Generate Python opcodes from opcode descriptors

Add Haskell module Hs2Py which contains the helper functions that
generate the Python opcodes as strings from the Haskell opcode
descriptors produced by Template Haskell.
Signed-off-by: Jose A. Lopes <jabolopes@google.com>
Reviewed-by: Guido Trotter <ultrotter@google.com>

Makefile.am

@@ -70,6 +70,7 @@ HS_DIRS = \
 	src/Ganeti/Curl \
 	src/Ganeti/Cpu \
 	src/Ganeti/DataCollectors \
+	src/Ganeti/Hs2Py \
 	src/Ganeti/HTools \
 	src/Ganeti/HTools/Backend \
 	src/Ganeti/HTools/Program \
@@ -601,6 +602,7 @@ HS_LIB_SRCS = \
 	src/Ganeti/Hypervisor/Xen/XmParser.hs \
 	src/Ganeti/Hypervisor/Xen/Types.hs \
 	src/Ganeti/Hash.hs \
+	src/Ganeti/Hs2Py/GenOpCodes.hs \
 	src/Ganeti/JQueue.hs \
 	src/Ganeti/JSON.hs \
 	src/Ganeti/Jobs.hs \

src/Ganeti/Hs2Py/GenOpCodes.hs

+{-| GenOpCodes handles Python opcode generation.
+
+GenOpCodes contains the helper functions that generate the Python
+opcodes as strings from the Haskell opcode description.
+
+-}
+
+{-
+
+Copyright (C) 2011, 2012, 2013 Google Inc.
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful, but
+WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program; if not, write to the Free Software
+Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+02110-1301, USA.
+
+-}
+
+module Ganeti.Hs2Py.GenOpCodes (showPyClasses) where
+
+import Data.List (intercalate, zipWith4)
+
+import Ganeti.OpCodes
+import Ganeti.THH
+
+-- | Generates the Python class docstring.
+pyClassDoc :: String -> String
+pyClassDoc doc
+  | length (lines doc) > 1 =
+    "  \"\"\"" ++ doc ++ "\n\n" ++ "  \"\"\"" ++ "\n"
+  | otherwise =
+    "  \"\"\"" ++ doc ++ "\"\"\"" ++ "\n"
+
+-- | Generates an opcode parameter in Python.
+pyClassField :: String -> String -> Maybe PyValueEx -> String -> String
+pyClassField name typ Nothing doc =
+  "(" ++ intercalate ", " [show name, "None", typ, show doc] ++ ")"
+  
+pyClassField name typ (Just (PyValueEx def)) doc =
+  "(" ++ intercalate ", " [show name, showValue def, typ, show doc] ++ ")"
+  
+-- | Comma intercalates and indents opcode parameters in Python.
+intercalateIndent :: [String] -> String
+intercalateIndent xs = intercalate "," (map ("\n    " ++) xs)
+
+-- | Generates an opcode as a Python class.
+showPyClass :: OpCodeDescriptor -> String
+showPyClass (name, typ, doc, fields, types, defs, docs, dsc) =
+  let
+    baseclass
+      | name == "OpInstanceMultiAlloc" = "OpInstanceMultiAllocBase"
+      | otherwise = "OpCode"
+    opDscField
+      | null dsc = ""
+      | otherwise = "  OP_DSC_FIELD = " ++ show dsc ++ "\n"
+    withLU
+      | name == "OpTestDummy" = "\n  WITH_LU = False"
+      | otherwise = ""
+  in
+   "class " ++ name ++ "(" ++ baseclass ++ "):" ++ "\n" ++
+   pyClassDoc doc ++
+   opDscField ++
+   "  OP_PARAMS = [" ++
+   intercalateIndent (zipWith4 pyClassField fields types defs docs) ++
+   "\n    ]" ++ "\n" ++
+   "  OP_RESULT = " ++ typ ++
+   withLU ++ "\n\n"
+
+-- | Generates all opcodes as Python classes.
+showPyClasses :: String
+showPyClasses = concatMap showPyClass pyClasses