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// Copyright (c) 2015 Daniel Grunwald // // Permission is hereby granted, free of charge, to any person obtaining a copy of this // software and associated documentation files (the "Software"), to deal in the Software // without restriction, including without limitation the rights to use, copy, modify, merge, // publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons // to whom the Software is furnished to do so, subject to the following conditions: // // The above copyright notice and this permission notice shall be included in all copies or // substantial portions of the Software. // // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, // INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR // PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE // FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR // OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER // DEALINGS IN THE SOFTWARE. use std; use ffi; use python::{Python, PythonObject, PythonObjectWithCheckedDowncast, PyClone}; use objects::PyObject; use err::PyResult; /// Conversion trait that allows various objects to be converted into Python objects. pub trait ToPyObject { type ObjectType : PythonObject; /// Converts self into a Python object. fn to_py_object(&self, py: Python) -> Self::ObjectType; /// Converts self into a Python object. /// /// May be more efficient than `to_py_object` in some cases because /// it can move out of the input object. #[inline] fn into_py_object(self, py: Python) -> Self::ObjectType where Self: Sized { self.to_py_object(py) } /// Converts self into a Python object and calls the specified closure /// on the native FFI pointer underlying the Python object. /// /// May be more efficient than `to_py_object` because it does not need /// to touch any reference counts when the input object already is a Python object. #[inline] fn with_borrowed_ptr<F, R>(&self, py: Python, f: F) -> R where F: FnOnce(*mut ffi::PyObject) -> R { let obj = self.to_py_object(py).into_object(); f(obj.as_ptr()) } // FFI functions that accept a borrowed reference will use: // input.with_borrowed_ptr(|obj| ffi::Call(obj) // 1) input is &PyObject // -> with_borrowed_ptr() just forwards to the closure // 2) input is PyObject // -> with_borrowed_ptr() just forwards to the closure // 3) input is &str, int, ... // -> to_py_object() allocates new Python object; FFI call happens; PyObject::drop() calls Py_DECREF() // FFI functions that steal a reference will use: // let input = try!(input.into_py_object()); ffi::Call(input.steal_ptr()) // 1) input is &PyObject // -> into_py_object() calls Py_INCREF // 2) input is PyObject // -> into_py_object() is no-op // 3) input is &str, int, ... // -> into_py_object() allocates new Python object } py_impl_to_py_object_for_python_object!(PyObject); /// FromPyObject is implemented by various types that can be extracted from a Python object. /// /// Normal usage is through the `PyObject::extract` helper method: /// ```let obj: PyObject = ...; /// let value = try!(obj.extract::<TargetType>(py)); /// ``` /// /// TODO: update this documentation /// Note: depending on the implementation, the lifetime of the extracted result may /// depend on the lifetime of the `obj` or the `prepared` variable. /// /// For example, when extracting `&str` from a python byte string, the resulting string slice will /// point to the existing string data (lifetime: `'source`). /// On the other hand, when extracting `&str` from a python unicode string, the preparation step /// will convert the string to UTF-8, and the resulting string slice will have lifetime `'prepared`. /// Since only which of these cases applies depends on the runtime type of the python object, /// both the `obj` and `prepared` variables must outlive the resulting string slice. /// /// In cases where the result does not depend on the `'prepared` lifetime, /// the inherent method `PyObject::extract()` can be used. pub trait FromPyObject<'source> : Sized { /// Extracts `Self` from the source `PyObject`. fn extract(py: Python, obj: &'source PyObject) -> PyResult<Self>; } py_impl_from_py_object_for_python_object!(PyObject); pub trait RefFromPyObject { fn with_extracted<F, R>(py: Python, obj: &PyObject, f: F) -> PyResult<R> where F: FnOnce(&Self) -> R; } impl <T: ?Sized> RefFromPyObject for T where for<'a> &'a T: FromPyObject<'a> { #[inline] fn with_extracted<F, R>(py: Python, obj: &PyObject, f: F) -> PyResult<R> where F: FnOnce(&Self) -> R { match FromPyObject::extract(py, obj) { Ok(val) => Ok(f(val)), Err(e) => Err(e) } } } /* impl <'prepared, T> ExtractPyObject<'prepared> for T where T: PythonObjectWithCheckedDowncast { type Prepared = PyObject; #[inline] fn prepare_extract(py: Python, obj: &PyObject) -> PyResult<Self::Prepared> { Ok(obj.clone_ref(py)) } #[inline] fn extract(py: Python, obj: &'prepared Self::Prepared) -> PyResult<T> { Ok(try!(obj.clone_ref(py).cast_into(py))) } } */ // ToPyObject for references impl <'a, T: ?Sized> ToPyObject for &'a T where T: ToPyObject { type ObjectType = T::ObjectType; #[inline] fn to_py_object(&self, py: Python) -> T::ObjectType { <T as ToPyObject>::to_py_object(*self, py) } #[inline] fn into_py_object(self, py: Python) -> T::ObjectType { <T as ToPyObject>::to_py_object(self, py) } #[inline] fn with_borrowed_ptr<F, R>(&self, py: Python, f: F) -> R where F: FnOnce(*mut ffi::PyObject) -> R { <T as ToPyObject>::with_borrowed_ptr(*self, py, f) } } /// `Option::Some<T>` is converted like `T`. /// `Option::None` is converted to Python `None`. impl <T> ToPyObject for Option<T> where T: ToPyObject { type ObjectType = PyObject; fn to_py_object(&self, py: Python) -> PyObject { match *self { Some(ref val) => val.to_py_object(py).into_object(), None => py.None() } } fn into_py_object(self, py: Python) -> PyObject { match self { Some(val) => val.into_py_object(py).into_object(), None => py.None() } } } impl <'source, T> FromPyObject<'source> for Option<T> where T: FromPyObject<'source> { fn extract(py: Python, obj: &'source PyObject) -> PyResult<Self> { if obj.as_ptr() == unsafe { ffi::Py_None() } { Ok(None) } else { match T::extract(py, obj) { Ok(v) => Ok(Some(v)), Err(e) => Err(e) } } } } /* impl <'prepared, T> ExtractPyObject<'prepared> for Option<T> where T: ExtractPyObject<'prepared> { type Prepared = Option<T::Prepared>; fn prepare_extract(py: Python, obj: &PyObject) -> PyResult<Self::Prepared> { if obj.as_ptr() == unsafe { ffi::Py_None() } { Ok(None) } else { Ok(Some(try!(T::prepare_extract(py, obj)))) } } fn extract(py: Python, obj: &'prepared Self::Prepared) -> PyResult<Option<T>> { match *obj { Some(ref inner) => { match T::extract(py, inner) { Ok(v) => Ok(Some(v)), Err(e) => Err(e) } }, None => Ok(None) } } } */