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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<Integer>] 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
alias count size
alias length size
def empty?
size == 0
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 pop!
@hash.delete @count - 1
@count -= 1
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
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