Left to right association with Treetop Grammar

l2r.treetop

  rule expression
    term (space? additive_operator space? term)* space? <Node::Expression>
  end
  
  rule term
    space? factor (space? multitive_operator space? factor)* <Node::Expression>
  end
  
  rule factor
    number
    /
    '(' expression ')' <Node::Expression>
  end

  rule additive_operator
    addition_operator / subtraction_operator
  end
  
  rule multitive_operator
    multiplication_operator / division_operator
  end
  
  rule addition_operator
    '+' <Node::Operator>
  end
  
  rule subtraction_operator
    '-' <Node::Operator>
  end
  
  rule multiplication_operator
    '*' <Node::Operator>
  end
  
  rule division_operator
    '/' <Node::Operator>
  end