1 /*
2  * Copyright (c) 2016-present, Yann Collet, Facebook, Inc.
3  * All rights reserved.
4  *
5  * This source code is licensed under both the BSD-style license (found in the
6  * LICENSE file in the root directory of this source tree) and the GPLv2 (found
7  * in the COPYING file in the root directory of this source tree).
8  * You may select, at your option, one of the above-listed licenses.
9  */
10 
11 #ifndef METHOD_H
12 #define METHOD_H
13 
14 #include <stddef.h>
15 
16 #include "data.h"
17 #include "config.h"
18 #include "result.h"
19 
20 /**
21  * The base class for state that methods keep.
22  * All derived method state classes must have a member of this type.
23  */
24 typedef struct {
25     data_t const* data;
26 } method_state_t;
27 
28 /**
29  * A method that compresses the data using config.
30  */
31 typedef struct {
32     char const* name;  /**< The identifier for this method in the results. */
33     /**
34      * Creates a state that must contain a member variable of method_state_t,
35      * and returns a pointer to that member variable.
36      *
37      * This method can be used to do expensive work that only depends on the
38      * data, like loading the data file into a buffer.
39      */
40     method_state_t* (*create)(data_t const* data);
41     /**
42      * Compresses the data in the state using the given config.
43      *
44      * @param state A pointer to the state returned by create().
45      *
46      * @returns The total compressed size on success, or an error code.
47      */
48     result_t (*compress)(method_state_t* state, config_t const* config);
49     /**
50      * Frees the state.
51      */
52     void (*destroy)(method_state_t* state);
53 } method_t;
54 
55 /**
56  * Set the zstd cli path. Must be called before any methods are used.
57  */
58 void method_set_zstdcli(char const* zstdcli);
59 
60 /**
61  * A NULL-terminated list of methods.
62  */
63 extern method_t const* const* methods;
64 
65 #endif
66