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
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
// 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 libc::c_char;
use std::borrow::Cow;
use std::{char, mem, str};

use super::{exc, PyObject};
use crate::conversion::{FromPyObject, RefFromPyObject, ToPyObject};
use crate::err::{self, PyErr, PyResult};
use crate::ffi;
use crate::python::{PyClone, Python, PythonObject, PythonObjectDowncastError, ToPythonPointer};

/// Represents a Python string.
/// Corresponds to `basestring` in Python 2, and `str` in Python 3.
pub struct PyString(PyObject);

#[cfg(feature = "python27-sys")]
pyobject_newtype!(PyString);
#[cfg(feature = "python3-sys")]
pyobject_newtype!(PyString, PyUnicode_Check, PyUnicode_Type);

/// Represents a Python byte string.
/// Corresponds to `str` in Python 2, and `bytes` in Python 3.
pub struct PyBytes(PyObject);

pyobject_newtype!(PyBytes, PyBytes_Check, PyBytes_Type);

/// Represents a Python unicode string.
/// Corresponds to `unicode` in Python 2, and `str` in Python 3.
#[cfg(feature = "python27-sys")]
pub struct PyUnicode(PyObject);

#[cfg(feature = "python27-sys")]
pyobject_newtype!(PyUnicode, PyUnicode_Check, PyUnicode_Type);

/// Represents a Python unicode string.
/// Corresponds to `unicode` in Python 2, and `str` in Python 3.
#[cfg(feature = "python3-sys")]
pub use PyString as PyUnicode;

#[cfg(feature = "python27-sys")]
impl crate::python::PythonObjectWithCheckedDowncast for PyString {
    #[inline]
    fn downcast_from(
        py: Python<'_>,
        obj: PyObject,
    ) -> Result<PyString, PythonObjectDowncastError<'_>> {
        if is_base_string(&obj) {
            Ok(PyString(obj))
        } else {
            Err(PythonObjectDowncastError::new(
                py,
                "PyString",
                obj.get_type(py),
            ))
        }
    }

    #[inline]
    fn downcast_borrow_from<'a, 'p>(
        py: Python<'p>,
        obj: &'a PyObject,
    ) -> Result<&'a PyString, PythonObjectDowncastError<'p>> {
        unsafe {
            if is_base_string(obj) {
                Ok(std::mem::transmute(obj))
            } else {
                Err(crate::python::PythonObjectDowncastError::new(
                    py,
                    "PyString",
                    obj.get_type(py),
                ))
            }
        }
    }
}

#[cfg(feature = "python27-sys")]
#[inline]
fn is_base_string(obj: &PyObject) -> bool {
    unsafe {
        ffi::PyType_FastSubclass(
            ffi::Py_TYPE(obj.as_ptr()),
            ffi::Py_TPFLAGS_STRING_SUBCLASS | ffi::Py_TPFLAGS_UNICODE_SUBCLASS,
        ) != 0
    }
}

#[cfg(feature = "python27-sys")]
impl crate::python::PythonObjectWithTypeObject for PyString {
    #[inline]
    fn type_object(py: Python) -> super::PyType {
        unsafe {
            crate::objects::typeobject::PyType::from_type_ptr(py, &mut ffi::PyBaseString_Type)
        }
    }
}

/// Enum of possible Python string representations.
#[derive(Clone, Copy, Debug)]
pub enum PyStringData<'a> {
    Latin1(&'a [u8]),
    Utf8(&'a [u8]),
    Utf16(&'a [u16]),
    Utf32(&'a [u32]),
}

impl<'a> From<&'a str> for PyStringData<'a> {
    #[inline]
    fn from(val: &'a str) -> PyStringData<'a> {
        PyStringData::Utf8(val.as_bytes())
    }
}

impl<'a> From<&'a [u16]> for PyStringData<'a> {
    #[inline]
    fn from(val: &'a [u16]) -> PyStringData<'a> {
        PyStringData::Utf16(val)
    }
}

impl<'a> From<&'a [u32]> for PyStringData<'a> {
    #[inline]
    fn from(val: &'a [u32]) -> PyStringData<'a> {
        PyStringData::Utf32(val)
    }
}

impl<'a> PyStringData<'a> {
    /// Convert the Python string data to a Rust string.
    ///
    /// For UTF-8 and ASCII-only latin-1, returns a borrow into the original string data.
    /// For Latin-1, UTF-16 and UTF-32, returns an owned string.
    ///
    /// Fails with UnicodeDecodeError if the string data isn't valid in its encoding.
    pub fn to_string(self, py: Python) -> PyResult<Cow<'a, str>> {
        match self {
            PyStringData::Utf8(data) => match str::from_utf8(data) {
                Ok(s) => Ok(Cow::Borrowed(s)),
                Err(e) => Err(PyErr::from_instance(
                    py,
                    exc::UnicodeDecodeError::new_utf8(py, data, e)?,
                )),
            },
            PyStringData::Latin1(data) => {
                if data.is_ascii() {
                    Ok(Cow::Borrowed(unsafe { str::from_utf8_unchecked(data) }))
                } else {
                    Ok(Cow::Owned(data.iter().map(|&b| b as char).collect()))
                }
            }
            PyStringData::Utf16(data) => {
                fn utf16_bytes(input: &[u16]) -> &[u8] {
                    unsafe { mem::transmute(input) }
                }
                match String::from_utf16(data) {
                    Ok(s) => Ok(Cow::Owned(s)),
                    Err(_) => Err(PyErr::from_instance(
                        py,
                        exc::UnicodeDecodeError::new(
                            py,
                            cstr!("utf-16"),
                            utf16_bytes(data),
                            0..2 * data.len(),
                            cstr!("invalid utf-16"),
                        )?,
                    )),
                }
            }
            PyStringData::Utf32(data) => {
                fn utf32_bytes(input: &[u32]) -> &[u8] {
                    unsafe { mem::transmute(input) }
                }
                match data.iter().map(|&u| char::from_u32(u)).collect() {
                    Some(s) => Ok(Cow::Owned(s)),
                    None => Err(PyErr::from_instance(
                        py,
                        exc::UnicodeDecodeError::new(
                            py,
                            cstr!("utf-32"),
                            utf32_bytes(data),
                            0..4 * data.len(),
                            cstr!("invalid utf-32"),
                        )?,
                    )),
                }
            }
        }
    }

    /// Convert the Python string data to a Rust string.
    ///
    /// Returns a borrow into the original string data if possible.
    ///
    /// Data that isn't valid in its encoding will be replaced
    /// with U+FFFD REPLACEMENT CHARACTER.
    pub fn to_string_lossy(self) -> Cow<'a, str> {
        match self {
            PyStringData::Utf8(data) => String::from_utf8_lossy(data),
            PyStringData::Latin1(data) => {
                if data.is_ascii() {
                    Cow::Borrowed(unsafe { str::from_utf8_unchecked(data) })
                } else {
                    Cow::Owned(data.iter().map(|&b| b as char).collect())
                }
            }
            PyStringData::Utf16(data) => Cow::Owned(String::from_utf16_lossy(data)),
            PyStringData::Utf32(data) => Cow::Owned(
                data.iter()
                    .map(|&u| char::from_u32(u).unwrap_or('\u{FFFD}'))
                    .collect(),
            ),
        }
    }
}

impl PyString {
    /// Creates a new Python string object.
    ///
    /// On Python 2.7, this function will create a byte string if the
    /// feature `py2-no-auto-unicode-promotion` is set, or the input
    /// input string is ASCII-only; otherwise, the input string will be
    /// converted to a unicode string.
    /// Use `PyUnicode::new()` to always create a unicode string.
    ///
    /// On Python 3.x, this function always creates unicode `str` objects.
    ///
    /// Panics if out of memory.
    pub fn new(py: Python, s: &str) -> PyString {
        #[cfg(feature = "python27-sys")]
        fn new_impl(py: Python, s: &str) -> PyString {
            if cfg!(feature = "py2-no-auto-unicode-promotion") || s.is_ascii() {
                PyBytes::new(py, s.as_bytes()).into_basestring()
            } else {
                PyUnicode::new(py, s).into_basestring()
            }
        }
        #[cfg(feature = "python3-sys")]
        fn new_impl(py: Python, s: &str) -> PyString {
            let ptr = s.as_ptr() as *const c_char;
            let len = s.len() as ffi::Py_ssize_t;
            unsafe {
                err::cast_from_owned_ptr_or_panic(py, ffi::PyUnicode_FromStringAndSize(ptr, len))
            }
        }
        new_impl(py, s)
    }

    /// Gets the python string data in its underlying representation.
    ///
    /// For Python 2 byte strings, this function always returns `PyStringData::Utf8`,
    /// even if the bytes are not valid UTF-8.
    /// For unicode strings, returns the underlying representation used by Python.
    pub fn data(&self, py: Python) -> PyStringData {
        self.data_impl(py)
    }

    #[cfg(feature = "python27-sys")]
    fn data_impl(&self, py: Python) -> PyStringData {
        if let Ok(bytes) = self.0.cast_as::<PyBytes>(py) {
            PyStringData::Utf8(bytes.data(py))
        } else if let Ok(unicode) = self.0.cast_as::<PyUnicode>(py) {
            unicode.data(py)
        } else {
            panic!("PyString is neither `str` nor `unicode`")
        }
    }

    #[cfg(feature = "python3-sys")]
    fn data_impl(&self, _py: Python) -> PyStringData {
        let ptr = self.as_ptr();
        unsafe {
            let ready = ffi::PyUnicode_READY(ptr);
            if ready < 0 {
                // should fail only on OOM
                ffi::PyErr_Print();
                panic!("PyUnicode_READY failed");
            }
            let size = ffi::PyUnicode_GET_LENGTH(ptr) as usize;
            let data = ffi::PyUnicode_DATA(ptr);
            let kind = ffi::PyUnicode_KIND(ptr);
            match kind {
                ffi::PyUnicode_1BYTE_KIND => {
                    PyStringData::Latin1(std::slice::from_raw_parts(data as *const u8, size))
                }
                ffi::PyUnicode_2BYTE_KIND => {
                    PyStringData::Utf16(std::slice::from_raw_parts(data as *const u16, size))
                }
                ffi::PyUnicode_4BYTE_KIND => {
                    PyStringData::Utf32(std::slice::from_raw_parts(data as *const u32, size))
                }
                _ => panic!("Unknown PyUnicode_KIND"),
            }
        }
    }

    /// Convert the `PyString` into a Rust string.
    ///
    /// On Python 2.7, if the `PyString` refers to a byte string,
    /// it will be decoded using UTF-8.
    ///
    /// Returns a `UnicodeDecodeError` if the input is not valid unicode
    /// (containing unpaired surrogates, or a Python 2.7 byte string that is
    /// not valid UTF-8).
    pub fn to_string(&self, py: Python) -> PyResult<Cow<str>> {
        #[cfg(feature = "python3-sys")]
        unsafe {
            // On Python 3, we can use the UTF-8 representation stored
            // inside the Python string.
            // This should produce identical results to
            // `self.data(py).to_string(py)` but avoids
            // re-encoding the string on every to_string call.
            let mut size: ffi::Py_ssize_t = 0;
            let data = ffi::PyUnicode_AsUTF8AndSize(self.as_ptr(), &mut size);
            if data.is_null() {
                Err(PyErr::fetch(py))
            } else {
                let slice = std::slice::from_raw_parts(data as *const u8, size as usize);
                Ok(Cow::Borrowed(std::str::from_utf8_unchecked(slice)))
            }
        }
        #[cfg(feature = "python27-sys")]
        {
            self.data(py).to_string(py)
        }
    }

    /// Convert the `PyString` into a Rust string.
    ///
    /// On Python 2.7, if the `PyString` refers to a byte string,
    /// it will be decoded using UTF-8.
    ///
    /// Unpaired surrogates and (on Python 2.7) invalid UTF-8 sequences are
    /// replaced with U+FFFD REPLACEMENT CHARACTER.
    pub fn to_string_lossy(&self, py: Python) -> Cow<str> {
        self.data(py).to_string_lossy()
    }
}

impl PyBytes {
    /// Creates a new Python byte string object.
    /// The byte string is initialized by copying the data from the `&[u8]`.
    ///
    /// Panics if out of memory.
    pub fn new(py: Python, s: &[u8]) -> PyBytes {
        let ptr = s.as_ptr() as *const c_char;
        let len = s.len() as ffi::Py_ssize_t;
        unsafe { err::cast_from_owned_ptr_or_panic(py, ffi::PyBytes_FromStringAndSize(ptr, len)) }
    }

    /// Gets the Python string data as byte slice.
    pub fn data(&self, _py: Python) -> &[u8] {
        unsafe {
            let buffer = ffi::PyBytes_AsString(self.as_ptr()) as *const u8;
            let length = ffi::PyBytes_Size(self.as_ptr()) as usize;
            std::slice::from_raw_parts(buffer, length)
        }
    }

    /// Converts from `PyBytes` to `PyString`.
    /// This method is only available on Python 2.
    #[cfg(feature = "python27-sys")]
    #[inline]
    pub fn as_basestring(&self) -> &PyString {
        unsafe { self.0.unchecked_cast_as() }
    }

    /// Converts from `PyBytes` to `PyString`.
    /// This method is only available on Python 2.
    #[cfg(feature = "python27-sys")]
    #[inline]
    pub fn into_basestring(self) -> PyString {
        unsafe { self.0.unchecked_cast_into() }
    }
}

#[cfg(feature = "python27-sys")]
impl PyUnicode {
    /// Creates a new Python unicode string object.
    ///
    /// Panics if out of memory.
    pub fn new(py: Python, s: &str) -> PyUnicode {
        let ptr = s.as_ptr() as *const c_char;
        let len = s.len() as ffi::Py_ssize_t;
        unsafe { err::cast_from_owned_ptr_or_panic(py, ffi::PyUnicode_FromStringAndSize(ptr, len)) }
    }

    /// Converts from `PyUnicode` to `PyString`.
    /// This method is only available on Python 2.
    /// (note: on Python 3, `PyUnicode` is a type alias for `PyString`)
    #[inline]
    pub fn as_basestring(&self) -> &PyString {
        unsafe { self.0.unchecked_cast_as() }
    }

    /// Converts from `PyUnicode` to `PyString`.
    /// This method is only available on Python 2.
    /// (note: on Python 3, `PyUnicode` is a type alias for `PyString`)
    #[inline]
    pub fn into_basestring(self) -> PyString {
        unsafe { self.0.unchecked_cast_into() }
    }

    /// Gets the python string data in its underlying representation.
    pub fn data(&self, _py: Python) -> PyStringData {
        unsafe {
            let buffer = ffi::PyUnicode_AS_UNICODE(self.as_ptr());
            let length = ffi::PyUnicode_GET_SIZE(self.as_ptr()) as usize;
            std::slice::from_raw_parts(buffer, length).into()
        }
    }

    /// Convert the `PyUnicode` into a Rust string.
    ///
    /// Returns a `UnicodeDecodeError` if the input is not valid unicode
    /// (containing unpaired surrogates).
    pub fn to_string(&self, py: Python) -> PyResult<Cow<str>> {
        self.data(py).to_string(py)
    }

    /// Convert the `PyUnicode` into a Rust string.
    ///
    /// Unpaired surrogates are replaced with U+FFFD REPLACEMENT CHARACTER.
    pub fn to_string_lossy(&self, py: Python) -> Cow<str> {
        self.data(py).to_string_lossy()
    }
}

/// Converts Rust `str` to Python object.
///
/// On Python 2.7, this impl will create a byte string if the
/// input string is ASCII-only; and a unicode string otherwise.
/// Use `PyUnicode::new()` to always create a unicode string.
///
/// On Python 3.x, this function always creates unicode `str` objects.
impl ToPyObject for str {
    type ObjectType = PyString;

    #[inline]
    fn to_py_object(&self, py: Python) -> PyString {
        PyString::new(py, self)
    }
}

/// Converts Rust `str` to Python object.
///
/// On Python 2.7, this impl will create a byte string if the
/// input string is ASCII-only; and a unicode string otherwise.
/// Use `PyUnicode::new()` to always create a unicode string.
///
/// On Python 3.x, this function always creates unicode `str` objects.
impl<'a> ToPyObject for Cow<'a, str> {
    type ObjectType = PyString;

    #[inline]
    fn to_py_object(&self, py: Python) -> PyString {
        PyString::new(py, self)
    }
}

/// Converts Rust `str` to Python object.
///
/// On Python 2.7, this impl will create a byte string if the
/// input string is ASCII-only; and a unicode string otherwise.
/// Use `PyUnicode::new()` to always create a unicode string.
///
/// On Python 3.x, this function always creates unicode `str` objects.
impl ToPyObject for String {
    type ObjectType = PyString;

    #[inline]
    fn to_py_object(&self, py: Python) -> PyString {
        PyString::new(py, self)
    }
}

/// Allows extracting strings from Python objects.
/// Accepts Python `str` and `unicode` objects.
/// In Python 2.7, `str` is expected to be UTF-8 encoded.
///
/// Returns a `UnicodeDecodeError` if the input is not valid unicode
/// (containing unpaired surrogates, or a Python 2.7 byte string that is
/// not valid UTF-8).
impl<'s> FromPyObject<'s> for Cow<'s, str> {
    fn extract(py: Python, obj: &'s PyObject) -> PyResult<Self> {
        obj.cast_as::<PyString>(py)?.to_string(py)
    }
}

/// Allows extracting strings from Python objects.
/// Accepts Python `str` and `unicode` objects.
/// In Python 2.7, `str` is expected to be UTF-8 encoded.
///
/// Returns a `UnicodeDecodeError` if the input is not valid unicode
/// (containing unpaired surrogates, or a Python 2.7 byte string that is
/// not valid UTF-8).
impl<'s> FromPyObject<'s> for String {
    fn extract(py: Python, obj: &'s PyObject) -> PyResult<Self> {
        obj.extract::<Cow<str>>(py).map(Cow::into_owned)
    }
}

/// For Python `bytes`, returns a reference to the existing immutable string data.
/// If the Python object is a single-dimensional [buffer] of format `c` or `B` (C: `char` or `unsigned char`),
/// returns an owned copy of the data in the buffer.
/// Otherwise, uses the sequence protocol and converts each individual element
/// via `impl FromPyObject for u8`.
///
/// [buffer]: https://docs.python.org/3/c-api/buffer.html
impl<'s> FromPyObject<'s> for Cow<'s, [u8]> {
    fn extract(py: Python, obj: &'s PyObject) -> PyResult<Self> {
        if let Ok(bytes) = obj.cast_as::<PyBytes>(py) {
            Ok(Cow::Borrowed(bytes.data(py)))
        } else {
            super::sequence::extract_buffer_or_sequence(py, obj).map(Cow::Owned)
        }
    }
}

/// Allows extracting strings from Python objects.
/// Accepts Python `str` and `unicode` objects.
/// In Python 2.7, `str` is expected to be UTF-8 encoded.
impl RefFromPyObject for str {
    fn with_extracted<F, R>(py: Python, obj: &PyObject, f: F) -> PyResult<R>
    where
        F: FnOnce(&str) -> R,
    {
        let s = obj.extract::<Cow<str>>(py)?;
        Ok(f(&s))
    }
}

/// For Python `bytes`, returns a reference to the existing immutable string data.
/// If the Python object is a single-dimensional [buffer] of format `c` or `B` (C: `char` or `unsigned char`),
/// returns an owned copy of the data in the buffer.
/// Otherwise, uses the sequence protocol and converts each individual element
/// via `impl FromPyObject for u8`.
///
/// [buffer]: https://docs.python.org/3/c-api/buffer.html
impl RefFromPyObject for [u8] {
    fn with_extracted<F, R>(py: Python, obj: &PyObject, f: F) -> PyResult<R>
    where
        F: FnOnce(&[u8]) -> R,
    {
        let s = obj.extract::<Cow<[u8]>>(py)?;
        Ok(f(&s))
    }
}

#[cfg(test)]
mod test {
    use super::{PyString, PyStringData};
    use crate::conversion::{RefFromPyObject, ToPyObject};
    use crate::python::{Python, PythonObject};

    #[test]
    fn test_non_bmp() {
        let gil = Python::acquire_gil();
        let py = gil.python();
        let s = "\u{1F30F}";
        let py_string = s.to_py_object(py).into_object();
        assert_eq!(s, py_string.extract::<String>(py).unwrap());
    }

    #[test]
    fn test_extract_str() {
        let gil = Python::acquire_gil();
        let py = gil.python();
        let s = "Hello Python";
        let py_string = s.to_py_object(py).into_object();
        let mut called = false;
        RefFromPyObject::with_extracted(py, &py_string, |s2: &str| {
            assert_eq!(s, s2);
            called = true;
        })
        .unwrap();
        assert!(called);
    }

    #[test]
    fn test_extract_byte_str() {
        let gil = Python::acquire_gil();
        let py = gil.python();
        let py_bytes = py.eval("b'Hello'", None, None).unwrap();
        let mut called = false;
        RefFromPyObject::with_extracted(py, &py_bytes, |s2: &[u8]| {
            assert_eq!(b"Hello", s2);
            called = true;
        })
        .unwrap();
        assert!(called);
    }

    #[test]
    #[cfg(feature = "nightly")] // only works with specialization
    fn test_extract_byte_str_to_vec() {
        let gil = Python::acquire_gil();
        let py = gil.python();
        let py_bytes = py.eval("b'Hello'", None, None).unwrap();
        let v = py_bytes.extract::<Vec<u8>>(py).unwrap();
        assert_eq!(b"Hello", &v[..]);
    }

    #[allow(unused_variables)] // when compiling for py2.7
    #[test]
    fn test_extract_umlaut() {
        let gil = Python::acquire_gil();
        let py = gil.python();
        let py_string = py.eval("u'x=\\u00e4'", None, None).unwrap();
        let data = py_string.cast_as::<PyString>(py).unwrap().data(py);
        #[cfg(feature = "python3-sys")]
        {
            if let PyStringData::Latin1(s) = data {
                assert_eq!([b'x', b'=', 0xe4], *s);
            } else {
                panic!("Expected PyStringData::Latin1");
            }
        }
        assert_eq!("x=ä", py_string.extract::<String>(py).unwrap());
    }

    #[allow(unused_variables)] // when compiling for py2.7
    #[test]
    fn test_extract_lone_surrogate() {
        let gil = Python::acquire_gil();
        let py = gil.python();
        let py_string = py.eval("u'x=\\ud800'", None, None).unwrap();
        let data = py_string.cast_as::<PyString>(py).unwrap().data(py);
        #[cfg(feature = "python3-sys")]
        {
            if let PyStringData::Utf16(s) = data {
                assert_eq!(['x' as u16, '=' as u16, 0xd800], *s);
            } else {
                panic!("Expected PyStringData::Utf16");
            }
        }
        assert!(py_string.extract::<String>(py).is_err());
    }

    #[test]
    fn test_extract_lone_surrogate_lossy() {
        let gil = Python::acquire_gil();
        let py = gil.python();
        let py_string = py.eval("u'x=\\ud800'", None, None).unwrap();
        let result = py_string
            .cast_as::<PyString>(py)
            .unwrap()
            .to_string_lossy(py);
        assert_eq!("x=\u{fffd}", result);
    }
}