-*- mode: org -*-
* grammar

    program ::= range assignments
      range ::= number ELLIPSIS number
assignments ::= assignment assignments
              | ε
 assignment ::= word EQUALS number
       word ::= WORD
     number ::= NUMBER

* grammar, refactored

  no need!

* first

    number      → NUMBER
    word        → WORD
    assignment  → WORD
    assignments → WORD, ε
    range       → NUMBER
    program     → NUMBER

* follow

    program     → $
    range       → WORD, $
    assignments → $
    assignment  → WORD, $
    word        → EQUALS
    number      → ELLIPSIS, WORD, $

* grammar, with semantic actions

    program ::= range assignments [make_program]
      range ::= number ELLIPSIS number [make_range]
assignments ::= assignment assignments
              | [make_assignments]            //  used to be ε
 assignment ::= word EQUALS number [make_assignment]
       word ::= WORD
     number ::= NUMBER

* table

                NUMBER                     WORD                       $
    program     → range assignments        ---                        ---
    range       → number ELLIPSIS number   ---                        ---
    assignments ---                        → assignment assignments   → ε
    assignment  ---                        → word EQUALS number       ---
    word        ---                        → WORD                     ---
    number      → NUMBER                   ---                        ---

  The columns for ELLPSIS and EQUALS are empty.

  I put the semantic actions into the table rules at the same
  points they appear in the grammar.

*