Module: Stupidedi::Parser::Navigation

Included in:
StateMachine
Defined in:
lib/stupidedi/parser/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)

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# File 'lib/stupidedi/parser/navigation.rb', line 488

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

#count!(id, *elements) ⇒ Integer

Returns:

  • (Integer)

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# File 'lib/stupidedi/parser/navigation.rb', line 493

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/parser/navigation.rb', line 16

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/parser/navigation.rb', line 68

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.


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# File 'lib/stupidedi/parser/navigation.rb', line 119

def element(m, n = nil, o = nil)
  if m <= 0 or (n || 1) <= 0 or (o || 1) <= 0
    raise ArgumentError,
      "all arguments must be positive"
  end

  if n.nil? and not o.nil?
    raise ArgumentError,
      "third argument cannot be present unless second argument is present"
  end

  segment.flatmap do |s|
    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

    segment_id  = s.node.id.to_s
    segment_def = s.node.definition
    descriptor  = segment_id

    unless m <= segment_def.element_uses.length
      raise ArgumentError,
        "segment #{descriptor} has only #{segment_def.element_uses.length} elements"
    end

    element_use = segment_def.element_uses.at(m - 1)
    element_def = element_use.definition
    element_zip = s.child(m - 1)

    if n.nil?
      return Either.success(element_zip)

    elsif element_use.composite? and not element_use.repeatable?
      # m: element   of segment
      # n: component of composite element
      # o: occurence of repeated component (commented-out below)
      descriptor = "%s%02d" % [segment_id, m]
      components = element_def.component_uses.length
      unless n <= components
        raise ArgumentError,
          "composite element #{descriptor} only has #{components} components"
      end

      # component_use = element_def.component_uses.at(n - 1)

      if o.nil?
        if element_zip.node.blank?
          Either.failure("#{descriptor} is empty")
        else
          # This is a component of a composite element
          Either.success(element_zip.child(n - 1))
        end

      # @todo: There currently doesn't seem to be any instances of this in
      # the real world (a composite element that has a component that can
      # repeat), but perhaps this will happen in the future.
      #
      # elsif component_use.repeatable?
      #   repeat_count = component_use.repeat_count
      #   occurs_count = component_val.children.length
      #   descriptor   = "%s%02d-%02d" % [segment_id, m, n]
      #   unless repeat_count.include?(o)
      #     raise ArgumentError,
      #       "repeatable component element #{descriptor} can only occur #{repeat_count.max} times"
      #   end
      #   component_zip = element_zip.child(n - 1)
      #   if component_zip.node.blank?
      #     return Either.failure("repeating component element #{descriptor} is blank")
      #   elsif occurs_count < n
      #     return Either.failure("repeating component element #{descriptor} only occurs #{occurs_count} times")
      #   else
      #     return Either.success(component_zip.child(o - 1))
      #   end

      else
        descriptor = "%s%02d-%02d" % [segment_id, m, n]
        raise ArgumentError,
          "component element #{descriptor} cannot be further deconstructed"
      end

    elsif element_use.repeatable?
      # m: element   of segment
      # n: occurence of repeated element
      # o: component of composite element
      descriptor   = "%s%02d" % [segment_id, m]
      occurs_count = element_zip.children.count
      unless element_use.repeat_count.include?(n)
        raise ArgumentError,
          "repeatable element #{descriptor} can only occur #{element_use.repeat_count.max} times"
      end

      if o.nil?
        description = (element_use.composite?) ? "repeatable composite" : "repeatable"
        if element_zip.node.blank?
          Either.failure("#{description} element #{descriptor} does not occur")
        elsif occurs_count < n
          Either.failure("#{description} element #{descriptor} only occurs #{occurs_count} times")
        else
          Either.success(element_zip.child(n - 1))
        end

      elsif element_use.composite?
        components = element_def.component_uses.length
        unless o <= components
          raise ArgumentError,
            "repeatable composite element #{descriptor} only has #{components} components"
        end

        descriptor = "%s%02d" % [segment_id, m]

        if element_zip.node.blank?
          Either.failure("repeatable composite element #{descriptor} does not occur")
        elsif occurs_count < n
          Either.failure("repeatable composite element #{descriptor} only occurs #{occurs_count} times")
        else
          component_zip = element_zip.children.at(n - 1)
          Either.success(component_zip.child(o - 1))
        end

      else
        raise ArgumentError,
          "repeatable element #{descriptor} cannot be further deconstructed"
      end

    else
      raise ArgumentError,
        "#{segment_id}#{"%02d" % m} is not a composite or repeated element"
    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.


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# File 'lib/stupidedi/parser/navigation.rb', line 259

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/parser/navigation.rb', line 20

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/parser/navigation.rb', line 470

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/parser/navigation.rb', line 483

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

#firstEither<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/parser/navigation.rb', line 270

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/parser/navigation.rb', line 31

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:


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# File 'lib/stupidedi/parser/navigation.rb', line 506

def iterate(id, *elements)
  a = []
  m = __find(false, id, elements, true)
  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

#lastEither<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/parser/navigation.rb', line 299

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/parser/navigation.rb', line 43

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/parser/navigation.rb', line 376

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

#parentEither<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/parser/navigation.rb', line 332

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/parser/navigation.rb', line 421

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

#segmentEither<Zipper::AbstractCursor<Values::SegmentVal>>

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


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# File 'lib/stupidedi/parser/navigation.rb', line 95

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

#segmentnEither<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/parser/navigation.rb', line 109

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/parser/navigation.rb', line 531

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

#successorsArray<InstructionTable>

Returns:


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# File 'lib/stupidedi/parser/navigation.rb', line 11

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

#zipperEither<Zipper::AbstractCursor<Values::AbstractVal>>

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


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# File 'lib/stupidedi/parser/navigation.rb', line 83

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