copilot-c99: Add specific Trigger representation. Refs Copilot-Lang…

…uage#296.

A backend specific representation of triggers allows us to keep track of
the internal name for a trigger.

copilot-c99/copilot-c99.cabal

@@ -59,6 +59,7 @@ library
                          , Copilot.Compile.C99.External
                          , Copilot.Compile.C99.Compile
                          , Copilot.Compile.C99.Settings
+                         , Copilot.Compile.C99.Representation
 
 test-suite unit-tests
   type:

copilot-c99/src/Copilot/Compile/C99/Representation.hs

@@ -0,0 +1,22 @@
+-- | C99 backend specific versions of selected `Copilot.Core` datatypes.
+module Copilot.Compile.C99.Representation
+    (
+      UniqueTrigger (..)
+    , UniqueTriggerId
+    , mkUniqueTriggers
+    )
+  where
+
+import Copilot.Core ( Trigger (..) )
+
+-- | Internal unique name for a trigger.
+type UniqueTriggerId = String
+
+-- | A `Copilot.Core.Trigger` with an unique name.
+data UniqueTrigger = UniqueTrigger UniqueTriggerId Trigger
+
+-- | Given a list of triggers, make their names unique.
+mkUniqueTriggers :: [Trigger] -> [UniqueTrigger]
+mkUniqueTriggers ts = zipWith mkUnique ts [0..]
+  where
+    mkUnique t@(Trigger name _ _) n = UniqueTrigger (name ++ "_" ++ show n) t