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:



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# File 'lib/stupidedi/builder/navigation.rb', line 432

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

#count!(id, *elements) ⇒ Integer

Returns:



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# File 'lib/stupidedi/builder/navigation.rb', line 437

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

#deterministic? ⇒ Boolean

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

Returns:

  • (Boolean) 


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# File 'lib/stupidedi/builder/navigation.rb', line 15

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:



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# File 'lib/stupidedi/builder/navigation.rb', line 67

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:



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# File 'lib/stupidedi/builder/navigation.rb', line 118

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:



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# File 'lib/stupidedi/builder/navigation.rb', line 203

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

#empty? ⇒ Boolean

Returns:

  • (Boolean) 


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

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:



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# File 'lib/stupidedi/builder/navigation.rb', line 414

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:



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# File 'lib/stupidedi/builder/navigation.rb', line 427

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:



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# File 'lib/stupidedi/builder/navigation.rb', line 214

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) 


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# File 'lib/stupidedi/builder/navigation.rb', line 30

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:

Returns:



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# File 'lib/stupidedi/builder/navigation.rb', line 450

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:



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# File 'lib/stupidedi/builder/navigation.rb', line 243

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) 


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# File 'lib/stupidedi/builder/navigation.rb', line 42

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:



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# File 'lib/stupidedi/builder/navigation.rb', line 320

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:



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# File 'lib/stupidedi/builder/navigation.rb', line 276

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:



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# File 'lib/stupidedi/builder/navigation.rb', line 365

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:



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# File 'lib/stupidedi/builder/navigation.rb', line 94

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:



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# File 'lib/stupidedi/builder/navigation.rb', line 108

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:



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# File 'lib/stupidedi/builder/navigation.rb', line 475

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

#successors ⇒ Array<InstructionTable>

Returns:



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# File 'lib/stupidedi/builder/navigation.rb', line 10

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:



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# File 'lib/stupidedi/builder/navigation.rb', line 82

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