeclaration()) return;
+    const status = getTDZStatus(path, bindingPath);
+    if (status === "outside") return;
+
+    if (status === "maybe") {
+      if (visitedMaybeTDZNodes.has(node)) {
+        return;
+      }
+
+      visitedMaybeTDZNodes.add(node);
+      const assert = buildTDZAssert(node, state);
+      bindingPath.parent._tdzThis = true;
+
+      if (path.parentPath.isUpdateExpression()) {
+        if (parent._ignoreBlockScopingTDZ) return;
+        path.parentPath.replaceWith(_core.types.sequenceExpression([assert, parent]));
+      } else {
+        path.replaceWith(assert);
+      }
+    } else if (status === "inside") {
+      path.replaceWith(_core.template.ast`${state.addHelper("tdz")}("${node.name}")`);
+    }
+  },
+
+  AssignmentExpression: {
+    exit(path, state) {
+      if (!state.tdzEnabled) return;
+      const {
+        node
+      } = path;
+      if (node._ignoreBlockScopingTDZ) return;
+      const nodes = [];
+      const ids = path.getBindingIdentifiers();
+
+      for (const name of Object.keys(ids)) {
+        const id = ids[name];
+
+        if (isReference(id, path.scope, state)) {
+          nodes.push(id);
+        }
+      }
+
+      if (nodes.length) {
+        node._ignoreBlockScopingTDZ = true;
+        nodes.push(node);
+        path.replaceWithMultiple(nodes.map(n => _core.types.expressionStatement(n)));
+      }
+    }
+
+  }
+};
+exports.visitor = visitor;