Initial commit

Last3Mon/64/workflow-lab/src/miniflow/template.py

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