cfg.py 文件源码

def _build_cfg(statements):

    enter = id(statements[0])

    exits = [enter]
    graph = Graph()

    jumps = Jumps()

    for i, node in enumerate(statements):

        cfg = _build_node_cfg(node)

        graph.update(cfg.graph)

        if i > 0:
            for exit_ in exits:
                graph.add_edge(exit_, cfg.enter)

        exits = cfg.exits
        jumps = jumps.join(cfg.jumps)

        if type(node) in (ast.Break, ast.Continue, ast.Return):
            # Issue a warning about unreachable code?
            break

    return ControlFlowSubgraph(graph, enter, exits=exits, jumps=jumps)