90 lines
2.2 KiB
Ruby
90 lines
2.2 KiB
Ruby
# frozen_string_literal: true
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class Pry
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# A ring is a thread-safe fixed-capacity array to which you can only add
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# elements. Older entries are overwritten as you add new elements, so that the
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# ring can never contain more than `max_size` elemens.
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#
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# @example
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# ring = Pry::Ring.new(3)
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# ring << 1 << 2 << 3
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# ring.to_a #=> [1, 2, 3]
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# ring << 4
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# ring.to_a #=> [2, 3, 4]
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#
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# ring[0] #=> 2
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# ring[-1] #=> 4
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# ring.clear
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# ring[0] #=> nil
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#
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# @api public
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# @since v0.12.0
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class Ring
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# @return [Integer] maximum buffer size
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attr_reader :max_size
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# @return [Integer] how many objects were added during the lifetime of the
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# ring
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attr_reader :count
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alias size count
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# @param [Integer] max_size Maximum buffer size. The buffer will start
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# overwriting elements once its reaches its maximum capacity
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def initialize(max_size)
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@max_size = max_size
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@mutex = Mutex.new
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clear
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end
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# Push `value` to the current index.
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#
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# @param [Object] value
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# @return [self]
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def <<(value)
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@mutex.synchronize do
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@buffer[count % max_size] = value
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@count += 1
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self
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end
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end
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# Read the value stored at `index`.
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#
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# @param [Integer, Range] index The element (if Integer) or elements
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# (if Range) associated with `index`
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# @return [Object, Array<Object>, nil] element(s) at `index`, `nil` if none
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# exist
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def [](index)
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@mutex.synchronize do
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return @buffer[index] if count <= max_size
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return @buffer[(count + index) % max_size] if index.is_a?(Integer)
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transpose_buffer_tail[index]
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end
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end
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# @return [Array<Object>] the buffer as unwinded array
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def to_a
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return @buffer.dup if count <= max_size
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transpose_buffer_tail
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end
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# Clear the buffer and reset count.
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# @return [void]
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def clear
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@mutex.synchronize do
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@buffer = []
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@count = 0
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end
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end
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private
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def transpose_buffer_tail
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tail = @buffer.slice(count % max_size, @buffer.size)
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tail.concat @buffer.slice(0, count % max_size)
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end
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end
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end
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