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/*
* icu_transform.c
*
* Part of icu_ext: a PostgreSQL extension to expose functionality from ICU
* (see http://icu-project.org)
*
* By Daniel Vérité, 2018-2025. See LICENSE.md
*/
#include "icu_ext.h"
#include "funcapi.h"
#include "utils/builtins.h"
#include "utils/pg_locale.h"
#include "utils/memutils.h"
#include "unicode/uenum.h"
#include "unicode/utrans.h"
PG_FUNCTION_INFO_V1(icu_transforms_list);
PG_FUNCTION_INFO_V1(icu_transform);
/*
* List the available pre-defined transforms/transliterations.
*/
Datum
icu_transforms_list(PG_FUNCTION_ARGS)
{
FuncCallContext *funcctx;
UErrorCode status = U_ZERO_ERROR;
UEnumeration *en;
const char *elt;
if (SRF_IS_FIRSTCALL())
{
funcctx = SRF_FIRSTCALL_INIT();
en = utrans_openIDs(&status);
if (U_FAILURE(status))
elog(ERROR, "utrans_openIDs failed: %s", u_errorName(status));
funcctx->user_fctx = (void *)en;
}
funcctx = SRF_PERCALL_SETUP();
en = (UEnumeration*) funcctx->user_fctx;
elt = uenum_next(en, NULL, &status);
if (U_FAILURE(status))
elog(ERROR, "uenum_next failed: %s", u_errorName(status));
if (elt)
{
text* item = cstring_to_text(elt);
SRF_RETURN_NEXT(funcctx, PointerGetDatum(item));
}
else
{
uenum_close(en);
SRF_RETURN_DONE(funcctx);
}
}
/*
* Cache for the last transformation used.
* This may come in handy in applications that use several times the same transformation
*/
static UTransliterator *utrans = NULL;
static char *cached_utrans_id = NULL;
/*
* Main function to apply a transformation based on UTransliterator.
* Input:
* 1st arg: string to transform
* 2nd arg: name (system identifier) of the transliterator
*/
Datum
icu_transform(PG_FUNCTION_ARGS)
{
text *arg1 = PG_GETARG_TEXT_PP(0);
text *arg2 = PG_GETARG_TEXT_PP(1);
int32_t len1 = VARSIZE_ANY_EXHDR(arg1);
const char *input_id = text_to_cstring(arg2);
UErrorCode status = U_ZERO_ERROR;
int32_t ulen, limit, capacity, start, original_ulen;
int32_t result_len, in_ulen;
UChar* utext;
UChar* trans_id;
char* result;
UChar* original;
bool done = false;
if (cached_utrans_id != NULL)
{
if (strcmp(cached_utrans_id, input_id) != 0)
{
pfree(cached_utrans_id);
cached_utrans_id = NULL;
utrans_close(utrans);
utrans = NULL;
}
}
if (utrans == NULL)
{
in_ulen = string_to_uchar(&trans_id, input_id, strlen(input_id));
utrans = utrans_openU(trans_id,
in_ulen,
UTRANS_FORWARD,
NULL, /* rules. NULL for system transliterators */
-1,
NULL, /* pointer to parseError. Not used */
&status);
if (U_FAILURE(status) || !utrans)
{
elog(ERROR, "utrans_open failed: %s", u_errorName(status));
}
else
{
cached_utrans_id = MemoryContextStrdup(TopMemoryContext, input_id);
}
}
ulen = string_to_uchar(&utext, text_to_cstring(arg1), len1);
/* utext is terminated by a zero UChar that we include in the copy. */
original = (UChar*) palloc((ulen+1)*sizeof(UChar));
original_ulen = ulen;
memcpy(original, utext, (ulen+1)*sizeof(UChar));
limit = ulen;
capacity = ulen + 1;
start = 0;
/*
* utrans_transUChars() updates the string in-place, stopping if
* it would go over `capacity`.
* The following loop doubles the capacity and restarts from
* scratch with a clean copy of the source if the buffer was
* too small.
* Although it looks like we could use `start` and `limit`
* to reallocate and make the transliteration continue from
* where it stopped, in practice this does not appear to work.
* The documentation is quite unclear about this function.
*/
do {
status = U_ZERO_ERROR;
utrans_transUChars(utrans,
utext,
&ulen,
capacity,
start, /* beginning index */
&limit,
&status);
if (U_FAILURE(status))
{
if (status != U_BUFFER_OVERFLOW_ERROR)
{
elog(ERROR, "utrans_transUChars failed: %s", u_errorName(status));
}
else
{
pfree(utext);
capacity = capacity * 2;
utext = (UChar*) palloc(capacity*sizeof(UChar));
/* restore the original text in the enlarged buffer */
ulen = original_ulen;
limit = ulen;
memcpy(utext, original, (ulen+1)*sizeof(UChar));
}
}
else
done = true;
} while (!done);
result_len = string_from_uchar(&result, utext, ulen);
PG_RETURN_TEXT_P(cstring_to_text_with_len(result, result_len));
}
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