Class | Generator |
In: |
lib/generator.rb
|
Parent: | Object |
Generator converts an internal iterator (i.e. an Enumerable object) to an external iterator.
Note that it is not very fast since it is implemented using continuations, which are currently slow.
require 'generator' # Generator from an Enumerable object g = Generator.new(['A', 'B', 'C', 'Z']) while g.next? puts g.next end # Generator from a block g = Generator.new { |g| for i in 'A'..'C' g.yield i end g.yield 'Z' } # The same result as above while g.next? puts g.next end
Creates a new generator either from an Enumerable object or from a block.
In the former, block is ignored even if given.
In the latter, the given block is called with the generator itself, and expected to call the yield method for each element.
# File lib/generator.rb, line 69 def initialize(enum = nil, &block) if enum @block = proc { |g| enum.each { |x| g.yield x } } else @block = block end @index = 0 @queue = [] @cont_next = @cont_yield = @cont_endp = nil if @cont_next = callcc { |c| c } @block.call(self) @cont_endp.call(nil) if @cont_endp end self end
Rewinds the generator and enumerates the elements.
# File lib/generator.rb, line 157 def each rewind until end? yield self.next end self end
Returns true if the generator has reached the end.
# File lib/generator.rb, line 102 def end?() if @cont_endp = callcc { |c| c } @cont_yield.nil? && @queue.empty? else @queue.empty? end end
Returns true if the generator has not reached the end yet.
# File lib/generator.rb, line 111 def next?() !end? end
Rewinds the generator.
# File lib/generator.rb, line 150 def rewind() initialize(nil, &@block) if @index.nonzero? self end