Method replaceReturnValue

valdi/vscode_debugger/src/adapter/evaluator.ts:165–190

* Replaces $returnValue in the given expression with the `hoisted` variable, * returning the modified expression if it was found.

(expr: string, hoistedVar: string)

   * returning the modified expression if it was found.
   */
  private replaceReturnValue(expr: string, hoistedVar: string): string | undefined {
    const sourceFile = ts.createSourceFile(
      'test.js',
      expr,
      ts.ScriptTarget.ESNext,
      /*setParentNodes */ true,
    );

    let adjust = 0;
    let found = false;

    const replacement = `(typeof ${hoistedVar} !== 'undefined' ? ${hoistedVar} : undefined)`;
    const replace = (node: ts.Node) => {
      if (ts.isIdentifier(node) && node.text === returnValueStr) {
        expr = expr.slice(0, node.getStart() + adjust) + replacement + expr.slice(node.getEnd());
        adjust += node.getEnd() - node.getStart() - replacement.length;
        found = true;
      }

      ts.forEachChild(node, replace);
    };

    replace(sourceFile);

    return found ? expr : undefined;
  }
}