Adding upstream version 86.0.1.upstream/86.0.1upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 199 insertions, 0 deletions

diff --git a/devtools/client/debugger/src/workers/parser/mapAwaitExpression.js b/devtools/client/debugger/src/workers/parser/mapAwaitExpression.js
new file mode 100644
index 0000000000..7eaa70afe6
--- /dev/null
+++ b/devtools/client/debugger/src/workers/parser/mapAwaitExpression.js
@@ -0,0 +1,199 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at <http://mozilla.org/MPL/2.0/>. */
+
+// @flow
+
+import generate from "@babel/generator";
+import * as t from "@babel/types";
+
+import { hasNode, replaceNode } from "./utils/ast";
+import { isTopLevel } from "./utils/helpers";
+
+function hasTopLevelAwait(ast: Object): boolean {
+  const hasAwait = hasNode(
+    ast,
+    (node, ancestors, b) => t.isAwaitExpression(node) && isTopLevel(ancestors)
+  );
+
+  return hasAwait;
+}
+
+// translates new bindings `var a = 3` into `a = 3`.
+function translateDeclarationIntoAssignment(node: Object): Object[] {
+  return node.declarations.reduce((acc, declaration) => {
+    // Don't translate declaration without initial assignment (e.g. `var a;`)
+    if (!declaration.init) {
+      return acc;
+    }
+    acc.push(
+      t.expressionStatement(
+        t.assignmentExpression("=", declaration.id, declaration.init)
+      )
+    );
+    return acc;
+  }, []);
+}
+
+/**
+ * Given an AST, compute its last statement and replace it with a
+ * return statement.
+ */
+function addReturnNode(ast: Object): Object {
+  const statements = ast.program.body;
+  const lastStatement = statements[statements.length - 1];
+  return statements
+    .slice(0, -1)
+    .concat(t.returnStatement(lastStatement.expression));
+}
+
+function getDeclarations(node: Object) {
+  const { kind, declarations } = node;
+  const declaratorNodes = declarations.reduce((acc, d) => {
+    const declarators = getVariableDeclarators(d.id);
+    return acc.concat(declarators);
+  }, []);
+
+  // We can't declare const variables outside of the async iife because we
+  // wouldn't be able to re-assign them. As a workaround, we transform them
+  // to `let` which should be good enough for those case.
+  return t.variableDeclaration(
+    kind === "const" ? "let" : kind,
+    declaratorNodes
+  );
+}
+
+function getVariableDeclarators(node: Object): Object[] | Object {
+  if (t.isIdentifier(node)) {
+    return t.variableDeclarator(t.identifier(node.name));
+  }
+
+  if (t.isObjectProperty(node)) {
+    return getVariableDeclarators(node.value);
+  }
+  if (t.isRestElement(node)) {
+    return getVariableDeclarators(node.argument);
+  }
+
+  if (t.isAssignmentPattern(node)) {
+    return getVariableDeclarators(node.left);
+  }
+
+  if (t.isArrayPattern(node)) {
+    return node.elements.reduce(
+      (acc, element) => acc.concat(getVariableDeclarators(element)),
+      []
+    );
+  }
+  if (t.isObjectPattern(node)) {
+    return node.properties.reduce(
+      (acc, property) => acc.concat(getVariableDeclarators(property)),
+      []
+    );
+  }
+  return [];
+}
+
+/**
+ * Given an AST and an array of variableDeclaration nodes, return a new AST with
+ * all the declarations at the top of the AST.
+ */
+function addTopDeclarationNodes(ast: Object, declarationNodes: Object[]) {
+  const statements = [];
+  declarationNodes.forEach(declarationNode => {
+    statements.push(getDeclarations(declarationNode));
+  });
+  statements.push(ast);
+  return t.program(statements);
+}
+
+/**
+ * Given an AST, return an object of the following shape:
+ *   - newAst: {AST} the AST where variable declarations were transformed into
+ *             variable assignments
+ *   - declarations: {Array<Node>} An array of all the declaration nodes needed
+ *                   outside of the async iife.
+ */
+function translateDeclarationsIntoAssignment(
+  ast: Object
+): { newAst: Object, declarations: Node[] } {
+  const declarations = [];
+  t.traverse(ast, (node, ancestors) => {
+    const parent = ancestors[ancestors.length - 1];
+
+    if (
+      t.isWithStatement(node) ||
+      !isTopLevel(ancestors) ||
+      t.isAssignmentExpression(node) ||
+      !t.isVariableDeclaration(node) ||
+      t.isForStatement(parent.node) ||
+      !Array.isArray(node.declarations) ||
+      node.declarations.length === 0
+    ) {
+      return;
+    }
+
+    const newNodes = translateDeclarationIntoAssignment(node);
+    replaceNode(ancestors, newNodes);
+    declarations.push(node);
+  });
+
+  return {
+    newAst: ast,
+    declarations,
+  };
+}
+
+/**
+ * Given an AST, wrap its body in an async iife, transform variable declarations
+ * in assignments and move the variable declarations outside of the async iife.
+ * Example: With the AST for the following expression: `let a = await 123`, the
+ * function will return:
+ * let a;
+ * (async => {
+ *   return a = await 123;
+ * })();
+ */
+function wrapExpressionFromAst(ast: Object): string {
+  // Transform let and var declarations into assignments, and get back an array
+  // of variable declarations.
+  let { newAst, declarations } = translateDeclarationsIntoAssignment(ast);
+  const body = addReturnNode(newAst);
+
+  // Create the async iife.
+  newAst = t.expressionStatement(
+    t.callExpression(
+      t.arrowFunctionExpression([], t.blockStatement(body), true),
+      []
+    )
+  );
+
+  // Now let's put all the variable declarations at the top of the async iife.
+  newAst = addTopDeclarationNodes(newAst, declarations);
+
+  return generate(newAst).code;
+}
+
+export default function mapTopLevelAwait(
+  expression: string,
+  ast?: Object
+): string {
+  if (!ast) {
+    // If there's no ast this means the expression is malformed. And if the
+    // expression contains the await keyword, we still want to wrap it in an
+    // async iife in order to get a meaningful message (without this, the
+    // engine will throw an Error stating that await keywords are only valid
+    // in async functions and generators).
+    if (expression.includes("await ")) {
+      return `(async () => { ${expression} })();`;
+    }
+
+    return expression;
+  }
+
+  if (!hasTopLevelAwait(ast)) {
+    return expression;
+  }
+
+  return wrapExpressionFromAst(ast);
+}