字典对象
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PyDictObject

    Python 的字典对象是 "PyObject" 的子类型。

PyTypeObject PyDict_Type

   Python字典类型表示为 "PyTypeObject" 的实例。这与Python层面的 "dict"
   是相同的对象。

int PyDict_Check(PyObject *p)

   如果 *p* 是字典对象或者字典类型的子类型的实例，则返回真。

int PyDict_CheckExact(PyObject *p)

   如果 *p* 是字典对象但不是字典类型的子类型的实例，则返回真。

PyObject* PyDict_New()
    *Return value: New reference.*

   返回一个新的空字典或者返回 *NULL* 表示失败。

PyObject* PyDictProxy_New(PyObject *mapping)
    *Return value: New reference.*

   返回 "types.MappingProxyType" 对象，用于强制执行只读行为的映射。这
   通常用于创建视图以防止修改非动态类类型的字典。

void PyDict_Clear(PyObject *p)

   清空现有字典的所有键值对。

int PyDict_Contains(PyObject *p, PyObject *key)

   确定 *key* 是否包含在字典 *p* 中。如果 *key* 匹配上 *p* 的某一项，
   则返回 "1" ，否则返回 "0" 。返回 "-1" 表示出错。这等同于Python表达
   式 "key in p" 。

PyObject* PyDict_Copy(PyObject *p)
    *Return value: New reference.*

   返回与 *p* 包含相同键值对的新词典。

int PyDict_SetItem(PyObject *p, PyObject *key, PyObject *val)

   使用 *key* 作为键将 *value* 插入字典 *p* 。 *key* 必须为 *hashable*
   ；如果不是，会抛出 "TypeError" 异常。成功返回 "0" ，失败返回 "-1"
   。

int PyDict_SetItemString(PyObject *p, const char *key, PyObject *val)

   Insert *value* into the dictionary *p* using *key* as a key. *key*
   should be a "char*".  The key object is created using
   "PyUnicode_FromString(key)".  Return "0" on success or "-1" on
   failure.

int PyDict_DelItem(PyObject *p, PyObject *key)

   使用键 *key* 删除字典 *p* 中的条目。 *key* 必须是可哈希的；如果不是
   ，则抛出 "TypeError" 异常。成功时返回 "0" ，失败时返回 "-1" 。

int PyDict_DelItemString(PyObject *p, const char *key)

   删除字典 *p* 中的条目，其中包含由字符串 *key* 指定的键。成功时返回
   “0，失败时返回“-1”。

PyObject* PyDict_GetItem(PyObject *p, PyObject *key)
    *Return value: Borrowed reference.*

   返回字典 *p* 中 *key* 作为键的对象。如果键 *key* 不存在则返回
   *NULL* ，但可以使用 *without* 设置例外。

PyObject* PyDict_GetItemWithError(PyObject *p, PyObject *key)

   Variant of "PyDict_GetItem()" that does not suppress exceptions.
   Return *NULL* **with** an exception set if an exception occurred.
   Return *NULL* **without** an exception set if the key wasn't
   present.

PyObject* PyDict_GetItemString(PyObject *p, const char *key)
    *Return value: Borrowed reference.*

   This is the same as "PyDict_GetItem()", but *key* is specified as a
   "char*", rather than a "PyObject*".

PyObject* PyDict_SetDefault(PyObject *p, PyObject *key, PyObject *default)
    *Return value: Borrowed reference.*

   This is the same as the Python-level "dict.setdefault()".  If
   present, it returns the value corresponding to *key* from the
   dictionary *p*.  If the key is not in the dict, it is inserted with
   value *defaultobj* and *defaultobj* is returned.  This function
   evaluates the hash function of *key* only once, instead of
   evaluating it independently for the lookup and the insertion.

   3.4 新版功能.

PyObject* PyDict_Items(PyObject *p)
    *Return value: New reference.*

   Return a "PyListObject" containing all the items from the
   dictionary.

PyObject* PyDict_Keys(PyObject *p)
    *Return value: New reference.*

   Return a "PyListObject" containing all the keys from the
   dictionary.

PyObject* PyDict_Values(PyObject *p)
    *Return value: New reference.*

   Return a "PyListObject" containing all the values from the
   dictionary *p*.

Py_ssize_t PyDict_Size(PyObject *p)

   Return the number of items in the dictionary.  This is equivalent
   to "len(p)" on a dictionary.

int PyDict_Next(PyObject *p, Py_ssize_t *ppos, PyObject **pkey, PyObject **pvalue)

   Iterate over all key-value pairs in the dictionary *p*.  The
   "Py_ssize_t" referred to by *ppos* must be initialized to "0" prior
   to the first call to this function to start the iteration; the
   function returns true for each pair in the dictionary, and false
   once all pairs have been reported.  The parameters *pkey* and
   *pvalue* should either point to "PyObject*" variables that will be
   filled in with each key and value, respectively, or may be *NULL*.
   Any references returned through them are borrowed.  *ppos* should
   not be altered during iteration. Its value represents offsets
   within the internal dictionary structure, and since the structure
   is sparse, the offsets are not consecutive.

   例如:

      PyObject *key, *value;
      Py_ssize_t pos = 0;

      while (PyDict_Next(self->dict, &pos, &key, &value)) {
          /* do something interesting with the values... */
          ...
      }

   The dictionary *p* should not be mutated during iteration.  It is
   safe to modify the values of the keys as you iterate over the
   dictionary, but only so long as the set of keys does not change.
   For example:

      PyObject *key, *value;
      Py_ssize_t pos = 0;

      while (PyDict_Next(self->dict, &pos, &key, &value)) {
          long i = PyLong_AsLong(value);
          if (i == -1 && PyErr_Occurred()) {
              return -1;
          }
          PyObject *o = PyLong_FromLong(i + 1);
          if (o == NULL)
              return -1;
          if (PyDict_SetItem(self->dict, key, o) < 0) {
              Py_DECREF(o);
              return -1;
          }
          Py_DECREF(o);
      }

int PyDict_Merge(PyObject *a, PyObject *b, int override)

   Iterate over mapping object *b* adding key-value pairs to
   dictionary *a*. *b* may be a dictionary, or any object supporting
   "PyMapping_Keys()" and "PyObject_GetItem()". If *override* is true,
   existing pairs in *a* will be replaced if a matching key is found
   in *b*, otherwise pairs will only be added if there is not a
   matching key in *a*. Return "0" on success or "-1" if an exception
   was raised.

int PyDict_Update(PyObject *a, PyObject *b)

   This is the same as "PyDict_Merge(a, b, 1)" in C, and is similar to
   "a.update(b)" in Python except that "PyDict_Update()" doesn't fall
   back to the iterating over a sequence of key value pairs if the
   second argument has no "keys" attribute.  Return "0" on success or
   "-1" if an exception was raised.

int PyDict_MergeFromSeq2(PyObject *a, PyObject *seq2, int override)

   Update or merge into dictionary *a*, from the key-value pairs in
   *seq2*. *seq2* must be an iterable object producing iterable
   objects of length 2, viewed as key-value pairs.  In case of
   duplicate keys, the last wins if *override* is true, else the first
   wins. Return "0" on success or "-1" if an exception was raised.
   Equivalent Python (except for the return value):

      def PyDict_MergeFromSeq2(a, seq2, override):
          for key, value in seq2:
              if override or key not in a:
                  a[key] = value

int PyDict_ClearFreeList()

   Clear the free list. Return the total number of freed items.

   3.3 新版功能.
