summaryrefslogtreecommitdiff
path: root/test/ruby/sentence.rb
blob: 9bfd7c75992f2d06d741598f93f8f5cc914eb2bd (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
# frozen_string_literal: false
# == sentence library
#
# = Features
#
# * syntax based sentences generation
# * sentence operations such as substitution.
#
# = Example
#
# Some arithmetic expressions using "+", "-", "*" and "/" are generated as follows.
#
#  require 'sentence'
#  Sentence.each({
#    :exp => [["num"],
#             [:exp, "+", :exp],
#             [:exp, "-", :exp],
#             [:exp, "*", :exp],
#             [:exp, "/", :exp]]
#  }, :exp, 2) {|sent| p sent }
#  #=>
#  #<Sentence: "num">
#  #<Sentence: ("num") "+" ("num")>
#  #<Sentence: ("num") "+" (("num") "+" ("num"))>
#  #<Sentence: ("num") "+" (("num") "-" ("num"))>
#  #<Sentence: ("num") "+" (("num") "*" ("num"))>
#  #<Sentence: ("num") "+" (("num") "/" ("num"))>
#  #<Sentence: (("num") "+" ("num")) "+" ("num")>
#  ...
#
# Sentence.each takes 3 arguments.
# The first argument is the syntax for the expressions.
# The second argument, :exp, is a generating nonterminal.
# The third argument, 2, limits derivation to restrict results finitely.
#
# Some arithmetic expressions including parenthesis can be generated as follows.
#
#  syntax = {
#    :factor => [["n"],
#                ["(", :exp, ")"]],
#    :term => [[:factor],
#              [:term, "*", :factor],
#              [:term, "/", :factor]],
#    :exp => [[:term],
#             [:exp, "+", :term],
#             [:exp, "-", :term]]
#  }
#  Sentence.each(syntax, :exp, 2) {|sent| p sent }
#  #=>
#  #<Sentence: (("n"))>
#  #<Sentence: (("(" ((("n"))) ")"))>
#  #<Sentence: (("(" ((("(" ((("n"))) ")"))) ")"))>
#  #<Sentence: (("(" (((("n")) "*" ("n"))) ")"))>
#  #<Sentence: (("(" (((("n")) "/" ("n"))) ")"))>
#  #<Sentence: (("(" (((("n"))) "+" (("n"))) ")"))>
#  #<Sentence: (("(" (((("n"))) "-" (("n"))) ")"))>
#  #<Sentence: ((("n")) "*" ("n"))>
#  #<Sentence: ((("n")) "*" ("(" ((("n"))) ")"))>
#  ...
#
#  Sentence#to_s can be used to concatenate strings
#  in a sentence:
#
#  Sentence.each(syntax, :exp, 2) {|sent| p sent.to_s }
#  #=>
#  "n"
#  "(n)"
#  "((n))"
#  "(n*n)"
#  "(n/n)"
#  "(n+n)"
#  "(n-n)"
#  "n*n"
#  "n*(n)"
#  ...
#

# Sentence() instantiates a sentence object.
#
#  Sentence("foo", "bar")
#  #=> #<Sentence: "foo" "bar">
#
#  Sentence("foo", ["bar", "baz"])
#  #=> #<Sentence: "foo" ("bar" "baz")>
#
def Sentence(*ary)
  Sentence.new(ary)
end

# Sentence class represents a tree with string leaves.
#
class Sentence
  # _ary_ represents a tree.
  # It should be a possibly nested array which contains strings.
  #
  # Note that _ary_ is not copied.
  # Don't modify _ary_ after the sentence object is instantiated.
  #
  #  Sentence.new(["a", "pen"])
  #  #<Sentence: "a" "pen">
  #
  #  Sentence.new(["I", "have", ["a", "pen"]])
  #  #<Sentence: "I" "have" ("a" "pen")>
  #
  def initialize(ary)
    @sent = ary
  end

  # returns a string which is concatenation of all strings.
  # No separator is used.
  #
  #  Sentence("2", "+", "3").to_s
  #  "2+3"
  #
  #  Sentence("2", "+", ["3", "*", "5"]).to_s
  #  "2+3*5"
  #
  def to_s
    @sent.join('')
  end

  # returns a string which is concatenation of all strings separated by _sep_.
  # If _sep_ is not given, single space is used.
  #
  #  Sentence("I", "have", ["a", "pen"]).join
  #  "I have a pen"
  #
  #  Sentence("I", "have", ["a", "pen"]).join("/")
  #  "I/have/a/pen"
  #
  #  Sentence("a", [], "b").join("/")
  #  "a/b"
  #
  def join(sep=' ')
    @sent.flatten.join(sep)
  end

  # returns a tree as a nested array.
  #
  # Note that the result is not copied.
  # Don't modify the result.
  #
  #  Sentence(["foo", "bar"], "baz").to_a
  #  #=> [["foo", "bar"], "baz"]
  #
  def to_a
    @sent
  end

  # returns <i>i</i>th element as a sentence or string.
  #
  #  s = Sentence(["foo", "bar"], "baz")
  #  s    #=> #<Sentence: ("foo" "bar") "baz">
  #  s[0] #=> #<Sentence: "foo" "bar">
  #  s[1] #=> "baz"
  #
  def [](i)
    e = @sent[i]
    e.respond_to?(:to_ary) ? Sentence.new(e) : e
  end

  # returns the number of top level elements.
  #
  #  Sentence.new(%w[foo bar]).length
  #  #=> 2
  #
  #  Sentence(%w[2 * 7], "+", %w[3 * 5]).length
  #  #=> 3
  #
  def length
    @sent.length
  end

  # iterates over children.
  #
  #  Sentence(%w[2 * 7], "+", %w[3 * 5]).each {|v| p v }
  #  #=>
  #  #<Sentence: "2" "*" "7">
  #  "+"
  #  #<Sentence: "3" "*" "5">
  #
  def each # :yield: element
    @sent.each_index {|i|
      yield self[i]
    }
  end
  include Enumerable

  def inspect
    "#<#{self.class}: #{inner_inspect(@sent, '')}>"
  end

  # :stopdoc:
  def inner_inspect(ary, r)
    first = true
    ary.each {|obj|
      r << ' ' if !first
      first = false
      if obj.respond_to? :to_ary
        r << '('
        inner_inspect(obj, r)
        r << ')'
      else
        r << obj.inspect
      end
    }
    r
  end
  # :startdoc:

  # returns new sentence object which
  # _target_ is substituted by the block.
  #
  # Sentence#subst invokes <tt>_target_ === _string_</tt> for each
  # string in the sentence.
  # The strings which === returns true are substituted by the block.
  # The block is invoked with the substituting string.
  #
  #  Sentence.new(%w[2 + 3]).subst("+") { "*" }
  #  #<Sentence: "2" "*" "3">
  #
  #  Sentence.new(%w[2 + 3]).subst(/\A\d+\z/) {|s| ((s.to_i)*2).to_s }
  #  #=> #<Sentence: "4" "+" "6">
  #
  def subst(target, &b) # :yield: string
    Sentence.new(subst_rec(@sent, target, &b))
  end

  # :stopdoc:
  def subst_rec(obj, target, &b)
    if obj.respond_to? :to_ary
      a = []
      obj.each {|e| a << subst_rec(e, target, &b) }
      a
    elsif target === obj
      yield obj
    else
      obj
    end
  end
  # :startdoc:

  # find a subsentence and return it.
  # The block is invoked for each subsentence in preorder manner.
  # The first subsentence which the block returns true is returned.
  #
  #  Sentence(%w[2 * 7], "+", %w[3 * 5]).find_subtree {|s| s[1] == "*" }
  #  #=> #<Sentence: "2" "*" "7">
  #
  def find_subtree(&b) # :yield: sentence
    find_subtree_rec(@sent, &b)
  end

  # :stopdoc:
  def find_subtree_rec(obj, &b)
    if obj.respond_to? :to_ary
      s = Sentence.new(obj)
      if b.call s
        return s
      else
        obj.each {|e|
          r = find_subtree_rec(e, &b)
          return r if r
        }
      end
    end
    nil
  end
  # :startdoc:

  # returns a new sentence object which expands according to the condition
  # given by the block.
  #
  # The block is invoked for each subsentence.
  # The subsentences which the block returns true are
  # expanded into parent.
  #
  #  s = Sentence(%w[2 * 7], "+", %w[3 * 5])
  #  #=> #<Sentence: ("2" "*" "7") "+" ("3" "*" "5")>
  #
  #  s.expand { true }
  #  #=> #<Sentence: "2" "*" "7" "+" "3" "*" "5">
  #
  #  s.expand {|s| s[0] == "3" }
  #  #=> #<Sentence: (("2" "*" "7") "+" "3" "*" "5")>
  #
  def expand(&b) # :yield: sentence
    Sentence.new(expand_rec(@sent, &b))
  end

  # :stopdoc:
  def expand_rec(obj, r=[], &b)
    if obj.respond_to? :to_ary
      obj.each {|o|
        s = Sentence.new(o)
        if b.call s
          expand_rec(o, r, &b)
        else
          a = []
          expand_rec(o, a, &b)
          r << a
        end
      }
    else
      r << obj
    end
    r
  end
  # :startdoc:

  # Sentence.each generates sentences
  # by deriving the start symbol _sym_ using _syntax_.
  # The derivation is restricted by an positive integer _limit_ to
  # avoid infinite generation.
  #
  # Sentence.each yields the block with a generated sentence.
  #
  #  Sentence.each({
  #    :exp => [["n"],
  #             [:exp, "+", :exp],
  #             [:exp, "*", :exp]]
  #    }, :exp, 1) {|sent| p sent }
  #  #=>
  #  #<Sentence: "n">
  #  #<Sentence: ("n") "+" ("n")>
  #  #<Sentence: ("n") "*" ("n")>
  #
  #  Sentence.each({
  #    :exp => [["n"],
  #             [:exp, "+", :exp],
  #             [:exp, "*", :exp]]
  #    }, :exp, 2) {|sent| p sent }
  #  #=>
  #  #<Sentence: "n">
  #  #<Sentence: ("n") "+" ("n")>
  #  #<Sentence: ("n") "+" (("n") "+" ("n"))>
  #  #<Sentence: ("n") "+" (("n") "*" ("n"))>
  #  #<Sentence: (("n") "+" ("n")) "+" ("n")>
  #  #<Sentence: (("n") "*" ("n")) "+" ("n")>
  #  #<Sentence: ("n") "*" ("n")>
  #  #<Sentence: ("n") "*" (("n") "+" ("n"))>
  #  #<Sentence: ("n") "*" (("n") "*" ("n"))>
  #  #<Sentence: (("n") "+" ("n")) "*" ("n")>
  #  #<Sentence: (("n") "*" ("n")) "*" ("n")>
  #
  def Sentence.each(syntax, sym, limit)
    Gen.new(syntax).each_tree(sym, limit) {|tree|
      yield Sentence.new(tree)
    }
  end

  # Sentence.expand_syntax returns an expanded syntax:
  # * No rule derives to empty sequence
  # * Underivable rule simplified
  # * No channel rule
  # * Symbols which has zero or one choices are not appeared in rhs.
  #
  # Note that the rules which can derive empty and non-empty
  # sequences are modified to derive only non-empty sequences.
  #
  #  Sentence.expand_syntax({
  #    :underivable1 => [],
  #    :underivable2 => [[:underivable1]],
  #    :underivable3 => [[:underivable3]],
  #    :empty_only1 => [[]],
  #    :empty_only2 => [[:just_empty1, :just_empty1]],
  #    :empty_or_not => [[], ["foo"]],
  #    :empty_or_not_2 => [[:empty_or_not, :empty_or_not]],
  #    :empty_or_not_3 => [[:empty_or_not, :empty_or_not, :empty_or_not]],
  #    :empty_or_not_4 => [[:empty_or_not_2, :empty_or_not_2]],
  #    :channel1 => [[:channeled_data]],
  #    :channeled_data => [["a", "b"], ["c", "d"]],
  #    :single_choice => [["single", "choice"]],
  #    :single_choice_2 => [[:single_choice, :single_choice]],
  #  })
  #  #=>
  #  {
  #   :underivable1=>[], # underivable rules are simplified to [].
  #   :underivable2=>[],
  #   :underivable3=>[],
  #   :empty_only1=>[], # derivation to empty sequence are removed.
  #   :empty_only2=>[],
  #   :empty_or_not=>[["foo"]], # empty sequences are removed too.
  #   :empty_or_not_2=>[["foo"], ["foo", "foo"]],
  #   :empty_or_not_3=>[["foo"], ["foo", "foo"], ["foo", "foo", "foo"]],
  #   :empty_or_not_4=> [["foo"], ["foo", "foo"], [:empty_or_not_2, :empty_or_not_2]],
  #   :channel1=>[["a", "b"], ["c", "d"]], # channel rules are removed.
  #   :channeled_data=>[["a", "b"], ["c", "d"]],
  #   :single_choice=>[["single", "choice"]], # single choice rules are expanded.
  #   :single_choice_2=>[["single", "choice", "single", "choice"]],
  #  }
  #
  #  Sentence.expand_syntax({
  #    :factor => [["n"],
  #                ["(", :exp, ")"]],
  #    :term => [[:factor],
  #              [:term, "*", :factor],
  #              [:term, "/", :factor]],
  #    :exp => [[:term],
  #             [:exp, "+", :term],
  #             [:exp, "-", :term]]
  #  })
  #  #=>
  #  {:exp=> [["n"],
  #           ["(", :exp, ")"],
  #           [:exp, "+", :term],
  #           [:exp, "-", :term],
  #           [:term, "*", :factor],
  #           [:term, "/", :factor]],
  #   :factor=> [["n"],
  #              ["(", :exp, ")"]],
  #   :term=> [["n"],
  #            ["(", :exp, ")"],
  #            [:term, "*", :factor],
  #            [:term, "/", :factor]]
  #  }
  #
  def Sentence.expand_syntax(syntax)
    Sentence::Gen.expand_syntax(syntax)
  end

  # :stopdoc:
  class Gen
    def Gen.each_tree(syntax, sym, limit, &b)
      Gen.new(syntax).each_tree(sym, limit, &b)
    end

    def Gen.each_string(syntax, sym, limit, &b)
      Gen.new(syntax).each_string(sym, limit, &b)
    end

    def initialize(syntax)
      @syntax = syntax
    end

    def self.expand_syntax(syntax)
      syntax = simplify_underivable_rules(syntax)
      syntax = simplify_emptyonly_rules(syntax)
      syntax = make_rules_no_empseq(syntax)
      syntax = expand_channel_rules(syntax)

      syntax = expand_noalt_rules(syntax)
      syntax = reorder_rules(syntax)
    end

    def self.simplify_underivable_rules(syntax)
      deribable_syms = {}
      changed = true
      while changed
        changed = false
        syntax.each {|sym, rules|
          next if deribable_syms[sym]
          rules.each {|rhs|
            if rhs.all? {|e| String === e || deribable_syms[e] }
              deribable_syms[sym] = true
              changed = true
              break
            end
          }
        }
      end
      result = {}
      syntax.each {|sym, rules|
        if deribable_syms[sym]
          rules2 = []
          rules.each {|rhs|
            rules2 << rhs if rhs.all? {|e| String === e || deribable_syms[e] }
          }
          result[sym] = rules2.uniq
        else
          result[sym] = []
        end
      }
      result
    end

    def self.simplify_emptyonly_rules(syntax)
      justempty_syms = {}
      changed = true
      while changed
        changed = false
        syntax.each {|sym, rules|
          next if justempty_syms[sym]
          if !rules.empty? && rules.all? {|rhs| rhs.all? {|e| justempty_syms[e] } }
            justempty_syms[sym] = true
            changed = true
          end
        }
      end
      result = {}
      syntax.each {|sym, rules|
        result[sym] = rules.map {|rhs| rhs.reject {|e| justempty_syms[e] } }.uniq
      }
      result
    end

    def self.expand_emptyable_syms(rhs, emptyable_syms)
      if rhs.empty?
        yield []
      else
        first = rhs[0]
        rest = rhs[1..-1]
        if emptyable_syms[first]
          expand_emptyable_syms(rest, emptyable_syms) {|rhs2|
            yield [first] + rhs2
            yield rhs2
          }
        else
          expand_emptyable_syms(rest, emptyable_syms) {|rhs2|
            yield [first] + rhs2
          }
        end
      end
    end

    def self.make_rules_no_empseq(syntax)
      emptyable_syms = {}
      changed = true
      while changed
        changed = false
        syntax.each {|sym, rules|
          next if emptyable_syms[sym]
          rules.each {|rhs|
            if rhs.all? {|e| emptyable_syms[e] }
              emptyable_syms[sym] = true
              changed = true
              break
            end
          }
        }
      end
      result = {}
      syntax.each {|sym, rules|
        rules2 = []
        rules.each {|rhs|
          expand_emptyable_syms(rhs, emptyable_syms) {|rhs2|
            next if rhs2.empty?
            rules2 << rhs2
          }
        }
        result[sym] = rules2.uniq
      }
      result
    end

    def self.expand_channel_rules(syntax)
      channel_rules = {}
      syntax.each {|sym, rules|
        channel_rules[sym] = {sym=>true}
        rules.each {|rhs|
          if rhs.length == 1 && Symbol === rhs[0]
            channel_rules[sym][rhs[0]] = true
          end
        }
      }
      changed = true
      while changed
        changed = false
        channel_rules.each {|sym, set|
          n1 = set.size
          set.keys.each {|s|
            set.update(channel_rules[s])
          }
          n2 = set.size
          changed = true if n1 < n2
        }
      end
      result = {}
      syntax.each {|sym, rules|
        rules2 = []
        channel_rules[sym].each_key {|s|
          syntax[s].each {|rhs|
            unless rhs.length == 1 && Symbol === rhs[0]
              rules2 << rhs
            end
          }
        }
        result[sym] = rules2.uniq
      }
      result
    end

    def self.expand_noalt_rules(syntax)
      noalt_syms = {}
      syntax.each {|sym, rules|
        if rules.length == 1
          noalt_syms[sym] = true
        end
      }
      result = {}
      syntax.each {|sym, rules|
        rules2 = []
        rules.each {|rhs|
          rhs2 = []
          rhs.each {|e|
            if noalt_syms[e]
              rhs2.concat syntax[e][0]
            else
              rhs2 << e
            end
          }
          rules2 << rhs2
        }
        result[sym] = rules2.uniq
      }
      result
    end

    def self.reorder_rules(syntax)
      result = {}
      syntax.each {|sym, rules|
        result[sym] = rules.sort_by {|rhs|
          [rhs.find_all {|e| Symbol === e }.length, rhs.length]
        }
      }
      result
    end

    def each_tree(sym, limit)
      generate_from_sym(sym, limit) {|_, tree|
        yield tree
      }
      nil
    end

    def each_string(sym, limit)
      generate_from_sym(sym, limit) {|_, tree|
        yield [tree].join('')
      }
      nil
    end

    def generate_from_sym(sym, limit, &b)
      return if limit < 0
      if String === sym
        yield limit, sym
      else
        rules = @syntax[sym]
        raise "undefined rule: #{sym}" if !rules
        rules.each {|rhs|
          if rhs.length == 1 || rules.length == 1
            limit1 = limit
          else
            limit1 = limit-1
          end
          generate_from_rhs(rhs, limit1, &b)
        }
      end
      nil
    end

    def generate_from_rhs(rhs, limit)
      return if limit < 0
      if rhs.empty?
        yield limit, []
      else
        generate_from_sym(rhs[0], limit) {|limit1, child|
          generate_from_rhs(rhs[1..-1], limit1) {|limit2, arr|
            yield limit2, [child, *arr]
          }
        }
      end
      nil
    end
  end
  # :startdoc:

end