1 files changed, 101 insertions, 0 deletions
diff --git a/compiler/GHC/Unit/Module/Graph.hs b/compiler/GHC/Unit/Module/Graph.hs
new file mode 100644
index 0000000000..faa3ae9b1a
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+++ b/compiler/GHC/Unit/Module/Graph.hs
@@ -0,0 +1,101 @@
+{-# LANGUAGE RecordWildCards #-}
+
+module GHC.Unit.Module.Graph
+   ( ModuleGraph
+   , emptyMG
+   , mkModuleGraph
+   , extendMG
+   , mapMG
+   , mgModSummaries
+   , mgElemModule
+   , mgLookupModule
+   , mgBootModules
+   , needsTemplateHaskellOrQQ
+   , isTemplateHaskellOrQQNonBoot
+   )
+where
+
+import GHC.Prelude
+
+import qualified GHC.LanguageExtensions as LangExt
+
+import GHC.Driver.Session
+
+import GHC.Unit.Module.ModSummary
+import GHC.Unit.Module.Env
+import GHC.Unit.Types
+
+
+-- | A ModuleGraph contains all the nodes from the home package (only).
+-- There will be a node for each source module, plus a node for each hi-boot
+-- module.
+--
+-- The graph is not necessarily stored in topologically-sorted order.  Use
+-- 'GHC.topSortModuleGraph' and 'GHC.Data.Graph.Directed.flattenSCC' to achieve this.
+data ModuleGraph = ModuleGraph
+  { mg_mss :: [ModSummary]
+  , mg_non_boot :: ModuleEnv ModSummary
+    -- a map of all non-boot ModSummaries keyed by Modules
+  , mg_boot :: ModuleSet
+    -- a set of boot Modules
+  , mg_needs_th_or_qq :: !Bool
+    -- does any of the modules in mg_mss require TemplateHaskell or
+    -- QuasiQuotes?
+  }
+
+-- | Determines whether a set of modules requires Template Haskell or
+-- Quasi Quotes
+--
+-- Note that if the session's 'DynFlags' enabled Template Haskell when
+-- 'depanal' was called, then each module in the returned module graph will
+-- have Template Haskell enabled whether it is actually needed or not.
+needsTemplateHaskellOrQQ :: ModuleGraph -> Bool
+needsTemplateHaskellOrQQ mg = mg_needs_th_or_qq mg
+
+-- | Map a function 'f' over all the 'ModSummaries'.
+-- To preserve invariants 'f' can't change the isBoot status.
+mapMG :: (ModSummary -> ModSummary) -> ModuleGraph -> ModuleGraph
+mapMG f mg@ModuleGraph{..} = mg
+  { mg_mss = map f mg_mss
+  , mg_non_boot = mapModuleEnv f mg_non_boot
+  }
+
+mgBootModules :: ModuleGraph -> ModuleSet
+mgBootModules ModuleGraph{..} = mg_boot
+
+mgModSummaries :: ModuleGraph -> [ModSummary]
+mgModSummaries = mg_mss
+
+mgElemModule :: ModuleGraph -> Module -> Bool
+mgElemModule ModuleGraph{..} m = elemModuleEnv m mg_non_boot
+
+-- | Look up a ModSummary in the ModuleGraph
+mgLookupModule :: ModuleGraph -> Module -> Maybe ModSummary
+mgLookupModule ModuleGraph{..} m = lookupModuleEnv mg_non_boot m
+
+emptyMG :: ModuleGraph
+emptyMG = ModuleGraph [] emptyModuleEnv emptyModuleSet False
+
+isTemplateHaskellOrQQNonBoot :: ModSummary -> Bool
+isTemplateHaskellOrQQNonBoot ms =
+  (xopt LangExt.TemplateHaskell (ms_hspp_opts ms)
+    || xopt LangExt.QuasiQuotes (ms_hspp_opts ms)) &&
+  (isBootSummary ms == NotBoot)
+
+-- | Add a ModSummary to ModuleGraph. Assumes that the new ModSummary is
+-- not an element of the ModuleGraph.
+extendMG :: ModuleGraph -> ModSummary -> ModuleGraph
+extendMG ModuleGraph{..} ms = ModuleGraph
+  { mg_mss = ms:mg_mss
+  , mg_non_boot = case isBootSummary ms of
+      IsBoot -> mg_non_boot
+      NotBoot -> extendModuleEnv mg_non_boot (ms_mod ms) ms
+  , mg_boot = case isBootSummary ms of
+      NotBoot -> mg_boot
+      IsBoot -> extendModuleSet mg_boot (ms_mod ms)
+  , mg_needs_th_or_qq = mg_needs_th_or_qq || isTemplateHaskellOrQQNonBoot ms
+  }
+
+mkModuleGraph :: [ModSummary] -> ModuleGraph
+mkModuleGraph = foldr (flip extendMG) emptyMG
+