Class: Stream::ImplicitStream

Inherits:
BasicStream show all
Defined in:
lib/stream.rb

Overview

An ImplicitStream is an easy way to create a stream on the fly without defining a subclass of BasicStream. The basic methods required for a stream are defined with blocks:

s = Stream::ImplicitStream.new { |s|

x = 0 s.at_end_proc = proc { x == 5 } s.forward_proc = proc { x += 1 }

}

s.to_a ==> [1, 2, 3, 4, 5]

Note that this stream is only partially defined since backward_proc and at_beginning_proc are not defined. It may as well be useful if only moving forward is required by the code fragment.

ImplicitStreams can be based on other streams using the method modify which is for example used in the methods for creating stream wrappers which remove the first or last element of an existing stream (see remove_first and remove_last).

Constant Summary

Constants included from Stream

VERSION

Instance Attribute Summary collapse

Instance Method Summary collapse

Methods included from Stream

#+, #backward, #collect, #concatenate, #concatenate_collected, #create_stream, #current, #current_edge, #each, #empty?, #filtered, #first, #forward, #last, #modify, #move_backward_until, #move_forward_until, #peek, #remove_first, #remove_last, #reverse, #unwrapped

Methods included from Enumerable

#create_stream

Constructor Details

#initialize(other_stream = nil) {|self| ... } ⇒ ImplicitStream

Create a new ImplicitStream which might wrap an existing stream other_stream. If other_stream is supplied the blocks for the basic stream methods are initialized with closures that delegate all operations to the wrapped stream.

If a block is given to new, than it is called with the new ImplicitStream stream as parameter letting the client overwriting the default blocks.

Parameters:

  • other_stream (Stream, nil) (defaults to: nil) —

    optional stream to wrap

Yields:

  • (self) —

    the new ImplicitStream instance for customization



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# File 'lib/stream.rb', line 632

def initialize(other_stream = nil)
  # Initialize with defaults
  @at_beginning_proc = proc { true }
  @at_end_proc = proc { true }

  @set_to_begin_proc = proc {}
  @set_to_end_proc = proc {}

  if other_stream
    @wrapped_stream = other_stream
    @at_beginning_proc = proc { other_stream.at_beginning? }
    @at_end_proc = proc { other_stream.at_end? }
    @forward_proc = proc { other_stream.basic_forward }
    @backward_proc = proc { other_stream.basic_backward }
    @set_to_end_proc = proc { other_stream.set_to_end }
    @set_to_begin_proc = proc { other_stream.set_to_begin }
  end
  yield self if block_given? # let client overwrite defaults
end

Instance Attribute Details

#at_beginning_proc=(value) ⇒ Object (writeonly)

Sets the attribute at_beginning_proc

Parameters:

  • value —

    the value to set the attribute at_beginning_proc to.



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# File 'lib/stream.rb', line 619

def at_beginning_proc=(value)
  @at_beginning_proc = value
end

#at_end_proc=(value) ⇒ Object (writeonly)

Sets the attribute at_end_proc

Parameters:

  • value —

    the value to set the attribute at_end_proc to.



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# File 'lib/stream.rb', line 619

def at_end_proc=(value)
  @at_end_proc = value
end

#backward_proc=(value) ⇒ Object (writeonly)

Sets the attribute backward_proc

Parameters:

  • value —

    the value to set the attribute backward_proc to.



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# File 'lib/stream.rb', line 619

def backward_proc=(value)
  @backward_proc = value
end

#forward_proc=(value) ⇒ Object (writeonly)

Sets the attribute forward_proc

Parameters:

  • value —

    the value to set the attribute forward_proc to.



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# File 'lib/stream.rb', line 619

def forward_proc=(value)
  @forward_proc = value
end

#set_to_begin_proc=(value) ⇒ Object (writeonly)

Sets the attribute set_to_begin_proc

Parameters:

  • value —

    the value to set the attribute set_to_begin_proc to.



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# File 'lib/stream.rb', line 619

def set_to_begin_proc=(value)
  @set_to_begin_proc = value
end

#set_to_end_proc=(value) ⇒ Object (writeonly)

Sets the attribute set_to_end_proc

Parameters:

  • value —

    the value to set the attribute set_to_end_proc to.



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# File 'lib/stream.rb', line 619

def set_to_end_proc=(value)
  @set_to_end_proc = value
end

#wrapped_stream ⇒ Object (readonly)

Returns the value of attribute wrapped_stream.



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# File 'lib/stream.rb', line 621

def wrapped_stream
  @wrapped_stream
end

Instance Method Details

#at_beginning? ⇒ Boolean

Returns the value of @at_beginning_proc.

Returns:

  • (Boolean) 


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# File 'lib/stream.rb', line 653

def at_beginning?
  @at_beginning_proc.call
end

#at_end? ⇒ Boolean

Returns the value of @at_end_proc.

Returns:

  • (Boolean) 


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# File 'lib/stream.rb', line 658

def at_end?
  @at_end_proc.call
end

#basic_backward ⇒ Object

Returns the value of @backward_proc_proc.



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# File 'lib/stream.rb', line 668

def basic_backward
  @backward_proc.call
end

#basic_forward ⇒ Object

Returns the value of @forward_proc.



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# File 'lib/stream.rb', line 663

def basic_forward
  @forward_proc.call
end

#set_to_begin ⇒ Object

Calls set_to_begin_proc or super if set_to_begin_proc is undefined.



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# File 'lib/stream.rb', line 678

def set_to_begin
  @set_to_begin_proc ? @set_to_begin_proc.call : super
end

#set_to_end ⇒ Object

Calls set_to_end_proc or super if set_to_end_proc is undefined.



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# File 'lib/stream.rb', line 673

def set_to_end
  @set_to_end_proc ? @set_to_end_proc.call : super
end