Function functionMapBabelPlugin

packages/metro-source-map/src/generateFunctionMap.js:108–148

()

}

function functionMapBabelPlugin(): PluginObj<> {
  return {
    // Eagerly traverse the tree on `pre`, before any visitors have run, so
    // that regardless of plugin order we're dealing with the AST before any
    // mutations.
    visitor: {},
    pre: ({path, metadata, opts}) => {
      const {filename} = nullthrows(opts);
      const encoder = new MappingEncoder();
      const visitor = getFunctionMapVisitor({filename}, mapping =>
        encoder.push(mapping),
      );
      invariant(
        path && t.isProgram(path.node),
        'path missing or not a program node',
      );
      // $FlowFixMe[prop-missing] checked above
      // $FlowFixMe[incompatible-type-arg] checked above
      const programPath: NodePath<BabelNodeProgram> = path as $FlowFixMe;

      visitor.enter(programPath);
      programPath.traverse({
        Function: visitor,
        Class: visitor,
      });
      visitor.exit(programPath);

      // $FlowFixMe[incompatible-type] Babel `File` is not generically typed
      const metroMetadata: MetroBabelFileMetadata = metadata;

      const functionMap = encoder.getResult();

      // Set the result on a metadata property
      if (!metroMetadata.metro) {
        metroMetadata.metro = {functionMap};
      } else {
        metroMetadata.metro.functionMap = functionMap;
      }
    },
  };
}

function getFunctionMapVisitor(
  context: ?Context,