yaml.py 文件源码

def _ordered_dict(loader: SafeLineLoader,
                  node: yaml.nodes.MappingNode) -> OrderedDict:
    """Load YAML mappings into an ordered dictionary to preserve key order."""
    loader.flatten_mapping(node)
    nodes = loader.construct_pairs(node)

    seen = {}  # type: Dict
    for (key, _), (child_node, _) in zip(nodes, node.value):
        line = child_node.start_mark.line

        try:
            hash(key)
        except TypeError:
            fname = getattr(loader.stream, 'name', '')
            raise yaml.MarkedYAMLError(
                context="invalid key: \"{}\"".format(key),
                context_mark=yaml.Mark(fname, 0, line, -1, None, None)
            )

        if key in seen:
            fname = getattr(loader.stream, 'name', '')
            first_mark = yaml.Mark(fname, 0, seen[key], -1, None, None)
            second_mark = yaml.Mark(fname, 0, line, -1, None, None)
            raise yaml.MarkedYAMLError(
                context="duplicate key: \"{}\"".format(key),
                context_mark=first_mark, problem_mark=second_mark,
            )
        seen[key] = line

    processed = OrderedDict(nodes)
    setattr(processed, '__config_file__', loader.name)
    setattr(processed, '__line__', node.start_mark.line)
    return processed