moved files around

Build/TestConfig.hs

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+{- Tests the system and generates Build.SysConfig.hs. -}
+
+module Build.TestConfig where
+
+import System.IO
+import System.Cmd
+import System.Exit
+
+type ConfigKey = String
+data ConfigValue =
+	BoolConfig Bool |
+	StringConfig String |
+	MaybeStringConfig (Maybe String)
+data Config = Config ConfigKey ConfigValue
+
+type Test = IO Config
+type TestName = String
+data TestCase = TestCase TestName Test
+
+instance Show ConfigValue where
+	show (BoolConfig b) = show b
+	show (StringConfig s) = show s
+	show (MaybeStringConfig s) = show s
+
+instance Show Config where
+	show (Config key value) = unlines
+		[ key ++ " :: " ++ valuetype value
+		, key ++ " = " ++ show value
+		]
+		where
+			valuetype (BoolConfig _) = "Bool"
+			valuetype (StringConfig _) = "String"
+			valuetype (MaybeStringConfig _) = "Maybe String"
+
+writeSysConfig :: [Config] -> IO ()
+writeSysConfig config = writeFile "Build/SysConfig.hs" body
+	where
+		body = unlines $ header ++ map show config ++ footer
+		header = [
+			  "{- Automatically generated. -}"
+			, "module Build.SysConfig where"
+			, ""
+			]
+		footer = []
+
+runTests :: [TestCase] -> IO [Config]
+runTests [] = return []
+runTests (TestCase tname t : ts) = do
+	testStart tname
+	c <- t
+	testEnd c
+	rest <- runTests ts
+	return $ c:rest
+
+{- Tests that a command is available, aborting if not. -}
+requireCmd :: ConfigKey -> String -> Test
+requireCmd k cmdline = do
+	ret <- testCmd k cmdline
+	handle ret
+	where
+		handle r@(Config _ (BoolConfig True)) = return r
+		handle r = do
+			testEnd r
+			error $ "** the " ++ c ++ " command is required"
+		c = head $ words cmdline
+
+{- Checks if a command is available by running a command line. -}
+testCmd :: ConfigKey -> String -> Test
+testCmd k cmdline = do
+	ret <- system $ quiet cmdline
+	return $ Config k (BoolConfig $ ret == ExitSuccess)
+
+{- Ensures that one of a set of commands is available by running each in
+ - turn. The Config is set to the first one found. -}
+selectCmd :: ConfigKey -> [String] -> String -> Test
+selectCmd k = searchCmd
+		(return . Config k . StringConfig)
+		(\cmds -> do
+			testEnd $ Config k $ BoolConfig False
+			error $ "* need one of these commands, but none are available: " ++ show cmds
+		)
+
+maybeSelectCmd :: ConfigKey -> [String] -> String -> Test
+maybeSelectCmd k = searchCmd
+		(return . Config k . MaybeStringConfig . Just)
+		(\_ -> return $ Config k $ MaybeStringConfig Nothing)
+
+searchCmd :: (String -> Test) -> ([String] -> Test) -> [String] -> String -> Test
+searchCmd success failure cmds param = search cmds
+	where
+		search [] = failure cmds
+		search (c:cs) = do
+			ret <- system $ quiet c ++ " " ++ param
+			if ret == ExitSuccess
+				then success c
+				else search cs
+
+quiet :: String -> String
+quiet s = s ++ " >/dev/null 2>&1"
+
+testStart :: TestName -> IO ()
+testStart s = do
+	putStr $ "  checking " ++ s ++ "..."
+	hFlush stdout
+
+testEnd :: Config -> IO ()
+testEnd (Config _ (BoolConfig True)) = status "yes"
+testEnd (Config _ (BoolConfig False)) = status "no"
+testEnd (Config _ (StringConfig s)) = status s
+testEnd (Config _ (MaybeStringConfig (Just s))) = status s
+testEnd (Config _ (MaybeStringConfig Nothing)) = status "not available"
+
+status :: String -> IO ()
+status s = putStrLn $ ' ':s