Module: Upkeep::Subscriptions::JsonSnapshot

Defined in:
lib/upkeep/subscriptions/json_snapshot.rb

Constant Summary collapse

VERSION = 
2
VERSION_KEY = 
"__upkeep_snapshot_version"
VALUE_KEY = 
"value"
SYMBOL_VALUE_KEY = 
"$sym"
SYMBOL_KEY_PREFIX = 
"$sym:"
STRING_KEY_PREFIX = 
"$str:"
JSON_KEY_PREFIX = 
"$json:"
RESERVED_STRING_KEYS = 
[SYMBOL_VALUE_KEY].freeze
RESERVED_STRING_KEY_PREFIXES = 
[SYMBOL_KEY_PREFIX, STRING_KEY_PREFIX, JSON_KEY_PREFIX].freeze

Class Method Summary collapse

Class Method Details

.decode(value) ⇒ Object 



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# File 'lib/upkeep/subscriptions/json_snapshot.rb', line 52

def decode(value)
  case value
  when Hash
    return value.fetch(SYMBOL_VALUE_KEY).to_sym if value.size == 1 && value.key?(SYMBOL_VALUE_KEY)

    value.each_with_object({}) do |(key, nested_value), decoded|
      decoded[decode_key(key)] = decode(nested_value)
    end
  when Array
    value.map { |nested_value| decode(nested_value) }
  else
    value
  end
end

.decode_key(key) ⇒ Object 



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# File 'lib/upkeep/subscriptions/json_snapshot.rb', line 80

def decode_key(key)
  if key.start_with?(SYMBOL_KEY_PREFIX)
    key.delete_prefix(SYMBOL_KEY_PREFIX).to_sym
  elsif key.start_with?(STRING_KEY_PREFIX)
    key.delete_prefix(STRING_KEY_PREFIX)
  elsif key.start_with?(JSON_KEY_PREFIX)
    decode(JSON.parse(key.delete_prefix(JSON_KEY_PREFIX)))
  else
    key
  end
end

.dump(value) ⇒ Object 



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# File 'lib/upkeep/subscriptions/json_snapshot.rb', line 20

def dump(value)
  {
    VERSION_KEY => VERSION,
    VALUE_KEY => encode(value)
  }
end

.encode(value) ⇒ Object 



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# File 'lib/upkeep/subscriptions/json_snapshot.rb', line 37

def encode(value)
  case value
  when Symbol
    { SYMBOL_VALUE_KEY => value.to_s }
  when Hash
    value.each_with_object({}) { |(key, nested_value), encoded| encoded[encode_key(key)] = encode(nested_value) }
  when Array
    value.map { |nested_value| encode(nested_value) }
  when nil, true, false, Numeric, String
    value
  else
    raise TypeError, "cannot persist #{value.class.name} in an Upkeep JSON snapshot"
  end
end

.encode_key(key) ⇒ Object 



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# File 'lib/upkeep/subscriptions/json_snapshot.rb', line 67

def encode_key(key)
  case key
  when Symbol
    "#{SYMBOL_KEY_PREFIX}#{key}"
  when String
    reserved_string_key?(key) ? "#{STRING_KEY_PREFIX}#{key}" : key
  when nil, true, false, Numeric
    "#{JSON_KEY_PREFIX}#{JSON.generate(encode(key))}"
  else
    raise TypeError, "cannot persist #{key.class.name} as an Upkeep JSON snapshot key"
  end
end

.load(snapshot) ⇒ Object 



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# File 'lib/upkeep/subscriptions/json_snapshot.rb', line 27

def load(snapshot)
  snapshot = JSON.parse(snapshot) if snapshot.is_a?(String)
  version = snapshot.fetch(VERSION_KEY)
  unless version.to_i == VERSION
    raise ArgumentError, "unsupported Upkeep JSON snapshot version: #{version.inspect}"
  end

  decode(snapshot.fetch(VALUE_KEY))
end

.reserved_string_key?(key) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/upkeep/subscriptions/json_snapshot.rb', line 92

def reserved_string_key?(key)
  RESERVED_STRING_KEYS.include?(key) || RESERVED_STRING_KEY_PREFIXES.any? { |prefix| key.start_with?(prefix) }
end