refactor: add plan module

* rename/add plan dirs
* add read plan func/data
* add call plan func/data
* add mutate plan func/data

src/PostgREST/Plan/MutatePlan.hs

@@ -0,0 +1,41 @@
+module PostgREST.Plan.MutatePlan
+  ( MutatePlan(..)
+  )
+where
+
+import qualified Data.ByteString.Lazy as LBS
+import qualified Data.Set             as S
+
+import PostgREST.DbStructure.Identifiers (FieldName,
+                                          QualifiedIdentifier)
+import PostgREST.RangeQuery              (NonnegRange)
+import PostgREST.Request.Preferences     (PreferResolution)
+import PostgREST.Request.Types           (LogicTree, OrderTerm)
+
+import Protolude
+
+data MutatePlan
+  = Insert
+      { in_        :: QualifiedIdentifier
+      , insCols    :: S.Set FieldName
+      , insBody    :: Maybe LBS.ByteString
+      , onConflict :: Maybe (PreferResolution, [FieldName])
+      , where_     :: [LogicTree]
+      , returning  :: [FieldName]
+      }
+  | Update
+      { in_       :: QualifiedIdentifier
+      , updCols   :: S.Set FieldName
+      , updBody   :: Maybe LBS.ByteString
+      , where_    :: [LogicTree]
+      , mutRange  :: NonnegRange
+      , mutOrder  :: [OrderTerm]
+      , returning :: [FieldName]
+      }
+  | Delete
+      { in_       :: QualifiedIdentifier
+      , where_    :: [LogicTree]
+      , mutRange  :: NonnegRange
+      , mutOrder  :: [OrderTerm]
+      , returning :: [FieldName]
+      }