readers.h

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#ifndef WU_READER_H
#define WU_READER_H
 
#include <stdio.h>
#include "types.h"
#include "data.h"
 
/**
 * Base for a reader, which defines the minimal interface for reading the
 * next data point from a data source and a method to free the reader's
 * resources. The delete method should be called by the runner taking
 * ownership of the reader. It is expected that specific reader
 * implementations will extend this base structure and implement the
 * defined methods.
 */
typedef struct WU_Reader_ {
    void* (*next)(struct WU_Reader_* reader);
    void (*delete)(struct WU_Reader_* reader);
}* WU_Reader;
 
#define wu_reader_next(reader) (((WU_Reader)(reader))->next((WU_Reader)(reader)))
 
#define wu_reader_last_error(reader) ((reader)->last_error)
 
#define wu_reader_delete(reader) do { \
    if ((reader) && ((WU_Reader)(reader))->delete) \
        ((WU_Reader)(reader))->delete((WU_Reader)(reader)); \
} while(0)
 
#define WU_CSV_MAX_LINE_SIZE 2048
#define WU_JSON_MAX_LINE_SIZE 4096
 
typedef enum {
    WU_CSV_OK = 0,
    WU_CSV_ERROR_EOF = 1,
    WU_CSV_ERROR_PARSE = 2
} WU_CsvError;
 
typedef enum {
    WU_JSON_OK = 0,
    WU_JSON_ERROR_EOF = 1,
    WU_JSON_ERROR_PARSE = 2,
    WU_JSON_ERROR_MISSING_FIELD = 3
} WU_JsonError;
 
/**
 * WU_CsvReader is a concrete implementation of the WU_Reader interface that
 * reads data from a CSV file.
 */
typedef struct WU_CsvReader_ {
    struct WU_Reader_ base;
    FILE* file;
    char line_buffer[WU_CSV_MAX_LINE_SIZE];
    bool has_headers;
    WU_DataType data_type;
    WU_CsvError last_error;
    union {
        WU_Candle candle;
        WU_Trade trade;
        WU_Single single_value;
    } data;
}* WU_CsvReader;
 
/**
 * WU_JsonReader is a concrete implementation of the WU_Reader interface that
 * reads data from a JSON Lines file (one valid JSON object per line).
 */
typedef struct WU_JsonReader_ {
    struct WU_Reader_ base;
    FILE* file;
    char line_buffer[WU_JSON_MAX_LINE_SIZE];
    WU_DataType data_type;
    WU_JsonError last_error;
    union {
        WU_Candle candle;
        WU_Trade trade;
        WU_Single single_value;
    } data;
}* WU_JsonReader;
 
WU_CsvReader wu_csv_reader_new(FILE *file, WU_DataType data_type,
        WU_TimeUnit time_units, bool has_headers);
 
WU_JsonReader wu_json_reader_new(FILE *file, WU_DataType data_type,
        WU_TimeUnit time_units);
 
#define WU_READER(r) ((WU_Reader)(r))
#define wu_reader_list(...) ((WU_Reader[]){__VA_ARGS__, NULL})
 
#endif // WU_READER_H