feat(parser): add dictionary expression

gen/python.py

@@ -157,6 +157,11 @@ class ListExpr:
     items: list[Expr]
 
 
+class DictExpr:
+    keys: list[Optional[Expr]]
+    values: list[Expr]
+
+
 class SubscriptExpr:
     object: Expr
     index: Expr

midas/ast/printer.py

@@ -745,6 +745,27 @@ class PythonAstPrinter(
                         self._mark_last()
                     item.accept(self)
 
+    def visit_dict_expr(self, expr: p.DictExpr) -> None:
+        self._write_line("DictExpr")
+        with self._child_level():
+            self._write_line("keys")
+            with self._child_level():
+                for i, key in enumerate(expr.keys):
+                    self._idx = i
+                    if i == len(expr.keys) - 1:
+                        self._mark_last()
+                    if key is None:
+                        self._write_line("None")
+                    else:
+                        key.accept(self)
+            self._write_line("values", last=True)
+            with self._child_level():
+                for i, value in enumerate(expr.values):
+                    self._idx = i
+                    if i == len(expr.values) - 1:
+                        self._mark_last()
+                    value.accept(self)
+
     def visit_subscript_expr(self, expr: p.SubscriptExpr) -> None:
         self._write_line("SubscriptExpr")
         with self._child_level():

midas/ast/python.py

@@ -259,6 +259,9 @@ class Expr(ABC):
         @abstractmethod
         def visit_list_expr(self, expr: ListExpr) -> T: ...
 
+        @abstractmethod
+        def visit_dict_expr(self, expr: DictExpr) -> T: ...
+
         @abstractmethod
         def visit_subscript_expr(self, expr: SubscriptExpr) -> T: ...
 
@@ -370,6 +373,15 @@ class ListExpr(Expr):
         return visitor.visit_list_expr(self)
 
 
+@dataclass(frozen=True)
+class DictExpr(Expr):
+    keys: list[Optional[Expr]]
+    values: list[Expr]
+
+    def accept(self, visitor: Expr.Visitor[T]) -> T:
+        return visitor.visit_dict_expr(self)
+
+
 @dataclass(frozen=True)
 class SubscriptExpr(Expr):
     object: Expr

midas/parser/python.py

@@ -10,6 +10,7 @@ from midas.ast.python import (
     CastExpr,
     CompareExpr,
     ConstraintType,
+    DictExpr,
     Expr,
     ExpressionStmt,
     ForStmt,
@@ -447,6 +448,16 @@ class PythonParser:
                     items=[self.parse_expr(item) for item in items],
                 )
 
+            case ast.Dict(keys=keys, values=values):
+                return DictExpr(
+                    location=location,
+                    keys=[
+                        self.parse_expr(key) if key is not None else None
+                        for key in keys
+                    ],
+                    values=[self.parse_expr(value) for value in values],
+                )
+
             case ast.Subscript(value=value, slice=index):
                 return SubscriptExpr(
                     location=location,

tests/serializer/python.py

@@ -9,6 +9,7 @@ from midas.ast.python import (
     CastExpr,
     CompareExpr,
     ConstraintType,
+    DictExpr,
     Expr,
     ExpressionStmt,
     ForStmt,
@@ -278,6 +279,13 @@ class PythonAstJsonSerializer(
             "items": [item.accept(self) for item in expr.items],
         }
 
+    def visit_dict_expr(self, expr: DictExpr) -> dict:
+        return {
+            "_type": "DictExpr",
+            "keys": [self._serialize_optional(key) for key in expr.keys],
+            "values": self._serialize_list(expr.values),
+        }
+
     def visit_subscript_expr(self, expr: SubscriptExpr) -> dict:
         return {
             "_type": "SubscriptExpr",