(WIP) Use -1 for dynamic dimensions

mcbackend/core.py

@@ -32,12 +32,12 @@ def is_rigid(nshape: Optional[Shape]):
         This "nullable shape" is interpreted as follows:
         - ``[]`` indicates scalar shape (rigid: True).
         - ``[2, 3]`` indicates a matrix with 2 rows and 3 columns (rigid: True).
-        - ``[2, 0]`` indicates a matrix with 2 rows and dynamic number of columns (rigid: False).
+        - ``[2, -1]`` indicates a matrix with 2 rows and dynamic number of columns (rigid: False).
         - ``None`` indicates dynamic dimensionality (rigid: False).
     """
     if nshape is None:
         return False
-    if any(s == 0 for s in nshape):
+    if any(s == -1 for s in nshape):
         return False
     return True
 

protobufs/meta.proto

@@ -25,7 +25,7 @@ message Variable {
     // The default value, an empty sequence, corresponds to scalar shape.
     // Note that for variables of dynamic dimensionality, ``undefined_ndim=True``
     // can be set to render ``shape`` and ``dims`` meaningless.
-    repeated uint64 shape = 3;
+    repeated int64 shape = 3;
     // Names of the variable's dimensions.
     // The default value, an empty sequence, corresponds to undefined dimension names
     // and applies to scalar variables, and variables where ``undefined_ndim=True``.