Start with positional errors (see #5)

4 files changed, 77 insertions, 26 deletions

diff --git a/Sil/Util/Parser.dcl b/Sil/Util/Parser.dcl
index 65b050e..8474b78 100644
--- a/Sil/Util/Parser.dcl
+++ b/Sil/Util/Parser.dcl
@@ -6,10 +6,26 @@ from Control.Applicative import class Applicative, class Alternative
 from Control.Monad import class Monad
 from Data.Error import :: MaybeError
 from Data.Functor import class Functor
+from Data.Maybe import :: Maybe
 
-from Sil.Parse import :: Error
+from Sil.Error import :: Error
 
-:: Parser a b = Parser ([a] -> (MaybeError Error b, [a]))
+:: Positioned a =
+	{ pos_line :: Int
+	, pos_val  :: a
+	}
+
+fromPositioned :: (Positioned a) -> a
+
+:: ParseState a
+
+:: ParseInput a
+	= PI_NewLine
+	| PI_Token a
+
+makeParseState :: [ParseInput a] -> ParseState a
+
+:: Parser a b = Parser ((ParseState a) -> (MaybeError Error b, ParseState a))
 
 instance Functor (Parser a)
 instance Applicative (Parser a) 
@@ -19,7 +35,8 @@ instance Alternative (Parser a)
 class name a :: a -> String
 instance name String
 
-runParser :: (Parser a b) [a] -> (MaybeError Error b, [a])
+runParser :: (Parser a b) (ParseState a) -> (MaybeError Error b, ParseState a)
+getPositioner :: Parser a (b -> Positioned b)
 (<?>) :: (Parser a b) Error -> Parser a b
 fail :: Parser a b
 top :: Parser a a
diff --git a/Sil/Util/Parser.icl b/Sil/Util/Parser.icl
index d13bc09..34cf057 100644
--- a/Sil/Util/Parser.icl
+++ b/Sil/Util/Parser.icl
@@ -9,34 +9,62 @@ import Data.Error
 from Data.Func import $
 import Data.Functor
 import Data.List
+import Data.Maybe
 
 import Sil.Error
 
+fromPositioned :: (Positioned a) -> a
+fromPositioned p = p.pos_val
+
+:: ParseState a =
+	{ ps_line  :: Int
+	, ps_input :: [ParseInput a]
+	, ps_read  :: [ParseInput a]
+	}
+
+makeParseState :: [ParseInput a] -> ParseState a
+makeParseState i = {ps_line=1, ps_input=i, ps_read=[]}
+
+nextToken :: (ParseState a) -> (Maybe a, ParseState a)
+nextToken ps = case ps.ps_input of
+	[]             -> (Nothing, ps)
+	[PI_Token t:i] -> (Just t, {ps & ps_read=[PI_Token t:ps.ps_read], ps_input=i})
+	[PI_NewLine:i] -> nextToken {ps & ps_line=ps.ps_line + 1, ps_read=[PI_NewLine:ps.ps_read], ps_input=i}
+
+tokenBack :: (ParseState a) -> ParseState a
+tokenBack ps = case ps.ps_read of
+	[]             -> ps
+	[PI_Token t:r] -> {ps & ps_read=r, ps_input=[PI_Token t:ps.ps_input]}
+	[PI_NewLine:r] -> tokenBack {ps & ps_read=r, ps_input=[PI_NewLine:ps.ps_input], ps_line=ps.ps_line-1}
+
 instance Functor (Parser a) where
 	fmap f m = liftM f m
 
 instance Applicative (Parser a) where
-	pure a     = Parser \i -> (Ok a, i)
+	pure a     = Parser \st -> (Ok a, st)
 	(<*>) sf p = ap sf p
 
 instance Monad (Parser a) where
-	bind p f = Parser \i -> case runParser p i of
+	bind p f = Parser \st -> case runParser p st of
 		(Ok r, rest) -> runParser (f r) rest
-		(Error e, _) -> (Error e, i)
+		(Error e, _) -> (Error e, st)
 
 instance Alternative (Parser a) where
-	empty       = Parser \i -> (Error $ UnknownError "empty in Parser", i)
-	(<|>) p1 p2 = Parser \i -> case runParser p1 i of
+	empty       = Parser \st -> (Error $ UnknownError "empty in Parser", st)
+	(<|>) p1 p2 = Parser \st -> case runParser p1 st of
 		(Ok r, rest)     -> (Ok r, rest)
-		(Error e1, rest) -> case runParser p2 i of
-			(Error e2, rest) -> (Error e2, i)
+		(Error e1, rest) -> case runParser p2 st of
+			(Error e2, rest) -> (Error e2, st)
 			(Ok r, rest)     -> (Ok r, rest)
 
 instance name String where name s = s
 
-runParser :: (Parser a b) [a] -> (MaybeError Error b, [a])
+runParser :: (Parser a b) (ParseState a) -> (MaybeError Error b, ParseState a)
 runParser (Parser f) i = f i
 
+getPositioner :: Parser a (b -> Positioned b)
+getPositioner = Parser \st -> (Ok \x -> {pos_line=st.ps_line, pos_val=x}, st)
+
 (<?>) :: (Parser a b) Error -> Parser a b
 (<?>) p e = Parser \i -> case runParser p i of
 	(Error _, rest) -> (Error e, rest)
@@ -46,14 +74,14 @@ fail :: Parser a b
 fail = empty
 
 top :: Parser a a
-top = Parser \i -> case i of
-	[]     = (Error $ UnknownError "top in Parser failed", [])
-	[x:xs] = (Ok x, xs)
+top = Parser \st -> case nextToken st of
+	(Nothing, st) -> (Error $ UnknownError "top in Parser failed", st)
+	(Just x,  st) -> (Ok x, st)
 
 peek :: Parser a a
-peek = Parser \i -> case i of
-	[]     = (Error $ UnknownError "peek in Parser failed", [])
-	[x:xs] = (Ok x, [x:xs])
+peek = Parser \st -> case nextToken st of
+	(Nothing, st) -> (Error $ UnknownError "peek in Parser failed", st)
+	(Just x,  st) -> (Ok x, tokenBack st)
 
 satisfy :: (a -> Bool) -> Parser a a
 satisfy f = top >>= \r -> if (f r) (pure r) fail
@@ -65,15 +93,15 @@ check f = peek >>= \r -> if (f r) (pure r) fail
 (until) p guard = try $ until` p guard [] 
 where
 	until` :: (Parser a b) (Parser a c) [b] -> Parser a [b]
-	until` p guard acc = Parser \i -> case runParser guard i of
+	until` p guard acc = Parser \st -> case runParser guard st of
 		(Ok _, rest) -> (Ok acc, rest)
-		(Error _, _) -> case runParser p i of
+		(Error _, _) -> case runParser p st of
 			(Ok r, rest) -> runParser (until` p guard [r:acc]) rest
-			(Error e, _) -> (Error e, i)
+			(Error e, _) -> (Error e, st)
 
 	try :: (Parser a b) -> Parser a b
-	try p = Parser \i -> case runParser p i of
-		(Error e, _) -> (Error e, i)
+	try p = Parser \st -> case runParser p st of
+		(Error e, _) -> (Error e, st)
 		(Ok r, rest) -> (Ok r, rest)
 
 item :: a -> Parser a a | ==, name a
@@ -88,6 +116,6 @@ seplist sep p = liftM2 (\es e-> es ++ [e]) (some (p <* item sep)) p
 	<|> pure empty
 
 eof :: Parser a ()
-eof = Parser \i -> case i of
-	[] = (Ok (), [])
-	_  = (Error $ P_Expected "eof", i)
+eof = Parser \st -> case nextToken st of
+	(Nothing, st) -> (Ok (), st)
+	(_, st)       -> (Error $ P_Expected "eof", st)
diff --git a/Sil/Util/Printer.dcl b/Sil/Util/Printer.dcl
index 5535dc2..56ad103 100644
--- a/Sil/Util/Printer.dcl
+++ b/Sil/Util/Printer.dcl
@@ -3,7 +3,7 @@ definition module Sil.Util.Printer
 from StdOverloaded import class toString, class zero
 
 from Sil.Parse import :: Token
-from Sil.Syntax import :: Program, :: Function, :: CodeBlock,
+from Sil.Syntax import :: Positioned, :: Program, :: Function, :: CodeBlock,
 	:: Initialisation, :: Statement
 
 :: PrintState
@@ -13,6 +13,8 @@ instance zero PrintState
 class PrettyPrinter t where
 	print :: PrintState t -> String
 
+instance PrettyPrinter String
+instance PrettyPrinter (Positioned a) | PrettyPrinter a
 instance PrettyPrinter [Token]
 instance PrettyPrinter Program
 instance PrettyPrinter Function
diff --git a/Sil/Util/Printer.icl b/Sil/Util/Printer.icl
index 979e478..2a028b6 100644
--- a/Sil/Util/Printer.icl
+++ b/Sil/Util/Printer.icl
@@ -16,6 +16,7 @@ import Text
 import Sil.Parse
 import Sil.Syntax
 import Sil.Types
+import Sil.Util.Parser
 
 :: PrintState =
 	{ indent :: Int
@@ -33,6 +34,9 @@ instance toString PrintState where toString st = {'\t' \\ _ <- [1..st.indent]}
 
 instance PrettyPrinter String where print _ s = s
 
+instance PrettyPrinter (Positioned a) | PrettyPrinter a
+where print st p = print st $ fromPositioned p
+
 instance PrettyPrinter [Token]
 where
 	print st []             = ""