Class: Mxrb::Semantic::Extractor

Inherits:
Object
  • Object
show all
Defined in:
lib/mxrb/semantic/extractor.rb

Overview

Extracts a contiguous subgraph of a microflow's activities into a new microflow and replaces the selection with a call to it.

Constant Summary collapse

FLOW_KINDS = 
%i[microflow nanoflow].freeze

Instance Method Summary collapse

Constructor Details

#initialize(project) ⇒ Extractor

Returns a new instance of Extractor.



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# File 'lib/mxrb/semantic/extractor.rb', line 194

def initialize(project)
  @project = project
end

Instance Method Details

#plan(source_name, as:, object_ids:) ⇒ Object

Plan an extraction.

Parameters:

  • source_name (String) —

    qualified name of the source microflow

  • as (String) —

    qualified name for the new extracted microflow

  • object_ids (Array) —

    $ID values of the objects to extract

Raises:

  • (ArgumentError) 


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# File 'lib/mxrb/semantic/extractor.rb', line 203

def plan(source_name, as:, object_ids:)
  source = resolve(source_name)
  raise ArgumentError, "#{source.qualified_name} is not a microflow or nanoflow" \
    unless FLOW_KINDS.include?(source.kind)

  source_module = source.qualified_name.split(".").first
  new_module    = as.split(".").first
  raise ArgumentError, "extracted microflow must be in the same module (#{source_module})" \
    unless new_module == source_module

  raise ArgumentError, "#{as.inspect} already exists" if @project.find_artifact(as)
  raise ArgumentError, "object_ids cannot be empty" if object_ids.empty?

  raw = @project.raw_unit(source.unit_id)
  doc = @project.parse_bson(raw)

  all_objects = parse_array(doc["ObjectCollection"]["Objects"]).map { normalize_ids(_1) }
  all_flows   = parse_array(doc["Flows"]).map { normalize_ids(_1) }
  by_id = all_objects.to_h { [_1["$ID"], _1] }

  selected = Set.new(object_ids.map { IO::BsonCodec.extract_id(_1)&.to_s || _1.to_s })
  missing  = selected - by_id.keys.to_set
  raise ArgumentError, "unknown object IDs: #{missing.to_a.join(', ')}" unless missing.empty?

  # Reject selection of start/end events — those belong to the frame
  all_objects.each do |obj|
    if selected.include?(obj["$ID"]) && %w[
      Microflows$StartEvent Microflows$EndEvent
    ].include?(obj["$Type"])
      raise ArgumentError, "cannot include start/end event in extraction selection"
    end
  end

  inner_flows  = all_flows.select do
    selected.include?(_1["OriginPointer"]) && selected.include?(_1["DestinationPointer"])
  end
  entry_flows  = all_flows.select do
    !selected.include?(_1["OriginPointer"]) && selected.include?(_1["DestinationPointer"])
  end
  exit_flows   = all_flows.select do
    selected.include?(_1["OriginPointer"]) && !selected.include?(_1["DestinationPointer"])
  end

  if entry_flows.size != 1 || exit_flows.size != 1
    raise ArgumentError,
          "selection must have exactly one entry point (found #{entry_flows.size}) " \
          "and one exit point (found #{exit_flows.size})"
  end

  inner_objects = all_objects.select { selected.include?(_1["$ID"]) }

  ExtractionPlan.new(
    project: @project,
    source: source,
    new_name: as,
    selected_ids: selected,
    inner_objects: inner_objects,
    inner_flows: inner_flows,
    entry_flow: entry_flows.first,
    exit_flow: exit_flows.first,
    source_doc: doc,
    source_raw: raw
  )
end