Class: Stupidedi::Builder::ConstraintTable::ValueBased

Inherits:
Stupidedi::Builder::ConstraintTable show all
Defined in:
lib/stupidedi/builder/constraint_table.rb

Overview

Chooses the subset of Instruction values based on the distinguishing values allowed by each Schema::SegmentUse. For instance, there are often several loops that begin with ‘NM1`, which are distinguished by the qualifier in element `NM101`.

Instance Method Summary collapse

Methods inherited from Stupidedi::Builder::ConstraintTable

build

Constructor Details

#initialize(instructions) ⇒ ValueBased

Returns a new instance of ValueBased.



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# File 'lib/stupidedi/builder/constraint_table.rb', line 100

def initialize(instructions)
  @instructions = instructions
end

Instance Method Details

#matches(segment_tok, strict) ⇒ Array<Instruction>

Returns:



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# File 'lib/stupidedi/builder/constraint_table.rb', line 105

def matches(segment_tok, strict)
  invalid = true  # Were all possibly distinguishing elements invalid?
  present = false # Were any possibly distinguishing elements present?

  @__basis ||= basis(shallowest(@instructions))
  @__basis.head.each do |(n, m), map|
    value = deconstruct(segment_tok.element_toks, n, m)

    case value
    when nil, :not_used, :default
      # ignore
    else
      singleton = map.at(value)
      present   = true

      unless singleton.nil?
        return singleton
      else
        if strict
          designator = "#{segment_tok.id}#{'%02d' % (n + 1)}"
          designator << "-%02d" % m unless m.nil?

          raise ArgumentError,
            "#{value.inspect} is not allowed in #{designator}"
        end
      end
    end
  end

  # If we reach this line, none of the present elements could, on its
  # own, narrow the search space to a single Instruction. We now test
  # the combination of elements to iteratively narrow the search space
  space = @instructions

  # @todo: These filters should be ordered by probable effectiveness,
  # so we narrow the search space by the largest amount in the fewest
  # number of steps.
  @__basis.last.each do |(n, m), map|
    value = deconstruct(segment_tok.element_toks, n, m)

    unless value.nil?
      subset  = map.at(value)
      present = true

      unless subset.blank?
        invalid = false
        space  &= subset

        if space.length <= 1
          return space
        end
      else
        if strict
          designator = "#{segment_tok.id}#{'%02d' % n}"
          designator << "-%02d" % m unless m.nil?

          raise ArgumentError,
            "#{value.inspect} is not allowed in #{designator}"
        end
      end
    end
  end

  if invalid and present
    []
  else
    space
  end
end