This file contains the bulk of the Pico reader, namely the parser. The parser heavily depends on the other, 'lower', part of the reader which is the scanner in the file Scan.pco.

What is really characteristic for a parser is that its procedural structure immediately follows the structure of the concrete grammar: for every production in the concrete grammar, there is a parsing procedure in the parser. The parser generates trees fullfilling the composition rules of the abstract grammar.