Overview

Grammar Editor allows you to compose and use a context-free grammar. Write your grammar in the ``Grammar:'' text area. For example, you might type the following into the blank.

S -> A | B
A -> a A |
B -> b B |

Each symbol (nonterminals) should be in all capital letters; atoms (terminals) can be any combination of letters and digits, as long as they're not all capital letters. The symbol on the first rule's left side is assumed to be the root symbol in the grammar.

At the bottom of the window are three buttons.

The Parse button parses the contents of the ``Text:'' field based on the current grammar. It displays the resulting parse tree in another window. The parser uses the CYK parsing algorithm. (Unlike many popular parsing algorithms, such as LR(1) parsers, the CYK algorithm can work with any grammar.)
The Generate button computes a randomly generated sentence from the language described by the current grammar, and it places this sentence into the ``Text:'' field.
The Clear button clears the ``Text:'' field.