Function findFiles

src/javascript/files.ts:39–120

(
  body: Node,
  path: string,
  input: string,
  aliases?: Iterable<string> // ["FileAttachment"] for implicit import
)

 * passed a dynamic argument, or references a file that is outside the root).
 */
export function findFiles(
  body: Node,
  path: string,
  input: string,
  aliases?: Iterable<string> // ["FileAttachment"] for implicit import
): FileExpression[] {
  const declarations = new Set<{name: string}>();
  const alias = new Set<string>(aliases);
  let globals: Set<string> | undefined;

  // Find the declared local names of FileAttachment. Currently only named
  // imports are supported, and stdlib must be imported without a version. TODO
  // Support namespace imports? Error if stdlib is expressed with a version?
  simple(body, {
    ImportDeclaration(node) {
      if (node.source.value === "observablehq:stdlib" || node.source.value === "npm:@observablehq/stdlib") {
        for (const specifier of node.specifiers) {
          if (
            specifier.type === "ImportSpecifier" &&
            specifier.imported.type === "Identifier" &&
            specifier.imported.name === "FileAttachment"
          ) {
            declarations.add(specifier.local);
            alias.add(specifier.local.name);
          }
        }
      }
    }
  });

  // If the import is masking a global, don’t treat it as a global (since we’ll
  // ignore the import declaration below).
  for (const name of alias.keys()) {
    if (defaultGlobals.has(name)) {
      (globals ??= new Set(defaultGlobals)).delete(name);
    }
  }

  // Collect all references to FileAttachment.
  const references = new Set(
    findReferences(body, {
      globals,
      filterDeclaration: (identifier) => !declarations.has(identifier) // treat the imported declaration as unbound
    })
  );

  const files: FileExpression[] = [];

  // Find all calls to FileAttachment. If the call is part of a member
  // expression such as FileAttachment("foo.txt").csv, use this to determine the
  // file method ("csv"); otherwise fallback to the to file extension to
  // determine the method. Also enforce that FileAttachment is passed a single
  // static string literal.
  //
  // Note that while dynamic imports require that paths start with ./, ../, or
  // /, the same requirement is not true for file attachments. Unlike imports,
  // you can’t reference a global file as a file attachment.
  ancestor(body, {