ahem/lib/ahem/ast/index.rb

class AST::Index
  attr_reader :object, :key

  def initialize(object, key)
    @object = object
    @key = key
  end

  def ==(other)
    other.is_a?(AST::Index) && other.object == @object && other.key == @key
  end

  def execute(env)
    object = @object.execute(env)
    key = @key.execute(env)

    if object.is_a?(Array)
      if key.is_a?(Float)
        if key.to_i == key && object.size > key
          object[key]
        elsif key.to_i != key
          raise "Array index requires integer key"
        elsif object.size <= key
          raise "Array index out of bounds"
        end
      else
        raise "Array index requires integer key"
      end
    elsif object.is_a?(Hash)
      if object.has_key?(key)
        object[key]
      else
        raise "Key #{key} does not exist on object"
      end
    end
  end
end