Module: DataModel::Scanner

Extended by:
Scanner
Includes:
Logging
Included in:
Scanner
Defined in:
lib/data_model/scanner.rb

Overview

The scanner is responsible for scanning a schema into a data structure that is easier to work with.

schema eg: [:string, { min: 1, max: 10}] [:tuple, { title: “coordinates” }, :double, :double] [:hash, { open: false }, [:first_name, :string] [:last_name, :string]]

first param is type, which is a key lookup in the registry second param is args, this is optional, but is a way to configure a type rest are type params. these are used to configure a type at the point of instantiation. Think of them as generics.

params are either symbol, for example tuple types

array, for object types to configure child properties.

Defined Under Namespace

Classes: Node

Instance Method Summary collapse

Methods included from Logging

#log

Instance Method Details

#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.



30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
 
# 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