text: #ifndef INCLUDE_LLHTTP_API_H_
  #define INCLUDE_LLHTTP_API_H_
  #ifdef __cplusplus
  extern "C" {
  #endif
  #include <stddef.h>
  
  #if defined(__wasm__)
  #define LLHTTP_EXPORT __attribute__((visibility("default")))
  #else
  #define LLHTTP_EXPORT
  #endif
  
  typedef llhttp__internal_t llhttp_t;
  typedef struct llhttp_settings_s llhttp_settings_t;
  
  typedef int (*llhttp_data_cb)(llhttp_t*, const char *at, size_t length);
  typedef int (*llhttp_cb)(llhttp_t*);
  
  struct llhttp_settings_s {
    /* Possible return values 0, -1, `HPE_PAUSED` */
    llhttp_cb      on_message_begin;
  
    /* Possible return values 0, -1, HPE_USER */
    llhttp_data_cb on_url;
    llhttp_data_cb on_status;
    llhttp_data_cb on_header_field;
    llhttp_data_cb on_header_value;
  
    /* Possible return values:
     * 0  - Proceed normally
     * 1  - Assume that request/response has no body, and proceed to parsing the
     *      next message
     * 2  - Assume absence of body (as above) and make `llhttp_execute()` return
     *      `HPE_PAUSED_UPGRADE`
     * -1 - Error
     * `HPE_PAUSED`
     */
    llhttp_cb      on_headers_complete;
  
    /* Possible return values 0, -1, HPE_USER */
    llhttp_data_cb on_body;
  
    /* Possible return values 0, -1, `HPE_PAUSED` */
    llhttp_cb      on_message_complete;
  
    /* When on_chunk_header is called, the current chunk length is stored
     * in parser->content_length.
     * Possible return values 0, -1, `HPE_PAUSED`
     */
    llhttp_cb      on_chunk_header;
    llhttp_cb      on_chunk_complete;
  
    /* Information-only callbacks, return value is ignored */
    llhttp_cb      on_url_complete;
    llhttp_cb      on_status_complete;
    llhttp_cb      on_header_field_complete;
    llhttp_cb      on_header_value_complete;
  };
  
  /* Initialize the parser with specific type and user settings.
   *
   * NOTE: lifetime of `settings` has to be at least the same as the lifetime of
   * the `parser` here. In practice, `settings` has to be either a static
   * variable or be allocated with `malloc`, `new`, etc.
   */
  LLHTTP_EXPORT
  void llhttp_init(llhttp_t* parser, llhttp_type_t type,
                   const llhttp_settings_t* settings);
  
  LLHTTP_EXPORT
  llhttp_t* llhttp_alloc(llhttp_type_t type);
  
  LLHTTP_EXPORT
  void llhttp_free(llhttp_t* parser);
  
  LLHTTP_EXPORT
  uint8_t llhttp_get_type(llhttp_t* parser);
  
  LLHTTP_EXPORT
  uint8_t llhttp_get_http_major(llhttp_t* parser);
  
  LLHTTP_EXPORT
  uint8_t llhttp_get_http_minor(llhttp_t* parser);
  
  LLHTTP_EXPORT
  uint8_t llhttp_get_method(llhttp_t* parser);
  
  LLHTTP_EXPORT
  int llhttp_get_status_code(llhttp_t* parser);
  
  LLHTTP_EXPORT
  uint8_t llhttp_get_upgrade(llhttp_t* parser);
  
  /* Reset an already initialized parser back to the start state, preserving the
   * existing parser type, callback settings, user data, and lenient flags.
   */
  LLHTTP_EXPORT
  void llhttp_reset(llhttp_t* parser);
  
  /* Initialize the settings object */
  LLHTTP_EXPORT
  void llhttp_settings_init(llhttp_settings_t* settings);
  
  /* Parse full or partial request/response, invoking user callbacks along the
   * way.
   *
   * If any of `llhttp_data_cb` returns errno not equal to `HPE_OK` - the parsing
   * interrupts, and such errno is returned from `llhttp_execute()`. If
   * `HPE_PAUSED` was used as a errno, the execution can be resumed with
   * `llhttp_resume()` call.
   *
   * In a special case of CONNECT/Upgrade request/response `HPE_PAUSED_UPGRADE`
   * is returned after fully parsing the request/response. If the user wishes to
   * continue parsing, they need to invoke `llhttp_resume_after_upgrade()`.
   *
   * NOTE: if this function ever returns a non-pause type error, it will continue
   * to return the same error upon each successive call up until `llhttp_init()`
   * is called.
   */
  LLHTTP_EXPORT
  llhttp_errno_t llhttp_execute(llhttp_t* parser, const char* data, size_t len);
  
  /* This method should be called when the other side has no further bytes to
   * send (e.g. shutdown of readable side of the TCP connection.)
   *
   * Requests without `Content-Length` and other messages might require treating
   * all incoming bytes as the part of the body, up to the last byte of the
   * connection. This method will invoke `on_message_complete()` callback if the
   * request was terminated safely. Otherwise a error code would be returned.
   */
  LLHTTP_EXPORT
  llhttp_errno_t llhttp_finish(llhttp_t* parser);
  
  /* Returns `1` if the incoming message is parsed until the last byte, and has
   * to be completed by calling `llhttp_finish()` on EOF
   */
  LLHTTP_EXPORT
  int llhttp_message_needs_eof(const llhttp_t* parser);
  
  /* Returns `1` if there might be any other messages following the last that was
   * successfully parsed.
   */
  LLHTTP_EXPORT
  int llhttp_should_keep_alive(const llhttp_t* parser);
  
  /* Make further calls of `llhttp_execute()` return `HPE_PAUSED` and set
   * appropriate error reason.
   *
   * Important: do not call this from user callbacks! User callbacks must return
   * `HPE_PAUSED` if pausing is required.
   */
  LLHTTP_EXPORT
  void llhttp_pause(llhttp_t* parser);
  
  /* Might be called to resume the execution after the pause in user's callback.
   * See `llhttp_execute()` above for details.
   *
   * Call this only if `llhttp_execute()` returns `HPE_PAUSED`.
   */
  LLHTTP_EXPORT
  void llhttp_resume(llhttp_t* parser);
  
  /* Might be called to resume the execution after the pause in user's callback.
   * See `llhttp_execute()` above for details.
   *
   * Call this only if `llhttp_execute()` returns `HPE_PAUSED_UPGRADE`
   */
  LLHTTP_EXPORT
  void llhttp_resume_after_upgrade(llhttp_t* parser);
  
  /* Returns the latest return error */
  LLHTTP_EXPORT
  llhttp_errno_t llhttp_get_errno(const llhttp_t* parser);
  
  /* Returns the verbal explanation of the latest returned error.
   *
   * Note: User callback should set error reason when returning the error. See
   * `llhttp_set_error_reason()` for details.
   */
  LLHTTP_EXPORT
  const char* llhttp_get_error_reason(const llhttp_t* parser);
  
  /* Assign verbal description to the returned error. Must be called in user
   * callbacks right before returning the errno.
   *
   * Note: `HPE_USER` error code might be useful in user callbacks.
   */
  LLHTTP_EXPORT
  void llhttp_set_error_reason(llhttp_t* parser, const char* reason);
  
  /* Returns the pointer to the last parsed byte before the returned error. The
   * pointer is relative to the `data` argument of `llhttp_execute()`.
   *
   * Note: this method might be useful for counting the number of parsed bytes.
   */
  LLHTTP_EXPORT
  const char* llhttp_get_error_pos(const llhttp_t* parser);
  
  /* Returns textual name of error code */
  LLHTTP_EXPORT
  const char* llhttp_errno_name(llhttp_errno_t err);
  
  /* Returns textual name of HTTP method */
  LLHTTP_EXPORT
  const char* llhttp_method_name(llhttp_method_t method);
  
  
  /* Enables/disables lenient header value parsing (disabled by default).
   *
   * Lenient parsing disables header value token checks, extending llhttp's
   * protocol support to highly non-compliant clients/server. No
   * `HPE_INVALID_HEADER_TOKEN` will be raised for incorrect header values when
   * lenient parsing is "on".
   *
   * **(USE AT YOUR OWN RISK)**
   */
  LLHTTP_EXPORT
  void llhttp_set_lenient_headers(llhttp_t* parser, int enabled);
  
  
  /* Enables/disables lenient handling of conflicting `Transfer-Encoding` and
   * `Content-Length` headers (disabled by default).
   *
   * Normally `llhttp` would error when `Transfer-Encoding` is present in
   * conjunction with `Content-Length`. This error is important to prevent HTTP
   * request smuggling, but may be less desirable for small number of cases
   * involving legacy servers.
   *
   * **(USE AT YOUR OWN RISK)**
   */
  LLHTTP_EXPORT
  void llhttp_set_lenient_chunked_length(llhttp_t* parser, int enabled);
  
  
  /* Enables/disables lenient handling of `Connection: close` and HTTP/1.0
   * requests responses.
   *
   * Normally `llhttp` would error on (in strict mode) or discard (in loose mode)
   * the HTTP request/response after the request/response with `Connection: close`
   * and `Content-Length`. This is important to prevent cache poisoning attacks,
   * but might interact badly with outdated and insecure clients. With this flag
   * the extra request/response will be parsed normally.
   *
   * **(USE AT YOUR OWN RISK)**
   */
  void llhttp_set_lenient_keep_alive(llhttp_t* parser, int enabled);
  
  #ifdef __cplusplus
  }  /* extern "C" */
  #endif
  #endif  /* INCLUDE_LLHTTP_API_H_ */
  