replace.js

export const magic = "MAGIC_ASSEMBLYSCRIPT_PRETTIER_1996";
const prefix = "/*" + magic;
const postfix = magic + "*/";

export async function preProcess(code) {
  const assemblyscript = await import("assemblyscript");
  const NodeKind = assemblyscript.NodeKind;
  const visitDecorators = (node) => {
    let list = [];
    let _visit = (_node) => {
      switch (_node.kind) {
        case NodeKind.Source: {
          _node.statements.forEach((statement) => {
            _visit(statement);
          });
          break;
        }
        case NodeKind.ClassDeclaration:
        case NodeKind.InterfaceDeclaration:
        case NodeKind.NamespaceDeclaration: {
          _node.members.forEach((statement) => {
            _visit(statement);
          });
          break;
        }
      }
      if (_node.decorators) {
        list.push(
          ..._node.decorators.map((decorator) => {
            return { start: decorator.range.start, end: decorator.range.end };
          })
        );
      }
    };
    _visit(node);
    return list;
  };

  let parser = new assemblyscript.Parser();
  parser.parseFile(code, "pre_process.ts", false);
  let source = parser.sources[0];

  const decorators = visitDecorators(source);
  decorators.sort((a, b) => a.start - b.start);
  let cursor = 0;
  const removeDecoratorCodes = decorators.map((decorator) => {
    let s1 = code.slice(cursor, decorator.start);
    let s2 = code.slice(decorator.start, decorator.end);
    cursor = decorator.end;
    return `${s1}${prefix}${s2}`;
  });
  removeDecoratorCodes.push(code.slice(cursor));
  return removeDecoratorCodes.join(postfix);
}