Greskell.GTraversal: add elementMap step

debug-ito · Nov 15, 2022 · a345c9d · a345c9d
1 parent 1ce8608
commit a345c9d
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Showing 2 changed files with 24 additions and 4 deletions.
diff --git a/greskell/src/Data/Greskell/GTraversal.hs b/greskell/src/Data/Greskell/GTraversal.hs
@@ -148,6 +148,7 @@ module Data.Greskell.GTraversal
     , gId
     , gLabel
     , gValueMap
+    , gElementMap
     , gSelect1
     , gSelectN
     , gSelectBy1
@@ -232,7 +233,7 @@ import           Data.Greskell.AsLabel    (AsLabel, LabeledP, SelectedMap)
 import           Data.Greskell.Graph      (AEdge, AVertex, AVertexProperty, Cardinality, Edge,
                                            Element (..), ElementID (..), Key, KeyValue (..),
                                            Keys (..), Path, Property (..), T, Vertex, cList, tId,
-                                           (-:), (=:))
+                                           toGremlinKeys, (-:), (=:))
 import           Data.Greskell.GraphSON   (FromGraphSON, GValue)
 import           Data.Greskell.Gremlin    (Comparator (..), P, oDecr, oIncr, pBetween, pEq, pLte)
 import           Data.Greskell.Greskell   (Greskell, ToGreskell (..), gvalueInt, toGremlin,
@@ -1391,9 +1392,14 @@ gValueMap :: Element s
           => Keys s
           -> Walk Transform s (PMap (ElementPropertyContainer s) GValue)
 gValueMap keys = unsafeWalk "valueMap" $ toGremlinKeys keys
-  where
-    toGremlinKeys KeysNil           = []
-    toGremlinKeys (KeysCons k rest) = toGremlin k : toGremlinKeys rest
+
+-- | @.elementMap@ step.
+--
+-- @since 2.0.0.1
+gElementMap :: Element s
+          => Keys s
+          -> Walk Transform s (PMap Single GValue)
+gElementMap keys = unsafeWalk "elementMap" $ toGremlinKeys keys
 
 -- | @.select@ step with one argument.
 --
@@ -1819,6 +1825,12 @@ examples =
   , ( toGremlin (source "g" & sV' [] &. gValueMap ("name" -: "age" -: KeysNil))
     , "g.V().valueMap(\"name\",\"age\")"
     )
+  , ( toGremlin (source "g" & sV' [] &. gElementMap KeysNil)
+    , "g.V().elementMap()"
+    )
+  , ( toGremlin (source "g" & sV' [] &. gElementMap ("name" -: "age" -: KeysNil))
+    , "g.V().elementMap(\"name\",\"age\")"
+    )
   , ( let name_label = "a" :: AsLabel Text
           name_key = "name" :: Key AVertex Text
           count_label = "b" :: AsLabel Int

diff --git a/greskell/src/Data/Greskell/Graph.hs b/greskell/src/Data/Greskell/Graph.hs
@@ -44,6 +44,7 @@ module Data.Greskell.Graph
       -- ** Heterogeneous list of keys
     , Keys (..)
     , singletonKeys
+    , toGremlinKeys
     , (-:)
       -- * Path
     , Path (..)
@@ -298,6 +299,13 @@ instance Monoid (Keys a) where
 singletonKeys :: Key a b -> Keys a
 singletonKeys k = KeysCons k KeysNil
 
+-- | Convert 'Keys' to a list of Gremlin scripts.
+--
+-- @since 2.0.0.1
+toGremlinKeys :: Keys a -> [Text]
+toGremlinKeys KeysNil = []
+toGremlinKeys (KeysCons k rest) = toGremlin k : toGremlinKeys rest
+
 -- | Prepend a 'Key' to 'Keys'.
 --
 -- @since 1.0.0.0