generator.h

#ifndef GENERATOR_H

#define GENERATOR_H

#include <stddef.h>

#include <stdbool.h>

#include <sys/types.h>

#define UNPACK(...) __VA_ARGS__

#define DECLARE_GENERATOR(NAME, INPUT, YIELDS) \

  struct gen_result_ ## NAME { \

    UNPACK YIELDS \

  }; \

  struct gen_args_ ## NAME { \

    UNPACK INPUT \

  }; \

  int gen_func_ ## NAME(void* private, int(*const yield)(void* private, struct gen_result_ ## NAME*), const struct gen_args_ ## NAME*const args);

#define DEFINE_GENERATOR(NAME, INPUT, YIELDS, BODY) \

  int gen_func_ ## NAME(void* private, int(*const yield)(void* private, struct gen_result_ ## NAME*), const struct gen_args_ ## NAME*const args){ \

    typedef struct gen_result_ ## NAME gen_result_type; \

    UNPACK BODY \

  }

#define GENERATOR_YIELD(...) do { if(yield(private, &(gen_result_type){__VA_ARGS__})) return -1; } while(0)

#define GENERATOR_TO_GENERIC(NAME) ((generic_generator_callback)(gen_func_ ## NAME))

#define GENERATOR_COUNT(NAME, ARGS) generator_count(GENERATOR_TO_GENERIC(NAME), &(struct gen_args_ ## NAME){ UNPACK ARGS })

#define GENERATOR_CALL(PRIVATE, NAME, ARGS) gen_func_ ## NAME((PRIVATE), GENERATOR_TO_GENERIC(NAME), &(struct gen_args_ ## NAME){ UNPACK ARGS })

#define GENERATOR_TO_ARRAY(NAME, ARGS, N, RES, REVERSE) generator_to_array(GENERATOR_TO_GENERIC(NAME), &(struct gen_args_ ## NAME){ UNPACK ARGS }, sizeof(struct gen_result_ ## NAME), (N), (void**)(struct gen_result_ ## NAME**){(RES)}, (REVERSE))

typedef int(*generic_generator_callback)(void* private, int(*const yield)(void*, void*), const void*const args);

int generator_count( const generic_generator_callback generator, const void*const args );

int generator_to_array( const generic_generator_callback generator, const void*const args, size_t result_size, size_t* n, void** result, bool reverse);

#endif