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Diffstat (limited to 'BackendList.hs')
| -rw-r--r-- | BackendList.hs | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/BackendList.hs b/BackendList.hs index c744949b6..77e4bd817 100644 --- a/BackendList.hs +++ b/BackendList.hs @@ -4,6 +4,7 @@ module BackendList where -- When adding a new backend, import it here and add it to the list. +import Types import qualified BackendFile import qualified BackendChecksum import qualified BackendUrl @@ -12,3 +13,20 @@ supportedBackends = , BackendChecksum.backend , BackendUrl.backend ] + +{- Parses a string with a list of backend names into + - a list of Backend objects. If the list is empty, + - defaults to supportedBackends. -} +parseBackendList :: String -> [Backend] +parseBackendList s = + if (length s == 0) + then supportedBackends + else map (lookupBackendName) $ words s + +{- Looks up a supported backed by name. -} +lookupBackendName :: String -> Backend +lookupBackendName s = + if ((length matches) /= 1) + then error $ "unknown backend " ++ s + else matches !! 0 + where matches = filter (\b -> s == name b) supportedBackends |