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）。

UTF-8 表示将按需创建并缓存在 Unicode 对象中。

备注:

  "Py_UNICODE" 表示形式在 Python 3.12 中同被弃用的 API 一起被移除了，
  查阅 **PEP 623** 以获得更多信息。


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)

   返回 "0"。 此 API 仅为向下兼容而保留。

   3.3 新版功能.

   3.10 版后已移除: 此 API 从 Python 3.12 起将不做任何事。

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)

   返回一个用于直接字符访问的指向转换为 UCS1、UCS2 或 UCS4 整数类型的
   规范表示的指针。 如果规范表示具有正确的字符大小，则不执行检查；使用
   "PyUnicode_KIND()" 选择正确的函数。

   3.3 新版功能.

PyUnicode_1BYTE_KIND
PyUnicode_2BYTE_KIND
PyUnicode_4BYTE_KIND

   返回 "PyUnicode_KIND()" 宏的值。

   3.3 新版功能.

   在 3.12 版更改: "PyUnicode_WCHAR_KIND" 已被移除。

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)

   Write into a canonical representation *data* (as obtained with
   "PyUnicode_DATA()").  This function performs no sanity checks, and
   is intended for usage in loops.  The caller should cache the *kind*
   value and *data* pointer as obtained from other calls.  *index* is
   the index in the string (starts at 0) and *value* is the new code
   point value which should be written to that location.

   3.3 新版功能.

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

   Read a code point from a canonical representation *data* (as
   obtained with "PyUnicode_DATA()").  No checks or ready calls are
   performed.

   3.3 新版功能.

Py_UCS4 PyUnicode_READ_CHAR(PyObject *o, Py_ssize_t index)

   Read a character from a Unicode object *o*, which must be in the
   "canonical" representation.  This is less efficient than
   "PyUnicode_READ()" if you do multiple consecutive reads.

   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.

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: The function does not call "Py_FatalError()" anymore
   if the string is not ready.


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)

   Return "1" or "0" depending on whether *ch* is a printable
   character. Nonprintable characters are those characters defined in
   the Unicode character database as "Other" or "Separator", excepting
   the ASCII space (0x20) which is considered printable.  (Note that
   printable characters in this context are those which should not be
   escaped when "repr()" is invoked on a string. It has no bearing on
   the handling of strings written to "sys.stdout" or "sys.stderr".)

These APIs can be used for fast direct character conversions:

Py_UCS4 Py_UNICODE_TOLOWER(Py_UCS4 ch)

   Return the character *ch* converted to lower case.

   3.3 版后已移除: This function uses simple case mappings.

Py_UCS4 Py_UNICODE_TOUPPER(Py_UCS4 ch)

   Return the character *ch* converted to upper case.

   3.3 版后已移除: This function uses simple case mappings.

Py_UCS4 Py_UNICODE_TOTITLE(Py_UCS4 ch)

   Return the character *ch* converted to title case.

   3.3 版后已移除: This function uses simple case mappings.

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 function 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 function 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 function does not raise exceptions.

These APIs can be used to work with surrogates:

int Py_UNICODE_IS_SURROGATE(Py_UCS4 ch)

   Check if *ch* is a surrogate ("0xD800 <= ch <= 0xDFFF").

int Py_UNICODE_IS_HIGH_SURROGATE(Py_UCS4 ch)

   Check if *ch* is a high surrogate ("0xD800 <= ch <= 0xDBFF").

int Py_UNICODE_IS_LOW_SURROGATE(Py_UCS4 ch)

   Check if *ch* is a low surrogate ("0xDC00 <= ch <= 0xDFFF").

Py_UCS4 Py_UNICODE_JOIN_SURROGATES(Py_UCS4 high, Py_UCS4 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. *high* must be in the range
   [0xD800; 0xDBFF] and *low* must be in the range [0xDC00; 0xDFFF].


Creating and accessing Unicode strings
--------------------------------------

To create Unicode objects and access their basic sequence properties,
use these APIs:

PyObject *PyUnicode_New(Py_ssize_t size, Py_UCS4 maxchar)
    *返回值：新的引用。*

   Create a new Unicode object.  *maxchar* should be the true maximum
   code point to be placed in the string.  As an approximation, it can
   be rounded up to the nearest value in the sequence 127, 255, 65535,
   1114111.

   This is the recommended way to allocate a new Unicode object.
   Objects created using this function are not resizable.

   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。*

   Create a new Unicode object with the given *kind* (possible values
   are "PyUnicode_1BYTE_KIND" etc., as returned by
   "PyUnicode_KIND()").  The *buffer* must point to an array of *size*
   units of 1, 2 or 4 bytes per character, as given by the kind.

   If necessary, the input *buffer* is copied and transformed into the
   canonical representation.  For example, if the *buffer* is a UCS4
   string ("PyUnicode_4BYTE_KIND") and it consists only of codepoints
   in the UCS1 range, it will be transformed into 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. The return value might be a shared object, i.e.
   modification of the data is not allowed.

   This function raises "SystemError" when:

   * *size* < 0,

   * *u* is "NULL" and *size* > 0

   在 3.12 版更改: *u* == "NULL" with *size* > 0 is not allowed
   anymore.

PyObject *PyUnicode_FromString(const char *u)
    *返回值：新的引用。** Part of the Stable ABI.*

   Create a Unicode object from a UTF-8 encoded null-terminated char
   buffer *u*.

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.

   转换标记符包含两个或更多字符并具有以下组成，且必须遵循此处规定的顺
   序：

   1. "'%'" 字符，用于标记转换符的起始。

   2. 转换旗标（可选），用于影响某些转换类型的结果。

   3. Minimum field width (optional). If specified as an "'*'"
      (asterisk), the actual width is given in the next argument,
      which must be of type int, and the object to convert comes after
      the minimum field width and optional precision.

   4. Precision (optional), given as a "'.'" (dot) followed by the
      precision. If specified as "'*'" (an asterisk), the actual
      precision is given in the next argument, which must be of type
      int, and the value to convert comes after the precision.

   5. 长度修饰符（可选）。

   6. 转换类型。

   转换旗标为：

   +---------+---------------------------------------------------------------+
   | 标志    | 含意                                                          |
   |=========|===============================================================|
   | "0"     | 转换将为数字值填充零字符。                                    |
   +---------+---------------------------------------------------------------+
   | "-"     | 转换值将靠左对齐（如果同时给出则会覆盖 "0" 旗标）。           |
   +---------+---------------------------------------------------------------+

   The length modifiers for following integer conversions ("d", "i",
   "o", "u", "x", or "X") specify the type of the argument (int by
   default):

   +------------+-------------------------------------------------------+
   | Modifier   | 类型                                                  |
   |============|=======================================================|
   | "l"        | long 或 unsigned long                                 |
   +------------+-------------------------------------------------------+
   | "ll"       | long long 或 unsigned long long                       |
   +------------+-------------------------------------------------------+
   | "j"        | "intmax_t" 或 "uintmax_t"                             |
   +------------+-------------------------------------------------------+
   | "z"        | "size_t" 或 "ssize_t"                                 |
   +------------+-------------------------------------------------------+
   | "t"        | "ptrdiff_t"                                           |
   +------------+-------------------------------------------------------+

   针对以下转换 "s" 或 "V" 的长度修饰符 "l" 指明参数的类型为 const
   wchar_t*。

   转换指示符如下:

   +-----------------------------------+-----------------------------------+-----------------------------------+
   | 转换指示符                        | 类型                              | 注释                              |
   |===================================|===================================|===================================|
   | "%"                               | *不适用*                          | 字面的 "%" 字符。                 |
   +-----------------------------------+-----------------------------------+-----------------------------------+
   | "d", "i"                          | 由长度修饰符指明                  | 有符号 C 整数的十进制表示。       |
   +-----------------------------------+-----------------------------------+-----------------------------------+
   | "u"                               | 由长度修饰符指明                  | 无符号 C 整数的十进制表示。       |
   +-----------------------------------+-----------------------------------+-----------------------------------+
   | "o"                               | 由长度修饰符指明                  | 无符号 C 整数的八进制表示。       |
   +-----------------------------------+-----------------------------------+-----------------------------------+
   | "x"                               | 由长度修饰符指明                  | 无符号 C 整数的十六进制表示（小写 |
   |                                   |                                   | ）。                              |
   +-----------------------------------+-----------------------------------+-----------------------------------+
   | "X"                               | 由长度修饰符指明                  | 无符号 C 整数的十六进制表示（大写 |
   |                                   |                                   | ）。                              |
   +-----------------------------------+-----------------------------------+-----------------------------------+
   | "c"                               | int                               | 单个字符。                        |
   +-----------------------------------+-----------------------------------+-----------------------------------+
   | "s"                               | const char* 或 const wchar_t*     | 以 null 为终止符的 C 字符数组。   |
   +-----------------------------------+-----------------------------------+-----------------------------------+
   | "p"                               | const void*                       | The hex representation of a C     |
   |                                   |                                   | pointer. Mostly equivalent to     |
   |                                   |                                   | "printf("%p")" except that it is  |
   |                                   |                                   | guaranteed to start with the      |
   |                                   |                                   | literal "0x" regardless of what   |
   |                                   |                                   | the platform's "printf" yields.   |
   +-----------------------------------+-----------------------------------+-----------------------------------+
   | "A"                               | PyObject*                         | "ascii()" 调用的结果。            |
   +-----------------------------------+-----------------------------------+-----------------------------------+
   | "U"                               | PyObject*                         | 一个 Unicode 对象。               |
   +-----------------------------------+-----------------------------------+-----------------------------------+
   | "V"                               | PyObject*, const char* or const   | A Unicode object (which may be    |
   |                                   | wchar_t*                          | "NULL") and a null-terminated C   |
   |                                   |                                   | character array as a second       |
   |                                   |                                   | parameter (which will be used, if |
   |                                   |                                   | the first parameter is "NULL").   |
   +-----------------------------------+-----------------------------------+-----------------------------------+
   | "S"                               | PyObject*                         | The result of calling             |
   |                                   |                                   | "PyObject_Str()".                 |
   +-----------------------------------+-----------------------------------+-----------------------------------+
   | "R"                               | PyObject*                         | The result of calling             |
   |                                   |                                   | "PyObject_Repr()".                |
   +-----------------------------------+-----------------------------------+-----------------------------------+

   备注:

     The width formatter unit is number of characters rather than
     bytes. The precision formatter unit is number of bytes or
     "wchar_t" items (if the length modifier "l" is used) 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").

   备注:

     Unlike to C "printf()" the "0" flag has effect even when a
     precision is given for integer conversions ("d", "i", "u", "o",
     "x", or "X").

   在 3.2 版更改: Support for ""%lld"" and ""%llu"" added.

   在 3.3 版更改: Support for ""%li"", ""%lli"" and ""%zi"" added.

   在 3.4 版更改: Support width and precision formatter for ""%s"",
   ""%A"", ""%U"", ""%V"", ""%S"", ""%R"" added.

   在 3.12 版更改: Support for conversion specifiers "o" and "X".
   Support for length modifiers "j" and "t". Length modifiers are now
   applied to all integer conversions. Length modifier "l" is now
   applied to conversion specifiers "s" and "V". Support for variable
   width and precision "*". Support for flag "-".An unrecognized
   format character now sets a "SystemError". In previous versions it
   caused all the rest of the format string to be copied as-is to the
   result string, and any extra arguments discarded.

PyObject *PyUnicode_FromFormatV(const char *format, va_list vargs)
    *返回值：新的引用。** Part of the Stable ABI.*

   Identical to "PyUnicode_FromFormat()" except that it takes exactly
   two arguments.

PyObject *PyUnicode_FromObject(PyObject *obj)
    *返回值：新的引用。** Part of the Stable ABI.*

   Copy an instance of a Unicode subtype to a new true Unicode object
   if necessary. If *obj* is already a true Unicode object (not a
   subtype), return a new *strong reference* to the object.

   Objects other than Unicode or its subtypes will cause a
   "TypeError".

PyObject *PyUnicode_FromEncodedObject(PyObject *obj, const char *encoding, const char *errors)
    *返回值：新的引用。** Part of the Stable ABI.*

   Decode an encoded object *obj* to a Unicode object.

   "bytes", "bytearray" and other *bytes-like objects* are decoded
   according to the given *encoding* and using the error handling
   defined by *errors*. Both can be "NULL" to have the interface use
   the default values (see Built-in Codecs for details).

   All other objects, including Unicode objects, cause a "TypeError"
   to be set.

   The API returns "NULL" if there was an error.  The caller is
   responsible for decref'ing the returned objects.

Py_ssize_t PyUnicode_GetLength(PyObject *unicode)
    * Part of the Stable ABI since version 3.7.*

   Return the length of the Unicode object, in code points.

   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)

   Copy characters from one Unicode object into another.  This
   function performs character conversion when necessary and falls
   back to "memcpy()" if possible.  Returns "-1" and sets an exception
   on error, otherwise returns the number of copied characters.

   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)

   Fill a string with a character: write *fill_char* into
   "unicode[start:start+length]".

   Fail if *fill_char* is bigger than the string maximum character, or
   if the string has more than 1 reference.

   Return the number of written character, or return "-1" and raise an
   exception on error.

   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.*

   Write a character to a string.  The string must have been created
   through "PyUnicode_New()".  Since Unicode strings are supposed to
   be immutable, the string must not be shared, or have been hashed
   yet.

   This function checks that *unicode* is a Unicode object, that the
   index is not out of bounds, and that the object can be modified
   safely (i.e. that it its reference count is one).

   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.*

   Read a character from a string.  This function checks that
   *unicode* is a Unicode object and the index is not out of bounds,
   in contrast to "PyUnicode_READ_CHAR()", which performs no error
   checking.

   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.*

   Return a substring of *str*, from character index *start*
   (included) to character index *end* (excluded).  Negative indices
   are not supported.

   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.*

   Copy the string *u* into a UCS4 buffer, including a null character,
   if *copy_null* is set.  Returns "NULL" and sets an exception on
   error (in particular, a "SystemError" if *buflen* is smaller than
   the length of *u*).  *buffer* is returned on success.

   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.


Locale Encoding
---------------

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
   the *filesystem encoding and error handler*.

   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 the
   *filesystem encoding and error handler*.

   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
----------------

Functions encoding to and decoding from the *filesystem encoding and
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 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: The *filesystem error handler* is now used.

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 the string length is known, use
   "PyUnicode_DecodeFSDefaultAndSize()".

   在 3.6 版更改: The *filesystem error handler* is now used.

PyObject *PyUnicode_EncodeFSDefault(PyObject *unicode)
    *返回值：新的引用。** Part of the Stable ABI.*

   Encode a Unicode object to the *filesystem encoding and error
   handler*, and return "bytes". Note that the resulting "bytes"
   object can contain null bytes.

   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: The *filesystem error handler* is now used.


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
*filesystem encoding and error handler* internally.

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.
