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C API is a part of the official RL3 binary package. In order to install it, please consult the Installation Guide page.

Example usage

#include <stdio.h>
#include <stdlib.h>

#include <rl3.h>

/* check for engine execution errors */
void check_for_errors(struct RL3_Engine* engine)
    if (rl3_engine_has_error(engine) != 0)
        printf("Failed with error: %s\n", rl3_engine_get_error_str(engine));

int main(void)
    /* create engine and init it as "rl3" engine */
    struct RL3_Engine* engine = rl3_engine_create(); check_for_errors(engine);
    rl3_engine_init(engine, "rl3"); check_for_errors(engine);

    /* parse and compile (link) simple annotation pattern */
    const char* definition = rl3_make_simple_annotation_def(engine, "text", "(?i:{dawg continent})", "continent"); check_for_errors(engine);
    rl3_engine_parse_inline(engine, definition, ".", 1); check_for_errors(engine);
    rl3_engine_link(engine, 1); check_for_errors(engine);

    /* create factsheet */
    struct RL3_Factsheet* fs = rl3_factsheet_create(engine); check_for_errors(engine);

    /* assert input text */
    rl3_factsheet_assert_simple_fact(engine, fs, "text", "Antarctica is Earth's southernmost continent... Europe is the sixth largest continent in size.", 1.0);

    /* run engine - it should now annotate a continent names mentioned in our text */
    rl3_engine_update(engine, fs); check_for_errors(engine);

    /* iterate and print all "continent" annotations */
    struct RL3_FactIterator* i = rl3_factsheet_get_fact_iterator(engine, fs, "continent"); check_for_errors(engine);
    while (!rl3_factiterator_is_end(engine, i))
        printf("%s\n", rl3_factiterator_get_value(engine, i)); check_for_errors(engine);
        rl3_factiterator_next(engine, i); check_for_errors(engine);
    /* release iterator */
    rl3_factiterator_destroy(engine, i); check_for_errors(engine);

    /* release factsheet */
    rl3_factsheet_destroy(engine, fs); check_for_errors(engine);

    /* release engine */

    return 0;



General notes

  • Use a -lrl3 compiler flag to link an RL3 library.
  • Almost every API call should be followed by an error check. In most cases errors can be interpreted as critical:
if (rl3_engine_has_error(engine) != 0)
    printf("Failed with error: %s\n", rl3_engine_get_error_str(engine));
  • Engine instance must be created first and deleted last!
  • All const char* are zero terminated UTF-8 encoded strings.
  • Positional parameters always contain symbol coordinates, which may differ from byte coordinates in case of UTF-8 encoded unicode symbols.
  • All const char* return values that must be copied (strcpy) or printed immediately after retrieving.
  • In case of const pointers, ownership is NOT transferred.
  • rl3_fact_get_factsheet does NOT transfer ownership of a return value.
  • In multithreading environment RL3 resources should not be shared between threads.