@function

@function is used to refer to the function. The comment block is used for the document for the function. After the script sees the end of the comment block, it consumes the lines as the function declaration until the line which ends with ; is encountered.

In Sphinx doc, usually the function argument is formatted like *this*. But in C, * is used for dereferencing a pointer and we must escape * with a back slash. To avoid this, we format the argument like |this|. The mkapiref.py translates it with *this*, as escaping * inside | and | as necessary. Note that this shadows the substitution feature of Sphinx.

The example follows:

/**
 * @function
 *
 * Submits PING frame to the |session|.
 */
int nghttp2_submit_ping(nghttp2_session *session);

@functypedef

@functypedef is used to refer to the typedef of the function pointer. The formatting rule is pretty much the same with @function, but this outputs type domain, rather than function domain.

The example follows:

/**
 * @functypedef
 *
 * Callback function invoked when |session| wants to send data to
 * remote peer.
 */
typedef ssize_t (*nghttp2_send_callback)
(nghttp2_session *session,
 const uint8_t *data, size_t length, int flags, void *user_data);

@enum

@enum is used to refer to the enum. Currently, only enum typedefs are supported. The comment block is used for the document for the enum type itself. To document each values, put comment block starting with the line /** and ending with the */ just before the enum value. When the line starts with } is encountered, the mkapiref.py extracts strings next to } as the name of enum.

At the time of this writing, Sphinx does not support enum type. So we use type domain for enum it self and macro domain for each value. To refer to the enum value, use :enum: pseudo role. The mkapiref.py replaces it with :macro:. By doing this, when Sphinx will support enum officially, we can replace :enum: with the official role easily.

The example follows:

/**
 * @enum
 * Error codes used in the nghttp2 library.
 */
typedef enum {
  /**
   * Invalid argument passed.
   */
  NGHTTP2_ERR_INVALID_ARGUMENT = -501,
  /**
   * Zlib error.
   */
  NGHTTP2_ERR_ZLIB = -502,
} nghttp2_error;

@struct

@struct is used to refer to the struct. Currently, only struct typedefs are supported. The comment block is used for the document for the struct type itself.To document each member, put comment block starting with the line /** and ending with the */ just before the member. When the line starts with } is encountered, the mkapiref.py extracts strings next to } as the name of struct. The block-less typedef is also supported. In this case, typedef declaration must be all in one line and the mkapiref.py uses last word as the name of struct.

Some examples follow:

/**
 * @struct
 * The control frame header.
 */
typedef struct {
  /**
   * SPDY protocol version.
   */
  uint16_t version;
  /**
   * The type of this control frame.
   */
  uint16_t type;
  /**
   * The control frame flags.
   */
  uint8_t flags;
  /**
   * The length field of this control frame.
   */
  int32_t length;
} nghttp2_ctrl_hd;

/**
 * @struct
 *
 * The primary structure to hold the resources needed for a SPDY
 * session. The details of this structure is hidden from the public
 * API.
 */
typedef struct nghttp2_session nghttp2_session;

@union

@union is used to refer to the union. Currently, @union is an alias of @struct.