Add using namespace as to scanner and parser

src/aeso_parser.erl

@@ -109,6 +109,7 @@ decl() ->
 
     , ?RULE(keyword(namespace), con(), tok('='), maybe_block(decl()), {namespace, _1, _2, _4})
     , ?RULE(keyword(include),   str(), {include, get_ann(_1), _2})
+    , using()
     , pragma()
 
       %% Type declarations  TODO: format annotation for "type bla" vs "type bla()"
@@ -135,6 +136,14 @@ fundef_or_decl() ->
     choice([?RULE(id(), tok(':'), type(), {fun_decl, get_ann(_1), _1, _3}),
             fundef()]).
 
+using() ->
+    ?RULE(keyword(using), con(), optional({keyword(as), id()}), using(get_ann(_1), _2, _3)).
+
+using(Ann, Con, none) ->
+    {using, Ann, Con};
+using(Ann, Con, {ok, {_, Id}}) ->
+    {using, Ann, Con, Id}.
+
 pragma() ->
     Op = choice([token(T) || T <- ['<', '=<', '==', '>=', '>']]),
     ?RULE(tok('@'), id("compiler"), Op, version(), {pragma, get_ann(_1), {compiler, element(1, _3), _4}}).

src/aeso_scan.erl

@@ -45,7 +45,7 @@ lexer() ->
 
     Keywords = ["contract", "include", "let", "switch", "type", "record", "datatype", "if", "elif", "else", "function",
                 "stateful", "payable", "true", "false", "mod", "public", "entrypoint", "private", "indexed", "namespace",
-                "interface", "main"
+                "interface", "main", "using", "as"
                ],
     KW = string:join(Keywords, "|"),
 

src/aeso_syntax.erl

@@ -44,6 +44,7 @@
               | {type_def, ann(), id(), [tvar()], typedef()}
               | {fun_clauses, ann(), id(), type(), [letfun() | fundecl()]}
               | {block, ann(), [decl()]}
+              | using()
               | fundecl()
               | letfun()
               | letval(). % Only for error msgs
@@ -52,6 +53,8 @@
 
 -type pragma() :: {compiler, '==' | '<' | '>' | '=<' | '>=', compiler_version()}.
 
+-type using() :: {using, ann(), con()}
+               | {using, ann(), con(), id()}.
 
 -type letval()  :: {letval, ann(), pat(), expr()}.
 -type letfun()  :: {letfun, ann(), id(), [pat()], type(), expr()}.