class Sequitur::ProductionRef

A production reference is a grammar symbol that may appear in the right-hand side of a production P1 and that refers to a production P2. Every time a production P2 appears in the left-hand side of production P1, this is implemented by inserting a production reference to P2 in the appropriate position in the RHS of P1. In the literature, production references are also called non terminal symbols @example

# Given a production rule...
prod = Sequitur::Production.new
puts prod.refcount # outputs 0
# ... Build a reference to it
ref = Sequitur::ProductionRef.new(prod)
# ... Production reference count is updated...
puts prod.refcount # outputs 1