Refactor to introduce pg_locale_deterministic().

Avoids the need of callers to test for NULL, and also avoids the need
to access the pg_locale_t structure directly.

Reviewed-by: Peter Eisentraut, Peter Geoghegan
Discussion: https://postgr.es/m/a581136455c940d7bd0ff482d3a2bd51af25a94f.camel%40j-davis.com

src/backend/access/hash/hashfunc.c

@@ -282,7 +282,7 @@ hashtext(PG_FUNCTION_ARGS)
 	if (!lc_collate_is_c(collid))
 		mylocale = pg_newlocale_from_collation(collid);
 
-	if (!mylocale || mylocale->deterministic)
+	if (pg_locale_deterministic(mylocale))
 	{
 		result = hash_any((unsigned char *) VARDATA_ANY(key),
 						  VARSIZE_ANY_EXHDR(key));
@@ -342,7 +342,7 @@ hashtextextended(PG_FUNCTION_ARGS)
 	if (!lc_collate_is_c(collid))
 		mylocale = pg_newlocale_from_collation(collid);
 
-	if (!mylocale || mylocale->deterministic)
+	if (pg_locale_deterministic(mylocale))
 	{
 		result = hash_any_extended((unsigned char *) VARDATA_ANY(key),
 								   VARSIZE_ANY_EXHDR(key),

src/backend/regex/regc_pg_locale.c

@@ -259,7 +259,7 @@ pg_set_regex_collation(Oid collation)
 		 */
 		pg_regex_locale = pg_newlocale_from_collation(collation);
 
-		if (pg_regex_locale && !pg_regex_locale->deterministic)
+		if (!pg_locale_deterministic(pg_regex_locale))
 			ereport(ERROR,
 					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
 					 errmsg("nondeterministic collations are not supported for regular expressions")));

src/backend/utils/adt/like.c

@@ -155,7 +155,7 @@ GenericMatchText(const char *s, int slen, const char *p, int plen, Oid collation
 	{
 		pg_locale_t locale = pg_newlocale_from_collation(collation);
 
-		if (locale && !locale->deterministic)
+		if (!pg_locale_deterministic(locale))
 			ereport(ERROR,
 					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
 					 errmsg("nondeterministic collations are not supported for LIKE")));
@@ -196,7 +196,7 @@ Generic_Text_IC_like(text *str, text *pat, Oid collation)
 	else
 		locale = pg_newlocale_from_collation(collation);
 
-	if (locale && !locale->deterministic)
+	if (!pg_locale_deterministic(locale))
 		ereport(ERROR,
 				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
 				 errmsg("nondeterministic collations are not supported for ILIKE")));

src/backend/utils/adt/pg_locale.c

@@ -1481,6 +1481,15 @@ report_newlocale_failure(const char *localename)
 }
 #endif							/* HAVE_LOCALE_T */
 
+bool
+pg_locale_deterministic(pg_locale_t locale)
+{
+	/* default locale must always be deterministic */
+	if (locale == NULL)
+		return true;
+	else
+		return locale->deterministic;
+}
 
 /*
  * Create a locale_t from a collation OID.  Results are cached for the

src/backend/utils/adt/varchar.c

@@ -762,7 +762,7 @@ bpchareq(PG_FUNCTION_ARGS)
 	else
 		mylocale = pg_newlocale_from_collation(collid);
 
-	if (locale_is_c || !mylocale || mylocale->deterministic)
+	if (locale_is_c || pg_locale_deterministic(mylocale))
 	{
 		/*
 		 * Since we only care about equality or not-equality, we can avoid all
@@ -807,7 +807,7 @@ bpcharne(PG_FUNCTION_ARGS)
 	else
 		mylocale = pg_newlocale_from_collation(collid);
 
-	if (locale_is_c || !mylocale || mylocale->deterministic)
+	if (locale_is_c || pg_locale_deterministic(mylocale))
 	{
 		/*
 		 * Since we only care about equality or not-equality, we can avoid all
@@ -1015,7 +1015,7 @@ hashbpchar(PG_FUNCTION_ARGS)
 	if (!lc_collate_is_c(collid))
 		mylocale = pg_newlocale_from_collation(collid);
 
-	if (!mylocale || mylocale->deterministic)
+	if (pg_locale_deterministic(mylocale))
 	{
 		result = hash_any((unsigned char *) keydata, keylen);
 	}
@@ -1077,7 +1077,7 @@ hashbpcharextended(PG_FUNCTION_ARGS)
 	if (!lc_collate_is_c(collid))
 		mylocale = pg_newlocale_from_collation(collid);
 
-	if (!mylocale || mylocale->deterministic)
+	if (pg_locale_deterministic(mylocale))
 	{
 		result = hash_any_extended((unsigned char *) keydata, keylen,
 								   PG_GETARG_INT64(1));

src/backend/utils/adt/varlena.c

@@ -1221,7 +1221,7 @@ text_position_setup(text *t1, text *t2, Oid collid, TextPositionState *state)
 	if (!lc_collate_is_c(collid))
 		mylocale = pg_newlocale_from_collation(collid);
 
-	if (mylocale && !mylocale->deterministic)
+	if (!pg_locale_deterministic(mylocale))
 		ereport(ERROR,
 				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
 				 errmsg("nondeterministic collations are not supported for substring searches")));
@@ -1572,8 +1572,7 @@ varstr_cmp(const char *arg1, int len1, const char *arg2, int len2, Oid collid)
 		result = pg_strncoll(arg1, len1, arg2, len2, mylocale);
 
 		/* Break tie if necessary. */
-		if (result == 0 &&
-			(!mylocale || mylocale->deterministic))
+		if (result == 0 && pg_locale_deterministic(mylocale))
 		{
 			result = memcmp(arg1, arg2, Min(len1, len2));
 			if ((result == 0) && (len1 != len2))
@@ -1628,7 +1627,7 @@ texteq(PG_FUNCTION_ARGS)
 	else
 		mylocale = pg_newlocale_from_collation(collid);
 
-	if (locale_is_c || !mylocale || mylocale->deterministic)
+	if (locale_is_c || pg_locale_deterministic(mylocale))
 	{
 		Datum		arg1 = PG_GETARG_DATUM(0);
 		Datum		arg2 = PG_GETARG_DATUM(1);
@@ -1687,7 +1686,7 @@ textne(PG_FUNCTION_ARGS)
 	else
 		mylocale = pg_newlocale_from_collation(collid);
 
-	if (locale_is_c || !mylocale || mylocale->deterministic)
+	if (locale_is_c || pg_locale_deterministic(mylocale))
 	{
 		Datum		arg1 = PG_GETARG_DATUM(0);
 		Datum		arg2 = PG_GETARG_DATUM(1);
@@ -1801,7 +1800,7 @@ text_starts_with(PG_FUNCTION_ARGS)
 	if (!lc_collate_is_c(collid))
 		mylocale = pg_newlocale_from_collation(collid);
 
-	if (mylocale && !mylocale->deterministic)
+	if (!pg_locale_deterministic(mylocale))
 		ereport(ERROR,
 				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
 				 errmsg("nondeterministic collations are not supported for substring searches")));
@@ -2217,8 +2216,7 @@ varstrfastcmp_locale(char *a1p, int len1, char *a2p, int len2, SortSupport ssup)
 	result = pg_strcoll(sss->buf1, sss->buf2, sss->locale);
 
 	/* Break tie if necessary. */
-	if (result == 0 &&
-		(!sss->locale || sss->locale->deterministic))
+	if (result == 0 && pg_locale_deterministic(sss->locale))
 		result = strcmp(sss->buf1, sss->buf2);
 
 	/* Cache result, perhaps saving an expensive strcoll() call next time */

src/include/utils/pg_locale.h

@@ -97,6 +97,7 @@ extern PGDLLIMPORT struct pg_locale_struct default_locale;
 extern void make_icu_collator(const char *iculocstr,
 							  struct pg_locale_struct *resultp);
 
+extern bool pg_locale_deterministic(pg_locale_t locale);
 extern pg_locale_t pg_newlocale_from_collation(Oid collid);
 
 extern char *get_collation_actual_version(char collprovider, const char *collcollate);