import { Source } from 'lexing';
import { Level } from './logger';
import { PDF } from './PDF';
export declare function setLoggerLevel(level: Level): void;
export interface ReadOptions {
    type?: string;
}
/**
Read a PDF from the given lexing.source.

options.type determines the return value.
- 'pdf': returns the full pdfi.PDF instance.
- 'paper': returns an academia.types.Paper
- 'string': returns a single string, which is like a flattened version of the
  'paper' option, where the section lines have been prefixed with '#',
  paragraphs are joined separated by single line breaks, and sections are
  separated by double line breaks.
- 'metadata': returns the PDF's trailer section
- 'xref': returns the PDF's trailer section
- anything else: returns null
*/
export declare function readSourceSync(source: Source, { type }: ReadOptions): any;
/**
simplify() will recursively simplify a PDF value into a non-circular, JSON-friendly object.
*/
export declare function simplify(value: any, seen?: any[]): any;
export declare type PDF = PDF;