{-# LANGUAGE BangPatterns #-} {-# LANGUAGE BlockArguments #-} {-# LANGUAGE CPP #-} {-# LANGUAGE ConstraintKinds #-} {-# LANGUAGE DefaultSignatures #-} {-# LANGUAGE DeriveAnyClass #-} {-# LANGUAGE DeriveGeneric #-} {-# LANGUAGE DerivingStrategies #-} {-# LANGUAGE DuplicateRecordFields #-} {-# LANGUAGE FlexibleContexts #-} {-# LANGUAGE FlexibleInstances #-} {-# LANGUAGE GADTs #-} {-# LANGUAGE GeneralizedNewtypeDeriving #-} {-# LANGUAGE MonadComprehensions #-} {-# LANGUAGE MultiParamTypeClasses #-} {-# LANGUAGE NamedFieldPuns #-} {-# LANGUAGE OverloadedStrings #-} {-# LANGUAGE PatternSynonyms #-} {-# LANGUAGE PolyKinds #-} {-# LANGUAGE RecordWildCards #-} {-# LANGUAGE ScopedTypeVariables #-} {-# LANGUAGE TypeFamilies #-} {-# LANGUAGE UndecidableInstances #-} {-# LANGUAGE ViewPatterns #-} module Ide.Types ( PluginDescriptor(..), defaultPluginDescriptor, defaultCabalPluginDescriptor , defaultPluginPriority , describePlugin , IdeCommand(..) , IdeMethod(..) , IdeNotification(..) , IdePlugins(IdePlugins, ipMap) , DynFlagsModifications(..) , Config(..), PluginConfig(..), CheckParents(..) , ConfigDescriptor(..), defaultConfigDescriptor, configForPlugin , CustomConfig(..), mkCustomConfig , FallbackCodeActionParams(..) , FormattingType(..), FormattingMethod, FormattingHandler, mkFormattingHandlers , HasTracing(..) , PluginCommand(..), CommandId(..), CommandFunction, mkLspCommand, mkLspCmdId , PluginId(..) , PluginHandler(..), mkPluginHandler , PluginHandlers(..) , PluginMethod(..) , PluginMethodHandler , PluginNotificationHandler(..), mkPluginNotificationHandler , PluginNotificationHandlers(..) , PluginRequestMethod(..) , getProcessID, getPid , installSigUsr1Handler , lookupCommandProvider , ResolveFunction , mkResolveHandler ) where #ifdef mingw32_HOST_OS import qualified System.Win32.Process as P (getCurrentProcessId) #else import qualified System.Posix.Process as P (getProcessID) import System.Posix.Signals #endif import Control.Applicative ((<|>)) import Control.Arrow ((&&&)) import Control.Lens (_Just, view, (.~), (?~), (^.), (^?)) import Control.Monad (void) import Control.Monad.Error.Class (MonadError (throwError)) import Control.Monad.Trans.Class (MonadTrans (lift)) import Control.Monad.Trans.Except (ExceptT, runExceptT) import Data.Aeson hiding (Null, defaultOptions) import Data.Default import Data.Dependent.Map (DMap) import qualified Data.Dependent.Map as DMap import qualified Data.DList as DList import Data.Foldable (foldl') import Data.GADT.Compare import Data.Hashable (Hashable) import Data.HashMap.Strict (HashMap) import qualified Data.HashMap.Strict as HashMap import Data.Kind (Type) import Data.List.Extra (find, sortOn) import Data.List.NonEmpty (NonEmpty (..), toList) import qualified Data.Map as Map import Data.Maybe import Data.Ord import Data.Semigroup import Data.String import qualified Data.Text as T import Data.Text.Encoding (encodeUtf8) import Development.IDE.Graph import GHC (DynFlags) import GHC.Generics import Ide.Plugin.Error import Ide.Plugin.HandleRequestTypes import Ide.Plugin.Properties import qualified Language.LSP.Protocol.Lens as L import Language.LSP.Protocol.Message import Language.LSP.Protocol.Types import Language.LSP.Server (LspM, LspT, getVirtualFile) import Language.LSP.VFS import Numeric.Natural import OpenTelemetry.Eventlog import Options.Applicative (ParserInfo) import Prettyprinter as PP import System.FilePath import System.IO.Unsafe import Text.Regex.TDFA.Text () -- --------------------------------------------------------------------- data IdePlugins ideState = IdePlugins_ { ipMap_ :: HashMap PluginId (PluginDescriptor ideState) , lookupCommandProvider :: CommandId -> Maybe PluginId } -- | Smart constructor that deduplicates plugins pattern IdePlugins :: [PluginDescriptor ideState] -> IdePlugins ideState pattern IdePlugins{ipMap} <- IdePlugins_ (sortOn (Down . pluginPriority) . HashMap.elems -> ipMap) _ where IdePlugins ipMap = IdePlugins_{ipMap_ = HashMap.fromList $ (pluginId &&& id) <$> ipMap , lookupCommandProvider = lookupPluginId ipMap } {-# COMPLETE IdePlugins #-} instance Semigroup (IdePlugins a) where (IdePlugins_ a f) <> (IdePlugins_ b g) = IdePlugins_ (a <> b) (\x -> f x <|> g x) instance Monoid (IdePlugins a) where mempty = IdePlugins_ mempty (const Nothing) -- | Lookup the plugin that exposes a particular command lookupPluginId :: [PluginDescriptor a] -> CommandId -> Maybe PluginId lookupPluginId ls cmd = pluginId <$> find go ls where go desc = cmd `elem` map commandId (pluginCommands desc) -- | Hooks for modifying the 'DynFlags' at different times of the compilation -- process. Plugins can install a 'DynFlagsModifications' via -- 'pluginModifyDynflags' in their 'PluginDescriptor'. data DynFlagsModifications = DynFlagsModifications { -- | Invoked immediately at the package level. Changes to the 'DynFlags' -- made in 'dynFlagsModifyGlobal' are guaranteed to be seen everywhere in -- the compilation pipeline. dynFlagsModifyGlobal :: DynFlags -> DynFlags -- | Invoked just before the parsing step, and reset immediately -- afterwards. 'dynFlagsModifyParser' allows plugins to enable language -- extensions only during parsing. for example, to let them enable -- certain pieces of syntax. , dynFlagsModifyParser :: DynFlags -> DynFlags } instance Semigroup DynFlagsModifications where DynFlagsModifications g1 p1 <> DynFlagsModifications g2 p2 = DynFlagsModifications (g2 . g1) (p2 . p1) instance Monoid DynFlagsModifications where mempty = DynFlagsModifications id id -- --------------------------------------------------------------------- newtype IdeCommand state = IdeCommand (state -> IO ()) instance Show (IdeCommand st) where show _ = "" -- --------------------------------------------------------------------- -- | We (initially anyway) mirror the hie configuration, so that existing -- clients can simply switch executable and not have any nasty surprises. There -- will initially be surprises relating to config options being ignored though. data Config = Config { checkParents :: CheckParents , checkProject :: !Bool , formattingProvider :: !T.Text , cabalFormattingProvider :: !T.Text , maxCompletions :: !Int , plugins :: !(Map.Map PluginId PluginConfig) } deriving (Show,Eq) instance ToJSON Config where toJSON Config{..} = object [ "checkParents" .= checkParents , "checkProject" .= checkProject , "formattingProvider" .= formattingProvider , "maxCompletions" .= maxCompletions , "plugin" .= Map.mapKeysMonotonic (\(PluginId p) -> p) plugins ] instance Default Config where def = Config { checkParents = CheckOnSave , checkProject = True , formattingProvider = "ormolu" -- , formattingProvider = "floskell" -- , formattingProvider = "stylish-haskell" , cabalFormattingProvider = "cabal-fmt" -- this string value needs to kept in sync with the value provided in HlsPlugins , maxCompletions = 40 , plugins = mempty } data CheckParents -- Note that ordering of constructors is meaningful and must be monotonically -- increasing in the scenarios where parents are checked = NeverCheck | CheckOnSave | AlwaysCheck deriving stock (Eq, Ord, Show, Generic) deriving anyclass (FromJSON, ToJSON) -- | A PluginConfig is a generic configuration for a given HLS plugin. It -- provides a "big switch" to turn it on or off as a whole, as well as small -- switches per feature, and a slot for custom config. -- This provides a regular naming scheme for all plugin config. data PluginConfig = PluginConfig { plcGlobalOn :: !Bool , plcCallHierarchyOn :: !Bool , plcCodeActionsOn :: !Bool , plcCodeLensOn :: !Bool , plcDiagnosticsOn :: !Bool , plcHoverOn :: !Bool , plcSymbolsOn :: !Bool , plcCompletionOn :: !Bool , plcRenameOn :: !Bool , plcSelectionRangeOn :: !Bool , plcFoldingRangeOn :: !Bool , plcSemanticTokensOn :: !Bool , plcConfig :: !Object } deriving (Show,Eq) instance Default PluginConfig where def = PluginConfig { plcGlobalOn = True , plcCallHierarchyOn = True , plcCodeActionsOn = True , plcCodeLensOn = True , plcDiagnosticsOn = True , plcHoverOn = True , plcSymbolsOn = True , plcCompletionOn = True , plcRenameOn = True , plcSelectionRangeOn = True , plcFoldingRangeOn = True , plcSemanticTokensOn = True , plcConfig = mempty } instance ToJSON PluginConfig where toJSON (PluginConfig g ch ca cl d h s c rn sr fr st cfg) = r where r = object [ "globalOn" .= g , "callHierarchyOn" .= ch , "codeActionsOn" .= ca , "codeLensOn" .= cl , "diagnosticsOn" .= d , "hoverOn" .= h , "symbolsOn" .= s , "completionOn" .= c , "renameOn" .= rn , "selectionRangeOn" .= sr , "foldingRangeOn" .= fr , "semanticTokensOn" .= st , "config" .= cfg ] -- --------------------------------------------------------------------- data PluginDescriptor (ideState :: Type) = PluginDescriptor { pluginId :: !PluginId , pluginDescription :: !T.Text -- ^ Unique identifier of the plugin. , pluginPriority :: Natural -- ^ Plugin handlers are called in priority order, higher priority first , pluginRules :: !(Rules ()) , pluginCommands :: ![PluginCommand ideState] , pluginHandlers :: PluginHandlers ideState , pluginConfigDescriptor :: ConfigDescriptor , pluginNotificationHandlers :: PluginNotificationHandlers ideState , pluginModifyDynflags :: DynFlagsModifications , pluginCli :: Maybe (ParserInfo (IdeCommand ideState)) , pluginFileType :: [T.Text] -- ^ File extension of the files the plugin is responsible for. -- The plugin is only allowed to handle files with these extensions. -- When writing handlers, etc. for this plugin it can be assumed that all handled files are of this type. -- The file extension must have a leading '.'. } describePlugin :: PluginDescriptor c -> Doc ann describePlugin p = let PluginId pid = pluginId p pdesc = pluginDescription p in pretty pid <> ":" <> nest 4 (PP.line <> pretty pdesc) -- | An existential wrapper of 'Properties' data CustomConfig = forall r. CustomConfig (Properties r) -- | Describes the configuration of a plugin. -- A plugin may be configurable as can be seen below: -- -- @ -- { -- "plugin-id": { -- "globalOn": true, -- "codeActionsOn": true, -- "codeLensOn": true, -- "config": { -- "property1": "foo" -- } -- } -- } -- @ -- -- @globalOn@, @codeActionsOn@, and @codeLensOn@ etc. are called generic configs -- which can be inferred from handlers registered by the plugin. -- @config@ is called custom config, which is defined using 'Properties'. data ConfigDescriptor = ConfigDescriptor { -- | Initial values for the generic config configInitialGenericConfig :: PluginConfig, -- | Whether or not to generate @diagnosticsOn@ config. -- Diagnostics emit in arbitrary shake rules, -- so we can't know statically if the plugin produces diagnostics configHasDiagnostics :: Bool, -- | Custom config. configCustomConfig :: CustomConfig } mkCustomConfig :: Properties r -> CustomConfig mkCustomConfig = CustomConfig defaultConfigDescriptor :: ConfigDescriptor defaultConfigDescriptor = ConfigDescriptor Data.Default.def False (mkCustomConfig emptyProperties) -- | Lookup the current config for a plugin configForPlugin :: Config -> PluginDescriptor c -> PluginConfig configForPlugin config PluginDescriptor{..} = Map.findWithDefault (configInitialGenericConfig pluginConfigDescriptor) pluginId (plugins config) -- | Checks that a specific plugin is globally enabled in order to respond to -- requests pluginEnabledGlobally :: PluginDescriptor c -> Config -> HandleRequestResult pluginEnabledGlobally desc conf = if plcGlobalOn (configForPlugin conf desc) then HandlesRequest else DoesNotHandleRequest DisabledGlobally -- | Checks that a specific feature for a given plugin is enabled in order -- to respond to requests pluginFeatureEnabled :: (PluginConfig -> Bool) -> PluginDescriptor c -> Config -> HandleRequestResult pluginFeatureEnabled f desc conf = if f (configForPlugin conf desc) then HandlesRequest else DoesNotHandleRequest FeatureDisabled -- |Determine whether this request should be routed to the plugin. Fails closed -- if we can't determine which plugin it should be routed to. pluginResolverResponsible :: L.HasData_ m (Maybe Value) => m -> PluginDescriptor c -> HandleRequestResult pluginResolverResponsible (view L.data_ -> (Just (fromJSON -> (Success (PluginResolveData o@(PluginId ot) _ _))))) pluginDesc = if pluginId pluginDesc == o then HandlesRequest else DoesNotHandleRequest $ NotResolveOwner ot -- If we can't determine who this request belongs to, then we don't want any plugin -- to handle it. pluginResolverResponsible _ _ = DoesNotHandleRequest $ NotResolveOwner "(unable to determine resolve owner)" -- | Check whether the given plugin descriptor supports the file with -- the given path. Compares the file extension from the msgParams with the -- file extension the plugin is responsible for. -- We are passing the msgParams here even though we only need the URI URI here. -- If in the future we need to be able to provide only an URI it can be -- separated again. pluginSupportsFileType :: (L.HasTextDocument m doc, L.HasUri doc Uri) => m -> PluginDescriptor c -> HandleRequestResult pluginSupportsFileType msgParams pluginDesc = case mfp of Just fp | T.pack (takeExtension fp) `elem` pluginFileType pluginDesc -> HandlesRequest _ -> DoesNotHandleRequest $ DoesNotSupportFileType (maybe "(unable to determine file type)" (T.pack . takeExtension) mfp) where mfp = uriToFilePath uri uri = msgParams ^. L.textDocument . L.uri -- | Methods that can be handled by plugins. -- 'ExtraParams' captures any extra data the IDE passes to the handlers for this method -- Only methods for which we know how to combine responses can be instances of 'PluginMethod' class HasTracing (MessageParams m) => PluginMethod (k :: MessageKind) (m :: Method ClientToServer k) where -- | Parse the configuration to check if this plugin is globally enabled, and -- if the feature which handles this method is enabled. Perform sanity checks -- on the message to see whether the plugin handles this message in particular. -- This class is only used to determine whether a plugin can handle a specific -- request. Commands and rules do not use this logic to determine whether or -- not they are run. -- -- -- A common reason why a plugin won't handle a request even though it is enabled: -- * The plugin cannot handle requests associated with the specific URI -- * Since the implementation of [cabal plugins](https://github.com/haskell/haskell-language-server/issues/2940) -- HLS knows plugins specific to Haskell and specific to [Cabal file descriptions](https://cabal.readthedocs.io/en/3.6/cabal-package.html) -- * The resolve request is not routed to that specific plugin. Each resolve -- request needs to be routed to only one plugin. -- -- Strictly speaking, we are conflating two concepts here: -- * Dynamically enabled (e.g. on a per-message basis) -- * Statically enabled (e.g. by configuration in the lsp-client) -- * Strictly speaking, this might also change dynamically -- -- But there is no use to split it up into two different methods for now. handlesRequest :: SMethod m -- ^ Method type. -> MessageParams m -- ^ Whether a plugin is enabled might depend on the message parameters -- e.g. 'pluginFileType' specifies which file extensions a plugin is allowed to handle -> PluginDescriptor c -- ^ Contains meta information such as PluginId and which file types this -- plugin is able to handle. -> Config -- ^ Generic config description, expected to contain 'PluginConfig' configuration -- for this plugin -> HandleRequestResult -- ^ Is this plugin enabled and allowed to respond to the given request -- with the given parameters? default handlesRequest :: (L.HasTextDocument (MessageParams m) doc, L.HasUri doc Uri) => SMethod m -> MessageParams m -> PluginDescriptor c -> Config -> HandleRequestResult handlesRequest _ params desc conf = pluginEnabledGlobally desc conf <> pluginSupportsFileType params desc -- | Check if a plugin is enabled, if one of it's specific config's is enabled, -- and if it supports the file pluginEnabledWithFeature :: (L.HasTextDocument (MessageParams m) doc, L.HasUri doc Uri) => (PluginConfig -> Bool) -> SMethod m -> MessageParams m -> PluginDescriptor c -> Config -> HandleRequestResult pluginEnabledWithFeature feature _ msgParams pluginDesc config = pluginEnabledGlobally pluginDesc config <> pluginFeatureEnabled feature pluginDesc config <> pluginSupportsFileType msgParams pluginDesc -- | Check if a plugin is enabled, if one of it's specific configs is enabled, -- and if it's the plugin responsible for a resolve request. pluginEnabledResolve :: L.HasData_ s (Maybe Value) => (PluginConfig -> Bool) -> p -> s -> PluginDescriptor c -> Config -> HandleRequestResult pluginEnabledResolve feature _ msgParams pluginDesc config = pluginEnabledGlobally pluginDesc config <> pluginFeatureEnabled feature pluginDesc config <> pluginResolverResponsible msgParams pluginDesc instance PluginMethod Request Method_TextDocumentCodeAction where handlesRequest = pluginEnabledWithFeature plcCodeActionsOn instance PluginMethod Request Method_CodeActionResolve where -- See Note [Resolve in PluginHandlers] handlesRequest = pluginEnabledResolve plcCodeActionsOn instance PluginMethod Request Method_TextDocumentDefinition where handlesRequest _ msgParams pluginDesc _ = pluginSupportsFileType msgParams pluginDesc instance PluginMethod Request Method_TextDocumentTypeDefinition where handlesRequest _ msgParams pluginDesc _ = pluginSupportsFileType msgParams pluginDesc instance PluginMethod Request Method_TextDocumentDocumentHighlight where handlesRequest _ msgParams pluginDesc _ = pluginSupportsFileType msgParams pluginDesc instance PluginMethod Request Method_TextDocumentReferences where handlesRequest _ msgParams pluginDesc _ = pluginSupportsFileType msgParams pluginDesc instance PluginMethod Request Method_WorkspaceSymbol where -- Unconditionally enabled, but should it really be? handlesRequest _ _ _ _ = HandlesRequest instance PluginMethod Request Method_TextDocumentCodeLens where handlesRequest = pluginEnabledWithFeature plcCodeLensOn instance PluginMethod Request Method_CodeLensResolve where -- See Note [Resolve in PluginHandlers] handlesRequest = pluginEnabledResolve plcCodeLensOn instance PluginMethod Request Method_TextDocumentRename where handlesRequest = pluginEnabledWithFeature plcRenameOn instance PluginMethod Request Method_TextDocumentHover where handlesRequest = pluginEnabledWithFeature plcHoverOn instance PluginMethod Request Method_TextDocumentDocumentSymbol where handlesRequest = pluginEnabledWithFeature plcSymbolsOn instance PluginMethod Request Method_CompletionItemResolve where -- See Note [Resolve in PluginHandlers] handlesRequest = pluginEnabledResolve plcCompletionOn instance PluginMethod Request Method_TextDocumentCompletion where handlesRequest = pluginEnabledWithFeature plcCompletionOn instance PluginMethod Request Method_TextDocumentFormatting where handlesRequest _ msgParams pluginDesc conf = (if PluginId (formattingProvider conf) == pid || PluginId (cabalFormattingProvider conf) == pid then HandlesRequest else DoesNotHandleRequest (NotFormattingProvider (formattingProvider conf)) ) <> pluginSupportsFileType msgParams pluginDesc where pid = pluginId pluginDesc instance PluginMethod Request Method_TextDocumentRangeFormatting where handlesRequest _ msgParams pluginDesc conf = (if PluginId (formattingProvider conf) == pid || PluginId (cabalFormattingProvider conf) == pid then HandlesRequest else DoesNotHandleRequest (NotFormattingProvider (formattingProvider conf))) <> pluginSupportsFileType msgParams pluginDesc where pid = pluginId pluginDesc instance PluginMethod Request Method_TextDocumentSemanticTokensFull where handlesRequest = pluginEnabledWithFeature plcSemanticTokensOn instance PluginMethod Request Method_TextDocumentPrepareCallHierarchy where handlesRequest = pluginEnabledWithFeature plcCallHierarchyOn instance PluginMethod Request Method_TextDocumentSelectionRange where handlesRequest = pluginEnabledWithFeature plcSelectionRangeOn instance PluginMethod Request Method_TextDocumentFoldingRange where handlesRequest = pluginEnabledWithFeature plcFoldingRangeOn instance PluginMethod Request Method_CallHierarchyIncomingCalls where -- This method has no URI parameter, thus no call to 'pluginResponsible' handlesRequest _ _ pluginDesc conf = pluginEnabledGlobally pluginDesc conf <> pluginFeatureEnabled plcCallHierarchyOn pluginDesc conf instance PluginMethod Request Method_CallHierarchyOutgoingCalls where -- This method has no URI parameter, thus no call to 'pluginResponsible' handlesRequest _ _ pluginDesc conf = pluginEnabledGlobally pluginDesc conf <> pluginFeatureEnabled plcCallHierarchyOn pluginDesc conf instance PluginMethod Request Method_WorkspaceExecuteCommand where handlesRequest _ _ _ _= HandlesRequest instance PluginMethod Request (Method_CustomMethod m) where handlesRequest _ _ _ _ = HandlesRequest -- Plugin Notifications instance PluginMethod Notification Method_TextDocumentDidOpen where instance PluginMethod Notification Method_TextDocumentDidChange where instance PluginMethod Notification Method_TextDocumentDidSave where instance PluginMethod Notification Method_TextDocumentDidClose where instance PluginMethod Notification Method_WorkspaceDidChangeWatchedFiles where -- This method has no URI parameter, thus no call to 'pluginResponsible'. handlesRequest _ _ desc conf = pluginEnabledGlobally desc conf instance PluginMethod Notification Method_WorkspaceDidChangeWorkspaceFolders where -- This method has no URI parameter, thus no call to 'pluginResponsible'. handlesRequest _ _ desc conf = pluginEnabledGlobally desc conf instance PluginMethod Notification Method_WorkspaceDidChangeConfiguration where -- This method has no URI parameter, thus no call to 'pluginResponsible'. handlesRequest _ _ desc conf = pluginEnabledGlobally desc conf instance PluginMethod Notification Method_Initialized where -- This method has no URI parameter, thus no call to 'pluginResponsible'. handlesRequest _ _ desc conf = pluginEnabledGlobally desc conf -- --------------------------------------------------------------------- -- Plugin Requests -- --------------------------------------------------------------------- class PluginMethod Request m => PluginRequestMethod (m :: Method ClientToServer Request) where -- | How to combine responses from different plugins. -- -- For example, for Hover requests, we might have multiple producers of -- Hover information. We do not want to decide which one to display to the user -- but instead allow to define how to merge two hover request responses into one -- glorious hover box. -- -- However, as sometimes only one handler of a request can realistically exist -- (such as TextDocumentFormatting), it is safe to just unconditionally report -- back one arbitrary result (arbitrary since it should only be one anyway). combineResponses :: SMethod m -> Config -- ^ IDE Configuration -> ClientCapabilities -> MessageParams m -> NonEmpty (MessageResult m) -> MessageResult m default combineResponses :: Semigroup (MessageResult m) => SMethod m -> Config -> ClientCapabilities -> MessageParams m -> NonEmpty (MessageResult m) -> MessageResult m combineResponses _method _config _caps _params = sconcat --- instance PluginRequestMethod Method_TextDocumentCodeAction where combineResponses _method _config (ClientCapabilities _ textDocCaps _ _ _ _) (CodeActionParams _ _ _ _ context) resps = InL $ fmap compat $ filter wasRequested $ concat $ mapMaybe nullToMaybe $ toList resps where compat :: (Command |? CodeAction) -> (Command |? CodeAction) compat x@(InL _) = x compat x@(InR action) | Just _ <- textDocCaps >>= _codeAction >>= _codeActionLiteralSupport = x | otherwise = InL cmd where cmd = mkLspCommand "hls" "fallbackCodeAction" (action ^. L.title) (Just cmdParams) cmdParams = [toJSON (FallbackCodeActionParams (action ^. L.edit) (action ^. L.command))] wasRequested :: (Command |? CodeAction) -> Bool wasRequested (InL _) = True wasRequested (InR ca) | Nothing <- _only context = True | Just allowed <- _only context -- See https://github.com/microsoft/language-server-protocol/issues/970 -- This is somewhat vague, but due to the hierarchical nature of action kinds, we -- should check whether the requested kind is a *prefix* of the action kind. -- That means, for example, we will return actions with kinds `quickfix.import` and -- `quickfix.somethingElse` if the requested kind is `quickfix`. , Just caKind <- ca ^. L.kind = any (`codeActionKindSubsumes` caKind) allowed | otherwise = False instance PluginRequestMethod Method_CodeActionResolve where -- A resolve request should only have one response. -- See Note [Resolve in PluginHandlers]. combineResponses _ _ _ _ (x :| _) = x instance PluginRequestMethod Method_TextDocumentDefinition where combineResponses _ _ caps _ (x :| xs) | Just (Just True) <- caps ^? (L.textDocument . _Just . L.definition . _Just . L.linkSupport) = foldl' mergeDefinitions x xs | otherwise = downgradeLinks $ foldl' mergeDefinitions x xs instance PluginRequestMethod Method_TextDocumentTypeDefinition where combineResponses _ _ caps _ (x :| xs) | Just (Just True) <- caps ^? (L.textDocument . _Just . L.typeDefinition . _Just . L.linkSupport) = foldl' mergeDefinitions x xs | otherwise = downgradeLinks $ foldl' mergeDefinitions x xs instance PluginRequestMethod Method_TextDocumentDocumentHighlight where instance PluginRequestMethod Method_TextDocumentReferences where instance PluginRequestMethod Method_WorkspaceSymbol where -- TODO: combine WorkspaceSymbol. Currently all WorkspaceSymbols are dumped -- as it is new of lsp-types 2.0.0.0 combineResponses _ _ _ _ xs = InL $ mconcat $ takeLefts $ toList xs instance PluginRequestMethod Method_TextDocumentCodeLens where instance PluginRequestMethod Method_CodeLensResolve where -- A resolve request should only ever get one response. -- See note Note [Resolve in PluginHandlers] combineResponses _ _ _ _ (x :| _) = x instance PluginRequestMethod Method_TextDocumentRename where instance PluginRequestMethod Method_TextDocumentHover where combineResponses _ _ _ _ (mapMaybe nullToMaybe . toList -> hs :: [Hover]) = if null hs then InR Null else InL $ Hover (InL mcontent) r where r = listToMaybe $ mapMaybe (^. L.range) hs -- We are only taking MarkupContent here, because MarkedStrings have been -- deprecated for a while and don't occur in the hls codebase mcontent :: MarkupContent mcontent = mconcat $ takeLefts $ map (^. L.contents) hs instance PluginRequestMethod Method_TextDocumentDocumentSymbol where combineResponses _ _ (ClientCapabilities _ tdc _ _ _ _) params xs = res where uri' = params ^. L.textDocument . L.uri supportsHierarchy = Just True == (tdc >>= _documentSymbol >>= _hierarchicalDocumentSymbolSupport) dsOrSi :: [Either [SymbolInformation] [DocumentSymbol]] dsOrSi = toEither <$> mapMaybe nullToMaybe' (toList xs) res :: [SymbolInformation] |? ([DocumentSymbol] |? Null) res | supportsHierarchy = InR $ InL $ concatMap (either (fmap siToDs) id) dsOrSi | otherwise = InL $ concatMap (either id ( concatMap dsToSi)) dsOrSi -- Is this actually a good conversion? It's what there was before, but some -- things such as tags are getting lost siToDs :: SymbolInformation -> DocumentSymbol siToDs (SymbolInformation name kind _tags cont dep (Location _uri range) ) = DocumentSymbol name cont kind Nothing dep range range Nothing dsToSi = go Nothing go :: Maybe T.Text -> DocumentSymbol -> [SymbolInformation] go parent ds = let children' :: [SymbolInformation] children' = concatMap (go (Just name')) (fromMaybe mempty (ds ^. L.children)) loc = Location uri' (ds ^. L.range) name' = ds ^. L.name si = SymbolInformation name' (ds ^. L.kind) Nothing parent (ds ^. L.deprecated) loc in [si] <> children' instance PluginRequestMethod Method_CompletionItemResolve where -- A resolve request should only have one response. -- See Note [Resolve in PluginHandlers] combineResponses _ _ _ _ (x :| _) = x instance PluginRequestMethod Method_TextDocumentCompletion where combineResponses _ conf _ _ (toList -> xs) = snd $ consumeCompletionResponse limit $ combine xs where limit = maxCompletions conf combine :: [[CompletionItem] |? (CompletionList |? Null)] -> ([CompletionItem] |? (CompletionList |? Null)) combine cs = go True mempty cs go :: Bool -> DList.DList CompletionItem -> [[CompletionItem] |? (CompletionList |? Null)] -> ([CompletionItem] |? (CompletionList |? Null)) go !comp acc [] = InR (InL (CompletionList comp Nothing ( DList.toList acc))) go comp acc ((InL ls) : rest) = go comp (acc <> DList.fromList ls) rest go comp acc ( (InR (InL (CompletionList comp' _ ls))) : rest) = go (comp && comp') (acc <> DList.fromList ls) rest go comp acc ( (InR (InR Null)) : rest) = go comp acc rest -- boolean disambiguators isCompleteResponse, isIncompleteResponse :: Bool isIncompleteResponse = True isCompleteResponse = False consumeCompletionResponse :: Int -> ([CompletionItem] |? (CompletionList |? Null)) -> (Int, [CompletionItem] |? (CompletionList |? Null)) consumeCompletionResponse limit it@(InR (InL (CompletionList _ _ xx))) = case splitAt limit xx of -- consumed all the items, return the result as is (_, []) -> (limit - length xx, it) -- need to crop the response, set the 'isIncomplete' flag (xx', _) -> (0, InR (InL (CompletionList isIncompleteResponse Nothing xx'))) consumeCompletionResponse n (InL xx) = consumeCompletionResponse n (InR (InL (CompletionList isCompleteResponse Nothing xx))) consumeCompletionResponse n (InR (InR Null)) = (n, InR (InR Null)) instance PluginRequestMethod Method_TextDocumentFormatting where combineResponses _ _ _ _ (x :| _) = x instance PluginRequestMethod Method_TextDocumentRangeFormatting where combineResponses _ _ _ _ (x :| _) = x instance PluginRequestMethod Method_TextDocumentPrepareCallHierarchy where instance PluginRequestMethod Method_TextDocumentSelectionRange where combineResponses _ _ _ _ (x :| _) = x instance PluginRequestMethod Method_TextDocumentFoldingRange where combineResponses _ _ _ _ x = sconcat x instance PluginRequestMethod Method_CallHierarchyIncomingCalls where instance PluginRequestMethod Method_CallHierarchyOutgoingCalls where instance PluginRequestMethod (Method_CustomMethod m) where combineResponses _ _ _ _ (x :| _) = x instance PluginRequestMethod Method_TextDocumentSemanticTokensFull where combineResponses _ _ _ _ (x :| _) = x takeLefts :: [a |? b] -> [a] takeLefts = mapMaybe (\x -> [res | (InL res) <- Just x]) nullToMaybe' :: (a |? (b |? Null)) -> Maybe (a |? b) nullToMaybe' (InL x) = Just $ InL x nullToMaybe' (InR (InL x)) = Just $ InR x nullToMaybe' (InR (InR _)) = Nothing type Definitions = (Definition |? ([DefinitionLink] |? Null)) -- | Merges two definition responses (TextDocumentDefinition | TextDocumentTypeDefinition) -- into one preserving all locations and their order (including order of the responses). -- Upgrades Location(s) into LocationLink(s) when one of the responses is LocationLink(s). With following fields: -- * LocationLink.originSelectionRange = Nothing -- * LocationLink.targetUri = Location.Uri -- * LocationLink.targetRange = Location.Range -- * LocationLink.targetSelectionRange = Location.Range -- Ignores Null responses. mergeDefinitions :: Definitions -> Definitions -> Definitions mergeDefinitions definitions1 definitions2 = case (definitions1, definitions2) of (InR (InR Null), def2) -> def2 (def1, InR (InR Null)) -> def1 (InL def1, InL def2) -> InL $ mergeDefs def1 def2 (InL def1, InR (InL links)) -> InR $ InL (defToLinks def1 ++ links) (InR (InL links), InL def2) -> InR $ InL (links ++ defToLinks def2) (InR (InL links1), InR (InL links2)) -> InR $ InL (links1 ++ links2) where defToLinks :: Definition -> [DefinitionLink] defToLinks (Definition (InL location)) = [locationToDefinitionLink location] defToLinks (Definition (InR locations)) = map locationToDefinitionLink locations locationToDefinitionLink :: Location -> DefinitionLink locationToDefinitionLink Location{_uri, _range} = DefinitionLink LocationLink{_originSelectionRange = Nothing, _targetUri = _uri, _targetRange = _range, _targetSelectionRange = _range} mergeDefs :: Definition -> Definition -> Definition mergeDefs (Definition (InL loc1)) (Definition (InL loc2)) = Definition $ InR [loc1, loc2] mergeDefs (Definition (InR locs1)) (Definition (InL loc2)) = Definition $ InR (locs1 ++ [loc2]) mergeDefs (Definition (InL loc1)) (Definition (InR locs2)) = Definition $ InR (loc1 : locs2) mergeDefs (Definition (InR locs1)) (Definition (InR locs2)) = Definition $ InR (locs1 ++ locs2) downgradeLinks :: Definitions -> Definitions downgradeLinks (InR (InL links)) = InL . Definition . InR . map linkToLocation $ links where linkToLocation :: DefinitionLink -> Location linkToLocation (DefinitionLink LocationLink{_targetUri, _targetRange}) = Location {_uri = _targetUri, _range = _targetRange} downgradeLinks defs = defs -- --------------------------------------------------------------------- -- Plugin Notifications -- --------------------------------------------------------------------- -- | Plugin Notification methods. No specific methods at the moment, but -- might contain more in the future. class PluginMethod Notification m => PluginNotificationMethod (m :: Method ClientToServer Notification) where instance PluginNotificationMethod Method_TextDocumentDidOpen where instance PluginNotificationMethod Method_TextDocumentDidChange where instance PluginNotificationMethod Method_TextDocumentDidSave where instance PluginNotificationMethod Method_TextDocumentDidClose where instance PluginNotificationMethod Method_WorkspaceDidChangeWatchedFiles where instance PluginNotificationMethod Method_WorkspaceDidChangeWorkspaceFolders where instance PluginNotificationMethod Method_WorkspaceDidChangeConfiguration where instance PluginNotificationMethod Method_Initialized where -- --------------------------------------------------------------------- -- | Methods which have a PluginMethod instance data IdeMethod (m :: Method ClientToServer Request) = PluginRequestMethod m => IdeMethod (SMethod m) instance GEq IdeMethod where geq (IdeMethod a) (IdeMethod b) = geq a b instance GCompare IdeMethod where gcompare (IdeMethod a) (IdeMethod b) = gcompare a b -- | Methods which have a PluginMethod instance data IdeNotification (m :: Method ClientToServer Notification) = PluginNotificationMethod m => IdeNotification (SMethod m) instance GEq IdeNotification where geq (IdeNotification a) (IdeNotification b) = geq a b instance GCompare IdeNotification where gcompare (IdeNotification a) (IdeNotification b) = gcompare a b -- | Combine handlers for the newtype PluginHandler a (m :: Method ClientToServer Request) = PluginHandler (PluginId -> a -> MessageParams m -> LspM Config (NonEmpty (Either PluginError (MessageResult m)))) newtype PluginNotificationHandler a (m :: Method ClientToServer Notification) = PluginNotificationHandler (PluginId -> a -> VFS -> MessageParams m -> LspM Config ()) newtype PluginHandlers a = PluginHandlers (DMap IdeMethod (PluginHandler a)) newtype PluginNotificationHandlers a = PluginNotificationHandlers (DMap IdeNotification (PluginNotificationHandler a)) instance Semigroup (PluginHandlers a) where (PluginHandlers a) <> (PluginHandlers b) = PluginHandlers $ DMap.unionWithKey go a b where go _ (PluginHandler f) (PluginHandler g) = PluginHandler $ \pid ide params -> (<>) <$> f pid ide params <*> g pid ide params instance Monoid (PluginHandlers a) where mempty = PluginHandlers mempty instance Semigroup (PluginNotificationHandlers a) where (PluginNotificationHandlers a) <> (PluginNotificationHandlers b) = PluginNotificationHandlers $ DMap.unionWithKey go a b where go _ (PluginNotificationHandler f) (PluginNotificationHandler g) = PluginNotificationHandler $ \pid ide vfs params -> f pid ide vfs params >> g pid ide vfs params instance Monoid (PluginNotificationHandlers a) where mempty = PluginNotificationHandlers mempty type PluginMethodHandler a m = a -> PluginId -> MessageParams m -> ExceptT PluginError (LspM Config) (MessageResult m) type PluginNotificationMethodHandler a m = a -> VFS -> PluginId -> MessageParams m -> LspM Config () -- | Make a handler for plugins. For how resolve works with this see -- Note [Resolve in PluginHandlers] mkPluginHandler :: forall ideState m. PluginRequestMethod m => SClientMethod m -> PluginMethodHandler ideState m -> PluginHandlers ideState mkPluginHandler m f = PluginHandlers $ DMap.singleton (IdeMethod m) (PluginHandler (f' m)) where f' :: SMethod m -> PluginId -> ideState -> MessageParams m -> LspT Config IO (NonEmpty (Either PluginError (MessageResult m))) -- We need to have separate functions for each method that supports resolve, so far we only support CodeActions -- CodeLens, and Completion methods. f' SMethod_TextDocumentCodeAction pid ide params@CodeActionParams{_textDocument=TextDocumentIdentifier {_uri}} = pure . fmap (wrapCodeActions pid _uri) <$> runExceptT (f ide pid params) f' SMethod_TextDocumentCodeLens pid ide params@CodeLensParams{_textDocument=TextDocumentIdentifier {_uri}} = pure . fmap (wrapCodeLenses pid _uri) <$> runExceptT (f ide pid params) f' SMethod_TextDocumentCompletion pid ide params@CompletionParams{_textDocument=TextDocumentIdentifier {_uri}} = pure . fmap (wrapCompletions pid _uri) <$> runExceptT (f ide pid params) -- This is the default case for all other methods f' _ pid ide params = pure <$> runExceptT (f ide pid params) -- Todo: use fancy pancy lenses to make this a few lines wrapCodeActions pid uri (InL ls) = let wrapCodeActionItem pid uri (InR c) = InR $ wrapResolveData pid uri c wrapCodeActionItem _ _ command@(InL _) = command in InL $ wrapCodeActionItem pid uri <$> ls wrapCodeActions _ _ (InR r) = InR r wrapCodeLenses pid uri (InL ls) = InL $ wrapResolveData pid uri <$> ls wrapCodeLenses _ _ (InR r) = InR r wrapCompletions pid uri (InL ls) = InL $ wrapResolveData pid uri <$> ls wrapCompletions pid uri (InR (InL cl@(CompletionList{_items}))) = InR $ InL $ cl & L.items .~ (wrapResolveData pid uri <$> _items) wrapCompletions _ _ (InR (InR r)) = InR $ InR r -- | Make a handler for plugins with no extra data mkPluginNotificationHandler :: PluginNotificationMethod m => SClientMethod (m :: Method ClientToServer Notification) -> PluginNotificationMethodHandler ideState m -> PluginNotificationHandlers ideState mkPluginNotificationHandler m f = PluginNotificationHandlers $ DMap.singleton (IdeNotification m) (PluginNotificationHandler f') where f' pid ide vfs = f ide vfs pid defaultPluginPriority :: Natural defaultPluginPriority = 1000 -- | Set up a plugin descriptor, initialized with default values. -- This plugin descriptor is prepared for @haskell@ files, such as -- -- * @.hs@ -- * @.lhs@ -- * @.hs-boot@ -- -- and handlers will be enabled for files with the appropriate file -- extensions. defaultPluginDescriptor :: PluginId -> T.Text -> PluginDescriptor ideState defaultPluginDescriptor plId desc = PluginDescriptor plId desc defaultPluginPriority mempty mempty mempty defaultConfigDescriptor mempty mempty Nothing [".hs", ".lhs", ".hs-boot"] -- | Set up a plugin descriptor, initialized with default values. -- This plugin descriptor is prepared for @.cabal@ files and as such, -- will only respond / run when @.cabal@ files are currently in scope. -- -- Handles files with the following extensions: -- * @.cabal@ defaultCabalPluginDescriptor :: PluginId -> T.Text -> PluginDescriptor ideState defaultCabalPluginDescriptor plId desc = PluginDescriptor plId desc defaultPluginPriority mempty mempty mempty defaultConfigDescriptor mempty mempty Nothing [".cabal"] newtype CommandId = CommandId T.Text deriving (Show, Read, Eq, Ord) instance IsString CommandId where fromString = CommandId . T.pack data PluginCommand ideState = forall a. (FromJSON a) => PluginCommand { commandId :: CommandId , commandDesc :: T.Text , commandFunc :: CommandFunction ideState a } -- --------------------------------------------------------------------- type CommandFunction ideState a = ideState -> a -> ExceptT PluginError (LspM Config) (Value |? Null) -- --------------------------------------------------------------------- type ResolveFunction ideState a (m :: Method ClientToServer Request) = ideState -> PluginId -> MessageParams m -> Uri -> a -> ExceptT PluginError (LspM Config) (MessageResult m) -- | Make a handler for resolve methods. In here we take your provided ResolveFunction -- and turn it into a PluginHandlers. See Note [Resolve in PluginHandlers] mkResolveHandler :: forall ideState a m. (FromJSON a, PluginRequestMethod m, L.HasData_ (MessageParams m) (Maybe Value)) => SClientMethod m -> ResolveFunction ideState a m -> PluginHandlers ideState mkResolveHandler m f = mkPluginHandler m $ \ideState plId params -> do case fromJSON <$> (params ^. L.data_) of (Just (Success (PluginResolveData owner@(PluginId ownerName) uri value) )) -> do if owner == plId then case fromJSON value of Success decodedValue -> let newParams = params & L.data_ ?~ value in f ideState plId newParams uri decodedValue Error msg -> -- We are assuming that if we can't decode the data, that this -- request belongs to another resolve handler for this plugin. throwError (PluginRequestRefused (NotResolveOwner (ownerName <> ": error decoding payload:" <> T.pack msg))) -- If we are getting an owner that isn't us, this means that there is an -- error, as we filter these our in `pluginEnabled` else throwError $ PluginInternalError invalidRequest -- If we are getting params without a decodable data field, this means that -- there is an error, as we filter these our in `pluginEnabled` (Just (Error err)) -> throwError $ PluginInternalError (parseError (params ^. L.data_) err) -- If there are no params at all, this also means that there is an error, -- as this is filtered out in `pluginEnabled` _ -> throwError $ PluginInternalError invalidRequest where invalidRequest = "The resolve request incorrectly got routed to the wrong resolve handler!" parseError value err = "Unable to decode: " <> T.pack (show value) <> ". Error: " <> T.pack (show err) wrapResolveData :: L.HasData_ a (Maybe Value) => PluginId -> Uri -> a -> a wrapResolveData pid uri hasData = hasData & L.data_ .~ (toJSON . PluginResolveData pid uri <$> data_) where data_ = hasData ^? L.data_ . _Just -- |Allow plugins to "own" resolve data, allowing only them to be queried for -- the resolve action. This design has added flexibility at the cost of nested -- Value types data PluginResolveData = PluginResolveData { resolvePlugin :: PluginId , resolveURI :: Uri , resolveValue :: Value } deriving (Generic, Show) deriving anyclass (ToJSON, FromJSON) newtype PluginId = PluginId T.Text deriving (Show, Read, Eq, Ord) deriving newtype (ToJSON, FromJSON, Hashable) instance IsString PluginId where fromString = PluginId . T.pack -- --------------------------------------------------------------------- -- | Format the given Text as a whole or only a @Range@ of it. -- Range must be relative to the text to format. -- To format the whole document, read the Text from the file and use 'FormatText' -- as the FormattingType. data FormattingType = FormatText | FormatRange Range type FormattingMethod m = ( L.HasOptions (MessageParams m) FormattingOptions , L.HasTextDocument (MessageParams m) TextDocumentIdentifier , MessageResult m ~ ([TextEdit] |? Null) ) type FormattingHandler a = a -> FormattingType -> T.Text -> NormalizedFilePath -> FormattingOptions -> ExceptT PluginError (LspM Config) ([TextEdit] |? Null) mkFormattingHandlers :: forall a. FormattingHandler a -> PluginHandlers a mkFormattingHandlers f = mkPluginHandler SMethod_TextDocumentFormatting ( provider SMethod_TextDocumentFormatting) <> mkPluginHandler SMethod_TextDocumentRangeFormatting (provider SMethod_TextDocumentRangeFormatting) where provider :: forall m. FormattingMethod m => SMethod m -> PluginMethodHandler a m provider m ide _pid params | Just nfp <- uriToNormalizedFilePath $ toNormalizedUri uri = do mf <- lift $ getVirtualFile $ toNormalizedUri uri case mf of Just vf -> do let typ = case m of SMethod_TextDocumentFormatting -> FormatText SMethod_TextDocumentRangeFormatting -> FormatRange (params ^. L.range) _ -> Prelude.error "mkFormattingHandlers: impossible" f ide typ (virtualFileText vf) nfp opts Nothing -> throwError $ PluginInvalidParams $ T.pack $ "Formatter plugin: could not get file contents for " ++ show uri | otherwise = throwError $ PluginInvalidParams $ T.pack $ "Formatter plugin: uriToFilePath failed for: " ++ show uri where uri = params ^. L.textDocument . L.uri opts = params ^. L.options -- --------------------------------------------------------------------- data FallbackCodeActionParams = FallbackCodeActionParams { fallbackWorkspaceEdit :: Maybe WorkspaceEdit , fallbackCommand :: Maybe Command } deriving (Generic, ToJSON, FromJSON) -- --------------------------------------------------------------------- otSetUri :: SpanInFlight -> Uri -> IO () otSetUri sp (Uri t) = setTag sp "uri" (encodeUtf8 t) class HasTracing a where traceWithSpan :: SpanInFlight -> a -> IO () traceWithSpan _ _ = pure () instance {-# OVERLAPPABLE #-} (L.HasTextDocument a doc, L.HasUri doc Uri) => HasTracing a where traceWithSpan sp a = otSetUri sp (a ^. L.textDocument . L.uri) instance HasTracing Value instance HasTracing ExecuteCommandParams instance HasTracing DidChangeWatchedFilesParams where traceWithSpan sp DidChangeWatchedFilesParams{_changes} = setTag sp "changes" (encodeUtf8 $ fromString $ show _changes) instance HasTracing DidChangeWorkspaceFoldersParams instance HasTracing DidChangeConfigurationParams instance HasTracing InitializeParams instance HasTracing InitializedParams instance HasTracing WorkspaceSymbolParams where traceWithSpan sp (WorkspaceSymbolParams _ _ query) = setTag sp "query" (encodeUtf8 query) instance HasTracing CallHierarchyIncomingCallsParams instance HasTracing CallHierarchyOutgoingCallsParams -- Instances for resolve types instance HasTracing CodeAction instance HasTracing CodeLens instance HasTracing CompletionItem instance HasTracing DocumentLink instance HasTracing InlayHint instance HasTracing WorkspaceSymbol -- --------------------------------------------------------------------- --Experimental resolve refactoring {-# NOINLINE pROCESS_ID #-} pROCESS_ID :: T.Text pROCESS_ID = unsafePerformIO getPid mkLspCommand :: PluginId -> CommandId -> T.Text -> Maybe [Value] -> Command mkLspCommand plid cn title args = Command title cmdId args where cmdId = mkLspCmdId pROCESS_ID plid cn mkLspCmdId :: T.Text -> PluginId -> CommandId -> T.Text mkLspCmdId pid (PluginId plid) (CommandId cid) = pid <> ":" <> plid <> ":" <> cid -- | Get the operating system process id for the running server -- instance. This should be the same for the lifetime of the instance, -- and different from that of any other currently running instance. getPid :: IO T.Text getPid = T.pack . show <$> getProcessID getProcessID :: IO Int installSigUsr1Handler :: IO () -> IO () #ifdef mingw32_HOST_OS getProcessID = fromIntegral <$> P.getCurrentProcessId installSigUsr1Handler _ = return () #else getProcessID = fromIntegral <$> P.getProcessID installSigUsr1Handler h = void $ installHandler sigUSR1 (Catch h) Nothing #endif {- Note [Resolve in PluginHandlers] Resolve methods have a few guarantees that need to be made by HLS, specifically they need to only be called once, as neither their errors nor their responses can be easily combined. Whereas commands, which similarly have the same requirements have their own codepaths for execution, for resolve methods we are relying on the standard PluginHandlers codepath. That isn't a problem, but it does mean we need to do some things extra for these methods. - First of all, whenever a handler that can be resolved sets the data_ field in their response, we need to intercept it, and wrap it in a data type PluginResolveData that allows us to route the future resolve request to the specific plugin which is responsible for it. (We also throw in the URI for convenience, because everyone needs that). We do that in mkPluginHandler. - When we get any resolve requests we check their data field for our PluginResolveData that will allow us to route the request to the right plugin. If we can't find out which plugin to route the request to, then we just don't route it at all. This is done in pluginEnabled, and pluginResolverResponsible. - Finally we have mkResolveHandler, which takes the resolve request and unwraps the plugins data from our PluginResolveData, parses it and passes it it on to the registered handler. It should be noted that there are some restrictions with this approach: First, if a plugin does not set the data_ field, than the request will not be able to be resolved. This is because we only wrap data_ fields that have been set with our PluginResolvableData tag. Second, if a plugin were to register two resolve handlers for the same method, than our assumptions that we never have two responses break, and behavior is undefined. -}