48 lines
1.5 KiB
Python
48 lines
1.5 KiB
Python
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"""Resolve {{path.to.value}} placeholders against the workflow context."""
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import json
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import re
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from typing import Any
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PLACEHOLDER = re.compile(r"\{\{\s*([a-zA-Z0-9_.\-]+)\s*\}\}")
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class TemplateError(KeyError):
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pass
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def lookup(context: dict[str, Any], path: str) -> Any:
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value: Any = context
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for part in path.split("."):
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if isinstance(value, dict) and part in value:
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value = value[part]
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elif isinstance(value, list) and part.isdigit() and int(part) < len(value):
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value = value[int(part)]
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else:
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raise TemplateError(f"Cannot resolve '{{{{{path}}}}}': '{part}' not found")
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return value
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def _to_text(value: Any) -> str:
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if isinstance(value, str):
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return value
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return json.dumps(value, ensure_ascii=False)
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def render(template: Any, context: dict[str, Any]) -> Any:
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"""Render strings, lists and dicts recursively.
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A string that is exactly one placeholder keeps the original type
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(dict, list, number). Mixed text is rendered as a string.
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"""
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if isinstance(template, dict):
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return {key: render(value, context) for key, value in template.items()}
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if isinstance(template, list):
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return [render(item, context) for item in template]
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if not isinstance(template, str):
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return template
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whole = PLACEHOLDER.fullmatch(template.strip())
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if whole:
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return lookup(context, whole.group(1))
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return PLACEHOLDER.sub(lambda m: _to_text(lookup(context, m.group(1))), template)
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