Module: Collapsium::PrototypeMatch

Included in:
UberHash
Defined in:
lib/collapsium/prototype_match.rb

Overview

Provides prototype matching for Hashes. See #prototype_match

Instance Method Summary collapse

Instance Method Details

#prototype_match(prototype, strict = false) ⇒ Boolean

Given a prototype Hash, returns true if (recursively):

  • this hash contains all the prototype’s keys, and

  • this hash contains all the prototype’s values

Note that this is not the same as equality. If the prototype provides a nil value for any key, then any value in this Hash is considered to be valid.

Parameters:

  • prototype (Hash) —

    The prototype to match against.

  • strict (Boolean) (defaults to: false) —

    If true, this Hash may not contain keys that are not present in the prototype.

Returns:

  • (Boolean) —

    True if matching succeeds, false otherwise.



25
26
27
28
29
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
 
# File 'lib/collapsium/prototype_match.rb', line 25

def prototype_match(prototype, strict = false)
  # Prototype contains keys not in the Hash,so that's a failure.
  if not (prototype.keys - keys).empty?
    return false
  end

  # In strict evaluation, the Hash may also not contain keys that are not
  # in the prototoype.
  if strict and not (keys - prototype.keys).empty?
    return false
  end

  # Now we have to examine the prototype's values.
  prototype.each do |key, value|
    # We can skip any nil values in the prototype. They exist only to ensure
    # the key is present.
    if value.nil?
      next
    end

    # If the prototype value is a Hash, then the Hash value also has to be,
    # and we have to recurse into this Hash.
    if value.is_a?(Hash)
      if not self[key].is_a?(Hash)
        return false
      end

      self[key].extend(PrototypeMatch)
      if not self[key].prototype_match(value)
        return false
      end

      next
    end

    # Otherwise the prototype value must be equal to the Hash's value
    if self[key] != value
      return false
    end
  end

  # All other cases must be true.
  return true
end