Unicode对象和编码解码器

Unicode对象

自从python3.3中实现了 PEP 393 以来，Unicode对象在内部使用各种表示形式，以便在保持内存效率的同时处理完整范围的Unicode字符。对于所有代码点都低于128、256或65536的字符串，有一些特殊情况；否则，代码点必须低于1114112（这是完整的Unicode范围）。

Py_UNICODE* 和 UTF-8 表示形式将按需创建并缓存至 Unicode 对象。 Py_UNICODE* 表示形式是已弃用且低效率的。

由于旧API和新API之间的转换，Unicode对象内部可以处于两种状态，这取决于它们的创建方式：

• “规范”Unicode对象是由非弃用的Unicode API创建的所有对象。它们使用实现所允许的最有效的表达方式。

• "legacy" Unicode objects have been created through one of the deprecated APIs (typically PyUnicode_FromUnicode()) and only bear the Py_UNICODE* representation; you will have to call PyUnicode_READY() on them before calling any other API.

备注

The "legacy" Unicode object will be removed in Python 3.12 with deprecated APIs. All Unicode objects will be "canonical" since then. See PEP 623 for more information.

Unicode类型

以下是用于Python中Unicode实现的基本Unicode对象类型：

type Py_UCS4

type Py_UCS2

type Py_UCS1

Part of the Stable ABI.

这些类型是无符号整数类型的类型定义，其宽度足以分别包含 32 位、16 位和 8 位字符。 当需要处理单个 Unicode 字符时，请使用 Py_UCS4。

3.3 新版功能.

type Py_UNICODE

这是 wchar_t 的类型定义，根据平台的不同它可能为 16 位类型或 32 位类型。

在 3.3 版更改: 在以前的版本中，这是16位类型还是32位类型，这取决于您在构建时选择的是“窄”还是“宽”Unicode版本的Python。

type PyASCIIObject

type PyCompactUnicodeObject

type PyUnicodeObject

这些关于 PyObject 的子类型表示了一个 Python Unicode 对象。 在几乎所有情形下，它们不应该被直接使用，因为所有处理 Unicode 对象的 API 函数都接受并返回 PyObject 类型的指针。

3.3 新版功能.

PyTypeObject PyUnicode_Type

Part of the Stable ABI.

这个 PyTypeObject 实例代表 Python Unicode 类型。 它作为 str 公开给 Python 代码。

以下API是C宏和静态内联函数，用于快速检查和访问Unicode对象的内部只读数据：

int PyUnicode_Check(PyObject *o)

如果对象*o*是Unicode对象或Unicode子类型的实例，则返回“真"。此函数始终成功。

int PyUnicode_CheckExact(PyObject *o)

如果对象*o*是Unicode对象，但不是子类型的实例，则返回“真”。此函数始终成功。

int PyUnicode_READY(PyObject *o)

确保字符串对象*o*处于“规范的”表达方式。在使用下面描述的任何访问宏之前，这是必需的。

Returns 0 on success and -1 with an exception set on failure, which in particular happens if memory allocation fails.

3.3 新版功能.

从 3.10 版起不建议使用，将在 3.12 版中移除: This API will be removed with PyUnicode_FromUnicode().

Py_ssize_t PyUnicode_GET_LENGTH(PyObject *o)

返回Unicode字符串的长度（以代码点为单位）*o*必须是“规范”表达方式中的Unicode对象（未选中）。

3.3 新版功能.

Py_UCS1 *PyUnicode_1BYTE_DATA(PyObject *o)

Py_UCS2 *PyUnicode_2BYTE_DATA(PyObject *o)

Py_UCS4 *PyUnicode_4BYTE_DATA(PyObject *o)

Return a pointer to the canonical representation cast to UCS1, UCS2 or UCS4 integer types for direct character access. No checks are performed if the canonical representation has the correct character size; use PyUnicode_KIND() to select the right macro. Make sure PyUnicode_READY() has been called before accessing this.

3.3 新版功能.

PyUnicode_WCHAR_KIND

PyUnicode_1BYTE_KIND

PyUnicode_2BYTE_KIND

PyUnicode_4BYTE_KIND

返回 PyUnicode_KIND() 宏的值。

3.3 新版功能.

从 3.10 版起不建议使用，将在 3.12 版中移除: PyUnicode_WCHAR_KIND 已被弃用。

int PyUnicode_KIND(PyObject *o)

返回一个PyUnicode类常量（见上文），指示此Unicode对象用于存储其数据的每个字符的字节数*o*必须是“规范”表达方式中的Unicode对象（未选中）。

3.3 新版功能.

void *PyUnicode_DATA(PyObject *o)

返回指向原始Unicode缓冲区的空指针*o*必须是“规范”表达方式中的Unicode对象（未选中）。

3.3 新版功能.

void PyUnicode_WRITE(int kind, void *data, Py_ssize_t index, Py_UCS4 value)

写入一个规范表示的 data (如同用 PyUnicode_DATA() 获取)。 此函数不会执行正确性检查，被设计为在循环中使用。 调用者应当如同从其他调用中获取一样缓存 kind 值和 data 指针。 index 是字符串中的索引号 (从 0 开始) 而 value 是应写入该位置的新码位值。

3.3 新版功能.

Py_UCS4 PyUnicode_READ(int kind, void *data, Py_ssize_t index)

从规范表示的 data (如同用 PyUnicode_DATA() 获取) 中读取一个码位。 不会执行检查或就绪调用。

3.3 新版功能.

Py_UCS4 PyUnicode_READ_CHAR(PyObject *o, Py_ssize_t index)

从 Unicode 对象 o 读取一个字符，必须使用“规范”表示形式。 如果你执行行多次连续读取则此函数的效率将低于 PyUnicode_READ()。

3.3 新版功能.

Py_UCS4 PyUnicode_MAX_CHAR_VALUE(PyObject *o)

返回适合于基于*o*创建另一个字符串的最大代码点，该字符串必须在“规范”表达方式中。这始终是一种近似，但比在字符串上迭代更有效。

3.3 新版功能.

Py_ssize_t PyUnicode_GET_SIZE(PyObject *o)

Return the size of the deprecated Py_UNICODE representation, in code units (this includes surrogate pairs as 2 units). o has to be a Unicode object (not checked).

从 3.3 版起不建议使用，将在 3.12 版中移除: 旧式 Unicode API 的一部分，请迁移到使用 PyUnicode_GET_LENGTH()。

Py_ssize_t PyUnicode_GET_DATA_SIZE(PyObject *o)

Return the size of the deprecated Py_UNICODE representation in bytes. o has to be a Unicode object (not checked).

从 3.3 版起不建议使用，将在 3.12 版中移除: 旧式 Unicode API 的一部分，请迁移到使用 PyUnicode_GET_LENGTH()。

Py_UNICODE *PyUnicode_AS_UNICODE(PyObject *o)

const char *PyUnicode_AS_DATA(PyObject *o)

Return a pointer to a Py_UNICODE representation of the object. The returned buffer is always terminated with an extra null code point. It may also contain embedded null code points, which would cause the string to be truncated when used in most C functions. The AS_DATA form casts the pointer to const char*. The o argument has to be a Unicode object (not checked).

在 3.3 版更改: This function is now inefficient -- because in many cases the Py_UNICODE representation does not exist and needs to be created -- and can fail (return NULL with an exception set). Try to port the code to use the new PyUnicode_nBYTE_DATA() macros or use PyUnicode_WRITE() or PyUnicode_READ().

从 3.3 版起不建议使用，将在 3.12 版中移除: 旧式 Unicode API 的一部分，请迁移到使用 PyUnicode_nBYTE_DATA() 宏族。

int PyUnicode_IsIdentifier(PyObject *o)

Part of the Stable ABI.

如果字符串按照语言定义是合法的标识符则返回 1，参见 标识符和关键字 小节。 否则返回 0。

在 3.9 版更改: 如果字符串尚未就绪则此函数不会再调用 Py_FatalError()。

Unicode字符属性

Unicode提供了许多不同的字符特性。最常需要的宏可以通过这些宏获得，这些宏根据Python配置映射到C函数。

int Py_UNICODE_ISSPACE(Py_UCS4 ch)

根据 ch 是否为空白字符返回 1 或 0。

int Py_UNICODE_ISLOWER(Py_UCS4 ch)

根据 ch 是否为小写字符返回 1 或 0。

int Py_UNICODE_ISUPPER(Py_UCS4 ch)

根据 ch 是否为大写字符返回 1 或 0

int Py_UNICODE_ISTITLE(Py_UCS4 ch)

根据 ch 是否为标题化的大小写返回 1 或 0。

int Py_UNICODE_ISLINEBREAK(Py_UCS4 ch)

根据 ch 是否为换行类字符返回 1 或 0。

int Py_UNICODE_ISDECIMAL(Py_UCS4 ch)

根据 ch 是否为十进制数字符返回 1 或 0。

int Py_UNICODE_ISDIGIT(Py_UCS4 ch)

根据 ch 是否为数码类字符返回 1 或 0。

int Py_UNICODE_ISNUMERIC(Py_UCS4 ch)

根据 ch 是否为数值类字符返回 1 或 0。

int Py_UNICODE_ISALPHA(Py_UCS4 ch)

根据 ch 是否为字母类字符返回 1 或 0。

int Py_UNICODE_ISALNUM(Py_UCS4 ch)

根据 ch 是否为字母数字类字符返回 1 或 0。

int Py_UNICODE_ISPRINTABLE(Py_UCS4 ch)

根据 ch 是否为可打印字符返回 1 或``0``。 不可打印字符是指在 Unicode 字符数据库中被定义为 "Other" 或 "Separator" 的字符，例外情况是 ASCII 空格 (0x20) 被视为可打印字符。 (请注意在此语境下可打印字符是指当在字符串上发起调用 repr() 时不应被转义的字符。 它们字符串写入 sys.stdout 或 sys.stderr 时所需的处理无关)。

这些 API 可用于快速直接的字符转换：

Py_UCS4 Py_UNICODE_TOLOWER(Py_UCS4 ch)

返回转换为小写形式的字符 ch。

3.3 版后已移除: 此函数使用简单的大小写映射。

Py_UCS4 Py_UNICODE_TOUPPER(Py_UCS4 ch)

返回转换为大写形式的字符 ch。

3.3 版后已移除: 此函数使用简单的大小写映射。

Py_UCS4 Py_UNICODE_TOTITLE(Py_UCS4 ch)

返回转换为标题大小写形式的字符 ch。

3.3 版后已移除: 此函数使用简单的大小写映射。

int Py_UNICODE_TODECIMAL(Py_UCS4 ch)

Return the character ch converted to a decimal positive integer. Return -1 if this is not possible. This macro does not raise exceptions.

int Py_UNICODE_TODIGIT(Py_UCS4 ch)

Return the character ch converted to a single digit integer. Return -1 if this is not possible. This macro does not raise exceptions.

double Py_UNICODE_TONUMERIC(Py_UCS4 ch)

Return the character ch converted to a double. Return -1.0 if this is not possible. This macro does not raise exceptions.

这些 API 可被用来操作代理项：

Py_UNICODE_IS_SURROGATE(ch)

检测 ch 是否为代理项 (0xD800 <= ch <= 0xDFFF)。

Py_UNICODE_IS_HIGH_SURROGATE(ch)

检测 ch 是否为高代理项 (0xD800 <= ch <= 0xDBFF)。

Py_UNICODE_IS_LOW_SURROGATE(ch)

检测 ch 是否为低代理项 (0xDC00 <= ch <= 0xDFFF)。

Py_UNICODE_JOIN_SURROGATES(high, low)

Join two surrogate characters and return a single Py_UCS4 value. high and low are respectively the leading and trailing surrogates in a surrogate pair.

创建和访问 Unicode 字符串

要创建 Unicode 对象和访问其基本序列属性，请使用这些 API：

PyObject *PyUnicode_New(Py_ssize_t size, Py_UCS4 maxchar)

返回值：新的引用。

创建一个新的 Unicode 对象。 maxchar 应为可放入字符串的实际最大码位。 作为一个近似值，它可被向上舍入到序列 127, 255, 65535, 1114111 中最接近的值。

这是分配新的 Unicode 对象的推荐方式。 使用此函数创建的对象不可改变大小。

3.3 新版功能.

PyObject *PyUnicode_FromKindAndData(int kind, const void *buffer, Py_ssize_t size)

返回值：新的引用。

以给定的 kind 创建一个新的 Unicode 对象（可能的值为 PyUnicode_1BYTE_KIND 等，即 PyUnicode_KIND() 所返回的值）。 buffer 必须指向由此分类所给出的，以每字符 1, 2 或 4 字节单位的 size 大小的数组。

如有必要，输入 buffer 将被拷贝并转换为规范表示形式。 例如，如果 buffer 是一个 UCS4 字符串 (PyUnicode_4BYTE_KIND) 且仅由 UCS1 范围内的码位组成，它将被转换为 UCS1 (PyUnicode_1BYTE_KIND)。

3.3 新版功能.

PyObject *PyUnicode_FromStringAndSize(const char *u, Py_ssize_t size)

返回值：新的引用。 Part of the Stable ABI.

Create a Unicode object from the char buffer u. The bytes will be interpreted as being UTF-8 encoded. The buffer is copied into the new object. If the buffer is not NULL, the return value might be a shared object, i.e. modification of the data is not allowed.

If u is NULL, this function behaves like PyUnicode_FromUnicode() with the buffer set to NULL. This usage is deprecated in favor of PyUnicode_New(), and will be removed in Python 3.12.

PyObject *PyUnicode_FromString(const char *u)

返回值：新的引用。 Part of the Stable ABI.

根据 UTF-8 编码的以空值结束的字符缓冲区 u 创建一个 Unicode 对象。

PyObject *PyUnicode_FromFormat(const char *format, ...)

返回值：新的引用。 Part of the Stable ABI.

Take a C printf()-style format string and a variable number of arguments, calculate the size of the resulting Python Unicode string and return a string with the values formatted into it. The variable arguments must be C types and must correspond exactly to the format characters in the format ASCII-encoded string. The following format characters are allowed:

格式字符	类型	注释
%%	不适用	文字%字符。
%c	int	单个字符，表示为C 语言的整型。
%d	int	相当于 printf("%d"). 1
%u	unsigned int	相当于 printf("%u"). 1
%ld	长整型	相当于 printf("%ld"). 1
%li	长整型	相当于 printf("%li"). 1
%lu	unsigned long	相当于 printf("%lu"). 1
%lld	long long	相当于 printf("%lld"). 1
%lli	long long	相当于 printf("%lli"). 1
%llu	unsigned long long	相当于 printf("%llu"). 1
%zd	Py_ssize_t	相当于 printf("%zd"). 1
%zi	Py_ssize_t	相当于 printf("%zi"). 1
%zu	size_t	相当于 printf("%zu"). 1
%i	int	相当于 printf("%i"). 1
%x	int	相当于 printf("%x"). 1
%s	const char*	以 null 为终止符的 C 字符数组。
%p	const void*	一个 C 指针的十六进制表示形式。 基本等价于 printf("%p") 但它会确保以字面值 0x 开头，不论系统平台上 printf 的输出是什么。
%A	PyObject*	ascii() 调用的结果。
%U	PyObject*	一个 Unicode 对象。
%V	PyObject*, const char*	一个 Unicode 对象 (可以为 NULL) 和一个以空值结束的 C 字符数组作为第二个形参（如果第一个形参为 NULL，第二个形参将被使用）。
%S	PyObject*	调用 PyObject_Str() 的结果。
%R	PyObject*	调用 PyObject_Repr() 的结果。

An unrecognized format character causes all the rest of the format string to be copied as-is to the result string, and any extra arguments discarded.

备注

The width formatter unit is number of characters rather than bytes. The precision formatter unit is number of bytes for "%s" and "%V" (if the PyObject* argument is NULL), and a number of characters for "%A", "%U", "%S", "%R" and "%V" (if the PyObject* argument is not NULL).

1(1,2,3,4,5,6,7,8,9,10,11,12,13)

For integer specifiers (d, u, ld, li, lu, lld, lli, llu, zd, zi, zu, i, x): the 0-conversion flag has effect even when a precision is given.

在 3.2 版更改: 增加了对 "%lld" 和 "%llu" 的支持。

在 3.3 版更改: 增加了对 "%li", "%lli" 和 "%zi" 的支持。

在 3.4 版更改: 增加了对 "%s", "%A", "%U", "%V", "%S", "%R" 的宽度和精度格式符支持。

PyObject *PyUnicode_FromFormatV(const char *format, va_list vargs)

返回值：新的引用。 Part of the Stable ABI.

等同于 PyUnicode_FromFormat() 但它将接受恰好两个参数。

PyObject *PyUnicode_FromObject(PyObject *obj)

返回值：新的引用。 Part of the Stable ABI.

如有必要将把一个 Unicode 子类型的实例拷贝为新的真实 Unicode 对象。 如果 obj 已经是一个真实 Unicode 对象（而非子类型），则返回一个新的指向该对象的 strong reference。

非 Unicode 或其子类型的对象将导致 TypeError。

PyObject *PyUnicode_FromEncodedObject(PyObject *obj, const char *encoding, const char *errors)

返回值：新的引用。 Part of the Stable ABI.

将一个已编码的对象 obj 解码为 Unicode 对象。

bytes, bytearray 和其他 字节类对象 将按照给定的 encoding 来解码并使用由 errors 定义的错误处理方式。 两者均可为 NULL 即让接口使用默认值（请参阅 Built-in Codecs 了解详情）。

所有其他对象，包括 Unicode 对象，都将导致设置 TypeError。

如有错误该 API 将返回 NULL。 调用方要负责递减指向所返回对象的引用。

Py_ssize_t PyUnicode_GetLength(PyObject *unicode)

Part of the Stable ABI since version 3.7.

返回 Unicode 对象码位的长度。

3.3 新版功能.

Py_ssize_t PyUnicode_CopyCharacters(PyObject *to, Py_ssize_t to_start, PyObject *from, Py_ssize_t from_start, Py_ssize_t how_many)

将一个 Unicode 对象中的字符拷贝到另一个对象中。 此函数会在必要时执行字符转换并会在可能的情况下回退到 memcpy()。 在出错时将返回 -1 并设置一个异常，在其他情况下将返回拷贝的字符数量。

3.3 新版功能.

Py_ssize_t PyUnicode_Fill(PyObject *unicode, Py_ssize_t start, Py_ssize_t length, Py_UCS4 fill_char)

使用一个字符填充字符串：将 fill_char 写入 unicode[start:start+length]。

如果 fill_char 值大于字符串最大字符值，或者如果字符串有 1 以上的引用将执行失败。

返回写入的字符数量，或者在出错时返回 -1 并引发一个异常。

3.3 新版功能.

int PyUnicode_WriteChar(PyObject *unicode, Py_ssize_t index, Py_UCS4 character)

Part of the Stable ABI since version 3.7.

将一个字符写入到字符串。 字符串必须通过 PyUnicode_New() 创建。 由于 Unicode 字符串应当是不可变的，因此该字符串不能被共享，或是被哈希。

该函数将检查 unicode 是否为 Unicode 对象，索引是否未越界，并且对象是否可被安全地修改（即其引用计数为一）。

3.3 新版功能.

Py_UCS4 PyUnicode_ReadChar(PyObject *unicode, Py_ssize_t index)

Part of the Stable ABI since version 3.7.

从字符串读取一个字符。 该函数将检查 unicode 是否为 Unicode 对象且索引是否未越界，这不同于 PyUnicode_READ_CHAR()，后者不会执行任何错误检查。

3.3 新版功能.

PyObject *PyUnicode_Substring(PyObject *str, Py_ssize_t start, Py_ssize_t end)

返回值：新的引用。 Part of the Stable ABI since version 3.7.

返回 str 的一个子串，从字符索引 start (包括) 到字符索引 end (不包括)。 不支持负索引号。

3.3 新版功能.

Py_UCS4 *PyUnicode_AsUCS4(PyObject *u, Py_UCS4 *buffer, Py_ssize_t buflen, int copy_null)

Part of the Stable ABI since version 3.7.

将字符串 u 拷贝到一个 UCS4 缓冲区，包括一个空字符，如果设置了 copy_null 的话。 出错时返回 NULL 并设置一个异常（特别是当 buflen 小于 u 的长度时，SystemError 将被设置）。 成功时返回 buffer。

3.3 新版功能.

Py_UCS4 *PyUnicode_AsUCS4Copy(PyObject *u)

Part of the Stable ABI since version 3.7.

Copy the string u into a new UCS4 buffer that is allocated using PyMem_Malloc(). If this fails, NULL is returned with a MemoryError set. The returned buffer always has an extra null code point appended.

3.3 新版功能.

已弃用的 Py_UNICODE API

从 3.3 版起不建议使用，将在 3.12 版中移除.

These API functions are deprecated with the implementation of PEP 393. Extension modules can continue using them, as they will not be removed in Python 3.x, but need to be aware that their use can now cause performance and memory hits.

PyObject *PyUnicode_FromUnicode(const Py_UNICODE *u, Py_ssize_t size)

返回值：新的引用。

Create a Unicode object from the Py_UNICODE buffer u of the given size. u may be NULL which causes the contents to be undefined. It is the user's responsibility to fill in the needed data. The buffer is copied into the new object.

If the buffer is not NULL, the return value might be a shared object. Therefore, modification of the resulting Unicode object is only allowed when u is NULL.

If the buffer is NULL, PyUnicode_READY() must be called once the string content has been filled before using any of the access macros such as PyUnicode_KIND().

从 3.3 版起不建议使用，将在 3.12 版中移除: Part of the old-style Unicode API, please migrate to using PyUnicode_FromKindAndData(), PyUnicode_FromWideChar(), or PyUnicode_New().

Py_UNICODE *PyUnicode_AsUnicode(PyObject *unicode)

Return a read-only pointer to the Unicode object's internal Py_UNICODE buffer, or NULL on error. This will create the Py_UNICODE* representation of the object if it is not yet available. The buffer is always terminated with an extra null code point. Note that the resulting Py_UNICODE string may also contain embedded null code points, which would cause the string to be truncated when used in most C functions.

从 3.3 版起不建议使用，将在 3.12 版中移除: Part of the old-style Unicode API, please migrate to using PyUnicode_AsUCS4(), PyUnicode_AsWideChar(), PyUnicode_ReadChar() or similar new APIs.

Py_UNICODE *PyUnicode_AsUnicodeAndSize(PyObject *unicode, Py_ssize_t *size)

Like PyUnicode_AsUnicode(), but also saves the Py_UNICODE() array length (excluding the extra null terminator) in size. Note that the resulting Py_UNICODE* string may contain embedded null code points, which would cause the string to be truncated when used in most C functions.

3.3 新版功能.

从 3.3 版起不建议使用，将在 3.12 版中移除: Part of the old-style Unicode API, please migrate to using PyUnicode_AsUCS4(), PyUnicode_AsWideChar(), PyUnicode_ReadChar() or similar new APIs.

Py_ssize_t PyUnicode_GetSize(PyObject *unicode)

Part of the Stable ABI.

Return the size of the deprecated Py_UNICODE representation, in code units (this includes surrogate pairs as 2 units).

从 3.3 版起不建议使用，将在 3.12 版中移除: 旧式 Unicode API 的一部分，请迁移到使用 PyUnicode_GET_LENGTH()。

语言区域编码格式

The current locale encoding can be used to decode text from the operating system.

PyObject *PyUnicode_DecodeLocaleAndSize(const char *str, Py_ssize_t len, const char *errors)

返回值：新的引用。 Part of the Stable ABI since version 3.7.

Decode a string from UTF-8 on Android and VxWorks, or from the current locale encoding on other platforms. The supported error handlers are "strict" and "surrogateescape" (PEP 383). The decoder uses "strict" error handler if errors is NULL. str must end with a null character but cannot contain embedded null characters.

Use PyUnicode_DecodeFSDefaultAndSize() to decode a string from Py_FileSystemDefaultEncoding (the locale encoding read at Python startup).

This function ignores the Python UTF-8 Mode.

参见

The Py_DecodeLocale() 函数。

3.3 新版功能.

在 3.7 版更改: The function now also uses the current locale encoding for the surrogateescape error handler, except on Android. Previously, Py_DecodeLocale() was used for the surrogateescape, and the current locale encoding was used for strict.

PyObject *PyUnicode_DecodeLocale(const char *str, const char *errors)

返回值：新的引用。 Part of the Stable ABI since version 3.7.

Similar to PyUnicode_DecodeLocaleAndSize(), but compute the string length using strlen().

3.3 新版功能.

PyObject *PyUnicode_EncodeLocale(PyObject *unicode, const char *errors)

返回值：新的引用。 Part of the Stable ABI since version 3.7.

Encode a Unicode object to UTF-8 on Android and VxWorks, or to the current locale encoding on other platforms. The supported error handlers are "strict" and "surrogateescape" (PEP 383). The encoder uses "strict" error handler if errors is NULL. Return a bytes object. unicode cannot contain embedded null characters.

Use PyUnicode_EncodeFSDefault() to encode a string to Py_FileSystemDefaultEncoding (the locale encoding read at Python startup).

This function ignores the Python UTF-8 Mode.

参见

The Py_EncodeLocale() function.

3.3 新版功能.

在 3.7 版更改: The function now also uses the current locale encoding for the surrogateescape error handler, except on Android. Previously, Py_EncodeLocale() was used for the surrogateescape, and the current locale encoding was used for strict.

文件系统编码格式

To encode and decode file names and other environment strings, Py_FileSystemDefaultEncoding should be used as the encoding, and Py_FileSystemDefaultEncodeErrors should be used as the error handler (PEP 383 and PEP 529). To encode file names to bytes during argument parsing, the "O&" converter should be used, passing PyUnicode_FSConverter() as the conversion function:

int PyUnicode_FSConverter(PyObject *obj, void *result)

Part of the Stable ABI.

ParseTuple converter: encode str objects -- obtained directly or through the os.PathLike interface -- to bytes using PyUnicode_EncodeFSDefault(); bytes objects are output as-is. result must be a PyBytesObject* which must be released when it is no longer used.

3.1 新版功能.

在 3.6 版更改: 接受一个 path-like object。

To decode file names to str during argument parsing, the "O&" converter should be used, passing PyUnicode_FSDecoder() as the conversion function:

int PyUnicode_FSDecoder(PyObject *obj, void *result)

Part of the Stable ABI.

ParseTuple converter: decode bytes objects -- obtained either directly or indirectly through the os.PathLike interface -- to str using PyUnicode_DecodeFSDefaultAndSize(); str objects are output as-is. result must be a PyUnicodeObject* which must be released when it is no longer used.

3.2 新版功能.

在 3.6 版更改: 接受一个 path-like object。

PyObject *PyUnicode_DecodeFSDefaultAndSize(const char *s, Py_ssize_t size)

返回值：新的引用。 Part of the Stable ABI.

Decode a string from the filesystem encoding and error handler.

If Py_FileSystemDefaultEncoding is not set, fall back to the locale encoding.

Py_FileSystemDefaultEncoding is initialized at startup from the locale encoding and cannot be modified later. If you need to decode a string from the current locale encoding, use PyUnicode_DecodeLocaleAndSize().

参见

The Py_DecodeLocale() 函数。

在 3.6 版更改: Use Py_FileSystemDefaultEncodeErrors error handler.

PyObject *PyUnicode_DecodeFSDefault(const char *s)

返回值：新的引用。 Part of the Stable ABI.

Decode a null-terminated string from the filesystem encoding and error handler.

If Py_FileSystemDefaultEncoding is not set, fall back to the locale encoding.

Use PyUnicode_DecodeFSDefaultAndSize() if you know the string length.

在 3.6 版更改: Use Py_FileSystemDefaultEncodeErrors error handler.

PyObject *PyUnicode_EncodeFSDefault(PyObject *unicode)

返回值：新的引用。 Part of the Stable ABI.

Encode a Unicode object to Py_FileSystemDefaultEncoding with the Py_FileSystemDefaultEncodeErrors error handler, and return bytes. Note that the resulting bytes object may contain null bytes.

If Py_FileSystemDefaultEncoding is not set, fall back to the locale encoding.

Py_FileSystemDefaultEncoding is initialized at startup from the locale encoding and cannot be modified later. If you need to encode a string to the current locale encoding, use PyUnicode_EncodeLocale().

参见

The Py_EncodeLocale() function.

3.2 新版功能.

在 3.6 版更改: Use Py_FileSystemDefaultEncodeErrors error handler.

wchar_t Support

wchar_t support for platforms which support it:

PyObject *PyUnicode_FromWideChar(const wchar_t *w, Py_ssize_t size)

返回值：新的引用。 Part of the Stable ABI.

Create a Unicode object from the wchar_t buffer w of the given size. Passing -1 as the size indicates that the function must itself compute the length, using wcslen. Return NULL on failure.

Py_ssize_t PyUnicode_AsWideChar(PyObject *unicode, wchar_t *w, Py_ssize_t size)

Part of the Stable ABI.

Copy the Unicode object contents into the wchar_t buffer w. At most size wchar_t characters are copied (excluding a possibly trailing null termination character). Return the number of wchar_t characters copied or -1 in case of an error. Note that the resulting wchar_t* string may or may not be null-terminated. It is the responsibility of the caller to make sure that the wchar_t* string is null-terminated in case this is required by the application. Also, note that the wchar_t* string might contain null characters, which would cause the string to be truncated when used with most C functions.

wchar_t *PyUnicode_AsWideCharString(PyObject *unicode, Py_ssize_t *size)

Part of the Stable ABI since version 3.7.

Convert the Unicode object to a wide character string. The output string always ends with a null character. If size is not NULL, write the number of wide characters (excluding the trailing null termination character) into *size. Note that the resulting wchar_t string might contain null characters, which would cause the string to be truncated when used with most C functions. If size is NULL and the wchar_t* string contains null characters a ValueError is raised.

Returns a buffer allocated by PyMem_New (use PyMem_Free() to free it) on success. On error, returns NULL and *size is undefined. Raises a MemoryError if memory allocation is failed.

3.2 新版功能.

在 3.7 版更改: Raises a ValueError if size is NULL and the wchar_t* string contains null characters.

Built-in Codecs

Python provides a set of built-in codecs which are written in C for speed. All of these codecs are directly usable via the following functions.

Many of the following APIs take two arguments encoding and errors, and they have the same semantics as the ones of the built-in str() string object constructor.

Setting encoding to NULL causes the default encoding to be used which is UTF-8. The file system calls should use PyUnicode_FSConverter() for encoding file names. This uses the variable Py_FileSystemDefaultEncoding internally. This variable should be treated as read-only: on some systems, it will be a pointer to a static string, on others, it will change at run-time (such as when the application invokes setlocale).

Error handling is set by errors which may also be set to NULL meaning to use the default handling defined for the codec. Default error handling for all built-in codecs is "strict" (ValueError is raised).

The codecs all use a similar interface. Only deviations from the following generic ones are documented for simplicity.

Generic Codecs

These are the generic codec APIs:

PyObject *PyUnicode_Decode(const char *s, Py_ssize_t size, const char *encoding, const char *errors)

返回值：新的引用。 Part of the Stable ABI.

Create a Unicode object by decoding size bytes of the encoded string s. encoding and errors have the same meaning as the parameters of the same name in the str() built-in function. The codec to be used is looked up using the Python codec registry. Return NULL if an exception was raised by the codec.

PyObject *PyUnicode_AsEncodedString(PyObject *unicode, const char *encoding, const char *errors)

返回值：新的引用。 Part of the Stable ABI.

Encode a Unicode object and return the result as Python bytes object. encoding and errors have the same meaning as the parameters of the same name in the Unicode encode() method. The codec to be used is looked up using the Python codec registry. Return NULL if an exception was raised by the codec.

UTF-8 编解码器

以下是 UTF-8 编解码器 API:

PyObject *PyUnicode_DecodeUTF8(const char *s, Py_ssize_t size, const char *errors)

返回值：新的引用。 Part of the Stable ABI.

Create a Unicode object by decoding size bytes of the UTF-8 encoded string s. Return NULL if an exception was raised by the codec.

PyObject *PyUnicode_DecodeUTF8Stateful(const char *s, Py_ssize_t size, const char *errors, Py_ssize_t *consumed)

返回值：新的引用。 Part of the Stable ABI.

If consumed is NULL, behave like PyUnicode_DecodeUTF8(). If consumed is not NULL, trailing incomplete UTF-8 byte sequences will not be treated as an error. Those bytes will not be decoded and the number of bytes that have been decoded will be stored in consumed.

PyObject *PyUnicode_AsUTF8String(PyObject *unicode)

返回值：新的引用。 Part of the Stable ABI.

Encode a Unicode object using UTF-8 and return the result as Python bytes object. Error handling is "strict". Return NULL if an exception was raised by the codec.

const char *PyUnicode_AsUTF8AndSize(PyObject *unicode, Py_ssize_t *size)

Part of the Stable ABI since version 3.10.

Return a pointer to the UTF-8 encoding of the Unicode object, and store the size of the encoded representation (in bytes) in size. The size argument can be NULL; in this case no size will be stored. The returned buffer always has an extra null byte appended (not included in size), regardless of whether there are any other null code points.

In the case of an error, NULL is returned with an exception set and no size is stored.

This caches the UTF-8 representation of the string in the Unicode object, and subsequent calls will return a pointer to the same buffer. The caller is not responsible for deallocating the buffer. The buffer is deallocated and pointers to it become invalid when the Unicode object is garbage collected.

3.3 新版功能.

在 3.7 版更改: The return type is now const char * rather of char *.

在 3.10 版更改: This function is a part of the limited API.

const char *PyUnicode_AsUTF8(PyObject *unicode)

As PyUnicode_AsUTF8AndSize(), but does not store the size.

3.3 新版功能.

在 3.7 版更改: The return type is now const char * rather of char *.

UTF-32 Codecs

These are the UTF-32 codec APIs:

PyObject *PyUnicode_DecodeUTF32(const char *s, Py_ssize_t size, const char *errors, int *byteorder)

返回值：新的引用。 Part of the Stable ABI.

Decode size bytes from a UTF-32 encoded buffer string and return the corresponding Unicode object. errors (if non-NULL) defines the error handling. It defaults to "strict".

If byteorder is non-NULL, the decoder starts decoding using the given byte order:

*byteorder == -1: little endian
*byteorder == 0:  native order
*byteorder == 1:  big endian

If *byteorder is zero, and the first four bytes of the input data are a byte order mark (BOM), the decoder switches to this byte order and the BOM is not copied into the resulting Unicode string. If *byteorder is -1 or 1, any byte order mark is copied to the output.

After completion, *byteorder is set to the current byte order at the end of input data.

If byteorder is NULL, the codec starts in native order mode.

Return NULL if an exception was raised by the codec.

PyObject *PyUnicode_DecodeUTF32Stateful(const char *s, Py_ssize_t size, const char *errors, int *byteorder, Py_ssize_t *consumed)

返回值：新的引用。 Part of the Stable ABI.

If consumed is NULL, behave like PyUnicode_DecodeUTF32(). If consumed is not NULL, PyUnicode_DecodeUTF32Stateful() will not treat trailing incomplete UTF-32 byte sequences (such as a number of bytes not divisible by four) as an error. Those bytes will not be decoded and the number of bytes that have been decoded will be stored in consumed.

PyObject *PyUnicode_AsUTF32String(PyObject *unicode)

返回值：新的引用。 Part of the Stable ABI.

Return a Python byte string using the UTF-32 encoding in native byte order. The string always starts with a BOM mark. Error handling is "strict". Return NULL if an exception was raised by the codec.

UTF-16 Codecs

These are the UTF-16 codec APIs:

PyObject *PyUnicode_DecodeUTF16(const char *s, Py_ssize_t size, const char *errors, int *byteorder)

返回值：新的引用。 Part of the Stable ABI.

Decode size bytes from a UTF-16 encoded buffer string and return the corresponding Unicode object. errors (if non-NULL) defines the error handling. It defaults to "strict".

If byteorder is non-NULL, the decoder starts decoding using the given byte order:

*byteorder == -1: little endian
*byteorder == 0:  native order
*byteorder == 1:  big endian

If *byteorder is zero, and the first two bytes of the input data are a byte order mark (BOM), the decoder switches to this byte order and the BOM is not copied into the resulting Unicode string. If *byteorder is -1 or 1, any byte order mark is copied to the output (where it will result in either a \ufeff or a \ufffe character).

After completion, *byteorder is set to the current byte order at the end of input data.

If byteorder is NULL, the codec starts in native order mode.

Return NULL if an exception was raised by the codec.

PyObject *PyUnicode_DecodeUTF16Stateful(const char *s, Py_ssize_t size, const char *errors, int *byteorder, Py_ssize_t *consumed)

返回值：新的引用。 Part of the Stable ABI.

If consumed is NULL, behave like PyUnicode_DecodeUTF16(). If consumed is not NULL, PyUnicode_DecodeUTF16Stateful() will not treat trailing incomplete UTF-16 byte sequences (such as an odd number of bytes or a split surrogate pair) as an error. Those bytes will not be decoded and the number of bytes that have been decoded will be stored in consumed.

PyObject *PyUnicode_AsUTF16String(PyObject *unicode)

返回值：新的引用。 Part of the Stable ABI.

Return a Python byte string using the UTF-16 encoding in native byte order. The string always starts with a BOM mark. Error handling is "strict". Return NULL if an exception was raised by the codec.

UTF-7 Codecs

These are the UTF-7 codec APIs:

PyObject *PyUnicode_DecodeUTF7(const char *s, Py_ssize_t size, const char *errors)

返回值：新的引用。 Part of the Stable ABI.

Create a Unicode object by decoding size bytes of the UTF-7 encoded string s. Return NULL if an exception was raised by the codec.

PyObject *PyUnicode_DecodeUTF7Stateful(const char *s, Py_ssize_t size, const char *errors, Py_ssize_t *consumed)

返回值：新的引用。 Part of the Stable ABI.

If consumed is NULL, behave like PyUnicode_DecodeUTF7(). If consumed is not NULL, trailing incomplete UTF-7 base-64 sections will not be treated as an error. Those bytes will not be decoded and the number of bytes that have been decoded will be stored in consumed.

Unicode-Escape 编解码器

These are the "Unicode Escape" codec APIs:

PyObject *PyUnicode_DecodeUnicodeEscape(const char *s, Py_ssize_t size, const char *errors)

返回值：新的引用。 Part of the Stable ABI.

Create a Unicode object by decoding size bytes of the Unicode-Escape encoded string s. Return NULL if an exception was raised by the codec.

PyObject *PyUnicode_AsUnicodeEscapeString(PyObject *unicode)

返回值：新的引用。 Part of the Stable ABI.

Encode a Unicode object using Unicode-Escape and return the result as a bytes object. Error handling is "strict". Return NULL if an exception was raised by the codec.

Raw-Unicode-Escape Codecs

These are the "Raw Unicode Escape" codec APIs:

PyObject *PyUnicode_DecodeRawUnicodeEscape(const char *s, Py_ssize_t size, const char *errors)

返回值：新的引用。 Part of the Stable ABI.

Create a Unicode object by decoding size bytes of the Raw-Unicode-Escape encoded string s. Return NULL if an exception was raised by the codec.

PyObject *PyUnicode_AsRawUnicodeEscapeString(PyObject *unicode)

返回值：新的引用。 Part of the Stable ABI.

Encode a Unicode object using Raw-Unicode-Escape and return the result as a bytes object. Error handling is "strict". Return NULL if an exception was raised by the codec.

Latin-1 Codecs

These are the Latin-1 codec APIs: Latin-1 corresponds to the first 256 Unicode ordinals and only these are accepted by the codecs during encoding.

PyObject *PyUnicode_DecodeLatin1(const char *s, Py_ssize_t size, const char *errors)

返回值：新的引用。 Part of the Stable ABI.

Create a Unicode object by decoding size bytes of the Latin-1 encoded string s. Return NULL if an exception was raised by the codec.

PyObject *PyUnicode_AsLatin1String(PyObject *unicode)

返回值：新的引用。 Part of the Stable ABI.

Encode a Unicode object using Latin-1 and return the result as Python bytes object. Error handling is "strict". Return NULL if an exception was raised by the codec.

ASCII Codecs

These are the ASCII codec APIs. Only 7-bit ASCII data is accepted. All other codes generate errors.

PyObject *PyUnicode_DecodeASCII(const char *s, Py_ssize_t size, const char *errors)

返回值：新的引用。 Part of the Stable ABI.

Create a Unicode object by decoding size bytes of the ASCII encoded string s. Return NULL if an exception was raised by the codec.

PyObject *PyUnicode_AsASCIIString(PyObject *unicode)

返回值：新的引用。 Part of the Stable ABI.

Encode a Unicode object using ASCII and return the result as Python bytes object. Error handling is "strict". Return NULL if an exception was raised by the codec.

Character Map Codecs

This codec is special in that it can be used to implement many different codecs (and this is in fact what was done to obtain most of the standard codecs included in the encodings package). The codec uses mappings to encode and decode characters. The mapping objects provided must support the __getitem__() mapping interface; dictionaries and sequences work well.

These are the mapping codec APIs:

PyObject *PyUnicode_DecodeCharmap(const char *data, Py_ssize_t size, PyObject *mapping, const char *errors)

返回值：新的引用。 Part of the Stable ABI.

Create a Unicode object by decoding size bytes of the encoded string s using the given mapping object. Return NULL if an exception was raised by the codec.

If mapping is NULL, Latin-1 decoding will be applied. Else mapping must map bytes ordinals (integers in the range from 0 to 255) to Unicode strings, integers (which are then interpreted as Unicode ordinals) or None. Unmapped data bytes -- ones which cause a LookupError, as well as ones which get mapped to None, 0xFFFE or '\ufffe', are treated as undefined mappings and cause an error.

PyObject *PyUnicode_AsCharmapString(PyObject *unicode, PyObject *mapping)

返回值：新的引用。 Part of the Stable ABI.

Encode a Unicode object using the given mapping object and return the result as a bytes object. Error handling is "strict". Return NULL if an exception was raised by the codec.

The mapping object must map Unicode ordinal integers to bytes objects, integers in the range from 0 to 255 or None. Unmapped character ordinals (ones which cause a LookupError) as well as mapped to None are treated as "undefined mapping" and cause an error.

The following codec API is special in that maps Unicode to Unicode.

PyObject *PyUnicode_Translate(PyObject *str, PyObject *table, const char *errors)

返回值：新的引用。 Part of the Stable ABI.

Translate a string by applying a character mapping table to it and return the resulting Unicode object. Return NULL if an exception was raised by the codec.

The mapping table must map Unicode ordinal integers to Unicode ordinal integers or None (causing deletion of the character).

Mapping tables need only provide the __getitem__() interface; dictionaries and sequences work well. Unmapped character ordinals (ones which cause a LookupError) are left untouched and are copied as-is.

errors has the usual meaning for codecs. It may be NULL which indicates to use the default error handling.

MBCS codecs for Windows

These are the MBCS codec APIs. They are currently only available on Windows and use the Win32 MBCS converters to implement the conversions. Note that MBCS (or DBCS) is a class of encodings, not just one. The target encoding is defined by the user settings on the machine running the codec.

PyObject *PyUnicode_DecodeMBCS(const char *s, Py_ssize_t size, const char *errors)

返回值：新的引用。 Part of the Stable ABI on Windows since version 3.7.

Create a Unicode object by decoding size bytes of the MBCS encoded string s. Return NULL if an exception was raised by the codec.

PyObject *PyUnicode_DecodeMBCSStateful(const char *s, Py_ssize_t size, const char *errors, Py_ssize_t *consumed)

返回值：新的引用。 Part of the Stable ABI on Windows since version 3.7.

If consumed is NULL, behave like PyUnicode_DecodeMBCS(). If consumed is not NULL, PyUnicode_DecodeMBCSStateful() will not decode trailing lead byte and the number of bytes that have been decoded will be stored in consumed.

PyObject *PyUnicode_AsMBCSString(PyObject *unicode)

返回值：新的引用。 Part of the Stable ABI on Windows since version 3.7.

Encode a Unicode object using MBCS and return the result as Python bytes object. Error handling is "strict". Return NULL if an exception was raised by the codec.

PyObject *PyUnicode_EncodeCodePage(int code_page, PyObject *unicode, const char *errors)

返回值：新的引用。 Part of the Stable ABI on Windows since version 3.7.

Encode the Unicode object using the specified code page and return a Python bytes object. Return NULL if an exception was raised by the codec. Use CP_ACP code page to get the MBCS encoder.

3.3 新版功能.

Methods & Slots

方法与槽位函数

The following APIs are capable of handling Unicode objects and strings on input (we refer to them as strings in the descriptions) and return Unicode objects or integers as appropriate.

They all return NULL or -1 if an exception occurs.

PyObject *PyUnicode_Concat(PyObject *left, PyObject *right)

返回值：新的引用。 Part of the Stable ABI.

Concat two strings giving a new Unicode string.

PyObject *PyUnicode_Split(PyObject *s, PyObject *sep, Py_ssize_t maxsplit)

返回值：新的引用。 Part of the Stable ABI.

Split a string giving a list of Unicode strings. If sep is NULL, splitting will be done at all whitespace substrings. Otherwise, splits occur at the given separator. At most maxsplit splits will be done. If negative, no limit is set. Separators are not included in the resulting list.

PyObject *PyUnicode_Splitlines(PyObject *s, int keepend)

返回值：新的引用。 Part of the Stable ABI.

Split a Unicode string at line breaks, returning a list of Unicode strings. CRLF is considered to be one line break. If keepend is 0, the line break characters are not included in the resulting strings.

PyObject *PyUnicode_Join(PyObject *separator, PyObject *seq)

返回值：新的引用。 Part of the Stable ABI.

Join a sequence of strings using the given separator and return the resulting Unicode string.

Py_ssize_t PyUnicode_Tailmatch(PyObject *str, PyObject *substr, Py_ssize_t start, Py_ssize_t end, int direction)

Part of the Stable ABI.

Return 1 if substr matches str[start:end] at the given tail end (direction == -1 means to do a prefix match, direction == 1 a suffix match), 0 otherwise. Return -1 if an error occurred.

Py_ssize_t PyUnicode_Find(PyObject *str, PyObject *substr, Py_ssize_t start, Py_ssize_t end, int direction)

Part of the Stable ABI.

Return the first position of substr in str[start:end] using the given direction (direction == 1 means to do a forward search, direction == -1 a backward search). The return value is the index of the first match; a value of -1 indicates that no match was found, and -2 indicates that an error occurred and an exception has been set.

Py_ssize_t PyUnicode_FindChar(PyObject *str, Py_UCS4 ch, Py_ssize_t start, Py_ssize_t end, int direction)

Part of the Stable ABI since version 3.7.

Return the first position of the character ch in str[start:end] using the given direction (direction == 1 means to do a forward search, direction == -1 a backward search). The return value is the index of the first match; a value of -1 indicates that no match was found, and -2 indicates that an error occurred and an exception has been set.

3.3 新版功能.

在 3.7 版更改: start and end are now adjusted to behave like str[start:end].

Py_ssize_t PyUnicode_Count(PyObject *str, PyObject *substr, Py_ssize_t start, Py_ssize_t end)

Part of the Stable ABI.

Return the number of non-overlapping occurrences of substr in str[start:end]. Return -1 if an error occurred.

PyObject *PyUnicode_Replace(PyObject *str, PyObject *substr, PyObject *replstr, Py_ssize_t maxcount)

返回值：新的引用。 Part of the Stable ABI.

Replace at most maxcount occurrences of substr in str with replstr and return the resulting Unicode object. maxcount == -1 means replace all occurrences.

int PyUnicode_Compare(PyObject *left, PyObject *right)

Part of the Stable ABI.

Compare two strings and return -1, 0, 1 for less than, equal, and greater than, respectively.

This function returns -1 upon failure, so one should call PyErr_Occurred() to check for errors.

int PyUnicode_CompareWithASCIIString(PyObject *uni, const char *string)

Part of the Stable ABI.

Compare a Unicode object, uni, with string and return -1, 0, 1 for less than, equal, and greater than, respectively. It is best to pass only ASCII-encoded strings, but the function interprets the input string as ISO-8859-1 if it contains non-ASCII characters.

This function does not raise exceptions.

PyObject *PyUnicode_RichCompare(PyObject *left, PyObject *right, int op)

返回值：新的引用。 Part of the Stable ABI.

对两个 Unicode 字符串执行富比较并返回以下值之一:

• NULL in case an exception was raised

• Py_True or Py_False for successful comparisons

• Py_NotImplemented in case the type combination is unknown

Possible values for op are Py_GT, Py_GE, Py_EQ, Py_NE, Py_LT, and Py_LE.

PyObject *PyUnicode_Format(PyObject *format, PyObject *args)

返回值：新的引用。 Part of the Stable ABI.

Return a new string object from format and args; this is analogous to format % args.

int PyUnicode_Contains(PyObject *container, PyObject *element)

Part of the Stable ABI.

Check whether element is contained in container and return true or false accordingly.

element has to coerce to a one element Unicode string. -1 is returned if there was an error.

void PyUnicode_InternInPlace(PyObject **string)

Part of the Stable ABI.

Intern the argument *string in place. The argument must be the address of a pointer variable pointing to a Python Unicode string object. If there is an existing interned string that is the same as *string, it sets *string to it (releasing the reference to the old string object and creating a new strong reference to the interned string object), otherwise it leaves *string alone and interns it (creating a new strong reference). (Clarification: even though there is a lot of talk about references, think of this function as reference-neutral; you own the object after the call if and only if you owned it before the call.)

PyObject *PyUnicode_InternFromString(const char *v)

返回值：新的引用。 Part of the Stable ABI.

A combination of PyUnicode_FromString() and PyUnicode_InternInPlace(), returning either a new Unicode string object that has been interned, or a new ("owned") reference to an earlier interned string object with the same value.