Further context system improvements

 - Make sure "external" is treated as a top-level keyword
 - Add struct/do to our keyword list
 - Treat arguments to open as a module body

Author: SquidDev

editor/amulet-mode.el

@@ -60,9 +60,10 @@ binding, making it easier to determine what a function does."
 
 
 (defconst amulet-mode--keywords
-  '("and" "as" "begin" "class" "deriving" "else" "end" "external" "false" "forall"
-    "fun" "function" "if" "import" "in" "include" "instance" "lazy" "let" "match"
-    "module" "of" "open" "private" "rec" "then" "true" "type" "val" "when" "with")
+  '("and" "as" "begin" "class" "deriving" "do" "else" "end" "external" "false"
+    "forall" "fun" "function" "if" "import" "in" "include" "instance" "lazy"
+    "let" "match" "module" "of" "open" "private" "rec" "struct" "then" "true"
+    "type" "val" "when" "with")
   "All Amulet keywords.  These are just extracted from Lexer.x.")
 
 (defconst amulet-mode--font-lock

src/Parser/Context.hs

@@ -460,6 +460,8 @@ handleContextBlock needsSep  tok@(Token tk tp te) c =
 
     -- @module@ ~~> Push a module context
     (TcModule, _) -> pure (Result tok Done, CtxModuleHead False (getMarginAt tp c):c)
+    -- @open@ ~~> Push an unresolved module
+    (TcOpen, _) | isToplevel c -> pure (Result tok Done, CtxModuleBodyUnresolved (getMarginAt tp c):c)
     -- @class@ ~~> Push a class context
     (TcClass, _) -> pure (Result tok Done, CtxClassHead (getMarginAt tp c):c)
     -- @instance@ ~~> Push an instance context
@@ -601,6 +603,7 @@ isIfContinue _ = False
 isTopTok :: TokenClass -> Bool
 isTopTok TcClass = True
 isTopTok TcDeriving = True
+isTopTok TcExternal = True
 isTopTok TcInclude = True
 isTopTok TcInstance = True
 isTopTok TcLet = True

src/Parser/Context.txt

@@ -32,7 +32,7 @@ _       DerivingHead | Offside  -> Pop
 _       ModuleHead<I> | Offside -> Add =, $begin, Replace with EmptyBlock+ModuleBody
 
         ModuleBody              -> Pop
-begin   ModuleBodyUnresolved | Not offside -> Push Block+ModuleBody+Bracket
+struct  ModuleBodyUnresolved | Not offside -> Push Block+ModuleBody+Bracket
 _       ModuleBodyUnresolved | Not offside, Is toplevel -> Add $begin, Push Block+ModuleBody
 _       ModuleBodyUnresolved    -> Pop
 =       ModuleHead              -> Replace with ModuleBodyUnresolved
@@ -73,6 +73,7 @@ else    _                       -> Push Else
 
 module  [Block<empty>]          -> Push ModuleHead[I]
 module  _                       -> Push ModuleHead
+open    _ | Is toplevel         -> Push ModuleBodyUnresolved
 
 class   _                       -> Push ClassHead
 instance _                      -> Push InstHead
@@ -83,7 +84,7 @@ _       TypeHead | Not offside, Is some top-level token
                                 -> Insert $begin, Replace with Block+TypeFunBody
 _       TypeFunBody             -> Pop
 
-begin   _                       -> Push Block+Monad+Bracket<end>
+do      _                       -> Push Block+Monad+Bracket<end>
 ({      _                       -> Push Bracket<_>
 
 [       _                       -> Push List+Bracket<]>

tests/lexer/context/module.ml

@@ -20,6 +20,10 @@ module X =
 
 module X = Y
 
+open struct
+  type x
+end
+
 (* Access modifiers *)
 private module Y =
   let a = 0

tests/lexer/context/module.out

@@ -20,6 +20,10 @@ $sep module X =
 
 $sep module X = Y
 
+$sep open struct
+  type x
+end
+
 
 $sep private module Y =
   $begin let a = 0