/* wrapper for Levenshtein string comparison */
void levenshtein_wrapper(sqlite3_context *ctx, int n_values, sqlite3_value **value)
{
// check for NULL values, return NULL if any of the input strings is NULL
if(sqlite3_value_type(value[0]) == SQLITE_NULL ||
sqlite3_value_type(value[1]) == SQLITE_NULL)
{
sqlite3_result_null(ctx);
return;
}
const unsigned char *str1 = sqlite3_value_text(value[0]);
const unsigned char *str2 = sqlite3_value_text(value[1]);
#ifdef DEBUG
Rprintf("String 1: %s\n", str1);
Rprintf("String 2: %s\n", str2);
#endif
double result;
int editDistance;
editDistance = levenshtein_internal(str1, str2, 1, 1, 1);
/* Only the string metric based on the edit distance is used in this
package, therefore transform right here */
result = 1.0 - (double) editDistance / (double) max(strlen(str1), strlen(str2));
#ifdef DEBUG
Rprintf("Ergebnis des Stringvergleichs: %f\n", result);
#endif
sqlite3_result_double(ctx, result);
}
Datum
levenshtein(PG_FUNCTION_ARGS)
{
text *src = PG_GETARG_TEXT_PP(0);
text *dst = PG_GETARG_TEXT_PP(1);
PG_RETURN_INT32(levenshtein_internal(src, dst, 1, 1, 1));
}
Datum
levenshtein_with_costs(PG_FUNCTION_ARGS)
{
text *src = PG_GETARG_TEXT_PP(0);
text *dst = PG_GETARG_TEXT_PP(1);
int ins_c = PG_GETARG_INT32(2);
int del_c = PG_GETARG_INT32(3);
int sub_c = PG_GETARG_INT32(4);
PG_RETURN_INT32(levenshtein_internal(src, dst, ins_c, del_c, sub_c));
}
