1 files changed, 93 insertions, 0 deletions
diff --git a/TestConfig.hs b/TestConfig.hs
new file mode 100644
index 000000000..5e59681dd
--- /dev/null
+++ b/TestConfig.hs
@@ -0,0 +1,93 @@
+{- Tests the system and generates SysConfig.hs. -}
+
+module TestConfig where
+
+import System.IO
+import System.Cmd
+import System.Exit
+
+type ConfigKey = String
+data ConfigValue = BoolConfig Bool | StringConfig 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
+
+instance Show Config where
+        show (Config key value) = unlines
+		[ key ++ " :: " ++ valuetype value
+		, key ++ " = " ++ show value
+		]
+		where
+			valuetype (BoolConfig _) = "Bool"
+			valuetype (StringConfig _) = "String"
+
+writeSysConfig :: [Config] -> IO ()
+writeSysConfig config = writeFile "SysConfig.hs" body
+	where
+		body = unlines $ header ++ map show config ++ footer
+		header = [
+			  "{- Automatically generated. -}"
+			, "module 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 = (words cmdline) !! 0
+
+{- 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] -> Test
+selectCmd k cmds = search cmds
+	where
+		search [] = do
+			testEnd $ Config k (BoolConfig False)
+			error $ "* need one of these commands, but none are available: " ++ show cmds
+		search (c:cs) = do
+			ret <- system $ quiet c
+			if (ret == ExitSuccess)
+				then return $ Config k (StringConfig 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)) = putStrLn $ " yes"
+testEnd (Config _ (BoolConfig False)) = putStrLn $ " no"
+testEnd (Config _ (StringConfig s)) = putStrLn $ " " ++ s