Context free grammar parser

Note: This was a challenge at one of my university courses (formal languages and compilators)

How does it work

So, first of all you have to supply the Grammar class with 3 strings representing grammar's nonterminals, terminals and specific productions (all comma separated). Starting symbol has to be first in nonterminals string. Productions starts with the nonterminal then an arrow (->) and production separated by vertical line (|). Resulting object can provide vectorial, list and table representation of given grammar.

Vectorial representation

In this form, grammar is represented as a vector starting with the start symbol and it's production, next production of the same nonterminal is maked by a vetical line (|) while the begginning of the next nonterminal productions is delimited by hash character (#). The end of representation is marked by dollar sign ($)

TODO: add example

List representation

In order to represent a grammar as a linked list we'll use the following representation of a node:

+-----------+
|     a     |
+-----------+
| b | c | d |
+-----------+

The above figure will be used to represent each right member of each production. Letters have the following meaning:

1. a - terminal or nonterminal symbol of given grammar (only right members of each production)

2. b - pointer or integer b := if (a ∈ alphabet) then b := 0 else (a ∈ nonterminals) b := pointer to the head of the first sublist with the same left hand member a endif

3. c - pointer or integer Let p and u be two statements, thus: p : a is the symbol of the second member in the current production u : a is the last symbol of the second member of all production rules with the same left hand memeber, and let n - number of rules with the same left hand member, and let L - pointer to the head of the next sublist associated to the production rule with the same lefthand memeber. Then, c := if p then if n = 1 then c := 0 else c := L endif else if u then c := 0 else c := -1 endif endif

4. d - pointer or integer d := if (a is the last symbol of the right hand member of any production) then d := 0 else d is a pointer to the next node of the sublist endif

Table representation

To be written FIXME: writte the section