Results

No Results
DatabaseError: Databased failed
Recieved Results 2:
  0: abc
  1: abc
Done

test-data.c

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

/* Data QueryResult = NoResult | DatabaseError String | Results [String] */
enum {NoResult, DatabaseError, Results};
struct QueryResult {
    int type;
    union {
        char* error_msg;
        struct {
            char** msgs;
            int len;
        } results;
    };
};

void noResult(struct QueryResult* results) {
    results->type = NoResult;
}

void databaseError(struct QueryResult* results) {
    results->type = DatabaseError;
    results->error_msg = "Databased failed\n";
}

void success(struct QueryResult* query_results) {
    int i=0;
    query_results->type = Results;
    query_results->results.msgs = malloc(sizeof(char*) * 2);
    for (i=0;i<2;i++) {
        query_results->results.msgs[i] = "abc";
    }
    query_results->results.len = 2;
}

void printQueryResult(struct QueryResult* query_results) {
    switch (query_results->type) {
        case NoResult:
            printf("No Results\n");
            break;
        case DatabaseError:
            printf("DatabaseError: %s", query_results->error_msg);
            break;
        case Results:
            printf("Recieved Results %d:\n", query_results->results.len);
            int i;
            for (i = 0; i < query_results->results.len; i++) {
                printf("  %d: %s\n", i, query_results->results.msgs[i]);
            }
            break;
    }
}

void freeQuery(struct QueryResult* query_results) {
    if (query_results->type == Results) {
        free(query_results->results.msgs);
    }
}

int main(int argc, char** argv) {
    struct QueryResult query;

    noResult(&query);
    printQueryResult(&query);


    databaseError(&query);
    printQueryResult(&query);


    success(&query);
    printQueryResult(&query);

    freeQuery(&query);

    printf("Done\n");
    
    return 0;
}