Blender Python Function To Evaluate User Input Property Paths without Eval

evaluatepath.py

def evaluate_path(path, alternative_root = None):
  #alternative_root can be used to define a default parent root object if user is not expected to enter full path
  #Note: full paths start with "bpy."
    if(path is None or path == ""):
        return (None, None, None)
    #Regular expression pattern to match segments of the path
    pattern = r'(.+?)\.|(?:\["(.+?)"\])|([^"\[\]]+)'
    segments = re.findall(pattern, path)
    parent_obj = None
    enumerate_from = 0

    # If full path, start with bpy
    if segments[0][0] == "bpy":
        current_obj = bpy
        enumerate_from = 1
    else:
        current_obj = alternative_root
        if(current_obj is None):
            return (None, None, None)
            

    for segment in segments[enumerate_from:]:
        prop_name = segment[0] or segment[1] or segment[2]
        
        # Check if the property exists
        if hasattr(current_obj, prop_name):
            parent_obj = current_obj
            current_obj = getattr(current_obj, prop_name)
        else:
            if isinstance(current_obj, list):
                # Check if the property is an indexed attribute in a list
                index = int(prop_name)  # Extract the index
                if 0 <= index < len(current_obj):
                    parent_obj = current_obj
                    current_obj = current_obj[index]
                else:
                    return (None, None, None)  # Index out of range
            elif prop_name in current_obj:
                parent_obj = current_obj
                current_obj = current_obj[prop_name]
            else:
                return (None, None, None)  # Key not found
    #return (target object of path, parent of target object, property name string of the target object)
    return (current_obj, parent_obj, prop_name)