Add STM function to snapshot VFS

Author: wz1000

lsp/src/Language/LSP/Server.hs

@@ -38,6 +38,7 @@ module Language.LSP.Server
   , persistVirtualFile
   , getVersionedTextDoc
   , reverseFileMap
+  , snapshotVirtualFiles
 
   -- * Diagnostics
   , publishDiagnostics

lsp/src/Language/LSP/Server/Core.hs

@@ -380,6 +380,13 @@ getVirtualFiles = vfsData <$> getsState resVFS
 
 {-# INLINE getVirtualFiles #-}
 
+-- | Take an atomic snapshot of the current state of the virtual file system.
+snapshotVirtualFiles :: LanguageContextEnv c -> STM VFS
+snapshotVirtualFiles env = vfsData <$> readTVar (resVFS $ resState env)
+
+{-# INLINE snapshotVirtualFiles #-}
+
+
 -- | Dump the current text for a given VFS file to a temporary file,
 -- and return the path to the file.
 persistVirtualFile :: MonadLsp config m => NormalizedUri -> m (Maybe FilePath)