Class: Sequitur::Digram

Inherits:
Object
  • Object
show all
Defined in:
lib/sequitur/digram.rb

Overview

In linguistics, a digram is a sequence of two letters. In Sequitur a digram is a sequence of two consecutive symbols that appear in a grammar (production) rule. Each symbol in a digram can be a terminal or not.

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(symbol1, symbol2, aProduction) ⇒ Digram

Constructor. the sequence symbol1 symbol2 appears.

Parameters:

  • symbol1 (StringOrSymbol) —

    First element of the digram

  • symbol2 (StringOrSymbol) —

    Second element of the digram

  • aProduction (Production) —

    Production in which the RHS



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# File 'lib/sequitur/digram.rb', line 24

def initialize(symbol1, symbol2, aProduction)
  @symbols = [symbol1, symbol2]
  @key = "#{symbol1.hash.to_s(16)}:#{symbol2.hash.to_s(16)}" 
  @production = aProduction
end

Instance Attribute Details

#key ⇒ Object (readonly)

An unique Hash key of the digram



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# File 'lib/sequitur/digram.rb', line 14

def key
  @key
end

#production ⇒ Object (readonly)

The production in which the digram occurs



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# File 'lib/sequitur/digram.rb', line 17

def production
  @production
end

#symbols ⇒ Object (readonly)

The sequence of two consecutive grammar symbols.



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# File 'lib/sequitur/digram.rb', line 11

def symbols
  @symbols
end

Instance Method Details

#==(other) ⇒ Object

Equality testing. Returns true when keys of both digrams are equal



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# File 'lib/sequitur/digram.rb', line 32

def ==(other)
  return key == other.key
end