Module: Stupidedi::Builder::Navigation

Included in:
StateMachine
Defined in:
lib/stupidedi/builder/navigation.rb

Querying the Current Position collapse

Accessing the Current Node collapse

Navigating the Tree collapse

Instance Method Details

#count(id, *elements) ⇒ Integer

Returns:

  • (Integer) 


434
435
436
 
# File 'lib/stupidedi/builder/navigation.rb', line 434

def count(id, *elements)
  __count(false, id, elements)
end

#count!(id, *elements) ⇒ Integer

Returns:

  • (Integer) 


439
440
441
 
# File 'lib/stupidedi/builder/navigation.rb', line 439

def count!(id, *elements)
  __count(true, id, elements)
end

#deterministic? ⇒ Boolean

Is there exactly one valid parse tree in the current state?

Returns:

  • (Boolean) 


17
18
19
 
# File 'lib/stupidedi/builder/navigation.rb', line 17

def deterministic?
  @active.length == 1
end

#distance(other) ⇒ Either<Integer>

Note:

This method uses AbstractCursor#between, which assumes the two cursors point to the same tree. If that is not the case, the results are undefined.

Returns the number of segments apart the current state is from the given ‘StateMachine`’s state. Note the direction is not indicated by the return value, so ‘a.distance(b) == b.distance(a)` for all states `a` and `b`.

Examples:

m.distance(m)                          #=> Either.success(0)
m.next(10).flatmap{|n| n.distance(m) } #=> Either.success(10)

Returns:



69
70
71
72
73
74
75
 
# File 'lib/stupidedi/builder/navigation.rb', line 69

def distance(other)
  zipper.flatmap do |a|
    other.zipper.map do |b|
      a.between(b).count(&:segment?) - 1
    end
  end
end

#element(m, n = nil, o = nil) ⇒ Either<Zipper::AbstractCursor<Values::AbstractElementVal>>

Extracts the mth element from the current segment, if the current state is deterministic. Accepts optional arguments to extract a specific occurrence of a repeated element and/or a specific component from a composite element.

Returns:



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
 
# File 'lib/stupidedi/builder/navigation.rb', line 120

def element(m, n = nil, o = nil)
  segment.flatmap do |s|
    unless m >= 1
      raise ArgumentError,
        "argument must be positive"
    end

    if s.node.invalid?
      # InvalidSegmentVal doesn't have child AbstractElementVals, its
      # children are SimpleElementTok, CompositeElementTok, etc, which
      # are not parsed values.
      return Either.failure("invalid segment")
    end

    designator = s.node.id.to_s
    definition = s.node.definition
    length     = definition.element_uses.length

    unless m <= length
      raise ArgumentError,
        "#{designator} segment has only #{length} elements"
    end

    designator << "%02d" % m
    value       = s.child(m - 1)

    if n.nil?
      return Either.success(value)
    elsif value.node.repeated?
      unless n >= 1
        raise ArgumentError,
          "argument must be positive"
      end

      limit = value.node.usage.repeat_count
      unless limit.include?(n)
        raise ArgumentError,
          "#{designator} can only occur #{limit.max} times"
      end

      unless value.node.children.defined_at?(n - 1)
        return Either.failure("#{designator} occurs only #{value.node.children.length} times")
      end

      value = value.child(n - 1)
      n, o  = o, nil

      return Either.success(value) if n.nil?
    end

    unless value.node.composite?
      raise ArgumentError,
        "#{designator} is a simple element"
    end

    unless o.nil?
      raise ArgumentError,
        "#{designator} is a non-repeatable composite element"
    end

    unless n >= 1
      raise ArgumentError,
        "argument must be positive"
    end

    length = definition.element_uses.at(m - 1).definition.component_uses.length
    unless n <= length
      raise ArgumentError,
        "#{designator} has only #{length} components"
    end

    if value.node.empty?
      Either.failure("#{designator} is empty")
    else
      Either.success(value.child(n - 1))
    end
  end
end

#elementn(m, n = nil, o = nil) ⇒ Either<Values::AbstractElementVal>

Extracts the mth element from the current segment, if the current state is deterministic. Accepts optional arguments to extract a specific occurrence of a repeated element and/or a specific component from a composite element.

Returns:



205
206
207
 
# File 'lib/stupidedi/builder/navigation.rb', line 205

def elementn(m, n = nil, o = nil)
  element(m, n, o).map(&:node)
end

#empty? ⇒ Boolean

Returns:

  • (Boolean) 


21
22
23
24
25
26
27
28
29
 
# File 'lib/stupidedi/builder/navigation.rb', line 21

def empty?
  value = @active.head.node.zipper

  until value.root?
    value = value.up
  end

  value.node.children.empty?
end

#find(id, *elements) ⇒ Either<StateMachine>

Returns a ‘StateMachine` positioned on the next matching segment, excluding Values::InvalidSegmentVals, that satisfies the given element constraints. The search space is limited to certain related elements described in [Navigating.md]

Examples:

machine.find(:ST, nil, nil, "005010X222")

Returns:



416
417
418
 
# File 'lib/stupidedi/builder/navigation.rb', line 416

def find(id, *elements)
  __find(false, id, elements)
end

#find!(id, *elements) ⇒ Either<StateMachine>

Returns a ‘StateMachine` positioned on the next matching segment, including Values::InvalidSegmentVals, that satisfies the given element constraints. The search space is limited to certain related elements described in [Navigating.md]

Examples:

machine.find!(:ST, nil, nil, "005010X222")

Returns:



429
430
431
 
# File 'lib/stupidedi/builder/navigation.rb', line 429

def find!(id, *elements)
  __find(true, id, elements)
end

#first ⇒ Either<StateMachine>

Returns a new ‘StateMachine` positioned on the first segment in the parse tree, if there are any segments in the parse tree.

Returns:



216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
 
# File 'lib/stupidedi/builder/navigation.rb', line 216

def first
  active = roots.map do |zipper|
    state = zipper
    value = zipper.node.zipper

    until value.node.segment? or value.leaf?
      value = value.down
      state = state.down
    end

    unless value.node.segment?
      return Either.failure("no segments")
    end

    # Synchronize the two parallel state and value nodes
    unless value.eql?(state.node.zipper)
      state = state.replace(state.node.copy(:zipper => value))
    end

    state
  end

  Either.success(StateMachine.new(@config, active))
end

#first? ⇒ Boolean

Is this the first segment?

Returns:

  • (Boolean) 


32
33
34
35
36
37
38
39
40
41
 
# File 'lib/stupidedi/builder/navigation.rb', line 32

def first?
  value = @active.head.node.zipper

  until value.root?
    return false unless value.first?
    value = value.up
  end

  return true
end

#iterate(id, *elements) {|| ... } ⇒ Either<Array<Object>>

Convenience method to iterate repeated occurrences of a segment by iteratively calling ‘find`. Beware this doesn’t check that the segment is allowed to repeat, so calling ‘iterate(:XYZ)` may yield an `XYZ` segment and then throw an exception when searching for the second, if `XYZ` is not repeatable.

Yield Parameters:

Yield Returns:

  • (Object)

Returns:



452
453
454
455
456
457
458
459
460
461
462
463
464
465
 
# File 'lib/stupidedi/builder/navigation.rb', line 452

def iterate(id, *elements)
  a = []
  m = find(id, *elements)
  return m unless m.defined?

  while m.defined?
    m = m.flatmap do |n|
      a << yield(n)
      n.find(id, *elements)
    end
  end

  Either.success(a)
end

#last ⇒ Either<StateMachine>

Returns a new ‘StateMachine` positioned on the last segment in the parse tree, if there are any segments in the parse tree.

Returns:



245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
 
# File 'lib/stupidedi/builder/navigation.rb', line 245

def last
  active = roots.map do |zipper|
    state = zipper
    value = zipper.node.zipper

    until value.node.segment? or value.leaf?
      value = value.down.last
      state = state.down.last
    end

    unless value.node.segment?
      return Either.failure("no segments")
    end

    # Synchronize the two parallel state and value nodes
    unless value.eql?(state.node.zipper)
      state = state.replace(state.node.copy(:zipper => value))
    end

    state
  end

  Either.success(StateMachine.new(@config, active))
end

#last? ⇒ Boolean

Is this the last segment?

Returns:

  • (Boolean) 


44
45
46
47
48
49
50
51
52
53
 
# File 'lib/stupidedi/builder/navigation.rb', line 44

def last?
  value = @active.head.node.zipper

  until value.root?
    return false unless value.last?
    value = value.up
  end

  return true
end

#next(count = 1) ⇒ Either<StateMachine>

Returns a new ‘StateMachine` positioned on the next segment, if there is a next segment. Optionally, a `count` argument may be provided that indicates how many segments to advance.

Returns:



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
 
# File 'lib/stupidedi/builder/navigation.rb', line 322

def next(count = 1)
  unless count > 0
    raise ArgumentError,
      "count must be positive"
  end

  active = @active.map do |zipper|
    state = zipper
    value = zipper.node.zipper

    count.times do
      while not value.root? and value.last?
        value = value.up
        state = state.up
      end

      if value.root?
        return Either.failure("cannot move to next after last segment")
      end

      value = value.next
      state = state.next

      until value.node.segment?
        value = value.down
        state = state.down
      end
    end

    # Synchronize the two parallel state and value nodes
    unless value.eql?(state.node.zipper)
      state = state.replace(state.node.copy(:zipper => value))
    end

    state
  end

  Either.success(StateMachine.new(@config, active))
end

#parent ⇒ Either<StateMachine>

Returns a new ‘StateMachine` positioned on the first segment of the parent structure. For example, when the current segment belongs to a loop but it’s not the first segment in that loop, this method will rewind to the first segment in the loop. If the current position is the first segment of a loop, this method will rewind to the first segment in the loop’s parent structure.

Returns:



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
 
# File 'lib/stupidedi/builder/navigation.rb', line 278

def parent
  active = []

  @active.each do |zipper|
    state = zipper
    value = zipper.node.zipper

    while value.first? and not value.root?
      value = value.up
      state = state.up
    end

    if value.root?
      break
    end

    value = value.first
    state = state.first

    until value.node.segment?
      value = value.down
      state = state.down
    end

    # Synchronize the two parallel state and value nodes
    unless value.eql?(state.node.zipper)
      state = state.replace(state.node.copy(:zipper => value))
    end

    active << state
  end

  if active.empty?
    Either.failure("no parent segment")
  else
    Either.success(StateMachine.new(@config, active))
  end
end

#prev(count = 1) ⇒ Either<StateMachine>

Returns a new ‘StateMachine` positioned on the previous segment, if there is a previous segment. Optionally, a `count` argument may be provided that indicates how many segments to rewind.

Returns:



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
 
# File 'lib/stupidedi/builder/navigation.rb', line 367

def prev(count = 1)
  unless count > 0
    raise ArgumentError,
      "count must be positive"
  end

  active = @active.map do |zipper|
    state = zipper
    value = zipper.node.zipper

    count.times do
      while not value.root? and value.first?
        value = value.up
        state = state.up
      end

      if value.root?
        return Either.failure("cannot move to prev before first segment")
      end

      state = state.prev
      value = value.prev

      until value.node.segment?
        value = value.down.last
        state = state.down.last
      end
    end

    # Synchronize the two parallel state and value nodes
    unless value.eql?(state.node.zipper)
      state = state.replace(state.node.copy(:zipper => value))
    end

    state
  end

  Either.success(StateMachine.new(@config, active))
end

#segment ⇒ Either<Zipper::AbstractCursor<Values::SegmentVal>>

Extracts the segment from the current state, if the current state is deterministic and positioned on a segment.

Returns:



96
97
98
99
100
101
102
103
104
 
# File 'lib/stupidedi/builder/navigation.rb', line 96

def segment
  zipper.flatmap do |z|
    if z.node.segment?
      Either.success(z)
    else
      Either.failure("not a segment")
    end
  end
end

#segmentn ⇒ Either<Values::SegmentVal>

Extracts the segment from the current state, if the current state is deterministic and positioned on a segment.

Returns:



110
111
112
 
# File 'lib/stupidedi/builder/navigation.rb', line 110

def segmentn
  segment.map(&:node)
end

#sequence(pattern, *patterns) ⇒ Either<StateMachine>

Sequence multiple traversals together, by iteratively calling ‘find`. Each argument must be either a single segment ID or a list whose first element is a segment ID and remaining elements are segment constraints.

Examples:

machine.sequence(:GS, :ST, :HL)
machine.sequence(:GS, [:ST, "837"], [:HL, nil, "20"])

Returns:



477
478
479
480
481
 
# File 'lib/stupidedi/builder/navigation.rb', line 477

def sequence(pattern, *patterns)
  patterns.inject(find(*pattern)) do |m, p|
    m = m.flatmap{|n| n.find(*p) }
  end
end

#successors ⇒ Array<InstructionTable>

Returns:



12
13
14
 
# File 'lib/stupidedi/builder/navigation.rb', line 12

def successors
  @active.map{|a| a.node.instructions }
end

#zipper ⇒ Either<Zipper::AbstractCursor<Values::AbstractVal>>

Returns the current position within the parse tree, if the current state is deterministic.

Returns:



84
85
86
87
88
89
90
 
# File 'lib/stupidedi/builder/navigation.rb', line 84

def zipper
  if deterministic?
    Either.success(@active.head.node.zipper)
  else
    Either.failure("non-deterministic state")
  end
end