From f8fe23fda7b97d5301bfb2ec1d89ce9967c5b200 Mon Sep 17 00:00:00 2001
From: "kr.angelov" <kr.angelov@gmail.com>
Date: Wed, 29 Aug 2012 11:43:02 +0000
Subject: A basic infrastructure for generating Teyjus bytecode from the GF
 abstract syntax

---
 src/compiler/GF/Compile/GenerateBC.hs | 75 +++++++++++++++++++++++++++++++++++
 1 file changed, 75 insertions(+)
 create mode 100644 src/compiler/GF/Compile/GenerateBC.hs

(limited to 'src/compiler/GF/Compile/GenerateBC.hs')

diff --git a/src/compiler/GF/Compile/GenerateBC.hs b/src/compiler/GF/Compile/GenerateBC.hs
new file mode 100644
index 000000000..d5b18c725
--- /dev/null
+++ b/src/compiler/GF/Compile/GenerateBC.hs
@@ -0,0 +1,75 @@
+module GF.Compile.GenerateBC(generateByteCode) where
+
+import GF.Grammar
+import GF.Compile.Instructions
+import PGF.Data
+
+import Data.Maybe
+import qualified Data.IntMap as IntMap
+import qualified Data.ByteString as BSS
+import qualified Data.ByteString.Lazy as BS
+import Data.Binary
+
+generateByteCode :: [(QIdent,Info)] -> ([(QIdent,Info,BCAddr)], BSS.ByteString)
+generateByteCode = runGenM . mapM genFun
+
+type BCLabel = (Int, BCAddr)
+
+genFun (id,info@(AbsFun (Just (L _ ty)) ma pty _)) = do
+  l1 <- newLabel
+  emitLabel l1
+  emit Ins_fail
+  l2 <- newLabel
+  l3 <- newLabel
+  emit (Ins_switch_on_reg (1,addr l2,addr l3))
+  emitLabel l2
+  emit (Ins_try (1,addr l3))
+  emit (Ins_trust_ext (1,1))
+  emit (Ins_try_me_else (0,addr l1))
+  emitLabel l3
+  l4 <- newLabel
+  l5 <- newLabel
+  emit (Ins_switch_on_term (addr l4,addr l5,addr l1,addr l4))
+  emitLabel l4
+  emitLabel l5
+  return (id,info,addr l1)
+genFun (id,info@(AbsCat (Just (L _ cont)))) = do
+  l1 <- newLabel
+  return (id,info,addr l1)
+
+newtype GenM a = GenM {unGenM :: IntMap.IntMap BCAddr ->
+                                 IntMap.IntMap BCAddr ->
+                                 [Instruction] -> 
+                                 (a,IntMap.IntMap BCAddr,[Instruction])}
+
+instance Monad GenM where
+  return x = GenM (\fm cm is -> (x,cm,is))
+  f >>= g  = GenM (\fm cm is -> case unGenM f fm cm is of
+                                  (x,cm,is) -> unGenM (g x) fm cm is)
+
+runGenM :: GenM a -> (a, BSS.ByteString)
+runGenM f = 
+  let (x, cm, is) = unGenM f cm IntMap.empty []
+  in (x, BSS.concat (BS.toChunks (encode (BC (reverse is)))))
+
+emit :: Instruction -> GenM ()
+emit i = GenM (\fm cm is -> ((), cm, i:is))
+
+newLabel :: GenM BCLabel
+newLabel = GenM (\fm cm is -> 
+  let lbl  = IntMap.size cm
+      addr = fromMaybe (error "newLabel") (IntMap.lookup lbl fm)
+  in ((lbl,addr), IntMap.insert lbl 0 cm, is))
+
+emitLabel :: BCLabel -> GenM ()
+emitLabel (lbl,addr) = GenM (\fm cm is ->
+  ((), IntMap.insert lbl (length is) cm, is))
+
+addr :: BCLabel -> BCAddr
+addr (lbl,addr) = addr
+
+data ByteCode = BC [Instruction]
+
+instance Binary ByteCode where
+  put (BC is) = mapM_ putInstruction is
+  get = error "get ByteCode"
-- 
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