pyo3/
type_object.rs

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
//! Python type object information

use crate::ffi_ptr_ext::FfiPtrExt;
use crate::types::any::PyAnyMethods;
use crate::types::{PyAny, PyType};
#[cfg(feature = "gil-refs")]
use crate::PyNativeType;
use crate::{ffi, Bound, Python};

/// `T: PyLayout<U>` represents that `T` is a concrete representation of `U` in the Python heap.
/// E.g., `PyClassObject` is a concrete representation of all `pyclass`es, and `ffi::PyObject`
/// is of `PyAny`.
///
/// This trait is intended to be used internally.
///
/// # Safety
///
/// This trait must only be implemented for types which represent valid layouts of Python objects.
pub unsafe trait PyLayout<T> {}

/// `T: PySizedLayout<U>` represents that `T` is not a instance of
/// [`PyVarObject`](https://docs.python.org/3/c-api/structures.html#c.PyVarObject).
///
/// In addition, that `T` is a concrete representation of `U`.
pub trait PySizedLayout<T>: PyLayout<T> + Sized {}

/// Specifies that this type has a "GIL-bound Reference" form.
///
/// This is expected to be deprecated in the near future, see <https://github.com/PyO3/pyo3/issues/3382>
///
/// # Safety
///
/// - `Py<Self>::as_ref` will hand out references to `Self::AsRefTarget`.
/// - `Self::AsRefTarget` must have the same layout as `UnsafeCell<ffi::PyAny>`.
#[cfg(feature = "gil-refs")]
pub unsafe trait HasPyGilRef {
    /// Utility type to make Py::as_ref work.
    type AsRefTarget: PyNativeType;
}

#[cfg(feature = "gil-refs")]
unsafe impl<T> HasPyGilRef for T
where
    T: PyNativeType,
{
    type AsRefTarget = Self;
}

/// Python type information.
/// All Python native types (e.g., `PyDict`) and `#[pyclass]` structs implement this trait.
///
/// This trait is marked unsafe because:
///  - specifying the incorrect layout can lead to memory errors
///  - the return value of type_object must always point to the same PyTypeObject instance
///
/// It is safely implemented by the `pyclass` macro.
///
/// # Safety
///
/// Implementations must provide an implementation for `type_object_raw` which infallibly produces a
/// non-null pointer to the corresponding Python type object.
#[cfg(feature = "gil-refs")]
pub unsafe trait PyTypeInfo: Sized + HasPyGilRef {
    /// Class name.
    const NAME: &'static str;

    /// Module name, if any.
    const MODULE: Option<&'static str>;

    /// Returns the PyTypeObject instance for this type.
    fn type_object_raw(py: Python<'_>) -> *mut ffi::PyTypeObject;

    /// Returns the safe abstraction over the type object.
    #[inline]
    #[cfg(feature = "gil-refs")]
    #[deprecated(
        since = "0.21.0",
        note = "`PyTypeInfo::type_object` will be replaced by `PyTypeInfo::type_object_bound` in a future PyO3 version"
    )]
    fn type_object(py: Python<'_>) -> &PyType {
        // This isn't implemented in terms of `type_object_bound` because this just borrowed the
        // object, for legacy reasons.
        #[allow(deprecated)]
        unsafe {
            py.from_borrowed_ptr(Self::type_object_raw(py) as _)
        }
    }

    /// Returns the safe abstraction over the type object.
    #[inline]
    fn type_object_bound(py: Python<'_>) -> Bound<'_, PyType> {
        // Making the borrowed object `Bound` is necessary for soundness reasons. It's an extreme
        // edge case, but arbitrary Python code _could_ change the __class__ of an object and cause
        // the type object to be freed.
        //
        // By making `Bound` we assume ownership which is then safe against races.
        unsafe {
            Self::type_object_raw(py)
                .cast::<ffi::PyObject>()
                .assume_borrowed_unchecked(py)
                .to_owned()
                .downcast_into_unchecked()
        }
    }

    /// Checks if `object` is an instance of this type or a subclass of this type.
    #[inline]
    #[cfg(feature = "gil-refs")]
    #[deprecated(
        since = "0.21.0",
        note = "`PyTypeInfo::is_type_of` will be replaced by `PyTypeInfo::is_type_of_bound` in a future PyO3 version"
    )]
    fn is_type_of(object: &PyAny) -> bool {
        Self::is_type_of_bound(&object.as_borrowed())
    }

    /// Checks if `object` is an instance of this type or a subclass of this type.
    #[inline]
    fn is_type_of_bound(object: &Bound<'_, PyAny>) -> bool {
        unsafe { ffi::PyObject_TypeCheck(object.as_ptr(), Self::type_object_raw(object.py())) != 0 }
    }

    /// Checks if `object` is an instance of this type.
    #[inline]
    #[cfg(feature = "gil-refs")]
    #[deprecated(
        since = "0.21.0",
        note = "`PyTypeInfo::is_exact_type_of` will be replaced by `PyTypeInfo::is_exact_type_of_bound` in a future PyO3 version"
    )]
    fn is_exact_type_of(object: &PyAny) -> bool {
        Self::is_exact_type_of_bound(&object.as_borrowed())
    }

    /// Checks if `object` is an instance of this type.
    #[inline]
    fn is_exact_type_of_bound(object: &Bound<'_, PyAny>) -> bool {
        unsafe { ffi::Py_TYPE(object.as_ptr()) == Self::type_object_raw(object.py()) }
    }
}

/// Python type information.
/// All Python native types (e.g., `PyDict`) and `#[pyclass]` structs implement this trait.
///
/// This trait is marked unsafe because:
///  - specifying the incorrect layout can lead to memory errors
///  - the return value of type_object must always point to the same PyTypeObject instance
///
/// It is safely implemented by the `pyclass` macro.
///
/// # Safety
///
/// Implementations must provide an implementation for `type_object_raw` which infallibly produces a
/// non-null pointer to the corresponding Python type object.
#[cfg(not(feature = "gil-refs"))]
pub unsafe trait PyTypeInfo: Sized {
    /// Class name.
    const NAME: &'static str;

    /// Module name, if any.
    const MODULE: Option<&'static str>;

    /// Returns the PyTypeObject instance for this type.
    fn type_object_raw(py: Python<'_>) -> *mut ffi::PyTypeObject;

    /// Returns the safe abstraction over the type object.
    #[inline]
    fn type_object_bound(py: Python<'_>) -> Bound<'_, PyType> {
        // Making the borrowed object `Bound` is necessary for soundness reasons. It's an extreme
        // edge case, but arbitrary Python code _could_ change the __class__ of an object and cause
        // the type object to be freed.
        //
        // By making `Bound` we assume ownership which is then safe against races.
        unsafe {
            Self::type_object_raw(py)
                .cast::<ffi::PyObject>()
                .assume_borrowed_unchecked(py)
                .to_owned()
                .downcast_into_unchecked()
        }
    }

    /// Checks if `object` is an instance of this type or a subclass of this type.
    #[inline]
    fn is_type_of_bound(object: &Bound<'_, PyAny>) -> bool {
        unsafe { ffi::PyObject_TypeCheck(object.as_ptr(), Self::type_object_raw(object.py())) != 0 }
    }

    /// Checks if `object` is an instance of this type.
    #[inline]
    fn is_exact_type_of_bound(object: &Bound<'_, PyAny>) -> bool {
        unsafe { ffi::Py_TYPE(object.as_ptr()) == Self::type_object_raw(object.py()) }
    }
}

/// Implemented by types which can be used as a concrete Python type inside `Py<T>` smart pointers.
#[cfg(feature = "gil-refs")]
pub trait PyTypeCheck: HasPyGilRef {
    /// Name of self. This is used in error messages, for example.
    const NAME: &'static str;

    /// Checks if `object` is an instance of `Self`, which may include a subtype.
    ///
    /// This should be equivalent to the Python expression `isinstance(object, Self)`.
    fn type_check(object: &Bound<'_, PyAny>) -> bool;
}

/// Implemented by types which can be used as a concrete Python type inside `Py<T>` smart pointers.
#[cfg(not(feature = "gil-refs"))]
pub trait PyTypeCheck {
    /// Name of self. This is used in error messages, for example.
    const NAME: &'static str;

    /// Checks if `object` is an instance of `Self`, which may include a subtype.
    ///
    /// This should be equivalent to the Python expression `isinstance(object, Self)`.
    fn type_check(object: &Bound<'_, PyAny>) -> bool;
}

impl<T> PyTypeCheck for T
where
    T: PyTypeInfo,
{
    const NAME: &'static str = <T as PyTypeInfo>::NAME;

    #[inline]
    fn type_check(object: &Bound<'_, PyAny>) -> bool {
        T::is_type_of_bound(object)
    }
}