utils.py 文件源码

def iter_expr_values(parent, node, child=None):
    """
    Yield each value for *node* which can be tracked. Literals are returned as
    their evaluated value where as nodes which fail to evaluate to literals are
    returned as is.

    :param node parent: The parent node used to mark the start of the search path.
    :param node node: The target ast.Name node to find literal values for.
    :param node child: An optional child node to mark the end of the search path.
    """
    child = child or node
    success, value = eval_ast.literal_expr(node)
    if success:
        yield value
        return
    if not isinstance(node, ast.Name):
        return

    test_nodes = collections.deque()
    def_nodes = get_definition_nodes(parent, node.id, child)
    for def_node_idx, def_node in enumerate(def_nodes):
        each = False
        next_node = (def_nodes[def_node_idx + 1] if len(def_nodes) > def_node_idx + 1 else child)
        src_node = None
        test_nodes.clear()
        if isinstance(def_node, ast.Assign):
            test_node = get_expr_value_src_dst(def_node.value, def_node.targets[0], node)
            if test_node:
                test_nodes.append(test_node)
        elif isinstance(def_node, ast.For):
            src_node = get_expr_value_src_dst(def_node.iter, def_node.target, node)
            each = node_is_child_of_parent(def_node.body, next_node)
        elif isinstance(def_node, ast.ListComp):
            for generator in def_node.generators:
                src_node = get_expr_value_src_dst(generator.iter, generator.target, node)
                if src_node:
                    break

        if isinstance(src_node, (ast.List, ast.Tuple, ast.Set)):
            test_nodes.extend(src_node.elts if each else src_node.elts[-1:])

        for test_node in test_nodes:
            success, value = eval_ast.literal_expr(test_node)
            if success:
                yield value
                continue
            for value in iter_expr_values(parent, test_node):
                success = True
                yield value
            if success:
                continue
            for def_node in get_definition_nodes(parent, test_node):
                for value in iter_expr_values(parent, def_node):
                    success = True
                    yield value
            yield test_node