58 lines
1.3 KiB
Ruby
58 lines
1.3 KiB
Ruby
require 'forwardable'
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# A FIFO queue contains elements in first-in, first-out order.
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# FIFO#push adds new elements to the end of the queue;
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# FIFO#pop or FIFO#shift removes elements from the front.
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class FIFO
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extend Forwardable
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# Creates a FIFO containing _objects_.
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def self.[](*objects)
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new.push(*objects)
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end
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# Creates an empty FIFO.
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def initialize; @ary = []; end
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# Appends _objects_ to the end of this FIFO. Returns self.
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def push(*objects)
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@ary.push(*objects)
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self
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end
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alias << push
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alias enqueue push
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##
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# :method: pop
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# :call-seq:
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# pop -> obj or nil
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# pop(n) -> ary
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#
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# Removes an element from the front of this FIFO, and returns it.
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# Returns nil if the FIFO is empty.
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#
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# If passing a number _n_, removes the first _n_ elements, and returns
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# an Array of them. If this FIFO contains fewer than _n_ elements,
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# returns them all. If this FIFO is empty, returns an empty Array.
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def_delegator :@ary, :shift, :pop
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alias shift pop
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alias dequeue shift
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##
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# :method: empty?
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# Returns true if this FIFO contains no elements.
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def_delegator :@ary, :empty?
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##
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# :method: size
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# Returns the number of elements in this FIFO.
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def_delegator :@ary, :size
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alias length size
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# Converts this FIFO to a String.
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def to_s
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"FIFO#{@ary.inspect}"
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end
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alias inspect to_s
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end
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