class GraphQL::StaticValidation::LiteralValidator

Test whether ‘ast_value` is a valid input for `type`

def constant_scalar?(ast_value)

doesn't support it so we won't either for simplicity
The GraphQL grammar supports variables embedded within scalars but graphql.js 
def constant_scalar?(ast_value)
  if ast_value.is_a?(GraphQL::Language::Nodes::VariableIdentifier)
    false
  elsif ast_value.is_a?(Array)
    ast_value.all? { |element| constant_scalar?(element) }
  elsif ast_value.is_a?(GraphQL::Language::Nodes::InputObject)
    ast_value.arguments.all? { |arg| constant_scalar?(arg.value) }
  else
    true
  end
end

def ensure_array(value) 

def ensure_array(value)
  value.is_a?(Array) ? value : [value]
end

def initialize(context:) 

def initialize(context:)
  @context = context
  @warden = context.warden
  @invalid_response = GraphQL::Query::InputValidationResult.new(valid: false, problems: [])
  @valid_response = GraphQL::Query::InputValidationResult.new(valid: true, problems: [])
end

def maybe_raise_if_invalid(ast_value)

Use `throw` to escape the current call stack, returning the invalid response.
When `error_bubbling` is false, we want to bail on the first failure that we find. 
def maybe_raise_if_invalid(ast_value)
  ret = yield
  if !@context.schema.error_bubbling && !ret.valid?
    throw(:invalid, ret)
  else
    ret
  end
end

def merge_results(results_list) 

def merge_results(results_list)
  merged_result = Query::InputValidationResult.new
  results_list.each do |inner_result|
    merged_result.merge_result!([], inner_result)
  end
  merged_result
end

def present_input_field_values_are_valid(type, ast_node) 

def present_input_field_values_are_valid(type, ast_node)
  results = ast_node.arguments.map do |value|
    field = @warden.get_argument(type, value.name)
    # we want to call validate on an argument even if it's an invalid one
    # so that our raise exception is on it instead of the entire InputObject
    field_type = field && field.type
    recursively_validate(value.value, field_type)
  end
  merge_results(results)
end

def recursively_validate(ast_value, type) 

def recursively_validate(ast_value, type)
  if type.nil?
    # this means we're an undefined argument, see #present_input_field_values_are_valid
    maybe_raise_if_invalid(ast_value) do
      @invalid_response
    end
  elsif ast_value.is_a?(GraphQL::Language::Nodes::NullValue)
    maybe_raise_if_invalid(ast_value) do
      type.kind.non_null? ? @invalid_response : @valid_response
    end
  elsif type.kind.non_null?
    maybe_raise_if_invalid(ast_value) do
      ast_value.nil? ?
        @invalid_response :
        recursively_validate(ast_value, type.of_type)
    end
  elsif type.kind.list?
    item_type = type.of_type
    results = ensure_array(ast_value).map { |val| recursively_validate(val, item_type) }
    merge_results(results)
  elsif ast_value.is_a?(GraphQL::Language::Nodes::VariableIdentifier)
    @valid_response
  elsif type.kind.scalar? && constant_scalar?(ast_value)
    maybe_raise_if_invalid(ast_value) do
      type.validate_input(ast_value, @context)
    end
  elsif type.kind.enum?
    maybe_raise_if_invalid(ast_value) do
      if ast_value.is_a?(GraphQL::Language::Nodes::Enum)
        type.validate_input(ast_value.name, @context)
      else
        # if our ast_value isn't an Enum it's going to be invalid so return false
        @invalid_response
      end
    end
  elsif type.kind.input_object? && ast_value.is_a?(GraphQL::Language::Nodes::InputObject)
    maybe_raise_if_invalid(ast_value) do
      merge_results([
        required_input_fields_are_present(type, ast_value),
        present_input_field_values_are_valid(type, ast_value)
      ])
    end
  else
    maybe_raise_if_invalid(ast_value) do
      @invalid_response
    end
  end
end

def required_input_fields_are_present(type, ast_node) 

def required_input_fields_are_present(type, ast_node)
  # TODO - would be nice to use these to create an error message so the caller knows
  # that required fields are missing
  required_field_names = type.arguments.each_value
    .select { |argument| argument.type.kind.non_null? && @warden.get_argument(type, argument.name) }
    .map(&:name)
  present_field_names = ast_node.arguments.map(&:name)
  missing_required_field_names = required_field_names - present_field_names
  if @context.schema.error_bubbling
    missing_required_field_names.empty? ? @valid_response : @invalid_response
  else
    results = missing_required_field_names.map do |name|
      arg_type = @warden.get_argument(type, name).type
      recursively_validate(GraphQL::Language::Nodes::NullValue.new(name: name), arg_type)
    end
    merge_results(results)
  end
end

def validate(ast_value, type) 

def validate(ast_value, type)
  catch(:invalid) do
    recursively_validate(ast_value, type)
  end
end