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 69: def initialize(enum = nil, &block) 70: if enum 71: @block = proc { |g| 72: enum.each { |x| g.yield x } 73: } 74: else 75: @block = block 76: end 77: 78: @index = 0 79: @queue = [] 80: @cont_next = @cont_yield = @cont_endp = nil 81: 82: if @cont_next = callcc { |c| c } 83: @block.call(self) 84: 85: @cont_endp.call(nil) if @cont_endp 86: end 87: 88: self 89: end
Rewinds the generator and enumerates the elements.
# File lib/generator.rb, line 157 157: def each 158: rewind 159: 160: until end? 161: yield self.next 162: end 163: 164: self 165: end
Returns true if the generator has reached the end.
# File lib/generator.rb, line 102 102: def end?() 103: if @cont_endp = callcc { |c| c } 104: @cont_yield.nil? && @queue.empty? 105: else 106: @queue.empty? 107: end 108: end
Returns the element at the current position and moves forward.
# File lib/generator.rb, line 126 126: def next() 127: if end? 128: raise EOFError, "no more elements available" 129: end 130: 131: if @cont_next = callcc { |c| c } 132: @cont_yield.call(nil) if @cont_yield 133: end 134: 135: @index += 1 136: 137: @queue.shift 138: end
Returns true if the generator has not reached the end yet.
# File lib/generator.rb, line 111 111: def next?() 112: !end? 113: end
Rewinds the generator.
# File lib/generator.rb, line 150 150: def rewind() 151: initialize(nil, &@block) if @index.nonzero? 152: 153: self 154: end