53 lines
1.5 KiB
Python
53 lines
1.5 KiB
Python
"""Resolution context — carries service and parent references during tree walk."""
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class Context:
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"""Evaluation frame for the resolver.
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Top-level context has ``service`` set and ``parent_object`` as None.
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Each selected/allocated object pushes a child context so children
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can reference ``parent`` and traverse its relations.
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"""
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def __init__(self, service, parent_object=None):
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self.service = service
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self.parent_object = parent_object
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def child(self, obj):
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return Context(
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service=self.service,
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parent_object=obj,
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)
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@property
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def parent(self):
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return self.parent_object
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def resolve_path(self, path):
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"""Resolve a dotted reference like ``parent.site.management_prefix``.
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Supported roots:
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- ``service`` → the Service instance
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- ``parent`` → the parent object (or None at service scope)
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Returns None if any segment is None or missing.
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"""
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parts = path.split(".")
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root = parts[0]
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if root == "service":
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obj = self.service
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elif root == "parent":
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obj = self.parent_object
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else:
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raise KeyError(f"Unknown context root: {root!r}")
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for part in parts[1:]:
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if obj is None:
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return None
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if isinstance(obj, dict):
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obj = obj.get(part)
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else:
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obj = getattr(obj, part, None)
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return obj
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