feat(tests): add AST JSON serializer

core/ast/json_serializer.py

@@ -0,0 +1,81 @@
+from core.ast.midas import (
+    ConstraintExpr,
+    ConstraintStmt,
+    Expr,
+    LiteralExpr,
+    OpStmt,
+    PropertyStmt,
+    Stmt,
+    TypeBodyExpr,
+    TypeExpr,
+    TypeStmt,
+    WildcardExpr,
+)
+
+
+class AstJsonSerializer(Stmt.Visitor[dict], Expr.Visitor[dict]):
+    """An AST serializer which produces a JSON-compatible structure"""
+
+    def serialize(self, stmts: list[Stmt]) -> list[dict]:
+        return [stmt.accept(self) for stmt in stmts]
+
+    def visit_type_stmt(self, stmt: TypeStmt) -> dict:
+        return {
+            "_type": "TypeStmt",
+            "name": stmt.name.lexeme,
+            "bases": [base.accept(self) for base in stmt.bases],
+            "body": stmt.body.accept(self) if stmt.body is not None else None,
+        }
+
+    def visit_type_expr(self, expr: TypeExpr) -> dict:
+        return {
+            "_type": "TypeExpr",
+            "name": expr.name.lexeme,
+            "constraints": [constraint.accept(self) for constraint in expr.constraints],
+        }
+
+    def visit_constraint_expr(self, expr: ConstraintExpr) -> dict:
+        return {
+            "_type": "ConstraintExpr",
+            "left": expr.left.accept(self),
+            "op": expr.op.lexeme,
+            "right": expr.right.accept(self),
+        }
+
+    def visit_wildcard_expr(self, expr: WildcardExpr) -> dict:
+        return {"_type": "WildcardExpr"}
+
+    def visit_literal_expr(self, expr: LiteralExpr) -> dict:
+        return {
+            "_type": "LiteralExpr",
+            "value": expr.value,
+        }
+
+    def visit_type_body_expr(self, expr: TypeBodyExpr) -> dict:
+        return {
+            "_type": "TypeBodyExpr",
+            "properties": [prop.accept(self) for prop in expr.properties],
+        }
+
+    def visit_property_stmt(self, stmt: PropertyStmt) -> dict:
+        return {
+            "_type": "PropertyStmt",
+            "name": stmt.name.lexeme,
+            "type": stmt.type.accept(self),
+        }
+
+    def visit_op_stmt(self, stmt: OpStmt) -> dict:
+        return {
+            "_type": "OpStmt",
+            "left": stmt.left.accept(self),
+            "op": stmt.op.lexeme,
+            "right": stmt.right.accept(self),
+            "result": stmt.result.accept(self),
+        }
+
+    def visit_constraint_stmt(self, stmt: ConstraintStmt) -> dict:
+        return {
+            "_type": "ConstraintStmt",
+            "name": stmt.name.lexeme,
+            "constraint": stmt.constraint.accept(self),
+        }