/lib/generator.rb
Ruby | 380 lines | 209 code | 75 blank | 96 comment | 22 complexity | d32d7126b3783e0b0de56bca8eff8350 MD5 | raw file
Possible License(s): GPL-2.0, BSD-3-Clause, LGPL-2.1, AGPL-3.0
- #!/usr/bin/env ruby
- #--
- # $Idaemons: /home/cvs/rb/generator.rb,v 1.8 2001/10/03 08:54:32 knu Exp $
- # $RoughId: generator.rb,v 1.10 2003/10/14 19:36:58 knu Exp $
- # $Id$
- #++
- #
- # = generator.rb: convert an internal iterator to an external one
- #
- # Copyright (c) 2001,2003 Akinori MUSHA <knu@iDaemons.org>
- #
- # All rights reserved. You can redistribute and/or modify it under
- # the same terms as Ruby.
- #
- # == Overview
- #
- # This library provides the Generator class, which converts an
- # internal iterator (i.e. an Enumerable object) to an external
- # iterator. In that form, you can roll many iterators independently.
- #
- # The SyncEnumerator class, which is implemented using Generator,
- # makes it easy to roll many Enumerable objects synchronously.
- #
- # See the respective classes for examples of usage.
- #
- # 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.
- #
- # == Example
- #
- # 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
- #
- class Generator
- include Enumerable
- # 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.
- 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
- # Yields an element to the generator.
- def yield(value)
- if @cont_yield = callcc { |c| c }
- @queue << value
- @cont_next.call(nil)
- end
- self
- end
- # Returns true if the generator has reached the end.
- 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.
- def next?()
- !end?
- end
- # Returns the current index (position) counting from zero.
- def index()
- @index
- end
- # Returns the current index (position) counting from zero.
- def pos()
- @index
- end
- # Returns the element at the current position and moves forward.
- def next()
- if end?
- raise EOFError, "no more elements available"
- end
- if @cont_next = callcc { |c| c }
- @cont_yield.call(nil) if @cont_yield
- end
- @index += 1
- @queue.shift
- end
- # Returns the element at the current position.
- def current()
- if @queue.empty?
- raise EOFError, "no more elements available"
- end
- @queue.first
- end
- # Rewinds the generator.
- def rewind()
- initialize(nil, &@block) if @index.nonzero?
- self
- end
- # Rewinds the generator and enumerates the elements.
- def each
- rewind
- until end?
- yield self.next
- end
- self
- end
- end
- #
- # SyncEnumerator creates an Enumerable object from multiple Enumerable
- # objects and enumerates them synchronously.
- #
- # == Example
- #
- # require 'generator'
- #
- # s = SyncEnumerator.new([1,2,3], ['a', 'b', 'c'])
- #
- # # Yields [1, 'a'], [2, 'b'], and [3,'c']
- # s.each { |row| puts row.join(', ') }
- #
- class SyncEnumerator
- include Enumerable
- # Creates a new SyncEnumerator which enumerates rows of given
- # Enumerable objects.
- def initialize(*enums)
- @gens = enums.map { |e| Generator.new(e) }
- end
- # Returns the number of enumerated Enumerable objects, i.e. the size
- # of each row.
- def size
- @gens.size
- end
- # Returns the number of enumerated Enumerable objects, i.e. the size
- # of each row.
- def length
- @gens.length
- end
- # Returns true if the given nth Enumerable object has reached the
- # end. If no argument is given, returns true if any of the
- # Enumerable objects has reached the end.
- def end?(i = nil)
- if i.nil?
- @gens.detect { |g| g.end? } ? true : false
- else
- @gens[i].end?
- end
- end
- # Enumerates rows of the Enumerable objects.
- def each
- @gens.each { |g| g.rewind }
- loop do
- count = 0
- ret = @gens.map { |g|
- if g.end?
- count += 1
- nil
- else
- g.next
- end
- }
- if count == @gens.size
- break
- end
- yield ret
- end
- self
- end
- end
- if $0 == __FILE__
- eval DATA.read, nil, $0, __LINE__+4
- end
- __END__
- require 'test/unit'
- class TC_Generator < Test::Unit::TestCase
- def test_block1
- g = Generator.new { |g|
- # no yield's
- }
- assert_equal(0, g.pos)
- assert_raises(EOFError) { g.current }
- end
- def test_block2
- g = Generator.new { |g|
- for i in 'A'..'C'
- g.yield i
- end
- g.yield 'Z'
- }
- assert_equal(0, g.pos)
- assert_equal('A', g.current)
- assert_equal(true, g.next?)
- assert_equal(0, g.pos)
- assert_equal('A', g.current)
- assert_equal(0, g.pos)
- assert_equal('A', g.next)
- assert_equal(1, g.pos)
- assert_equal(true, g.next?)
- assert_equal(1, g.pos)
- assert_equal('B', g.current)
- assert_equal(1, g.pos)
- assert_equal('B', g.next)
- assert_equal(g, g.rewind)
- assert_equal(0, g.pos)
- assert_equal('A', g.current)
- assert_equal(true, g.next?)
- assert_equal(0, g.pos)
- assert_equal('A', g.current)
- assert_equal(0, g.pos)
- assert_equal('A', g.next)
- assert_equal(1, g.pos)
- assert_equal(true, g.next?)
- assert_equal(1, g.pos)
- assert_equal('B', g.current)
- assert_equal(1, g.pos)
- assert_equal('B', g.next)
- assert_equal(2, g.pos)
- assert_equal(true, g.next?)
- assert_equal(2, g.pos)
- assert_equal('C', g.current)
- assert_equal(2, g.pos)
- assert_equal('C', g.next)
- assert_equal(3, g.pos)
- assert_equal(true, g.next?)
- assert_equal(3, g.pos)
- assert_equal('Z', g.current)
- assert_equal(3, g.pos)
- assert_equal('Z', g.next)
- assert_equal(4, g.pos)
- assert_equal(false, g.next?)
- assert_raises(EOFError) { g.next }
- end
- def test_each
- a = [5, 6, 7, 8, 9]
- g = Generator.new(a)
- i = 0
- g.each { |x|
- assert_equal(a[i], x)
- i += 1
- break if i == 3
- }
- assert_equal(3, i)
- i = 0
- g.each { |x|
- assert_equal(a[i], x)
- i += 1
- }
- assert_equal(5, i)
- end
- end
- class TC_SyncEnumerator < Test::Unit::TestCase
- def test_each
- r = ['a'..'f', 1..10, 10..20]
- ra = r.map { |x| x.to_a }
- a = (0...(ra.map {|x| x.size}.max)).map { |i| ra.map { |x| x[i] } }
- s = SyncEnumerator.new(*r)
- i = 0
- s.each { |x|
- assert_equal(a[i], x)
- i += 1
- break if i == 3
- }
- assert_equal(3, i)
- i = 0
- s.each { |x|
- assert_equal(a[i], x)
- i += 1
- }
- assert_equal(a.size, i)
- end
- end