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919f456de8
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@6044 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
380 lines
7.1 KiB
Ruby
380 lines
7.1 KiB
Ruby
#!/usr/bin/env ruby
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#--
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# $Idaemons: /home/cvs/rb/generator.rb,v 1.8 2001/10/03 08:54:32 knu Exp $
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# $RoughId: generator.rb,v 1.10 2003/10/14 19:36:58 knu Exp $
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# $Id$
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#++
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#
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# = generator.rb: convert an internal iterator to an external one
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#
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# Copyright (c) 2001,2003 Akinori MUSHA <knu@iDaemons.org>
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#
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# All rights reserved. You can redistribute and/or modify it under
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# the same terms as Ruby.
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#
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# == Overview
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#
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# This library provides the Generator class, which converts an
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# internal iterator (i.e. an Enumerable object) to an external
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# iterator. In that form, you can roll many iterators independently.
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#
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# The SyncEnumerator class, which is implemented using Generator,
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# makes it easy to roll many Enumerable objects synchronously.
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#
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# See the respective classes for examples of usage.
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#
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# Generator converts an internal iterator (i.e. an Enumerable object)
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# to an external iterator.
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#
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# Note that it is not very fast since it is implemented using
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# continuations, which are currently slow.
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#
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# == Example
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#
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# require 'generator'
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#
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# # Generator from an Enumerable object
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# g = Generator.new(['A', 'B', 'C', 'Z'])
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#
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# while g.next?
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# puts g.next
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# end
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#
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# # Generator from a block
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# g = Generator.new { |g|
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# for i in 'A'..'C'
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# g.yield i
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# end
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#
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# g.yield 'Z'
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# }
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#
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# # The same result as above
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# while g.next?
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# puts g.next
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# end
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#
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class Generator
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include Enumerable
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# Creates a new generator either from an Enumerable object or from a
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# block.
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#
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# In the former, block is ignored even if given.
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#
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# In the latter, the given block is called with the generator
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# itself, and expected to call the +yield+ method for each element.
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def initialize(enum = nil, &block)
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if enum
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@block = proc { |g|
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enum.each { |x| g.yield x }
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}
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else
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@block = block
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end
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@index = 0
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@queue = []
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@cont_next = @cont_yield = @cont_endp = nil
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if @cont_next = callcc { |c| c }
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@block.call(self)
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@cont_endp.call(nil) if @cont_endp
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end
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self
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end
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# Yields an element to the generator.
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def yield(value)
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if @cont_yield = callcc { |c| c }
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@queue << value
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@cont_next.call(nil)
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end
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self
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end
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# Returns true if the generator has reached the end.
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def end?()
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if @cont_endp = callcc { |c| c }
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@cont_yield.nil? && @queue.empty?
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else
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@queue.empty?
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end
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end
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# Returns true if the generator has not reached the end yet.
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def next?()
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!end?
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end
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# Returns the current index (position) counting from zero.
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def index()
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@index
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end
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# Returns the current index (position) counting from zero.
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def pos()
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@index
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end
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# Returns the element at the current position and moves forward.
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def next()
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if end?
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raise EOFError, "no more elements available"
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end
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if @cont_next = callcc { |c| c }
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@cont_yield.call(nil) if @cont_yield
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end
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@index += 1
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@queue.shift
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end
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# Returns the element at the current position.
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def current()
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if @queue.empty?
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raise EOFError, "no more elements available"
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end
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@queue.first
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end
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# Rewinds the generator.
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def rewind()
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initialize(nil, &@block) if @index.nonzero?
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self
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end
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# Rewinds the generator and enumerates the elements.
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def each
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rewind
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until end?
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yield self.next
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end
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self
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end
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end
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#
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# SyncEnumerator creates an Enumerable object from multiple Enumerable
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# objects and enumerates them synchronously.
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#
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# == Example
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#
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# require 'generator'
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#
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# s = SyncEnumerator.new([1,2,3], ['a', 'b', 'c'])
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#
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# # Yields [1, 'a'], [2, 'b'], and [3,'c']
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# s.each { |row| puts row.join(', ') }
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#
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class SyncEnumerator
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include Enumerable
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# Creates a new SyncEnumerator which enumerates rows of given
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# Enumerable objects.
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def initialize(*enums)
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@gens = enums.map { |e| Generator.new(e) }
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end
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# Returns the number of enumerated Enumerable objects, i.e. the size
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# of each row.
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def size
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@gens.size
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end
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# Returns the number of enumerated Enumerable objects, i.e. the size
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# of each row.
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def length
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@gens.length
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end
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# Returns true if the given nth Enumerable object has reached the
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# end. If no argument is given, returns true if any of the
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# Enumerable objects has reached the end.
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def end?(i = nil)
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if i.nil?
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@gens.detect { |g| g.end? } ? true : false
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else
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@gens[i].end?
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end
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end
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# Enumerates rows of the Enumerable objects.
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def each
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@gens.each { |g| g.rewind }
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loop do
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count = 0
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ret = @gens.map { |g|
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if g.end?
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count += 1
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nil
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else
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g.next
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end
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}
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if count == @gens.size
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break
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end
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yield ret
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end
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self
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end
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end
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if $0 == __FILE__
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eval DATA.read, nil, $0, __LINE__+4
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end
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__END__
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require 'test/unit'
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class TC_Generator < Test::Unit::TestCase
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def test_block1
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g = Generator.new { |g|
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# no yield's
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}
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assert_equal(0, g.pos)
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assert_raises(EOFError) { g.current }
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end
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def test_block2
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g = Generator.new { |g|
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for i in 'A'..'C'
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g.yield i
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end
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g.yield 'Z'
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}
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assert_equal(0, g.pos)
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assert_equal('A', g.current)
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assert_equal(true, g.next?)
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assert_equal(0, g.pos)
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assert_equal('A', g.current)
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assert_equal(0, g.pos)
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assert_equal('A', g.next)
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assert_equal(1, g.pos)
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assert_equal(true, g.next?)
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assert_equal(1, g.pos)
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assert_equal('B', g.current)
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assert_equal(1, g.pos)
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assert_equal('B', g.next)
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assert_equal(g, g.rewind)
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assert_equal(0, g.pos)
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assert_equal('A', g.current)
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assert_equal(true, g.next?)
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assert_equal(0, g.pos)
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assert_equal('A', g.current)
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assert_equal(0, g.pos)
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assert_equal('A', g.next)
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assert_equal(1, g.pos)
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assert_equal(true, g.next?)
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assert_equal(1, g.pos)
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assert_equal('B', g.current)
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assert_equal(1, g.pos)
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assert_equal('B', g.next)
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assert_equal(2, g.pos)
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assert_equal(true, g.next?)
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assert_equal(2, g.pos)
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assert_equal('C', g.current)
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assert_equal(2, g.pos)
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assert_equal('C', g.next)
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assert_equal(3, g.pos)
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assert_equal(true, g.next?)
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assert_equal(3, g.pos)
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assert_equal('Z', g.current)
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assert_equal(3, g.pos)
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assert_equal('Z', g.next)
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assert_equal(4, g.pos)
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assert_equal(false, g.next?)
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assert_raises(EOFError) { g.next }
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end
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def test_each
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a = [5, 6, 7, 8, 9]
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g = Generator.new(a)
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i = 0
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g.each { |x|
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assert_equal(a[i], x)
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i += 1
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break if i == 3
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}
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assert_equal(3, i)
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i = 0
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g.each { |x|
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assert_equal(a[i], x)
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i += 1
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}
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assert_equal(5, i)
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end
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end
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class TC_SyncEnumerator < Test::Unit::TestCase
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def test_each
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r = ['a'..'f', 1..10, 10..20]
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ra = r.map { |x| x.to_a }
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a = (0...(ra.map {|x| x.size}.max)).map { |i| ra.map { |x| x[i] } }
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s = SyncEnumerator.new(*r)
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i = 0
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s.each { |x|
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assert_equal(a[i], x)
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i += 1
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break if i == 3
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}
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assert_equal(3, i)
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i = 0
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s.each { |x|
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assert_equal(a[i], x)
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i += 1
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}
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assert_equal(a.size, i)
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end
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end
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