basic.py 文件源码

def _has(self, pattern):
        """Helper for .has()"""
        from sympy.core.function import UndefinedFunction, Function
        if isinstance(pattern, UndefinedFunction):
            return any(f.func == pattern or f == pattern
            for f in self.atoms(Function, UndefinedFunction))

        pattern = sympify(pattern)
        if isinstance(pattern, BasicType):
            return any(isinstance(arg, pattern)
            for arg in preorder_traversal(self))

        try:
            match = pattern._has_matcher()
            return any(match(arg) for arg in preorder_traversal(self))
        except AttributeError:
            return any(arg == pattern for arg in preorder_traversal(self))