root / src / Ganeti / THH / PyRPC.hs @ dee434c2
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{-# LANGUAGE TemplateHaskell #-} |
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{-# OPTIONS_GHC -fno-warn-warnings-deprecations #-} |
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{-| Combines the construction of RPC server components and their Python stubs. |
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-} |
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{- |
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Copyright (C) 2013 Google Inc. |
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This program is free software; you can redistribute it and/or modify |
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it under the terms of the GNU General Public License as published by |
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the Free Software Foundation; either version 2 of the License, or |
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(at your option) any later version. |
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|
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This program is distributed in the hope that it will be useful, but |
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WITHOUT ANY WARRANTY; without even the implied warranty of |
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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General Public License for more details. |
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|
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You should have received a copy of the GNU General Public License |
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along with this program; if not, write to the Free Software |
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Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA |
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02110-1301, USA. |
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-} |
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module Ganeti.THH.PyRPC |
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( genPyUDSRpcStub |
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, genPyUDSRpcStubStr |
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) where |
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|
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import Control.Monad |
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import Data.Char (toLower, toUpper) |
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import Data.Functor |
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import Data.Maybe (fromMaybe) |
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import Language.Haskell.TH |
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import Language.Haskell.TH.Syntax (liftString) |
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import Text.PrettyPrint |
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import Ganeti.THH.Types |
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-- | The indentation step in generated Python files. |
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pythonIndentStep :: Int |
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pythonIndentStep = 2 |
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|
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-- | A helper function that nests a block of generated output by the default |
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-- step (see 'pythonIndentStep'). |
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nest' :: Doc -> Doc |
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nest' = nest pythonIndentStep |
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|
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-- | The name of an abstract function to which all method in a Python stub |
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-- are forwarded to. |
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genericInvokeName :: String |
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genericInvokeName = "_GenericInvoke" |
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|
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-- | The name of a function that returns the socket path for reaching the |
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-- appropriate RPC client. |
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socketPathName :: String |
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socketPathName = "_GetSocketPath" |
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|
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-- | Create a Python expression that applies a given function to a list of |
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-- given expressions |
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apply :: String -> [Doc] -> Doc |
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apply name as = text name <> parens (hcat $ punctuate (text ", ") as) |
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|
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-- | An empty line block. |
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emptyLine :: Doc |
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emptyLine = text "" -- apparently using 'empty' doesn't work |
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lowerFirst :: String -> String |
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lowerFirst (x:xs) = toLower x : xs |
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lowerFirst [] = [] |
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upperFirst :: String -> String |
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upperFirst (x:xs) = toUpper x : xs |
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upperFirst [] = [] |
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-- | Creates a method declaration given a function name and a list of |
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-- Haskell types corresponding to its arguments. |
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toFunc :: String -> [Type] -> Q Doc |
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toFunc fname as = do |
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args <- zipWithM varName [1..] as |
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let args' = text "self" : args |
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callName = lowerFirst fname |
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return $ (text "def" <+> apply fname args') <> colon $+$ |
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nest' (text "return" <+> |
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text "self." <> |
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apply genericInvokeName (text (show callName) : args) |
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) |
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where |
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-- | Create a name for a method argument, given its index position |
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-- and Haskell type. |
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varName :: Int -> Type -> Q Doc |
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varName _ (VarT n) = lowerFirstNameQ n |
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varName _ (ConT n) = lowerFirstNameQ n |
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varName idx (AppT ListT t) = listOf idx t |
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varName idx (AppT (ConT n) t) |
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| n == ''[] = listOf idx t |
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varName idx (AppT (AppT (TupleT 2) t) t') |
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= pairOf idx t t' |
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varName idx (AppT (AppT (ConT n) t) t') |
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| n == ''(,) = pairOf idx t t' |
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varName idx t = do |
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report False $ "Don't know how to make a Python variable name from " |
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++ show t ++ "; using a numbered one." |
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return $ text ('_' : show idx) |
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|
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-- | Create a name for a method argument, knowing that its a list of |
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-- a given type. |
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listOf :: Int -> Type -> Q Doc |
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listOf idx t = (<> text "List") <$> varName idx t |
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|
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-- | Create a name for a method argument, knowing that its a pair of |
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-- the given types. |
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pairOf :: Int -> Type -> Type -> Q Doc |
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pairOf idx t t' = do |
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tn <- varName idx t |
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tn' <- varName idx t' |
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return $ tn <> text "_" <> tn' <> text "_Pair" |
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lowerFirstNameQ :: Name -> Q Doc |
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lowerFirstNameQ = return . text . lowerFirst . nameBase |
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|
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-- | Creates a method declaration by inspecting (reifying) Haskell's function |
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-- name. |
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nameToFunc :: Name -> Q Doc |
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nameToFunc name = do |
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(as, _) <- funArgs `liftM` typeOfFun name |
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-- If the function has just one argument, try if it isn't a tuple; |
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-- if not, use the arguments as they are. |
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let as' = fromMaybe as $ case as of |
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[t] -> tupleArgs t -- TODO CHECK! |
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_ -> Nothing |
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toFunc (upperFirst $ nameBase name) as' |
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|
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-- | Generates a Python class stub, given a class name, the list of Haskell |
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-- functions to expose as methods, and a optionally a piece of code to |
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-- include. |
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namesToClass |
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:: String -- ^ the class name |
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-> Doc -- ^ Python code to include in the class |
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-> [Name] -- ^ the list of functions to include |
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-> Q Doc |
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namesToClass cname pycode fns = do |
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fnsCode <- mapM (liftM ($+$ emptyLine) . nameToFunc) fns |
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return $ vcat [ text "class" <+> apply cname [text "object"] <> colon |
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, nest' ( |
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pycode $+$ vcat fnsCode |
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) |
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] |
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|
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-- | Takes a list of function names and creates a RPC handler that delegates |
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-- calls to them, as well as writes out the corresponding Python stub. |
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-- |
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-- See 'mkRpcM' for the requirements on the passed functions and the returned |
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-- expression. |
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genPyUDSRpcStub |
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:: String -- ^ the name of the class to be generated |
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-> String -- ^ the name of the constant from @constants.py@ holding |
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-- the path to a UDS socket |
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-> [Name] -- ^ names of functions to include |
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-> Q Doc |
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genPyUDSRpcStub className constName = liftM (header $+$) . |
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namesToClass className stubCode |
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where |
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header = text "# This file is automatically generated, do not edit!" $+$ |
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text "# pylint: disable-all" |
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stubCode = |
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abstrMethod genericInvokeName [ text "method", text "*args"] $+$ |
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method socketPathName [] ( |
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text "from ganeti import pathutils" $+$ |
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text "return" <+> text "pathutils." <> text constName) |
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method name args body = |
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text "def" <+> apply name (text "self" : args) <> colon $+$ |
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nest' body $+$ |
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emptyLine |
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abstrMethod name args = method name args $ |
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text "raise" <+> apply "NotImplementedError" [] |
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|
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-- The same as 'genPyUDSRpcStub', but returns the result as a @String@ |
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-- expression. |
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genPyUDSRpcStubStr |
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:: String -- ^ the name of the class to be generated |
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-> String -- ^ the constant in @pathutils.py@ holding the socket path |
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-> [Name] -- ^ functions to include |
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-> Q Exp |
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genPyUDSRpcStubStr className constName names = |
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liftString . render =<< genPyUDSRpcStub className constName names |