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{- This Source Code Form is subject to the terms of the Mozilla Public License,
v. 2.0. If a copy of the MPL was not distributed with this file, You can
obtain one at https://mozilla.org/MPL/2.0/. -}
-- | Definitions used by the validation rules and the validator itself.
module Language.GraphQL.Validate.Validation
( Validation(..)
, Rule(..)
, RuleT
) where
import Control.Monad.Trans.Reader (ReaderT(..))
import Data.HashMap.Strict (HashMap)
import Language.GraphQL.AST.Document
import Language.GraphQL.Type.Schema (Schema)
import qualified Language.GraphQL.Type.Schema as Schema
-- | Validation rule context.
data Validation m = Validation
{ ast :: Document
, schema :: Schema m
, types :: HashMap Name (Schema.Type m)
, rules :: [Rule m]
}
-- | 'Rule' assigns a function to each AST node that can be validated. If the
-- validation fails, the function should return an error message, or 'Nothing'
-- otherwise.
data Rule m
= DefinitionRule (Definition -> RuleT m)
| OperationDefinitionRule (OperationDefinition -> RuleT m)
-- | Monad transformer used by the rules.
type RuleT m = ReaderT (Validation m) Maybe String