lib.data.{Field, Layout, Const}: add __hash__

Author: rroohhh

amaranth/lib/data.py

@@ -65,6 +65,9 @@ def width(self):
         """
         return Shape.cast(self.shape).width
 
+    def __hash__(self):
+        return hash((self.shape, self.offset))
+
     def __eq__(self, other):
         """Compare fields.
 
@@ -166,6 +169,11 @@ def as_shape(self):
         """
         return unsigned(self.size)
 
+    def __hash__(self):
+        if not hasattr(self, "_Layout__hash"):
+            setattr(self, "_Layout__hash", hash((self.size, frozenset(iter(self)))))
+        return self.__hash
+
     def __eq__(self, other):
         """Compare layouts.
 
@@ -1123,6 +1131,9 @@ def __len__(self):
                 f"`len()` can only be used on constants of array layout, not {self.__layout!r}")
         return self.__layout.length
 
+    def __hash__(self):
+        return hash((self.__target, self.__layout))
+
     def __eq__(self, other):
         if isinstance(other, View) and self.__layout == other._View__layout:
             return self.as_value() == other._View__target

docs/changes.rst

@@ -64,6 +64,7 @@ Standard library changes
 
 * Added: :py:`payload_init=` argument in :class:`amaranth.lib.stream.Signature`.
 * Added: :meth:`enum.EnumView.matches`. (`RFC 71`_)
+* Added: :class:`data.Field`, :class:`data.Layout` and :class:`data.Const` are hashable.
 * Changed: (deprecated in 0.5.1) providing :meth:`io.PortLike.__add__` is now mandatory. (`RFC 69`_)
 * Removed: (deprecated in 0.5.0) :mod:`amaranth.lib.coding`. (`RFC 63`_)
 

tests/test_lib_data.py

@@ -74,6 +74,9 @@ def test_immutable(self):
         with self.assertRaises(AttributeError):
             data.Field(1, 0).offset = 1
 
+    def test_hash(self):
+        hash(data.Field(unsigned(2), 1))
+
 
 class StructLayoutTestCase(FHDLTestCase):
     def test_construct(self):
@@ -520,6 +523,9 @@ def test_signal_init(self):
         self.assertEqual(Signal(sl).as_value().init, 0)
         self.assertEqual(Signal(sl, init={"a": 0b1, "b": 0b10}).as_value().init, 5)
 
+    def test_hash(self):
+        hash(data.StructLayout({}))
+
 
 class ViewTestCase(FHDLTestCase):
     def test_construct(self):
@@ -1167,6 +1173,9 @@ def test_repr(self):
         s1 = data.Const(data.StructLayout({"a": unsigned(2)}), 2)
         self.assertRepr(s1, "Const(StructLayout({'a': unsigned(2)}), 2)")
 
+    def test_hash(self):
+        hash(data.Const(data.StructLayout({"a": unsigned(2)}), 2))
+
 
 class StructTestCase(FHDLTestCase):
     def test_construct(self):