Merge pull request #1794 from indygreg/pystringdata

string: implement API to access raw string data
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David Hewitt 2021-08-21 22:54:58 +01:00 committed by GitHub
commit 591f44ea6d
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@ -12,6 +12,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
- Add `PyList::get_item_unchecked()` and `PyTuple::get_item_unchecked()` to get items without bounds checks. [#1733](https://github.com/PyO3/pyo3/pull/1733) - Add `PyList::get_item_unchecked()` and `PyTuple::get_item_unchecked()` to get items without bounds checks. [#1733](https://github.com/PyO3/pyo3/pull/1733)
- Add `PyAny::py()` as a convenience for `PyNativeType::py()`. [#1751](https://github.com/PyO3/pyo3/pull/1751) - Add `PyAny::py()` as a convenience for `PyNativeType::py()`. [#1751](https://github.com/PyO3/pyo3/pull/1751)
- Implement `PyString.data()` to access the raw bytes storing a Python string. [#1794](https://github.com/PyO3/pyo3/issues/1794)
### Changed ### Changed

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@ -23,6 +23,8 @@ pub use self::num::PyLong as PyInt;
pub use self::sequence::PySequence; pub use self::sequence::PySequence;
pub use self::set::{PyFrozenSet, PySet}; pub use self::set::{PyFrozenSet, PySet};
pub use self::slice::{PySlice, PySliceIndices}; pub use self::slice::{PySlice, PySliceIndices};
#[cfg(not(Py_LIMITED_API))]
pub use self::string::PyStringData;
pub use self::string::{PyString, PyString as PyUnicode}; pub use self::string::{PyString, PyString as PyUnicode};
pub use self::tuple::PyTuple; pub use self::tuple::PyTuple;
pub use self::typeobject::PyType; pub use self::typeobject::PyType;

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@ -1,14 +1,133 @@
// Copyright (c) 2017-present PyO3 Project and Contributors // Copyright (c) 2017-present PyO3 Project and Contributors
#[cfg(not(Py_LIMITED_API))]
use crate::exceptions::PyUnicodeDecodeError;
use crate::types::PyBytes; use crate::types::PyBytes;
use crate::{ use crate::{
ffi, AsPyPointer, FromPyObject, IntoPy, PyAny, PyObject, PyResult, PyTryFrom, Python, ffi, AsPyPointer, FromPyObject, IntoPy, PyAny, PyObject, PyResult, PyTryFrom, Python,
ToPyObject, ToPyObject,
}; };
use std::borrow::Cow; use std::borrow::Cow;
#[cfg(not(Py_LIMITED_API))]
use std::ffi::CStr;
use std::os::raw::c_char; use std::os::raw::c_char;
use std::str; use std::str;
/// Represents raw data backing a Python `str`.
///
/// Python internally stores strings in various representations. This enumeration
/// represents those variations.
#[cfg(not(Py_LIMITED_API))]
#[cfg_attr(docsrs, doc(cfg(not(Py_LIMITED_API))))]
#[derive(Clone, Copy, Debug, PartialEq)]
pub enum PyStringData<'a> {
/// UCS1 representation.
Ucs1(&'a [u8]),
/// UCS2 representation.
Ucs2(&'a [u16]),
/// UCS4 representation.
Ucs4(&'a [u32]),
}
#[cfg(not(Py_LIMITED_API))]
impl<'a> PyStringData<'a> {
/// Obtain the raw bytes backing this instance as a [u8] slice.
pub fn as_bytes(&self) -> &[u8] {
match self {
Self::Ucs1(s) => s,
Self::Ucs2(s) => unsafe {
std::slice::from_raw_parts(
s.as_ptr() as *const u8,
s.len() * self.value_width_bytes(),
)
},
Self::Ucs4(s) => unsafe {
std::slice::from_raw_parts(
s.as_ptr() as *const u8,
s.len() * self.value_width_bytes(),
)
},
}
}
/// Size in bytes of each value/item in the underlying slice.
#[inline]
pub fn value_width_bytes(&self) -> usize {
match self {
Self::Ucs1(_) => 1,
Self::Ucs2(_) => 2,
Self::Ucs4(_) => 4,
}
}
/// Convert the raw data to a Rust string.
///
/// For UCS-1 / UTF-8, returns a borrow into the original slice. For UCS-2 and UCS-4,
/// returns an owned string.
///
/// Returns [PyUnicodeDecodeError] if the string data isn't valid in its purported
/// storage format. This should only occur for strings that were created via Python
/// C APIs that skip input validation (like `PyUnicode_FromKindAndData`) and should
/// never occur for strings that were created from Python code.
pub fn to_string(self, py: Python) -> PyResult<Cow<'a, str>> {
match self {
Self::Ucs1(data) => match str::from_utf8(data) {
Ok(s) => Ok(Cow::Borrowed(s)),
Err(e) => Err(crate::PyErr::from_instance(PyUnicodeDecodeError::new_utf8(
py, data, e,
)?)),
},
Self::Ucs2(data) => match String::from_utf16(data) {
Ok(s) => Ok(Cow::Owned(s)),
Err(e) => {
let mut message = e.to_string().as_bytes().to_vec();
message.push(0);
Err(crate::PyErr::from_instance(PyUnicodeDecodeError::new(
py,
CStr::from_bytes_with_nul(b"utf-16\0").unwrap(),
self.as_bytes(),
0..self.as_bytes().len(),
CStr::from_bytes_with_nul(&message).unwrap(),
)?))
}
},
Self::Ucs4(data) => match data.iter().map(|&c| std::char::from_u32(c)).collect() {
Some(s) => Ok(Cow::Owned(s)),
None => Err(crate::PyErr::from_instance(PyUnicodeDecodeError::new(
py,
CStr::from_bytes_with_nul(b"utf-32\0").unwrap(),
self.as_bytes(),
0..self.as_bytes().len(),
CStr::from_bytes_with_nul(b"error converting utf-32\0").unwrap(),
)?)),
},
}
}
/// Convert the raw data to a Rust string, possibly with data loss.
///
/// Invalid code points will be replaced with `U+FFFD REPLACEMENT CHARACTER`.
///
/// Returns a borrow into original data, when possible, or owned data otherwise.
///
/// The return value of this function should only disagree with [Self::to_string]
/// when that method would error.
pub fn to_string_lossy(self) -> Cow<'a, str> {
match self {
Self::Ucs1(data) => String::from_utf8_lossy(data),
Self::Ucs2(data) => Cow::Owned(String::from_utf16_lossy(data)),
Self::Ucs4(data) => Cow::Owned(
data.iter()
.map(|&c| std::char::from_u32(c).unwrap_or('\u{FFFD}'))
.collect(),
),
}
}
}
/// Represents a Python `string` (a Unicode string object). /// Represents a Python `string` (a Unicode string object).
/// ///
/// This type is immutable. /// This type is immutable.
@ -89,6 +208,45 @@ impl PyString {
} }
} }
} }
/// Obtains the raw data backing the Python string.
///
/// If the Python string object was created through legacy APIs, its internal
/// storage format will be canonicalized before data is returned.
#[cfg(not(Py_LIMITED_API))]
#[cfg_attr(docsrs, doc(cfg(not(Py_LIMITED_API))))]
pub fn data(&self) -> PyResult<PyStringData<'_>> {
let ptr = self.as_ptr();
if cfg!(not(Py_3_12)) {
#[allow(deprecated)]
let ready = unsafe { ffi::PyUnicode_READY(ptr) };
if ready != 0 {
// Exception was created on failure.
return Err(crate::PyErr::api_call_failed(self.py()));
}
}
// The string should be in its canonical form after calling `PyUnicode_READY()`.
// And non-canonical form not possible after Python 3.12. So it should be safe
// to call these APIs.
let length = unsafe { ffi::PyUnicode_GET_LENGTH(ptr) } as usize;
let raw_data = unsafe { ffi::PyUnicode_DATA(ptr) };
let kind = unsafe { ffi::PyUnicode_KIND(ptr) };
match kind {
ffi::PyUnicode_1BYTE_KIND => Ok(PyStringData::Ucs1(unsafe {
std::slice::from_raw_parts(raw_data as *const u8, length)
})),
ffi::PyUnicode_2BYTE_KIND => Ok(PyStringData::Ucs2(unsafe {
std::slice::from_raw_parts(raw_data as *const u16, length)
})),
ffi::PyUnicode_4BYTE_KIND => Ok(PyStringData::Ucs4(unsafe {
std::slice::from_raw_parts(raw_data as *const u32, length)
})),
_ => unreachable!(),
}
}
} }
/// Converts a Rust `str` to a Python object. /// Converts a Rust `str` to a Python object.
@ -193,8 +351,16 @@ impl FromPyObject<'_> for char {
#[cfg(test)] #[cfg(test)]
mod tests { mod tests {
use super::PyString; use super::PyString;
#[cfg(not(Py_LIMITED_API))]
use super::PyStringData;
#[cfg(not(Py_LIMITED_API))]
use crate::exceptions::PyUnicodeDecodeError;
#[cfg(not(Py_LIMITED_API))]
use crate::type_object::PyTypeObject;
use crate::Python; use crate::Python;
use crate::{FromPyObject, PyObject, PyTryFrom, ToPyObject}; use crate::{FromPyObject, PyObject, PyTryFrom, ToPyObject};
#[cfg(not(Py_LIMITED_API))]
use std::borrow::Cow;
#[test] #[test]
fn test_non_bmp() { fn test_non_bmp() {
@ -297,4 +463,124 @@ mod tests {
assert_eq!(format!("{}", s), "Hello\n"); assert_eq!(format!("{}", s), "Hello\n");
}) })
} }
#[test]
#[cfg(not(Py_LIMITED_API))]
fn test_string_data_ucs1() {
Python::with_gil(|py| {
let s = PyString::new(py, "hello, world");
let data = s.data().unwrap();
assert_eq!(data, PyStringData::Ucs1(b"hello, world"));
assert_eq!(data.to_string(py).unwrap(), Cow::Borrowed("hello, world"));
assert_eq!(data.to_string_lossy(), Cow::Borrowed("hello, world"));
})
}
#[test]
#[cfg(not(Py_LIMITED_API))]
fn test_string_data_ucs1_invalid() {
Python::with_gil(|py| {
// 0xfe is not allowed in UTF-8.
let buffer = b"f\xfe\0";
let ptr = unsafe {
crate::ffi::PyUnicode_FromKindAndData(
crate::ffi::PyUnicode_1BYTE_KIND as _,
buffer.as_ptr() as *const _,
2,
)
};
assert!(!ptr.is_null());
let s: &PyString = unsafe { py.from_owned_ptr(ptr) };
let data = s.data().unwrap();
assert_eq!(data, PyStringData::Ucs1(b"f\xfe"));
let err = data.to_string(py).unwrap_err();
assert_eq!(err.ptype(py), PyUnicodeDecodeError::type_object(py));
assert!(err
.to_string()
.contains("'utf-8' codec can't decode byte 0xfe in position 1"));
assert_eq!(data.to_string_lossy(), Cow::Borrowed("f<EFBFBD>"));
});
}
#[test]
#[cfg(not(Py_LIMITED_API))]
fn test_string_data_ucs2() {
Python::with_gil(|py| {
let s = py.eval("'foo\\ud800'", None, None).unwrap();
let py_string = s.cast_as::<PyString>().unwrap();
let data = py_string.data().unwrap();
assert_eq!(data, PyStringData::Ucs2(&[102, 111, 111, 0xd800]));
assert_eq!(
data.to_string_lossy(),
Cow::Owned::<str>("foo<EFBFBD>".to_string())
);
})
}
#[test]
#[cfg(not(Py_LIMITED_API))]
fn test_string_data_ucs2_invalid() {
Python::with_gil(|py| {
// U+FF22 (valid) & U+d800 (never valid)
let buffer = b"\x22\xff\x00\xd8\x00\x00";
let ptr = unsafe {
crate::ffi::PyUnicode_FromKindAndData(
crate::ffi::PyUnicode_2BYTE_KIND as _,
buffer.as_ptr() as *const _,
2,
)
};
assert!(!ptr.is_null());
let s: &PyString = unsafe { py.from_owned_ptr(ptr) };
let data = s.data().unwrap();
assert_eq!(data, PyStringData::Ucs2(&[0xff22, 0xd800]));
let err = data.to_string(py).unwrap_err();
assert_eq!(err.ptype(py), PyUnicodeDecodeError::type_object(py));
assert!(err
.to_string()
.contains("'utf-16' codec can't decode bytes in position 0-3"));
assert_eq!(data.to_string_lossy(), Cow::Owned::<str>("<EFBFBD>".into()));
});
}
#[test]
#[cfg(not(Py_LIMITED_API))]
fn test_string_data_ucs4() {
Python::with_gil(|py| {
let s = "哈哈🐈";
let py_string = PyString::new(py, s);
let data = py_string.data().unwrap();
assert_eq!(data, PyStringData::Ucs4(&[21704, 21704, 128008]));
assert_eq!(data.to_string_lossy(), Cow::Owned::<str>(s.to_string()));
})
}
#[test]
#[cfg(not(Py_LIMITED_API))]
fn test_string_data_ucs4_invalid() {
Python::with_gil(|py| {
// U+20000 (valid) & U+d800 (never valid)
let buffer = b"\x00\x00\x02\x00\x00\xd8\x00\x00\x00\x00\x00\x00";
let ptr = unsafe {
crate::ffi::PyUnicode_FromKindAndData(
crate::ffi::PyUnicode_4BYTE_KIND as _,
buffer.as_ptr() as *const _,
2,
)
};
assert!(!ptr.is_null());
let s: &PyString = unsafe { py.from_owned_ptr(ptr) };
let data = s.data().unwrap();
assert_eq!(data, PyStringData::Ucs4(&[0x20000, 0xd800]));
let err = data.to_string(py).unwrap_err();
assert_eq!(err.ptype(py), PyUnicodeDecodeError::type_object(py));
assert!(err
.to_string()
.contains("'utf-32' codec can't decode bytes in position 0-7"));
assert_eq!(data.to_string_lossy(), Cow::Owned::<str>("𠀀<EFBFBD>".into()));
});
}
} }