Class: History

Inherits:
Object
  • Object
show all
Defined in:
lib/tools/history.rb

Overview

A History object, which holds the last size objects in memory.

Implemented as a ring buffer which wraps over.

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(size) ⇒ History 



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# File 'lib/tools/history.rb', line 7

def initialize(size)
  @buffer = Array.new(size)
  @size   = size
  @writer = 0
end

Instance Attribute Details

#size ⇒ Object (readonly)

:nodoc:



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# File 'lib/tools/history.rb', line 5

def size
  @size
end

Instance Method Details

#<<(element) ⇒ Object 



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# File 'lib/tools/history.rb', line 21

def <<(element)
  @writer = (@writer + 1) % @size
  @buffer[@writer] = element
end

#last_nth(idx) ⇒ Object

returns the nth-last entry

Raises:

  • (ArgumentError) 


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# File 'lib/tools/history.rb', line 14

def last_nth(idx)
  raise ArgumentError, "RingBuffer size #{@size} is too small to hold #{idx} entries" if idx > @size

  pos = (@writer - idx) % @size
  @buffer[pos]
end