54 lines
1.5 KiB
Python
54 lines
1.5 KiB
Python
"""Placeholder helpers."""
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from typing import Any, Dict, Set
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from homeassistant.util.yaml import Placeholder
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class UndefinedSubstitution(Exception):
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"""Error raised when we find a substitution that is not defined."""
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def __init__(self, placeholder: str) -> None:
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"""Initialize the undefined substitution exception."""
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super().__init__(f"No substitution found for placeholder {placeholder}")
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self.placeholder = placeholder
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def extract_placeholders(obj: Any) -> Set[str]:
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"""Extract placeholders from a structure."""
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found: Set[str] = set()
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_extract_placeholders(obj, found)
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return found
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def _extract_placeholders(obj: Any, found: Set[str]) -> None:
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"""Extract placeholders from a structure."""
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if isinstance(obj, Placeholder):
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found.add(obj.name)
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return
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if isinstance(obj, list):
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for val in obj:
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_extract_placeholders(val, found)
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return
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if isinstance(obj, dict):
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for val in obj.values():
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_extract_placeholders(val, found)
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return
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def substitute(obj: Any, substitutions: Dict[str, Any]) -> Any:
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"""Substitute values."""
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if isinstance(obj, Placeholder):
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if obj.name not in substitutions:
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raise UndefinedSubstitution(obj.name)
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return substitutions[obj.name]
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if isinstance(obj, list):
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return [substitute(val, substitutions) for val in obj]
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if isinstance(obj, dict):
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return {key: substitute(val, substitutions) for key, val in obj.items()}
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return obj
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