Class: Surus::Hstore::Serializer

Inherits:
Object
  • Object
show all
Defined in:
lib/surus/hstore/serializer.rb

Constant Summary collapse

KEY_VALUE_REGEX = 
%r{
  "
  ((?:[^"\\]|\\.)*)
  "
  =>
  (
    "
    (?:[^"\\]|\\.)*
    "
    |(NULL)
  )
}x

Instance Method Summary collapse

Instance Method Details

#dump(hash) ⇒ Object 



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# File 'lib/surus/hstore/serializer.rb', line 57

def dump(hash)
  return unless hash
  
  key_types = {}
  value_types = {}
  
  stringified_hash = hash.each_with_object({}) do |key_value, stringified_hash|
    key_string, key_type = stringify(key_value[0])
    value_string, value_type = stringify(key_value[1])
    
    stringified_hash[key_string] = value_string
    
    key_types[key_string] = key_type unless key_type == "String"
    value_types[key_string] = value_type unless value_type == "String"
  end

  # Use YAML for recording types as it is much simpler than trying to
  # handle all the special characters that could be in a key or value
  # and encoding them again to fit into one string. Let YAML handle all
  # the mess for us.
  stringified_hash["__key_types"] = YAML.dump(key_types) if key_types.present?
  stringified_hash["__value_types"] = YAML.dump(value_types) if value_types.present?
  
  stringified_hash.map do |key, value|
    "#{format_key(key)}=>#{format_value(value)}"
  end.join(", ")
end

#escape(value) ⇒ Object

Escape a value for use as a key or value in an hstore



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# File 'lib/surus/hstore/serializer.rb', line 94

def escape(value)
  value
    .gsub('\\', '\\\\\\')
    .gsub('"', '\\"')
end

#format_key(key) ⇒ Object 



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# File 'lib/surus/hstore/serializer.rb', line 85

def format_key(key)
  %Q("#{escape(key)}")
end

#format_value(value) ⇒ Object 



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# File 'lib/surus/hstore/serializer.rb', line 89

def format_value(value)
  value ? %Q("#{escape(value)}") : "NULL"
end

#load(string) ⇒ Object 



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# File 'lib/surus/hstore/serializer.rb', line 17

def load(string)
  return unless string
  stringified_hash = string.scan(KEY_VALUE_REGEX).each_with_object({}) do |key_value, hash|
    key, value = key_value
    key = unescape(key)
    value = if value == "NULL"
      nil
    else
      unescape(value[1..-2])
    end
    
    hash[key] = value
  end

  key_types = stringified_hash.delete "__key_types"
  key_types = YAML.load key_types if key_types
  value_types = stringified_hash.delete "__value_types"
  value_types = YAML.load value_types if value_types
  
  return stringified_hash unless key_types || value_types
  
  stringified_hash.each_with_object({}) do |key_value, hash|
    string_key, string_value = key_value
    
    key = if key_types && key_types.key?(string_key) 
      typecast(string_key, key_types[string_key])
    else
      string_key
    end
    
    value = if value_types && value_types.key?(string_key)
      typecast(string_value, value_types[string_key])
    else
      string_value
    end
    
    hash[key] = value
  end    
end

#stringify(value) ⇒ Object

Returns an array of value as a string and value type



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# File 'lib/surus/hstore/serializer.rb', line 108

def stringify(value)
  if value.kind_of?(String)
    [value, "String"]
  elsif value.kind_of?(Symbol)
    [value.to_s, "Symbol"]
  elsif value.kind_of?(Integer)
    [value.to_s, "Integer"]
  elsif value.kind_of?(Float)
    [value.to_s, "Float"]
  elsif value.kind_of?(BigDecimal)
    [value.to_s, "BigDecimal"]
  elsif value.kind_of?(Date)
    [value.to_s(:db), "Date"]
  elsif value.kind_of?(TrueClass)
    [value.to_s, "TrueClass"]
  elsif value.kind_of?(FalseClass)
    [value.to_s, "FalseClass"]
  elsif value == nil
    [nil, "String"] # we don't actually stringify nil because format_value special cases nil
  else
    [YAML.dump(value), "YAML"]
  end  
end

#typecast(value, type) ⇒ Object 



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# File 'lib/surus/hstore/serializer.rb', line 132

def typecast(value, type)
  case type
  when "Symbol"
    value.to_sym
  when "Integer"
    Integer(value)
  when "Float"
    Float(value)
  when "BigDecimal"
    BigDecimal(value)
  when "Date"
    Date.parse(value)
  when "TrueClass"
    true
  when "FalseClass"
    false
  when "YAML"
    YAML.load(value)
  else
    raise ArgumentError, "Can't typecast: #{type}"
  end
end

#unescape(value) ⇒ Object

Unescape a value from a key or value in an hstore



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# File 'lib/surus/hstore/serializer.rb', line 101

def unescape(value)
  value
    .gsub('\\\\', '\\')
    .gsub('\\"', '"')
end