feat: to/from json for extension/package (#1575)

Closes #1523

hugr-py/src/hugr/_serialization/extension.py

@@ -5,6 +5,7 @@
 import pydantic as pd
 from pydantic_extra_types.semantic_version import SemanticVersion  # noqa: TCH002
 
+from hugr.hugr.base import Hugr
 from hugr.utils import deser_it
 
 from .ops import Value
@@ -156,5 +157,14 @@ class Package(ConfiguredBaseModel):
     def get_version(cls) -> str:
         return serialization_version()
 
+    def deserialize(self) -> package.Package:
+        return package.Package(
+            modules=[Hugr._from_serial(m) for m in self.modules],
+            extensions=[e.deserialize() for e in self.extensions],
+        )
+
 
-from hugr import ext  # noqa: E402
+from hugr import (  # noqa: E402
+    ext,
+    package,
+)

hugr-py/src/hugr/ext.py

@@ -272,6 +272,22 @@ def _to_serial(self) -> ext_s.Extension:
             operations={k: v._to_serial() for k, v in self.operations.items()},
         )
 
+    def to_json(self) -> str:
+        """Serialize the extension to a JSON string."""
+        return self._to_serial().model_dump_json()
+
+    @classmethod
+    def from_json(cls, json_str: str) -> Extension:
+        """Deserialize a JSON string to a Extension object.
+
+        Args:
+            json_str: The JSON string representing a Extension.
+
+        Returns:
+            The deserialized Extension object.
+        """
+        return ext_s.Extension.model_validate_json(json_str).deserialize()
+
     def add_op_def(self, op_def: OpDef) -> OpDef:
         """Add an operation definition to the extension.
 

hugr-py/src/hugr/package.py

@@ -46,6 +46,18 @@ def _to_serial(self) -> ext_s.Package:
     def to_json(self) -> str:
         return self._to_serial().model_dump_json()
 
+    @classmethod
+    def from_json(cls, json_str: str) -> Package:
+        """Deserialize a JSON string to a Package object.
+
+        Args:
+            json_str: The JSON string representing a Package.
+
+        Returns:
+            The deserialized Package object.
+        """
+        return ext_s.Package.model_validate_json(json_str).deserialize()
+
 
 @dataclass(frozen=True)
 class PackagePointer:

hugr-py/tests/serialization/test_extension.py

@@ -8,6 +8,7 @@
     TypeDef,
     TypeDefBound,
 )
+from hugr._serialization.ops import Module, OpType
 from hugr._serialization.serial_hugr import SerialHugr, serialization_version
 from hugr._serialization.tys import (
     FunctionType,
@@ -109,6 +110,8 @@ def test_extension():
     dumped_json = ext.model_dump_json()
 
     assert Extension.model_validate_json(dumped_json) == ext
+    hugr_ext = ext.deserialize()
+    assert hugr_ext.from_json(hugr_ext.to_json()) == hugr_ext
 
 
 def test_package():
@@ -123,9 +126,14 @@ def test_package():
         operations={},
     )
     ext_load = Extension.model_validate_json(EXAMPLE)
+
     package = Package(
-        extensions=[ext, ext_load], modules=[SerialHugr(nodes=[], edges=[])]
+        extensions=[ext, ext_load],
+        modules=[SerialHugr(nodes=[OpType(root=Module(parent=0))], edges=[])],
     )
 
     package_load = Package.model_validate_json(package.model_dump_json())
     assert package == package_load
+
+    hugr_package = package.deserialize()
+    assert hugr_package.from_json(hugr_package.to_json()) == hugr_package