Handle printer

Author: shulhi

compiler/syntax/src/res_ast_debugger.ml

@@ -641,6 +641,13 @@ module SexpAst = struct
             longident longident_loc.Asttypes.txt;
             expression expr2;
           ]
+      | Pexp_index (e1, e2, e3) ->
+        Sexp.list
+          ([Sexp.atom "Pexp_index"; expression e1; expression e2]
+          @
+          match e3 with
+          | None -> []
+          | Some e -> [expression e])
       | Pexp_array exprs ->
         Sexp.list
           [Sexp.atom "Pexp_array"; Sexp.list (map_empty ~f:expression exprs)]

compiler/syntax/src/res_comments_table.ml

@@ -476,6 +476,7 @@ let rec is_block_expr expr =
   | Pexp_constraint (expr, _) when is_block_expr expr -> true
   | Pexp_field (expr, _) when is_block_expr expr -> true
   | Pexp_setfield (expr, _, _) when is_block_expr expr -> true
+  | Pexp_index (expr, _, _) when is_block_expr expr -> true
   | _ -> false
 
 let is_if_then_else_expr expr =
@@ -1313,6 +1314,12 @@ and walk_expression expr t comments =
       attach t.leading expr2.pexp_loc leading;
       walk_expression expr2 t inside;
       attach t.trailing expr2.pexp_loc trailing
+  | Pexp_index (container, index, value_opt) -> (
+    walk_expression container t comments;
+    walk_expression index t comments;
+    match value_opt with
+    | None -> ()
+    | Some value -> walk_expression value t comments)
   | Pexp_ifthenelse (if_expr, then_expr, else_expr) -> (
     let leading, rest = partition_leading_trailing comments expr.pexp_loc in
     attach t.leading expr.pexp_loc leading;

compiler/syntax/src/res_printer.ml

@@ -3374,6 +3374,31 @@ and print_expression ~state (e : Parsetree.expression) cmt_tbl =
     | Pexp_setfield (expr1, longident_loc, expr2) ->
       print_set_field_expr ~state e.pexp_attributes expr1 longident_loc expr2
         e.pexp_loc cmt_tbl
+    | Pexp_index (container, index, value_opt) -> (
+      let container_doc =
+        let doc = print_expression_with_comments ~state container cmt_tbl in
+        match Parens.field_expr container with
+        | Parens.Parenthesized -> add_parens doc
+        | Braced braces -> print_braces doc container braces
+        | Nothing -> doc
+      in
+      let index_doc = print_expression_with_comments ~state index cmt_tbl in
+      match value_opt with
+      | None ->
+        (* Read: container[index] *)
+        Doc.concat [container_doc; Doc.lbracket; index_doc; Doc.rbracket]
+      | Some value ->
+        (* Write: container[index] = value *)
+        let value_doc = print_expression_with_comments ~state value cmt_tbl in
+        Doc.concat
+          [
+            container_doc;
+            Doc.lbracket;
+            index_doc;
+            Doc.rbracket;
+            Doc.text " = ";
+            value_doc;
+          ])
     | Pexp_ifthenelse (_ifExpr, _thenExpr, _elseExpr)
       when ParsetreeViewer.is_ternary_expr e ->
       let parts, alternate = ParsetreeViewer.collect_ternary_parts e in