Method: DataModel::Scanner#scan

Defined in:
lib/data_model/scanner.rb

#scan(schema, registry = Registry.instance) ⇒ Node

Scan a schema, which is defined as a data structure, into a struct that is easier to work with. “Syntax” validations will be enforced at this level.

Parameters:

  • schema (Array) —

    the schema to scan

  • registry (Registry) (defaults to: Registry.instance) —

    the registry to use

Returns:

  • (Node) —

    the scanned node



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# File 'lib/data_model/scanner.rb', line 30

def scan(schema, registry = Registry.instance)
  # state:
  #  nil (start) -> :type (we have a type) -> :args (we have arguments)
  scanned = Node.new
  state = nil

  log.debug("scanning schema: #{schema.inspect}")

  for pos in (0...schema.length)
    token = schema[pos]
    dbg = "pos: #{pos}, token: #{token.inspect}, state: #{state.inspect}"
    log.debug(dbg)

    # detect optional args missing
    if !token.is_a?(Hash) && state == :type
      log.debug("detected optional args missing at (#{dbg}), moving state to :args")

      # move state forward
      state = :args
    end

    # we are just collecting params at this point
    if state == :args

      if !token.is_a?(Array) && !token.is_a?(Symbol)
        raise "expected type params at (#{dbg}), which should be either a symbol or an array"
      end

      scanned.params ||= []
      scanned.params << token
      log.debug("collecting params at (#{dbg})")

      next
    end

    # we can determine meaning based on type and state
    case token
    when Symbol
      if !state.nil?
        raise "got a symbol at(#{dbg}), but validator already defined"
      end

      if !registry.type?(token)
        # TODO: need a much better error here, this is what people see when registration is not there
        raise "expected a type in (#{dbg}), but found #{token.inspect} which is not a registered type"
      end

      scanned.type = token
      state = :type
      log.debug("got a symbol, determined token is a type at (#{dbg}), moving state to :type")

    when Hash
      if state != :type
        raise "got a hash at (#{dbg}), but state is not :type (#{state.inspect})"
      end

      scanned.args = token
      state = :args
      log.debug("got a hash, determined token is args at (#{dbg}), moving state to :args")

    else
      raise "got token #{token.inspect} at (#{dbg}) which was unexpected given the scanner was in a state of #{state}"
    end
  end

  return scanned
end