Class: SPCore::CircularBuffer

Inherits:
Object
  • Object
show all
Defined in:
lib/spcore/core/circular_buffer.rb

Overview

Author:

  • James Tunnell

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(size, opts = {}) ⇒ CircularBuffer

A new instance of CircularBuffer.

Parameters:

  • size (Fixnum) —

    The buffer size (and maximum fill count).

  • opts (Hash) (defaults to: {}) —

    Contain optional arguments to modify buffer push/pop behavior. Valid keys are :override_when_full and :fifo.



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# File 'lib/spcore/core/circular_buffer.rb', line 24

def initialize size, opts = {}
  
  opts = { :fifo => true, :override_when_full => true }.merge opts
  
  @buffer = Array.new(size)
  @oldest = 0;
  @newest = 0;
  @fill_count = 0;

  @fifo = opts[:fifo]
  @override_when_full = opts[:override_when_full]
end

Instance Attribute Details

#fifo ⇒ Object

Returns the value of attribute fifo.



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# File 'lib/spcore/core/circular_buffer.rb', line 17

def fifo
  @fifo
end

#fill_count ⇒ Object (readonly)

Returns the value of attribute fill_count.



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# File 'lib/spcore/core/circular_buffer.rb', line 18

def fill_count
  @fill_count
end

#override_when_full ⇒ Object

Returns the value of attribute override_when_full.



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# File 'lib/spcore/core/circular_buffer.rb', line 17

def override_when_full
  @override_when_full
end

Instance Method Details

#empty? ⇒ Boolean

Return true if the buffer is empty.

Returns:

  • (Boolean) 


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# File 'lib/spcore/core/circular_buffer.rb', line 43

def empty?
  return @fill_count == 0
end

#full? ⇒ Boolean

Return true if the buffer is full (fill count == buffer size).

Returns:

  • (Boolean) 


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# File 'lib/spcore/core/circular_buffer.rb', line 48

def full?
  return (@fill_count == size)
end

#newest(relative_index = 0) ⇒ Object

access the latest data element.

Raises:

  • (ArgumentError) 


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# File 'lib/spcore/core/circular_buffer.rb', line 116

def newest relative_index = 0
  raise ArgumentError, "buffer is empty" if empty?
  raise ArgumentError, "relative_index is greater or equal to @fill_count" if relative_index >= @fill_count

  # newestIdx is actually @newest - 1
  newestIdx = @newest - 1;
  if(newestIdx < 0)
    newestIdx += @buffer.count;
  end

  absIdx = newestIdx - relative_index;
  if(absIdx < 0)
    absIdx += @buffer.count;
  end

  return @buffer[absIdx];
end

#oldest(relative_index = 0) ⇒ Object

access the oldest data element.

Raises:

  • (ArgumentError) 


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# File 'lib/spcore/core/circular_buffer.rb', line 135

def oldest relative_index = 0
  raise ArgumentError, "buffer is empty" if empty?
  raise ArgumentError, "relative_index is greater or equal to @fill_count" if relative_index >= @fill_count
  
  absIdx = @oldest + relative_index;
  if(absIdx >= @buffer.count)
      absIdx -= @buffer.count;
  end
  
  return @buffer[absIdx];
end

#pop ⇒ Object

Pop the oldest/newest element, depending on @fifo flag. When true, pop the oldest, otherwise pop the newest. Set to true by default, can override during initialize or later using fifo=.

Raises:

  • (ArgumentError) 


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# File 'lib/spcore/core/circular_buffer.rb', line 150

def pop
  raise ArgumentError, "buffer is empty" if empty?
  
  if @fifo
    # FIFO - pop the oldest element
    element = oldest
    @oldest += 1
    if(@oldest >= @buffer.count)
      @oldest = 0
    end
    @fill_count -= 1
    return element    
  else
    # FILO - pop the newest element
    element = newest
    if(@newest > 0)
      @newest -= 1
    else
      @newest = @buffer.count - 1
    end
    @fill_count -= 1
    return element      
  end
end

#push(element) ⇒ Object

push a single data element.



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# File 'lib/spcore/core/circular_buffer.rb', line 86

def push element
  if full?
    raise ArgumentError, "buffer is full, and override_when_full is false" unless @override_when_full
    
    @buffer[@newest] = element;
    @newest += 1
    @oldest += 1
  else
    @buffer[@newest] = element;
    @newest += 1
    @fill_count += 1      
  end

  if @oldest >= @buffer.count
    @oldest = 0
  end

  if @newest >= @buffer.count
    @newest = 0
  end
end

#push_ary(ary) ⇒ Object

push an array of data elements.



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# File 'lib/spcore/core/circular_buffer.rb', line 109

def push_ary ary
  ary.each do |element|
    push element
  end
end

#resize(size) ⇒ Object

Change the buffer size, allocating a new backing array at the same time.



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# File 'lib/spcore/core/circular_buffer.rb', line 53

def resize size
  rv = false
  if(size != @buffer.count)
    rv = true
    @buffer = Array.new(size)
    @oldest = 0
    @newest = 0
    @fill_count = 0
  end
  return rv
end

#size ⇒ Object

Return the buffer size (max fill count).



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# File 'lib/spcore/core/circular_buffer.rb', line 38

def size
  return @buffer.count
end

#to_ary ⇒ Object

Return an array containing the data layed out contiguously (data normally is split somewhere along the backing array).



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# File 'lib/spcore/core/circular_buffer.rb', line 67

def to_ary
  if empty?
    return []
  end

  # newest index is actually @newest - 1
  newest_idx = @newest - 1;
  if(newest_idx < 0)
    newest_idx += @buffer.count;
  end

  if newest_idx >= @oldest
    return @buffer[@oldest..newest_idx]
  else
    return @buffer[@oldest...@buffer.count] + @buffer[0..newest_idx]
  end
end