1 files changed, 63 insertions, 0 deletions
diff --git a/compiler/GHC/Unit/Parser.hs b/compiler/GHC/Unit/Parser.hs
new file mode 100644
index 0000000000..6ae38259af
--- /dev/null
+++ b/compiler/GHC/Unit/Parser.hs
@@ -0,0 +1,63 @@
+-- | Parsers for unit/module identifiers
+module GHC.Unit.Parser
+   ( parseUnit
+   , parseIndefUnitId
+   , parseHoleyModule
+   , parseModSubst
+   )
+where
+
+import GHC.Prelude
+
+import GHC.Unit.Types
+import GHC.Unit.Module.Name
+import GHC.Data.FastString
+
+import qualified Text.ParserCombinators.ReadP as Parse
+import Text.ParserCombinators.ReadP (ReadP, (<++))
+import Data.Char (isAlphaNum)
+
+parseUnit :: ReadP Unit
+parseUnit = parseVirtUnitId <++ parseDefUnitId
+  where
+    parseVirtUnitId = do
+        uid   <- parseIndefUnitId
+        insts <- parseModSubst
+        return (mkVirtUnit uid insts)
+    parseDefUnitId = do
+        s <- parseUnitId
+        return (RealUnit (Definite s))
+
+parseUnitId :: ReadP UnitId
+parseUnitId = do
+   s <- Parse.munch1 (\c -> isAlphaNum c || c `elem` "-_.+")
+   return (UnitId (mkFastString s))
+
+parseIndefUnitId :: ReadP IndefUnitId
+parseIndefUnitId = do
+   uid <- parseUnitId
+   return (Indefinite uid Nothing)
+
+parseHoleyModule :: ReadP Module
+parseHoleyModule = parseModuleVar <++ parseModule
+    where
+      parseModuleVar = do
+        _ <- Parse.char '<'
+        modname <- parseModuleName
+        _ <- Parse.char '>'
+        return (Module HoleUnit modname)
+      parseModule = do
+        uid <- parseUnit
+        _ <- Parse.char ':'
+        modname <- parseModuleName
+        return (Module uid modname)
+
+parseModSubst :: ReadP [(ModuleName, Module)]
+parseModSubst = Parse.between (Parse.char '[') (Parse.char ']')
+      . flip Parse.sepBy (Parse.char ',')
+      $ do k <- parseModuleName
+           _ <- Parse.char '='
+           v <- parseHoleyModule
+           return (k, v)
+
+