Class: Rley::GFG::Vertex

Inherits:
Object
  • Object
show all
Defined in:
lib/rley/gfg/vertex.rb

Overview

Abstract class. Represents a vertex in a grammar flow graph Responsibilities:

  • To know its outgoing edges
  • To know its label

Direct Known Subclasses

ItemVertex, NonTerminalVertex

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize ⇒ Vertex

Constructor to extend in subclasses.



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# File 'lib/rley/gfg/vertex.rb', line 13

def initialize()
  @edges = []
end

Instance Attribute Details

#edges ⇒ Array<Edge> (readonly)

The edges linking the successor vertices to this one.

Returns:

  • (Array<Edge>) —

    The edge(s) linking this vertex to successor(s)



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# File 'lib/rley/gfg/vertex.rb', line 10

def edges
  @edges
end

Instance Method Details

#add_edge(anEdge) ⇒ Object

Add an graph edge to this vertex.

Parameters:

  • anEdge (Edge) —

    the edge to be added.



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# File 'lib/rley/gfg/vertex.rb', line 19

def add_edge(anEdge)
  arrow = check_add_edge(anEdge)
  edges << arrow
end

#complete? ⇒ Boolean

Determine if the vertex corresponds to an dotted item that has its dot at the end of a production (i.e. is a reduced item).

Returns:

  • (Boolean) —

    true iff vertex corresponds to reduced item.



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# File 'lib/rley/gfg/vertex.rb', line 27

def complete?()
  return false # Default implementation
end

#next_symbol ⇒ GrmSymbol, NilClass

Retrieve the grammar symbol after the dot.

Returns:

  • (GrmSymbol, NilClass) —

    The symbol or otherwise nil.



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# File 'lib/rley/gfg/vertex.rb', line 39

def next_symbol()
  return nil # Default implementation
end

#prev_symbol ⇒ GrmSymbol, NilClass

Retrieve the grammar symbol before the dot.

Returns:

  • (GrmSymbol, NilClass) —

    The symbol or otherwise nil.



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# File 'lib/rley/gfg/vertex.rb', line 33

def prev_symbol()
  return nil # Default implementation
end