Class: Oryx::SymbolTable

Inherits:
Object
  • Object
show all
Defined in:
lib/oryx/symbol_table.rb

Instance Method Summary collapse

Constructor Details

#initialize ⇒ SymbolTable

Returns a new instance of SymbolTable.



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# File 'lib/oryx/symbol_table.rb', line 5

def initialize
  @values = [{}]
end

Instance Method Details

#current_scope ⇒ Object 



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# File 'lib/oryx/symbol_table.rb', line 33

def current_scope
  values.length - 1
end

#enter_scope ⇒ Object 



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# File 'lib/oryx/symbol_table.rb', line 9

def enter_scope
  values.push Hash.new
end

#exit_scope ⇒ Object

Raises:



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# File 'lib/oryx/symbol_table.rb', line 13

def exit_scope
  raise SymbolTableError, "Cannot exit global scope." if current_scope == 0
  values.pop
end

#insert(variable, value = nil) ⇒ Object

Raises:



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# File 'lib/oryx/symbol_table.rb', line 27

def insert variable, value=nil
  raise SymbolTableError, "Re-definition of #{variable} not allowed" if values.last.include? variable.to_sym

  values[current_scope][variable.to_sym] = value
end

#lookup(variable) ⇒ Object 



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# File 'lib/oryx/symbol_table.rb', line 18

def lookup variable
  return values[scope_level_of variable][variable.to_sym]
end

#update(variable, value = nil) ⇒ Object 



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# File 'lib/oryx/symbol_table.rb', line 22

def update variable, value=nil
  level = scope_level_of variable
  values[level][variable.to_sym] = value
end