Merge pull request #254 from dwango/support_try_expression

Support try expression

lib/from_erlang.ml

@@ -313,13 +313,7 @@ and expr_of_erlang_expr' = function
      raise Known_error.(FialyzerError (NotImplemented {issue_links=["https://github.com/dwango/fialyzer/issues/222"];
                                                        message="support block expr"}))
   | ExprCase {line; expr; clauses} ->
-     let cs = clauses |> List.map ~f:(function
-       | F.ClsCase {line; pattern; guard_sequence; body; _} ->
-          if Option.is_some guard_sequence then Log.debug [%here] "line:%d %s" line "Guard (when clauses) are not supported";
-          ((pattern_of_erlang_pattern pattern, Constant (line, Atom "true")), expr_of_erlang_expr' body)
-       | F.ClsCatch _ | F.ClsFun _ | F.ClsIf _ ->
-          failwith "cannot reach here"
-    ) in
+    let cs = case_clauses_of_clauses clauses in
     Case (line, expr_of_erlang_expr' expr, cs)
   | ExprCatch {line; expr} ->
      let e = expr_of_erlang_expr' expr in
@@ -381,9 +375,20 @@ and expr_of_erlang_expr' = function
      raise Known_error.(FialyzerError (NotImplemented {issue_links=["https://github.com/dwango/fialyzer/issues/227"];
                                                        message="support record expr"}))
   | ExprTuple {line; elements} -> Tuple (line, List.map ~f:expr_of_erlang_expr' elements)
-  | ExprTry _ ->
-     raise Known_error.(FialyzerError (NotImplemented {issue_links=["https://github.com/dwango/fialyzer/issues/223"];
-                                                       message="support try expr"}))
+  | ExprTry {line; exprs; case_clauses; catch_clauses; after} ->
+    (* TODO: ignore catch clauses, see the issue https://github.com/dwango/fialyzer/issues/252 *)
+    let e =
+      if List.is_empty case_clauses then
+        expr_of_erlang_exprs exprs
+      else
+        let cs = case_clauses_of_clauses case_clauses in
+        Case (line, expr_of_erlang_exprs exprs, cs)
+    in
+    if List.is_empty after then
+      e
+    else
+      let e_after = expr_of_erlang_exprs after in
+      Let (line, "_", e, e_after)
   | ExprVar {line; id} -> Ref (line, Var id)
   | ExprLit {lit} -> expr_of_literal lit
   | ExprCons {line; head; tail; _} -> ListCons (line, expr_of_erlang_expr' head, expr_of_erlang_expr' tail)
@@ -462,6 +467,15 @@ and function_of_clauses' clauses =
         let arity = List.nth_exn arities 0 in
         let fresh_variables = (make_fresh_variables arity) in
         {args=fresh_variables; body=make_case cs fresh_variables}
+and case_clauses_of_clauses clauses =
+  let f = function
+    | F.ClsCase {line; pattern; guard_sequence; body; _} ->
+      if Option.is_some guard_sequence then Log.debug [%here] "line:%d %s" line "Guard (when clauses) are not supported";
+      ((pattern_of_erlang_pattern pattern, Constant (line, Atom "true")), expr_of_erlang_expr' body)
+    | F.ClsCatch _ | F.ClsFun _ | F.ClsIf _ ->
+      failwith "cannot reach here"
+  in
+  List.map ~f clauses
 
 let expr_of_erlang_expr e = e |> extract_toplevel |> expr_of_erlang_expr'
 

test/blackbox-test/test-cases/try_catch_expr.erl

@@ -1,8 +1,34 @@
 -module(try_catch_expr).
 
--export([main/0]).
+-export([catch_expr/0, expr_try1/0, expr_try2/0, expr_try3/0]).
 
--spec main() -> any().
-main() ->
+-spec catch_expr() -> any().
+catch_expr() ->
     catch 1 + 2.
-
+
+
+-spec expr_try1() -> number().
+expr_try1() ->
+    try
+        1 + 2
+    catch
+        Err:Stack -> {hoge, Err, Stack}
+    end.
+
+-spec expr_try2() -> number().
+expr_try2() ->
+    try 1 + 2 of
+        X -> 2 * X
+    catch
+        Err:Stack -> {hoge, Err, Stack}
+    end.
+
+-spec expr_try3() -> ok.
+expr_try3() ->
+    try 1 + 2 of
+        X -> 2 * X
+    catch
+        Err:Stack -> {hoge, Err, Stack}
+    after
+        ok
+    end.