feat(zig): native Arboricx bundle parser and C ABI

src/Main.hs

@@ -1,6 +1,7 @@
 module Main where
 
-import ContentStore (initContentStore, loadEnvironment, resolveExportTarget)
+import ContentStore (initContentStore, loadEnvironment, loadTerm, resolveExportTarget)
+import System.Exit (die)
 import Server (runServer)
 import Eval                   (evalTricu, mainResult, result)
 import FileEval
@@ -32,6 +33,7 @@ data TricuArgs
   | Export { hash :: String, exportNameOpt :: String, outFile :: FilePath, names :: [String] }
   | Import { inFile :: FilePath }
   | Serve { host :: String, port :: Int }
+  | ExportDag { target :: String, outFile :: FilePath }
   deriving (Show, Data, Typeable)
 
 replMode :: TricuArgs
@@ -112,10 +114,21 @@ serveMode = Serve
   &= explicit
   &= name "server"
 
+exportDagMode :: TricuArgs
+exportDagMode = ExportDag
+  { target = def &= help "Stored term name or hash to export as a DAG node table."
+                 &= name "t" &= typ "NAME_OR_HASH"
+  , outFile = def &= help "Optional output file path. Defaults to stdout."
+                  &= name "o" &= typ "FILE"
+  }
+  &= help "Export a term's Merkle DAG as a topologically-sorted node table for host embedding."
+  &= explicit
+  &= name "export-dag"
+
 main :: IO ()
 main = do
   let versionStr = "tricu Evaluator and REPL " ++ showVersion version
-  cmdArgsParsed <- cmdArgs $ modes [replMode, evaluateMode, decodeMode, compileMode, exportMode, importMode, serveMode]
+  cmdArgsParsed <- cmdArgs $ modes [replMode, evaluateMode, decodeMode, compileMode, exportMode, importMode, serveMode, exportDagMode]
     &= help "tricu: Exploring Tree Calculus"
     &= program "tricu"
     &= summary versionStr
@@ -191,6 +204,18 @@ main = do
       putStrLn $ "  GET /bundle/name/:name   -- convenience endpoint"
       putStrLn $ "  Content-Type: application/vnd.arboricx.bundle"
       runServer hostStr portNum
+    ExportDag { target = targetName, outFile = dagOutFile } -> do
+      conn <- initContentStore
+      maybeTerm <- loadTerm conn targetName
+      close conn
+      case maybeTerm of
+        Nothing -> die $ "Term not found: " ++ targetName
+        Just term -> do
+          let (rootIdx, nodes) = exportDag term
+              output = unlines $ show rootIdx : map (\(tag, refs) -> unwords (tag : map show refs)) nodes
+          if null dagOutFile
+            then putStr output
+            else writeFile dagOutFile output
 
 runTricu :: String -> String
 runTricu = formatT TreeCalculus . runTricuT