Class: Dendroid::Syntax::NonTerminal

Inherits:
GrmSymbol
  • Object
show all
Defined in:
lib/dendroid/syntax/non_terminal.rb

Overview

A non-terminal symbol (sometimes called a syntactic variable) represents a composition of terminal or non-terminal symbols

Instance Attribute Summary collapse

Attributes inherited from GrmSymbol

#name

Instance Method Summary collapse

Methods inherited from GrmSymbol

#==, #initialize, #to_s

Constructor Details

This class inherits a constructor from Dendroid::Syntax::GrmSymbol

Instance Attribute Details

#nullable ⇒ Boolean

Returns true if symbol can derive the null token.

Returns:

  • (Boolean) —

    true if symbol can derive the null token



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# File 'lib/dendroid/syntax/non_terminal.rb', line 11

def nullable
  @nullable
end

#productive ⇒ Boolean

Returns true iff the symbol always matches a non-empty sequence of terminal symbols.

Returns:

  • (Boolean) —

    true iff the symbol always matches a non-empty sequence of terminal symbols



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# File 'lib/dendroid/syntax/non_terminal.rb', line 15

def productive
  @productive
end

Instance Method Details

#nullable? ⇒ Boolean

Predicate method to check whether the symbol can derive (match) the null token.

Returns:

  • (Boolean) 


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# File 'lib/dendroid/syntax/non_terminal.rb', line 26

def nullable?
  @nullable
end

#productive? ⇒ Boolean

Predicate method to check whether the symbol always matches a non-empty sequence of terminal symbols.

Returns:

  • (Boolean) 


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# File 'lib/dendroid/syntax/non_terminal.rb', line 33

def productive?
  @productive
end

#terminal? ⇒ FalseClass

Predicate method to check whether the symbol is a terminal symbol.

Returns:

  • (FalseClass) 


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# File 'lib/dendroid/syntax/non_terminal.rb', line 19

def terminal?
  false
end