Class: Rley::GFG::ItemVertex

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

Overview

Specialization of Vertex class. Represents a vertex in a grammar flow graph associated to a given dotted item. Responsibilities (in addition to inherited ones):

  • Know its related non-terminal symbol

Instance Attribute Summary collapse

Attributes inherited from Vertex

#edges

Instance Method Summary collapse

Methods inherited from Vertex

#add_edge

Constructor Details

#initialize(aDottedItem) ⇒ ItemVertex

Constructor.

Parameters:

  • aDottedItem (DottedItem) —

    the corresponding dotted item.



23
24
25
26
 
# File 'lib/rley/gfg/item_vertex.rb', line 23

def initialize(aDottedItem)
  super()
  @dotted_item = aDottedItem
end

Instance Attribute Details

#dotted_item ⇒ DottedItem (readonly)

Link to the dotted item object

Returns:

  • (DottedItem) —

    The corresponding dotted item



14
15
16
 
# File 'lib/rley/gfg/item_vertex.rb', line 14

def dotted_item
  @dotted_item
end

#shortcut ⇒ ShortcutEdge

Optional link to a "shortcut" edge. Applicable only if the dotted expects a non-terminal symbol.

Returns:



19
20
21
 
# File 'lib/rley/gfg/item_vertex.rb', line 19

def shortcut
  @shortcut
end

Instance Method Details

#complete? ⇒ Boolean

Returns true if the dotted item has a dot at the end of the production.

Returns:

  • (Boolean) 


57
58
59
 
# File 'lib/rley/gfg/item_vertex.rb', line 57

def complete?()
  return dotted_item.reduce_item?
end

#label ⇒ String

The label of this vertex. It is the same as the label of the corresponding dotted item.

Returns:

  • (String) —

    Label for this vertex



51
52
53
 
# File 'lib/rley/gfg/item_vertex.rb', line 51

def label()
  return dotted_item.to_s
end

#lhs ⇒ Syntax::GrmSymbol

Return the non-terminal symbol at the left-hand side of the production

Returns:



75
76
77
 
# File 'lib/rley/gfg/item_vertex.rb', line 75

def lhs()
  return dotted_item.lhs
end

#next_symbol ⇒ Syntax::GrmSymbol, NilClass

Return the symbol after the dot.

Returns:



69
70
71
 
# File 'lib/rley/gfg/item_vertex.rb', line 69

def next_symbol()
  return dotted_item.next_symbol
end

#prev_symbol ⇒ Syntax::GrmSymbol, NilClass

Return the symbol before the dot.

Returns:



63
64
65
 
# File 'lib/rley/gfg/item_vertex.rb', line 63

def prev_symbol()
  return dotted_item.prev_symbol
end