README

PASPARGEN

PASPARGEN is a parser generator written in Object Pascal, capable of generating parsers also in Objective Pascal. It takes input grammars in extended Backus–Naur Form and produces a Unicode capable lexer and a recursive descent parser that automatically constructs an abstract sintax tree.

Motivation

When I decided to start this project I was writing a Object Pascal parser using Yacc and Lex. Why was it necessary to spend so much time writing boiler-plate code and manually assembling a AST, I asked.

Could it be possible to generate a complete parser just from a grammar description?

The answer is yes, as long as we're ok with cutting some corners.

How it works

Paspargen requires just a single grammar file as input.

A grammar file is just composed of a big list of rules, and Paspargen automatically deduces what rules should be handled to the lexer, and what should be handled by the parser.

Rules are turned into nodes of a abstract sintax tree and checked for redundancy and circular references.

Node types supported

• Literals/Keywords
• Regular expressions
• Class hierarchies

Warning

The current code is a mess, this was a experiment done in a week. Will be cleaned later, if I have the time. However is already in a functional state, capable of generating parsers for complex languages.