Question

我有一个应用程序，它将接受一个字符串，然后将其作为任意python代码运行。我希望在尝试运行它之前验证此字符串并对其进行评估：

语法正确（可以通过compile(stringCode, foo.py, "execute")内置）
所有导入均可在本地获取
任意代码字符串中的类是否继承自特定类
来自＃3的类是否也实现了一个特定命名的方法（因此我可以稍后在任意代码上调用foo.bar()而不会有太多麻烦）

我已经查看了代码对象，但除非我尝试直接运行代码，否则他们似乎无法做任何事情，而我宁愿事先验证它是否正常工作

Answer 1

您可以使用ast.parse创建字符串的语法树。然后你可以迭代树并验证你喜欢的任何解析时间质量。

正如internet_user所说，这将不告诉你代码的运行时质量;如果模块是通过通常的import语句以外的机制导入的，则不会对这些模块进行验证。如果您的类被动态更改为添加或删除方法，那么仅仅通过查看类定义中的defs就不会知道。

如果您不担心任何问题，请参考以下示例：

import ast
import sys
import os
import imp

s = """
import math, gzip
from os import system
import numpy
import obviouslyFakeModuleName

class A(int):
    def troz(self):
        return 23

class B(str):
    def zort(self):
        return 42
"""

def can_be_imported(name):
    try:
        imp.find_module(name)
        return True
    except ImportError:
        return False

def iter_nodes_by_type(code, type_or_types):
    for node in ast.walk(code):
        if isinstance(node, type_or_types):
            yield node

def iter_imported_module_names(code):
    for node in iter_nodes_by_type(code, ast.Import):
        for alias in node.names:
            yield alias.name
    for node in iter_nodes_by_type(code, ast.ImportFrom):
        yield node.module

def iter_globally_defined_classes(code):
    for child in ast.iter_child_nodes(code):
        if isinstance(child, ast.ClassDef):
            yield child

def iter_methods(class_):
    for node in ast.iter_child_nodes(class_):
        if isinstance(node, ast.FunctionDef):
            yield node

try:
    code = ast.parse(s)
except SyntaxError:
    print("That string is not valid Python.")
    sys.exit(0)

#inspection of imports
for name in iter_imported_module_names(code):
    if can_be_imported(name):
        print("module {} is available for import.".format(name))
    else:
        print("module {} is not available for import.".format(name))

#inspection of classes
for class_ in iter_globally_defined_classes(code):
    class_name = class_.name
    base_class_names = [name.id for name in class_.bases]
    function_names = [func.name for func in iter_methods(class_)]
    print("Inspecting class {}...".format(class_name))
    #we want to know if this class inherits directly from int
    if "int" in base_class_names:
        print("  Does inherit from int.")
    else:
        print("  Does not inherit from int.")

    #and does it implement zort()?
    if "zort" in function_names:
        print("  Implements `zort`.")
    else:
        print("  Does not implement `zort`.")

结果：

module math is available for import.
module gzip is available for import.
module numpy is not available for import.
module obviouslyFakeModuleName is not available for import.
module os is available for import.
Inspecting class A...
  Does inherit from int.
  Does not implement `zort`.
Inspecting class B...
  Does not inherit from int.
  Implements `zort`.

验证任意Python代码

1 个答案: