parser

Grammar/Tokens

@@ -54,6 +54,7 @@ RARROW                  '->'
 ELLIPSIS                '...'
 COLONEQUAL              ':='
 EXCLAMATION             '!'
+BACKTICK                '`'
 
 OP
 TYPE_IGNORE

Grammar/python.gram

@@ -846,6 +846,7 @@ atom[expr_ty]:
     | &'[' (list | listcomp)
     | &'{' (dict | set | dictcomp | setcomp)
     | '...' { _PyAST_Constant(Py_Ellipsis, NULL, EXTRA) }
+    | '`' a=expression '`' { _PyAST_Repr(a, EXTRA) }
 
 group[expr_ty]:
     | '(' a=(yield_expr | named_expression) ')' { a }

Parser/Python.asdl

@@ -69,6 +69,7 @@ module Python
          | SetComp(expr elt, comprehension* generators)
          | DictComp(expr key, expr value, comprehension* generators)
          | GeneratorExp(expr elt, comprehension* generators)
+         | Repr(expr value)
          -- the grammar constrains where yield expressions can occur
          | Await(expr value)
          | Yield(expr? value)

Python/ast.c

@@ -291,6 +291,9 @@ validate_expr(struct validator *state, expr_ty exp, expr_context_ty ctx)
             validate_expr(state, exp->v.IfExp.body, Load) &&
             validate_expr(state, exp->v.IfExp.orelse, Load);
         break;
+    case Repr_kind:
+        ret = validate_expr(state, exp->v.Repr.value, Load);
+        break;
     case Dict_kind:
         if (asdl_seq_LEN(exp->v.Dict.keys) != asdl_seq_LEN(exp->v.Dict.values)) {
             PyErr_SetString(PyExc_ValueError,

Python/ast_opt.c

@@ -761,6 +761,9 @@ astfold_expr(expr_ty node_, PyArena *ctx_, _PyASTOptimizeState *state)
         CALL(astfold_arguments, arguments_ty, node_->v.Lambda.args);
         CALL(astfold_expr, expr_ty, node_->v.Lambda.body);
         break;
+    case Repr_kind:
+        CALL(astfold_expr, expr_ty, node_->v.Repr.value);
+        break;
     case IfExp_kind:
         CALL(astfold_expr, expr_ty, node_->v.IfExp.test);
         CALL(astfold_expr, expr_ty, node_->v.IfExp.body);

Python/ast_unparse.c

@@ -303,6 +303,15 @@ append_ast_ifexp(_PyUnicodeWriter *writer, expr_ty e, int level)
     return 0;
 }
 
+static int
+append_ast_repr(_PyUnicodeWriter *writer, expr_ty e)
+{
+    APPEND_STR("`");
+    APPEND_EXPR(e->v.Repr.value, PR_TEST);
+    APPEND_STR("`");
+    return 0;
+}
+
 static int
 append_ast_dict(_PyUnicodeWriter *writer, expr_ty e)
 {
@@ -854,6 +863,8 @@ append_ast_expr(_PyUnicodeWriter *writer, expr_ty e, int level)
         return append_ast_lambda(writer, e, level);
     case IfExp_kind:
         return append_ast_ifexp(writer, e, level);
+    case Repr_kind:
+        return append_ast_repr(writer, e);
     case Dict_kind:
         return append_ast_dict(writer, e);
     case Set_kind:

Python/codegen.c

@@ -4883,6 +4883,10 @@ codegen_visit_expr(compiler *c, expr_ty e)
         ADDOP_I(c, loc, COPY, 1);
         VISIT(c, expr, e->v.NamedExpr.target);
         break;
+    case Repr_kind:
+        // TODO
+        abort();
+        break;
     case BoolOp_kind:
         return codegen_boolop(c, e);
     case BinOp_kind:

Python/symtable.c

@@ -2372,6 +2372,9 @@ symtable_visit_expr(struct symtable *st, expr_ty e)
         VISIT(st, expr, e->v.IfExp.body);
         VISIT(st, expr, e->v.IfExp.orelse);
         break;
+    case Repr_kind:
+        VISIT(st, expr, e->v.Repr.value);
+        break;
     case Dict_kind:
         VISIT_SEQ_WITH_NULL(st, expr, e->v.Dict.keys);
         VISIT_SEQ(st, expr, e->v.Dict.values);