diff options
Diffstat (limited to 'Types/MetaData.hs')
| -rw-r--r-- | Types/MetaData.hs | 7 |
1 files changed, 6 insertions, 1 deletions
diff --git a/Types/MetaData.hs b/Types/MetaData.hs index 6f8a300b2..c37b31c51 100644 --- a/Types/MetaData.hs +++ b/Types/MetaData.hs @@ -219,6 +219,7 @@ data ModMeta = AddMeta MetaField MetaValue | DelMeta MetaField MetaValue | SetMeta MetaField MetaValue -- removes any existing values + | MaybeSetMeta MetaField MetaValue -- when field has no existing value {- Applies a ModMeta, generating the new MetaData. - Note that the new MetaData does not include all the @@ -229,12 +230,16 @@ modMeta _ (DelMeta f oldv) = updateMetaData f (unsetMetaValue oldv) emptyMetaDat modMeta m (SetMeta f v) = updateMetaData f v $ foldr (updateMetaData f) emptyMetaData $ map unsetMetaValue $ S.toList $ currentMetaDataValues f m +modMeta m (MaybeSetMeta f v) + | S.null (currentMetaDataValues f m) = updateMetaData f v emptyMetaData + | otherwise = emptyMetaData -{- Parses field=value, field+=value, field-=value -} +{- Parses field=value, field+=value, field-=value, field?=value -} parseModMeta :: String -> Either String ModMeta parseModMeta p = case lastMaybe f of Just '+' -> AddMeta <$> mkMetaField f' <*> v Just '-' -> DelMeta <$> mkMetaField f' <*> v + Just '?' -> MaybeSetMeta <$> mkMetaField f' <*> v _ -> SetMeta <$> mkMetaField f <*> v where (f, sv) = separate (== '=') p |