Unicode对象和编码解码器

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 representation is created on demand and cached in the Unicode object.

备注

The Py_UNICODE representation has been removed since Python 3.12 with deprecated APIs. See PEP 623 for more information.

These are the basic Unicode object types used for the Unicode implementation in Python:

These types are typedefs for unsigned integer types wide enough to contain characters of 32 bits, 16 bits and 8 bits, respectively. When dealing with single Unicode characters, use Py_UCS4.

在 3.3 版本加入.

This is a typedef of wchar_t, which is a 16-bit type or 32-bit type depending on the platform.

在 3.3 版本发生变更: In previous versions, this was a 16-bit type or a 32-bit type depending on whether you selected a "narrow" or "wide" Unicode version of Python at build time.

从版本 3.13 开始标记为过时，将在版本 3.15 中移除。.

These subtypes of PyObject represent a Python Unicode object. In almost all cases, they shouldn't be used directly, since all API functions that deal with Unicode objects take and return PyObject pointers.

在 3.3 版本加入.

This instance of PyTypeObject represents the Python Unicode type. It is exposed to Python code as str.

The following APIs are C macros and static inlined functions for fast checks and access to internal read-only data of Unicode objects:

Return true if the object o is a Unicode object or an instance of a Unicode subtype. This function always succeeds.

Return true if the object o is a Unicode object, but not an instance of a subtype. This function always succeeds.

Returns 0. This API is kept only for backward compatibility.

在 3.3 版本加入.

自 3.10 版本弃用: This API does nothing since Python 3.12.

Return the length of the Unicode string, in code points. o has to be a Unicode object in the "canonical" representation (not checked).

在 3.3 版本加入.

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 function.

在 3.3 版本加入.

返回 PyUnicode_KIND() 宏的值。

在 3.3 版本加入.

在 3.12 版本发生变更: PyUnicode_WCHAR_KIND has been removed.

Return one of the PyUnicode kind constants (see above) that indicate how many bytes per character this Unicode object uses to store its data. o has to be a Unicode object in the "canonical" representation (not checked).

在 3.3 版本加入.

Return a void pointer to the raw Unicode buffer. o has to be a Unicode object in the "canonical" representation (not checked).

在 3.3 版本加入.

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.

在 3.3 版本加入.

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

在 3.3 版本加入.

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.

在 3.3 版本加入.

Return the maximum code point that is suitable for creating another string based on o, which must be in the "canonical" representation. This is always an approximation but more efficient than iterating over the string.

在 3.3 版本加入.

Return 1 if the string is a valid identifier according to the language definition, section 标识符和关键字. Return 0 otherwise.

在 3.9 版本发生变更: The function does not call Py_FatalError() anymore if the string is not ready.

Unicode provides many different character properties. The most often needed ones are available through these macros which are mapped to C functions depending on the Python configuration.

根据 ch 是否为空白字符返回 1 或 0。

根据 ch 是否为小写字符返回 1 或 0。

Return 1 or 0 depending on whether ch is an uppercase character.

Return 1 or 0 depending on whether ch is a titlecase character.

Return 1 or 0 depending on whether ch is a linebreak character.

Return 1 or 0 depending on whether ch is a decimal character.

Return 1 or 0 depending on whether ch is a digit character.

Return 1 or 0 depending on whether ch is a numeric character.

Return 1 or 0 depending on whether ch is an alphabetic character.

Return 1 or 0 depending on whether ch is an alphanumeric character.

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:

Return the character ch converted to lower case.

自 3.3 版本弃用: This function uses simple case mappings.

Return the character ch converted to upper case.

自 3.3 版本弃用: This function uses simple case mappings.

Return the character ch converted to title case.

自 3.3 版本弃用: This function uses simple case mappings.

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

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

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:

Check if ch is a surrogate (0xD800