class Pry # A history array is an array to which you can only add elements. Older # entries are removed progressively, so that the aray never contains more than # N elements. # # History arrays are used by Pry to store the output of the last commands. # # @example # ary = Pry::HistoryArray.new 10 # ary << 1 << 2 << 3 # ary[0] # => 1 # ary[1] # => 2 # 10.times { |n| ary << n } # ary[0] # => nil # ary[-1] # => 9 class HistoryArray include Enumerable # @param [Integer] size Maximum amount of objects in the array def initialize(size) @max_size = size @hash = {} @count = 0 end # Pushes an object at the end of the array # @param [Object] value Object to be added def <<(value) @hash[@count] = value if @hash.size > max_size @hash.delete(@count - max_size) end @count += 1 self end # @overload [](index) # @param [Integer] index Index of the item to access. # @return [Object, nil] Item at that index or nil if it has been removed. # @overload [](index, size) # @param [Integer] index Index of the first item to access. # @param [Integer] size Amount of items to access # @return [Array, nil] The selected items. Nil if index is greater than # the size of the array. # @overload [](range) # @param [Range] range Range of indices to access. # @return [Array, nil] The selected items. Nil if index is greater than # the size of the array. def [](index_or_range, size = nil) if index_or_range.is_a? Integer index = convert_index(index_or_range) if size end_index = index + size index > @count ? nil : (index...[end_index, @count].min).map do |n| @hash[n] end else @hash[index] end else range = convert_range(index_or_range) range.begin > @count ? nil : range.map { |n| @hash[n] } end end # @return [Integer] Amount of objects in the array def size @count end def each ((@count - size)...@count).each do |n| yield @hash[n] end end def to_a ((@count - size)...@count).map { |n| @hash[n] } end def inspect "#<#{self.class} size=#{size} first=#{@count - size} max_size=#{max_size}>" end # @return [Integer] Maximum amount of objects in the array attr_reader :max_size private def convert_index(n) n >= 0 ? n : @count + n end def convert_range(range) end_index = convert_index(range.end) end_index += 1 unless range.exclude_end? Range.new(convert_index(range.begin), [end_index, @count].min, true) end end end