Connectivity Class (AVD-1595)

lib/iris/common/metadata.py

@@ -37,6 +37,7 @@
     "CoordMetadata",
     "CubeMetadata",
     "DimCoordMetadata",
+    "ConnectivityMetadata",
     "metadata_manager_factory",
 ]
 
@@ -1316,6 +1317,120 @@ def equal(self, other, lenient=None):
         return super().equal(other, lenient=lenient)
 
 
+class ConnectivityMetadata(BaseMetadata):
+    """
+    Metadata container for a :class:`~iris.coords.Connectivity`.
+
+    """
+
+    _members = ("cf_role", "start_index", "element_dim")
+
+    __slots__ = ()
+
+    @wraps(BaseMetadata.__eq__, assigned=("__doc__",), updated=())
+    @lenient_service
+    def __eq__(self, other):
+        return super().__eq__(other)
+
+    def _combine_lenient(self, other):
+        """
+        Perform lenient combination of metadata members for connectivities.
+
+        Args:
+
+        * other (ConnectivityMetadata):
+            The other connectivity metadata participating in the lenient
+            combination.
+
+        Returns:
+            A list of combined metadata member values.
+
+        """
+        # Perform "strict" combination for "cf_role", "start_index", "element_dim".
+        def func(field):
+            left = getattr(self, field)
+            right = getattr(other, field)
+            return left if left == right else None
+
+        # Note that, we use "_members" not "_fields".
+        values = [func(field) for field in ConnectivityMetadata._members]
+        # Perform lenient combination of the other parent members.
+        result = super()._combine_lenient(other)
+        result.extend(values)
+
+        return result
+
+    def _compare_lenient(self, other):
+        """
+        Perform lenient equality of metadata members for connectivities.
+
+        Args:
+
+        * other (ConnectivityMetadata):
+            The other connectivity metadata participating in the lenient
+            comparison.
+
+        Returns:
+            Boolean.
+
+        """
+        # Perform "strict" comparison for "cf_role", "start_index", "element_dim".
+        result = all(
+            [
+                getattr(self, field) == getattr(other, field)
+                for field in ConnectivityMetadata._members
+            ]
+        )
+        if result:
+            # Perform lenient comparison of the other parent members.
+            result = super()._compare_lenient(other)
+
+        return result
+
+    def _difference_lenient(self, other):
+        """
+        Perform lenient difference of metadata members for connectivities.
+
+        Args:
+
+        * other (ConnectivityMetadata):
+            The other connectivity metadata participating in the lenient
+            difference.
+
+        Returns:
+            A list of difference metadata member values.
+
+        """
+        # Perform "strict" difference for "cf_role", "start_index", "element_dim".
+        def func(field):
+            left = getattr(self, field)
+            right = getattr(other, field)
+            return None if left == right else (left, right)
+
+        # Note that, we use "_members" not "_fields".
+        values = [func(field) for field in ConnectivityMetadata._members]
+        # Perform lenient difference of the other parent members.
+        result = super()._difference_lenient(other)
+        result.extend(values)
+
+        return result
+
+    @wraps(BaseMetadata.combine, assigned=("__doc__",), updated=())
+    @lenient_service
+    def combine(self, other, lenient=None):
+        return super().combine(other, lenient=lenient)
+
+    @wraps(BaseMetadata.difference, assigned=("__doc__",), updated=())
+    @lenient_service
+    def difference(self, other, lenient=None):
+        return super().difference(other, lenient=lenient)
+
+    @wraps(BaseMetadata.equal, assigned=("__doc__",), updated=())
+    @lenient_service
+    def equal(self, other, lenient=None):
+        return super().equal(other, lenient=lenient)
+
+
 def metadata_manager_factory(cls, **kwargs):
     """
     A class instance factory function responsible for manufacturing
@@ -1462,6 +1577,7 @@ def values(self):
     CoordMetadata.combine,
     CubeMetadata.combine,
     DimCoordMetadata.combine,
+    ConnectivityMetadata.combine,
 )
 
 
@@ -1473,6 +1589,7 @@ def values(self):
     CoordMetadata.difference,
     CubeMetadata.difference,
     DimCoordMetadata.difference,
+    ConnectivityMetadata.difference,
 )
 
 
@@ -1490,6 +1607,8 @@ def values(self):
     CubeMetadata.equal,
     DimCoordMetadata.__eq__,
     DimCoordMetadata.equal,
+    ConnectivityMetadata.__eq__,
+    ConnectivityMetadata.equal,
 )