2 files changed, 70 insertions, 0 deletions
diff --git a/src/Language/Fiddle/Compiler/Stage0.hs b/src/Language/Fiddle/Compiler/Stage0.hs
new file mode 100644
index 0000000..d00d7cb
--- /dev/null
+++ b/src/Language/Fiddle/Compiler/Stage0.hs
@@ -0,0 +1,61 @@
+module Language.Fiddle.Compiler.Stage0 (toStage0, toStage1) where
+
+import Control.Monad.Identity (Identity)
+import Control.Monad.Writer
+import qualified Data.Text
+import Language.Fiddle.Ast
+import Language.Fiddle.Compiler
+import qualified Language.Fiddle.Parser
+import Language.Fiddle.Types (Commented, SourceSpan(..))
+import Text.Parsec (ParseError, errorPos)
+import Text.Parsec.Error (errorMessages, showErrorMessages)
+
+newtype Stage0Diagnostic = SyntaxError String
+
+toStage0 ::
+  String ->
+  Data.Text.Text ->
+  Compile () (FiddleUnit Stage1 (Either ParseError) (Commented SourceSpan))
+toStage0 filePath text =
+  case Language.Fiddle.Parser.parseFiddleText filePath text of
+    Left pe -> do
+      tell [parseErrorToDiagnostic pe]
+      hoistMaybe Nothing
+    Right a -> return a
+
+-- Gets the AST ready for Stage1 processing .This will report primarily
+-- SyntaxErrors and errors parsing the tree.
+--
+-- In the process, the tree is un-deferred and all parts of the
+toStage1 ::
+  FiddleUnit Stage1 (Either ParseError) a ->
+  Compile () (FiddleUnit Stage1 Identity a)
+toStage1 ast = do
+  alter
+    ( \case
+        (Left l) -> do
+          tell [parseErrorToDiagnostic l]
+          return (Left l)
+        r -> return r
+    )
+    return
+    ast
+
+  hoistMaybe $
+    case squeeze ast of
+      (Left _) -> Nothing
+      (Right a) -> Just a
+
+parseErrorToDiagnostic :: ParseError -> Diagnostic
+parseErrorToDiagnostic pe =
+  Diagnostic
+    Error
+    ( showErrorMessages
+        "or"
+        "unknown"
+        "expecting"
+        "unexpected"
+        "end of body or input (maybe a missing semicolon?)"
+        (errorMessages pe)
+    )
+    (SourceSpan (errorPos pe) (errorPos pe))
diff --git a/src/Language/Fiddle/Compiler/Stage1.hs b/src/Language/Fiddle/Compiler/Stage1.hs
new file mode 100644
index 0000000..d3f3e10
--- /dev/null
+++ b/src/Language/Fiddle/Compiler/Stage1.hs
@@ -0,0 +1,9 @@
+module Language.Fiddle.Compiler.Stage1 (toStage2) where
+
+import Control.Monad.Identity (Identity)
+import Language.Fiddle.Ast
+
+-- The second stage is a simplified version of the AST without anonymous
+-- declarations.
+toStage2 :: FiddleUnit Stage1 Identity a -> FiddleUnit Stage2 Identity a
+toStage2 = undefined