First sketch of a deepcopy between tiled instances

tiled/client/copy.py

@@ -0,0 +1,70 @@
+from ..structures.core import StructureFamily
+from .container import Container
+
+
+def _walk_readables(node, nodes=None):
+    "Walk nodes in depth first order, yielding readable nodes."
+    if nodes is None:
+        for child in node:
+            yield from _walk_readables(node, [child])
+    else:
+        value = node[nodes[-1]]
+        if value.structure_family == StructureFamily.container:
+            if any(spec.name == "composite" for spec in value.specs):
+                value = value.base
+            yield nodes
+            for k, v in value.items():
+                yield from _walk_readables(value, nodes + [k])
+        else:
+            yield nodes
+
+
+def deepcopy(src, dst):
+    "Copy metadata and underlying data from src to dst."
+    src = src.new_variation(structure_clients="dask")
+    for path in _walk_readables(src):
+        # Use Container.__getitem__ explicitly in two places here to
+        # work around an oddity (bug?) in bluesky-tiled-plugins.
+        s = Container.__getitem__(src, tuple(path))
+        copy_func = _registry[s.structure_family]
+        copy_func(s, Container.__getitem__(dst, tuple(path[:-1])), path[-1])
+
+
+_registry = {}
+
+
+def _register(structure_family: StructureFamily):
+    def f(func):
+        _registry[structure_family] = func
+        return func
+
+    return f
+
+
+@_register(StructureFamily.array)
+def copy_array(src, dst, key):
+    dst.write_array(
+        src.read(),
+        key=key,
+        metadata=dict(src.metadata),
+        specs=src.specs,
+    )
+
+
+@_register(StructureFamily.container)
+def copy_container(src, dst, key):
+    dst.create_container(
+        key=key,
+        metadata=dict(src.metadata),
+        specs=src.specs,
+    )
+
+
+@_register(StructureFamily.table)
+def copy_table(src, dst, key):
+    dst.write_table(
+        src.read(),
+        key=key,
+        metadata=dict(src.metadata),
+        specs=src.specs,
+    )