refactor, add getCurrentAndPrevious2Positions to scanner

frontend/parse.icl

@@ -2206,7 +2206,7 @@ where
 									gcf_generic_info = gcf_generic_info, gcf_body = GCB_None, gcf_kind = KindError,
 									gcf_generic_instance_deps = generic_instance_deps}
 			}
-		= (derive_def, token, pState) 
+		= (derive_def, token, pState)
 
 	want_derive_class_types :: Ident !*ParseState -> ([GenericCaseDef], !*ParseState)			
 	want_derive_class_types class_ident pState
@@ -3312,13 +3312,7 @@ trySimpleType_strictness_ignored attr pState
 	= (result==ParseOk,atype,pState)
 
 is_tail_strict_list_or_nil pState
-	# (square_close_position, pState) = getPosition pState
-	# pState=tokenBack pState
-	# (exclamation_position, pState) = getPosition pState
-	# pState=tokenBack pState
-	# (square_open_position, pState) = getPosition pState
-	# (exclamation_token,pState) = nextToken TypeContext pState
-	# (square_close_token,pState) = nextToken TypeContext pState
+	# (square_close_position,exclamation_position,square_open_position,pState) = getCurrentAndPrevious2Positions pState
 	| exclamation_position.fp_col+1==square_close_position.fp_col && exclamation_position.fp_line==square_close_position.fp_line
 		&& (square_open_position.fp_col+1<>exclamation_position.fp_col || square_open_position.fp_line<>exclamation_position.fp_line)
 		= (True,pState)
@@ -4189,7 +4183,7 @@ wantListPatternWithoutDefinitions pState
 	# (token, pState) = nextToken FunctionContext pState
 	# pState=appScanState clearNoNewOffsideForSeqLetBit pState	
 	# (head_strictness,token,pState) = want_head_strictness token pState
-	| token=:ExclamationToken && (head_strictness<>HeadOverloaded && head_strictness<>HeadUnboxedAndTailStrict)
+	| token=:ExclamationToken && head_strictness<=HeadUnboxed
 		# (token, pState) = nextToken FunctionContext pState
 		| token==SquareCloseToken
 			= (makeTailStrictNilExpression head_strictness cIsAPattern,pState)
@@ -4286,7 +4280,7 @@ wantListExp is_pattern pState
 	# (token, pState) = nextToken FunctionContext pState
 	# pState=appScanState clearNoNewOffsideForSeqLetBit pState	
 	# (head_strictness,token,pState) = want_head_strictness token pState
-	| token=:ExclamationToken && (head_strictness<>HeadOverloaded && head_strictness<>HeadUnboxedAndTailStrict)
+	| token=:ExclamationToken && head_strictness<=HeadUnboxed
 		# (token, pState) = nextToken FunctionContext pState
 		| token==SquareCloseToken
 			= (makeTailStrictNilExpression head_strictness is_pattern,pState)
@@ -5493,6 +5487,12 @@ instance getPosition ParseState
 where
 	getPosition pState = accScanState getPosition pState
 
+instance getCurrentAndPrevious2Positions ParseState
+where
+	getCurrentAndPrevious2Positions pState=:{ps_scanState}
+		# (p1,p2,p3,ps_scanState) = getCurrentAndPrevious2Positions ps_scanState
+		= (p1,p2,p3,{pState & ps_scanState = ps_scanState})
+
 warnIfStrictAnnot NoAnnot pState = pState
 warnIfStrictAnnot (StrictAnnotWithPosition position) pState = parseWarningWithPosition "" "! ignored" position pState
 

frontend/scanner.dcl

@@ -153,6 +153,9 @@ instance currentToken ScanState
 class getPosition state :: !*state -> (!FilePosition,!*state)  // Position of current Token (or Char)
 instance getPosition ScanState
 
+class getCurrentAndPrevious2Positions state :: !*state -> (!FilePosition,!FilePosition,!FilePosition,!*state)
+instance getCurrentAndPrevious2Positions ScanState
+
 fopenInSearchPaths :: !{#Char} !{#Char} !SearchPaths !Int (ModTimeFunction *Files) !*Files -> (Optional (*File, {#Char}, {#Char}),!*Files) 
 
 openScanner :: !*File !String !String -> ScanState

frontend/scanner.icl

@@ -51,6 +51,11 @@ where
 		# (position,scan_state) = getPosition scan_state
 		= (position,ScanState scan_state)
 
+instance getCurrentAndPrevious2Positions ScanState
+where
+	getCurrentAndPrevious2Positions scanState=:(ScanState {ss_tokenBuffer=Buffer3 x y z})
+		= (x.lt_position, y.lt_position, z.lt_position, scanState)
+
 ::	* RScanState =
 	{	ss_input		::	ScanInput
 	,	ss_offsides		::	! [(Int, Bool) ]	// (column, defines newDefinition)