schneidmaster/eqn

module Eqn
  # Node class for a simple number.
  class Number < EqnNode
    def value(vars = {})
      base = elements.shift.value(vars)

      return base if term?

      if instance_of?(Float)
        # Apply any decimal if a float.
        base + elements.shift.value(vars)
      else
        # Apply any exponent if a simple number.
        base * elements.shift.value(vars)
      end
    end

    class Float < Number; end

    # Node class for a signed number.
    class SignedNumber < EqnNode
      def value(vars = {})
        first_element = elements.shift
        # If first element is unary minus, negate the following value.
        # Otherwise, simply return the positive value.
        if first_element.is_a?(Terminal::UnaryMinus)
          -elements.shift.value(vars)
        else
          first_element.value(vars)
        end
      end
    end

    # Node class for the decimal part of a non-integer.
    class Decimal < EqnNode
      def value(_vars = {})
        elements.shift.dec_value
      end
    end

    # Node class for the exponent part of a number.
    class Exponent < EqnNode
      def value(vars = {})
        10**elements.shift.value(vars)
      end
    end
  end
end