--- factorcss/FactorCSS.hs	2004/12/27 19:45:02	63
+++ factorcss/FactorCSS.hs	2004/12/30 21:22:59	66
@@ -16,31 +16,65 @@
 -- the stylesheet depends on the order of rules (see CSS 2.1 6.4.1).
 
 import List
+import System
 import Tokeniser
 import Parser
 import CSS
 
+-- Program entry function.
+main :: IO ()
 main = do
-	s <- getContents
---	print (alexScanTokens s)
---	(print . process . parser . alexScanTokens) s
-	(putStr . unlines . show_stylesheet . process .
-			parser . alexScanTokens) s
+	args <- getArgs
+	interact (run args)
+
+-- Produce output from arguments and input.
+run :: [String] -> String -> String
+run args input
+	| argument "help" args		= usage
+	| null args			= go factor
+	| argument "factor" args	= go factor
+	| argument "explode" args	= go (concatMap explode)
+	| otherwise			= usage
+	where	go f = (unlines . show_stylesheet . process f .
+				parser . alexScanTokens) input
+
+-- Check an argument list for an argument in short or long form.
+argument :: String -> [String] -> Bool
+argument long args = elem short shorts || elem ("--" ++ long) args
+		where	short = head long
+			shorts = (concat . filter is_short) args
+			is_short ('-':'-':_) = False
+			is_short ('-':_) = True
+			is_short _ = False
+
+-- Usage help string.
+usage :: String
+usage = unlines ["Usage: factorcss [OPTION]... <FILE",
+		"\"Factor out\" common declarations in a CSS stylesheet by splitting, reordering,",
+		"and combining rulesets.",
+		"The stylesheet is read from standard input, and the result is produced on",
+		"standard output.",
+		"",
+		"Output mode:",
+		"  -f, --factor   factor out common declarations (default)",
+		"  -e, --explode  produce rulesets with one selector and declaration each",
+		"",
+		"  -h, --help     display this help and exit"]
 
 -- Process a Stylesheet.
-process :: Stylesheet -> Stylesheet
-process (Stylesheet charset imports stmts) =
-		Stylesheet charset imports (process_stmts stmts)
+process :: ([Statement] -> [Statement]) -> Stylesheet -> Stylesheet
+process f (Stylesheet charset imports stmts) =
+		Stylesheet charset imports (process_stmts f stmts)
 
 -- Process a list of Statements.
-process_stmts :: [Statement] -> [Statement]
-process_stmts stmts = (factor . filter is_ruleset) stmts ++
-		(map process_media . filter is_media) stmts ++
+process_stmts :: ([Statement] -> [Statement]) -> [Statement] -> [Statement]
+process_stmts f stmts = (f . filter is_ruleset) stmts ++
+		(map (process_media f) . filter is_media) stmts ++
 		filter is_page stmts
 
 -- Process a Media Statement.
-process_media :: Statement -> Statement
-process_media (Media media stmts) = Media media (factor stmts)
+process_media :: ([Statement] -> [Statement]) -> Statement -> Statement
+process_media f (Media media stmts) = Media media (f stmts)
 
 -- Factor a list of Ruleset Statements.
 factor :: [Statement] -> [Statement]
@@ -87,7 +121,8 @@
 eq_sel :: Statement -> Statement -> Bool
 eq_sel z = (== EQ) . cmp_sel z
 
--- Compare two Ruleset Statements for equality by the first declaration in each.
+-- Compare two Ruleset Statements for equality by the first declaration in
+-- each.
 eq_decl :: Statement -> Statement -> Bool
 eq_decl z = (== EQ) . cmp_decl z