summaryrefslogtreecommitdiffstats
path: root/ext/tk/sample/tktextio.rb
blob: 9f012feada5b4ad4a836a8271a1fa048bf843be6 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
#!/usr/bin/env ruby
#
#  TkTextIO class :: handling I/O stream on a TkText widget
#                             by Hidetoshi NAGAI (nagai@ai.kyutech.ac.jp)
#
#  NOTE: TkTextIO supports 'character' (not 'byte') access only. 
#        So, for example, TkTextIO#getc returns a character, TkTextIO#pos 
#        means the character position, TkTextIO#read(size) counts by 
#        characters, and so on.
#        Of course, it is available to make TkTextIO class to suuport 
#        'byte' access. However, it may break multi-byte characters. 
#        and then, displayed string on the text widget may be garbled.
#        I think that it is not good on the supposed situation of using 
#        TkTextIO. 
#
require 'tk'
require 'tk/text'
require 'tk/textmark'
require 'thread'

class TkTextIO < TkText
  # keep safe level
  @@create_queues = proc{ [Queue.new, Mutex.new, Queue.new, Mutex.new] }

  OPT_DEFAULTS = {
    'mode'       => nil,
    'overwrite'  => false, 
    'text'       => nil, 
    'show'       => :pos, 
    'wrap'       => 'char', 
    'sync'       => true, 
    'prompt'     => nil, 
    'prompt_cmd' => nil, 
    'hist_size'  => 1000, 
  }

  def create_self(keys)
    opts = _get_io_params((keys.kind_of?(Hash))? keys: {})

    super(keys)

    @count_var = TkVariable.new

    @write_buffer = ''
    @read_buffer  = ''
    @buf_size = 0
    @buf_max = 1024

    @write_buf_queue, @write_buf_mutex, 
    @read_buf_queue,  @read_buf_mutex  = @@create_queues.call

    @idle_flush  = TkTimer.new(:idle, 1, proc{ @flusher.run rescue nil })
    @timer_flush = TkTimer.new(250, -1, proc{ @flusher.run rescue nil })

    @flusher = Thread.new{ loop { Thread.stop; flush() } }

    @receiver = Thread.new{
      begin
        loop {
          str = @write_buf_queue.deq
          @write_buf_mutex.synchronize { @write_buffer << str }
          @idle_flush.start
        }
      ensure
        @flusher.kill
      end
    }

    @timer_flush.start

    _setup_io(opts)
  end
  private :create_self

  def destroy
    @flusher.kill rescue nil

    @idle_flush.stop rescue nil
    @timer_flush.stop rescue nil

    @receiver.kill rescue nil

    super()
  end

  ####################################

  def _get_io_params(keys)
    opts = {}
    self.class.const_get(:OPT_DEFAULTS).each{|k, v| 
      if keys.has_key?(k)
        opts[k] = keys.delete(k)
      else
        opts[k] = v
      end
    }
    opts
  end

  def _setup_io(opts)
    unless defined? @txtpos
      @txtpos = TkTextMark.new(self, '1.0')
    else
      @txtpos.set('1.0')
    end
    @txtpos.gravity = :left

    @lineno = 0
    @line_offset = 0

    @hist_max = opts['hist_size'].to_i
    @hist_index = 0
    @history = Array.new(@hist_max)
    @history[0] = ''

    self['wrap'] = wrap

    self.show_mode = opts['show']

    self.value = opts['text'] if opts['text']

    @overwrite = (opts['overwrite'])? true: false

    @sync = opts['sync']

    @prompt = opts['prompt']
    @prompt_cmd = opts['prompt_cmd']

    @open  = {:r => true,  :w => true}  # default is 'r+'

    @console_mode = false
    @end_of_stream = false
    @console_buffer = nil

    case opts['mode']
    when nil
      # do nothing

    when :console, 'console'
      @console_mode = true
      # @console_buffer = TkTextIO.new(:mode=>'r')
      @console_buffer = self.class.new(:mode=>'r')
      self.show_mode = :insert

    when 'r', 'rb'
      @open[:r] = true; @open[:w] = nil

    when 'r+', 'rb+', 'r+b'
      @open[:r] = true; @open[:w] = true

    when 'w', 'wb'
      @open[:r] = nil;  @open[:w] = true
      self.value=''

    when 'w+', 'wb+', 'w+b'
      @open[:r] = true; @open[:w] = true
      self.value=''

    when 'a', 'ab'
      @open[:r] = nil;  @open[:w] = true
      @txtpos.set('end - 1 char')
      @txtpos.gravity = :right

    when 'a+', 'ab+', 'a+b'
      @open[:r] = true;  @open[:w] = true
      @txtpos.set('end - 1 char')
      @txtpos.gravity = :right

    else
      fail ArgumentError, "unknown mode `#{opts['mode']}'"
    end

    unless defined? @ins_head
      @ins_head = TkTextMark.new(self, 'insert')
      @ins_head.gravity = :left
    end

    unless defined? @ins_tail
      @ins_tail = TkTextMark.new(self, 'insert')
      @ins_tail.gravity = :right
    end

    unless defined? @tmp_mark
      @tmp_mark = TkTextMark.new(self, 'insert')
      @tmp_mark.gravity = :left
    end

    if @console_mode
      _set_console_line
      _setup_console_bindings
    end
  end
  private :_get_io_params, :_setup_io

  def _set_console_line
    @tmp_mark.set(@ins_tail)

    mark_set('insert', 'end')

    prompt = ''
    prompt << @prompt_cmd.call if @prompt_cmd
    prompt << @prompt if @prompt
    insert(@tmp_mark, prompt)

    @ins_head.set(@ins_tail)
    @ins_tail.set('insert')

    @txtpos.set(@tmp_mark)

    _see_pos
  end

  def _replace_console_line(str)
    self.delete(@ins_head, @ins_tail)
    self.insert(@ins_head, str)
  end

  def _get_console_line
    @tmp_mark.set(@ins_tail)
    s = self.get(@ins_head, @tmp_mark)
    _set_console_line
    s
  end
  private :_set_console_line, :_replace_console_line, :_get_console_line

  def _cb_up
    @history[@hist_index].replace(self.get(@ins_head, @ins_tail))
    @hist_index += 1
    @hist_index -= 1 if @hist_index >= @hist_max || !@history[@hist_index]
    _replace_console_line(@history[@hist_index]) if @history[@hist_index]
    Tk.callback_break
  end
  def _cb_down
    @history[@hist_index].replace(self.get(@ins_head, @ins_tail))
    @hist_index -= 1
    @hist_index = 0 if @hist_index < 0
    _replace_console_line(@history[@hist_index]) if @history[@hist_index]
    Tk.callback_break
  end
  def _cb_left
    if @console_mode && compare('insert', '<=', @ins_head)
      mark_set('insert', @ins_head)
      Tk.callback_break
    end
  end
  def _cb_backspace
    if @console_mode && compare('insert', '<=', @ins_head)
      Tk.callback_break
    end
  end
  def _cb_ctrl_a
    if @console_mode
      mark_set('insert', @ins_head)
      Tk.callback_break
    end
  end
  def _cb_ctrl_u
    if @console_mode
      mark_set('insert', @ins_head)
      delete('insert', 'insert lineend')
      Tk.callback_break
    end
  end
  private :_cb_up, :_cb_down, :_cb_left, :_cb_backspace, 
          :_cb_ctrl_a, :_cb_ctrl_u

  def _setup_console_bindings
    @bindtag = TkBindTag.new

    tags = self.bindtags
    tags[tags.index(self)+1, 0] = @bindtag
    self.bindtags = tags

    @bindtag.bind('Return'){
      insert('end - 1 char', "\n")
      if (str = _get_console_line)
        @read_buf_queue.push(str)

        @history[0].replace(str.chomp)
        @history.pop
        @history.unshift('')
        @hist_index = 0
      end

      Tk.update
      Tk.callback_break
    }
    @bindtag.bind('Alt-Return'){
      Tk.callback_continue
    }

    @bindtag.bind('FocusIn'){
      if @console_mode
        mark_set('insert', @ins_tail)
        Tk.callback_break
      end
    }

    ins_mark = TkTextMark.new(self, 'insert')

    @bindtag.bind('ButtonPress'){
      if @console_mode
        ins_mark.set('insert')
      end
    }

    @bindtag.bind('ButtonRelease-1'){
      if @console_mode && compare('insert', '<=', @ins_head)
        mark_set('insert', ins_mark)
        Tk.callback_break
      end
    }

    @bindtag.bind('ButtonRelease-2', '%x %y'){|x, y|
      if @console_mode
        # paste a text at 'insert' only
        x1, y1, x2, y2 =  bbox(ins_mark)
        unless x == x1 && y == y1
          Tk.event_generate(self, 'ButtonRelease-2', :x=>x1, :y=>y1)
          Tk.callback_break
        end
      end
    }

    @bindtag.bind('Up'){ _cb_up }
    @bindtag.bind('Control-p'){ _cb_up }

    @bindtag.bind('Down'){ _cb_down }
    @bindtag.bind('Control-n'){ _cb_down }

    @bindtag.bind('Left'){ _cb_left }
    @bindtag.bind('Control-b'){ _cb_left }

    @bindtag.bind('BackSpace'){ _cb_backspace }
    @bindtag.bind('Control-h'){ _cb_backspace }

    @bindtag.bind('Home'){ _cb_ctrl_a }
    @bindtag.bind('Control-a'){ _cb_ctrl_a }

    @bindtag.bind('Control-u'){ _cb_ctrl_u }
  end
  private :_setup_console_bindings

  def _block_read(size = nil, ret = '', block_mode = true)
    return '' if size == 0
    return nil if ! @read_buf_queue && @read_buffer.empty?
    ret = '' unless ret.kind_of?(String)
    ret.replace('') unless ret.empty?

    if block_mode == nil # partial
      if @read_buffer.empty?
        ret << @read_buffer.slice!(0..-1)
        return ret
      end
    end

    if size.kind_of?(Numeric)
      loop{
        @read_buf_mutex.synchronize {
          buf_len = @read_buffer.length
          if buf_len >= size
            ret << @read_buffer.slice!(0, size)
            return ret
          else
            ret << @read_buffer.slice!(0..-1)
            size -= buf_len
            return ret unless @read_buf_queue
          end
        }
        @read_buffer << @read_buf_queue.pop
      }
    else # readline
      rs = (size)? size: $/
      rs = rs.to_s if rs.kind_of?(Regexp)
      loop{
        @read_buf_mutex.synchronize {
          if (str = @read_buffer.slice!(/\A(.*)(#{rs})/m))
            ret << str
            return ret
          else
            ret << @read_buffer.slice!(0..-1)
            return ret unless @read_buf_queue
          end
        }
        @read_buffer << @read_buf_queue.pop
      }
    end
  end

  def _block_write
    ###### currently, not support
  end
  private :_block_read, :_block_write

  ####################################

  def <<(obj)
    _write(obj)
    self
  end

  def binmode
    self
  end

  def clone
    fail NotImplementedError, 'cannot clone TkTextIO'
  end
  def dup
    fail NotImplementedError, 'cannot duplicate TkTextIO'
  end

  def close
    close_read
    close_write
    nil
  end
  def close_read
    @open[:r] = false if @open[:r]
    nil
  end
  def close_write
    @open[:w] = false if @opne[:w]
    nil
  end

  def closed?(dir=nil)
    case dir
    when :r, 'r'
      !@open[:r]
    when :w, 'w'
      !@open[:w]
    else
      !@open[:r] && !@open[:w]
    end
  end

  def _check_readable
    fail IOError, "not opened for reading" if @open[:r].nil?
    fail IOError, "closed stream" if !@open[:r]
  end
  def _check_writable
    fail IOError, "not opened for writing" if @open[:w].nil?
    fail IOError, "closed stream" if !@open[:w]
  end
  private :_check_readable, :_check_writable

  def each_line(rs = $/)
    _check_readable
    while(s = self.gets(rs))
      yield(s)
    end
    self
  end
  alias each each_line

  def each_char
    _check_readable
    while(c = self.getc)
      yield(c)
    end
    self
  end
  alias each_byte each_char

  def eof?
    compare(@txtpos, '==', 'end - 1 char')
  end
  alias eof eof?

  def fcntl(*args)
    fail NotImplementedError, "fcntl is not implemented on #{self.class}"
  end

  def fsync
    0
  end

  def fileno
    nil
  end

  def flush
    Thread.pass
    if @open[:w] || ! @write_buffer.empty?
      @write_buf_mutex.synchronize {
        _sync_write_buf(@write_buffer) 
        @write_buffer[0..-1] = ''
      }
    end
    self
  end

  def getc
    return _block_read(1) if @console_mode

    _check_readable
    return nil if eof?
    c = get(@txtpos)
    @txtpos.set(@txtpos + '1 char')
    _see_pos
    c
  end

  def gets(rs = $/)
    return _block_read(rs) if @console_mode

    _check_readable
    return nil if eof?
    _readline(rs)
  end

  def ioctrl(*args)
    fail NotImplementedError, 'iocntl is not implemented on TkTextIO'
  end

  def isatty
    false
  end
  def tty?
    false
  end

  def lineno
    @lineno + @line_offset
  end

  def lineno=(num)
    @line_offset = num - @lineno
    num
  end

  def overwrite?
    @overwrite
  end

  def overwrite=(ovwt)
    @overwrite = (ovwt)? true: false
  end

  def pid
    nil
  end

  def index_pos
    index(@txtpos)
  end
  alias tell_index index_pos

  def index_pos=(idx)
    @txtpos.set(idx)
    @txtpos.set('end - 1 char') if compare(@txtpos, '>=', :end)
    _see_pos
    idx
  end

  def pos
    s = get('1.0', @txtpos)
    number(tk_call('string', 'length', s))
  end
  alias tell pos

  def pos=(idx)
    seek(idx, IO::SEEK_SET)
    idx
  end

  def pos_gravity
    @txtpos.gravity
  end

  def pos_gravity=(side)
    @txtpos.gravity = side
    side
  end

  def print(arg=$_, *args)
    _check_writable
    args.unshift(arg)
    args.map!{|val| (val == nil)? 'nil': val.to_s }
    str = args.join($,)
    str << $\ if $\
    _write(str)
    nil
  end
  def printf(*args)
    _check_writable
    _write(sprintf(*args))
    nil
  end

  def putc(c)
    _check_writable
    c = c.chr if c.kind_of?(Fixnum)
    _write(c)
    c
  end

  def puts(*args)
    _check_writable
    if args.empty?
      _write("\n")
      return nil
    end
    args.each{|arg|
      if arg == nil
        _write("nil\n")
      elsif arg.kind_of?(Array)
        puts(*arg)
      elsif arg.kind_of?(String)
        _write(arg.chomp)
        _write("\n")
      else
        begin
          arg = arg.to_ary
          puts(*arg)
        rescue
          puts(arg.to_s)
        end
      end
    }
    nil
  end

  def _read(len)
    epos = @txtpos + "#{len} char"
    s = get(@txtpos, epos)
    @txtpos.set(epos)
    @txtpos.set('end - 1 char') if compare(@txtpos, '>=', :end)
    _see_pos
    s
  end
  private :_read

  def read(len=nil, buf=nil)
    return _block_read(len, buf) if @console_mode

    _check_readable
    if len
      return "" if len == 0
      return nil if eof?
      s = _read(len)
    else
      s = get(@txtpos, 'end - 1 char')
      @txtpos.set('end - 1 char')
      _see_pos
    end
    buf.replace(s) if buf.kind_of?(String)
    s
  end

  def readchar
    return _block_read(1) if @console_mode

    _check_readable
    fail EOFError if eof?
    c = get(@txtpos)
    @txtpos.set(@txtpos + '1 char')
    _see_pos
    c
  end

  def _readline(rs = $/)
    if rs == nil
      s = get(@txtpos, 'end - 1 char')
      @txtpos.set('end - 1 char')
    elsif rs == ''
      @count_var.value  # make it global
      idx = tksearch_with_count([:regexp], @count_var, 
                                   "\n(\n)+", @txtpos, 'end - 1 char')
      if idx
        s = get(@txtpos, idx) << "\n"
        @txtpos.set("#{idx} + #{@count_var.value} char")
        @txtpos.set('end - 1 char') if compare(@txtpos, '>=', :end)
      else
        s = get(@txtpos, 'end - 1 char')
        @txtpos.set('end - 1 char')
      end
    else
      @count_var.value  # make it global
      idx = tksearch_with_count(@count_var, rs, @txtpos, 'end - 1 char')
      if idx
        s = get(@txtpos, "#{idx} + #{@count_var.value} char")
        @txtpos.set("#{idx} + #{@count_var.value} char")
        @txtpos.set('end - 1 char') if compare(@txtpos, '>=', :end)
      else
        s = get(@txtpos, 'end - 1 char')
        @txtpos.set('end - 1 char')
      end
    end

    _see_pos
    @lineno += 1
    $_ = s
  end
  private :_readline

  def readline(rs = $/)
    return _block_readline(rs) if @console_mode

    _check_readable
    fail EOFError if eof?
    _readline(rs)
  end

  def readlines(rs = $/)
    if @console_mode
      lines = []
      while (line = _block_readline(rs))
        lines << line
      end
      return lines
    end

    _check_readable
    lines = []
    until(eof?)
      lines << _readline(rs)
    end
    $_ = nil
    lines
  end

  def readpartial(maxlen, buf=nil)
    #return @console_buffer.readpartial(maxlen, buf) if @console_mode
    return _block_read(maxlen, buf, nil) if @console_mode

    _check_readable
    fail EOFError if eof?
    s = _read(maxlen)
    buf.replace(s) if buf.kind_of?(String)
    s
  end

  def reopen(*args)
    fail NotImplementedError, 'reopen is not implemented on TkTextIO'
  end

  def rewind
    @txtpos.set('1.0')
    _see_pos
    @lineno = 0
    @line_offset = 0
    self
  end

  def seek(offset, whence=IO::SEEK_SET)
    case whence
    when IO::SEEK_SET
      offset = "1.0 + #{offset} char" if offset.kind_of?(Numeric)
      @txtpos.set(offset)

    when IO::SEEK_CUR
      offset = "#{offset} char" if offset.kind_of?(Numeric)
      @txtpos.set(@txtpos + offset)

    when IO::SEEK_END
      offset = "#{offset} char" if offset.kind_of?(Numeric)
      @txtpos.set("end - 1 char + #{offset}")

    else
      fail Errno::EINVAL, 'invalid whence argument'
    end

    @txtpos.set('end - 1 char') if compare(@txtpos, '>=', :end)
    _see_pos

    0
  end
  alias sysseek seek

  def _see_pos
    see(@show) if @show
  end
  private :_see_pos

  def show_mode
    (@show == @txtpos)? :pos : @show
  end

  def show_mode=(mode)
    # define show mode  when file position is changed. 
    #  mode == :pos or "pos" or true :: see current file position. 
    #  mode == :insert or "insert"   :: see insert cursor position. 
    #  mode == nil or false          :: do nothing
    #  else see 'mode' position ('mode' should be text index or mark)
    case mode
    when :pos, 'pos', true
      @show = @txtpos
    when :insert, 'insert'
      @show = :insert
    when nil, false
      @show = false
    else
      begin
        index(mode)
      rescue
        fail ArgumentError, 'invalid show-position'
      end
      @show = mode
    end

    _see_pos

    mode
  end

  def stat
    fail NotImplementedError, 'stat is not implemented on TkTextIO'
  end

  def sync
    @sync
  end

  def sync=(mode)
    @sync = mode
  end

  def sysread(len, buf=nil)
    return _block_read(len, buf) if @console_mode

    _check_readable
    fail EOFError if eof?
    s = _read(len)
    buf.replace(s) if buf.kind_of?(String)
    s
  end

  def syswrite(obj)
    _write(obj)
  end

  def to_io
    self
  end

  def trancate(len)
    delete("1.0 + #{len} char", :end)
    0
  end

  def ungetc(c)
    if @console_mode
      @read_buf_mutex.synchronize {
        @read_buffer[0,0] = c.chr
      }
      return nil
    end

    _check_readable
    c = c.chr if c.kind_of?(Fixnum)
    if compare(@txtpos, '>', '1.0')
      @txtpos.set(@txtpos - '1 char')
      delete(@txtpos)
      insert(@txtpos, tk_call('string', 'range', c, 0, 1))
      @txtpos.set(@txtpos - '1 char') if @txtpos.gravity == 'right'
      _see_pos
    else
      fail IOError, 'cannot ungetc at head of stream'
    end
    nil
  end

=begin
  def _write(obj)
    #s = _get_eval_string(obj)
    s = (obj.kind_of?(String))? obj: obj.to_s
    n = number(tk_call('string', 'length', s))
    delete(@txtpos, @txtpos + "#{n} char") if @overwrite
    self.insert(@txtpos, s)
    @txtpos.set(@txtpos + "#{n} char")
    @txtpos.set('end - 1 char') if compare(@txtpos, '>=', :end)
    _see_pos
    Tk.update if @sync
    n
  end
  private :_write
=end
#=begin
  def _sync_write_buf(s)
    if (n = number(tk_call('string', 'length', s))) > 0
      delete(@txtpos, @txtpos + "#{n} char") if @overwrite
      self.insert(@txtpos, s)
      #Tk.update

      @txtpos.set(@txtpos + "#{n} char")
      @txtpos.set('end - 1 char') if compare(@txtpos, '>=', :end)

      @ins_head.set(@txtpos) if compare(@txtpos, '>', @ins_head)

      _see_pos
    end
    self
  end
  private :_sync_write_buf

  def _write(obj)
    s = (obj.kind_of?(String))? obj: obj.to_s
    n = number(tk_call('string', 'length', s))
    @write_buf_queue.enq(s)
    if @sync
      Thread.pass
      Tk.update
    end
    n
  end
  private :_write
#=end

  def write(obj)
    _check_writable
    _write(obj)
  end
end

####################
#  TEST
####################
if __FILE__ == $0
  ev_loop = Thread.new{Tk.mainloop}

  f = TkFrame.new.pack
  #tio = TkTextIO.new(f, :show=>:nil, 
  #tio = TkTextIO.new(f, :show=>:pos, 
  tio = TkTextIO.new(f, :show=>:insert, 
                     :text=>">>> This is an initial text line. <<<\n\n"){
#    yscrollbar(TkScrollbar.new(f).pack(:side=>:right, :fill=>:y))
    pack(:side=>:left, :fill=>:both, :expand=>true)
  }

  Tk.update

  $stdin  = tio
  $stdout = tio
  $stderr = tio

  STDOUT.print("\n========= TkTextIO#gets for inital text ========\n\n")

  while(s = gets)
    STDOUT.print(s)
  end

  STDOUT.print("\n============ put strings to TkTextIO ===========\n\n")

  puts "On this sample, a text widget works as if it is a I/O stream."
  puts "Please see the code."
  puts
  printf("printf message: %d %X\n", 123456, 255)
  puts
  printf("(output by 'p' method) This TkTextIO object is ...\n")
  p tio
  print(" [ Current wrap mode of this object is 'char'. ]\n")
  puts
  warn("This is a warning message generated by 'warn' method.")
  puts
  puts "current show_mode is #{tio.show_mode}."
  if tio.show_mode == :pos
    puts "So, you can see the current file position on this text widget."
  else
    puts "So, you can see the position '#{tio.show_mode}' on this text widget."
  end
  print("Please scroll up this text widget to see the head of lines.\n")
  print("---------------------------------------------------------\n")

  STDOUT.print("\n=============== TkTextIO#readlines =============\n\n")

  tio.seek(0)
  lines = readlines
  STDOUT.puts(lines.inspect)

  STDOUT.print("\n================== TkTextIO#each ===============\n\n")

  tio.rewind
  tio.each{|line| STDOUT.printf("%2d: %s\n", tio.lineno, line.chomp)}

  STDOUT.print("\n================================================\n\n")

  STDOUT.print("\n========= reverse order (seek by lines) ========\n\n")

  tio.seek(-1, IO::SEEK_END)
  begin
    begin
      tio.seek(:linestart, IO::SEEK_CUR)
    rescue
      # maybe use old version of tk/textmark.rb
      tio.seek('0 char linestart', IO::SEEK_CUR)
    end
    STDOUT.print(gets)
    tio.seek('-1 char linestart -1 char', IO::SEEK_CUR)
  end while(tio.pos > 0)

  STDOUT.print("\n================================================\n\n")

  tio.seek(0, IO::SEEK_END)

  STDOUT.print("tio.sync ==  #{tio.sync}\n")
#  tio.sync = false
#  STDOUT.print("tio.sync ==  #{tio.sync}\n")

  (0..10).each{|i|
    STDOUT.print("#{i}\n")
    s = ''
    (0..1000).each{ s << '*' }
    print(s)
  }
  print("\n")
  print("\n=========================================================\n\n")

  s = ''
  timer = TkTimer.new(:idle, -1, proc{
                        #STDOUT.print("idle call\n")
                        unless s.empty?
                          print(s)
                          s = ''
                        end
                      }).start
  (0..10).each{|i|
    STDOUT.print("#{i}\n")
    (0..1000).each{ s << '*' }
  }
#  timer.stop
  until s.empty?
    sleep 0.1
  end
  timer.stop

=begin
  tio.sync = false
  print("\n")
  #(0..10000).each{ putc('*') }
  (0..10).each{|i|
    STDOUT.print("#{i}\n")
    (0..1000).each{ putc('*') }
  }

  (0..10).each{|i|
    STDOUT.print("#{i}\n")
    s = ''
    (0..1000).each{ s << '*' }
    print(s)
  }
=end

  num = 0
#  io = TkTextIO.new(:mode=>:console, :prompt=>'').pack
#=begin
  io = TkTextIO.new(:mode=>:console, 
                    :prompt_cmd=>proc{
                      s = "[#{num}]"
                      num += 1
                      s
                    }, 
                    :prompt=>'-> ').pack
#=end
  Thread.new{loop{sleep 2; io.puts 'hoge'}}
  Thread.new{loop{p io.gets}}

  ev_loop.join
end