Method: Janeway::Functions#parse_function_length

Defined in:
lib/janeway/functions/length.rb

#parse_function_length ⇒ Object

The length() function extension provides a way to compute the length of a value and make that available for further processing in the filter expression:

JSONPath return type: ValueType



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# File 'lib/janeway/functions/length.rb', line 10

def parse_function_length
  consume # function
  raise "expect group_start token, found #{current}" unless current.type == :group_start

  consume # (

  # Read parameter
  arg = parse_function_parameter
  parameters = [arg]
  unless arg.singular_query? || arg.literal?
    raise Error, "Invalid parameter - length() expects literal value or singular query, got #{arg.value.inspect}"
  end
  raise err('Too many parameters for length() function call') unless current.type == :group_end

  # Meaning of return value depends on the JSON type:
  #   * string - number of Unicode scalar values in the string.
  #   * array -  number of elements in the array.
  #   * object - number of members in the object.
  # For any other argument value, the result is the special result Nothing.
  AST::Function.new('length', parameters) do |value|
    if [Array, Hash, String].include?(value.class)
      value.size
    else
      :nothing
    end
  end
end