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      1 /*
      2  * Copyright (c) Meta Platforms, Inc. and affiliates.
      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