Support reloptions of enum type

All our current in core relation options of type string (not many,
admittedly) behave in reality like enums.  But after seeing an
implementation for enum reloptions, it's clear that strings are messier,
so introduce the new reloption type.  Switch all string options to be
enums instead.

Fortunately we have a recently introduced test module for reloptions, so
we don't lose coverage of string reloptions, which may still be used by
third-party modules.

Authors: Nikolay Shaplov, Álvaro Herrera
Reviewed-by: Nikita Glukhov, Aleksandr Parfenov
Discussion: https://postgr.es/m/43332102.S2V5pIjXRx@x200m

2 files changed, 40 insertions, 7 deletions

diff --git a/src/test/modules/dummy_index_am/dummy_index_am.c b/src/test/modules/dummy_index_am/dummy_index_am.c
index 59a918bd613..bc68767f3a0 100644
--- a/src/test/modules/dummy_index_am/dummy_index_am.c
+++ b/src/test/modules/dummy_index_am/dummy_index_am.c
@@ -25,11 +25,16 @@ PG_MODULE_MAGIC;
 void		_PG_init(void);
 
 /* parse table for fillRelOptions */
-relopt_parse_elt di_relopt_tab[5];
+relopt_parse_elt di_relopt_tab[6];
 
 /* Kind of relation options for dummy index */
 relopt_kind di_relopt_kind;
 
+typedef enum DummyAmEnum {
+	DUMMY_AM_ENUM_ONE,
+	DUMMY_AM_ENUM_TWO
+} DummyAmEnum;
+
 /* Dummy index options */
 typedef struct DummyIndexOptions
 {
@@ -37,10 +42,18 @@ typedef struct DummyIndexOptions
 	int			option_int;
 	double		option_real;
 	bool		option_bool;
+	DummyAmEnum	option_enum;
 	int			option_string_val_offset;
 	int			option_string_null_offset;
 } DummyIndexOptions;
 
+relopt_enum_elt_def dummyAmEnumValues[] =
+{
+	{"one", DUMMY_AM_ENUM_ONE},
+	{"two", DUMMY_AM_ENUM_TWO},
+	{(const char *)NULL}		/* list terminator */
+};
+
 /* Handler for index AM */
 PG_FUNCTION_INFO_V1(dihandler);
 
@@ -85,13 +98,23 @@ create_reloptions_table(void)
 	di_relopt_tab[2].opttype = RELOPT_TYPE_BOOL;
 	di_relopt_tab[2].offset = offsetof(DummyIndexOptions, option_bool);
 
+	add_enum_reloption(di_relopt_kind, "option_enum",
+					   "Enum option for dummy_index_am",
+					   dummyAmEnumValues,
+					   DUMMY_AM_ENUM_ONE,
+					   "Valid values are \"one\" and \"two\".",
+					   AccessExclusiveLock);
+	di_relopt_tab[3].optname = "option_enum";
+	di_relopt_tab[3].opttype = RELOPT_TYPE_ENUM;
+	di_relopt_tab[3].offset = offsetof(DummyIndexOptions, option_enum);
+
 	add_string_reloption(di_relopt_kind, "option_string_val",
 						 "String option for dummy_index_am with non-NULL default",
 						 "DefaultValue", &validate_string_option,
 						 AccessExclusiveLock);
-	di_relopt_tab[3].optname = "option_string_val";
-	di_relopt_tab[3].opttype = RELOPT_TYPE_STRING;
-	di_relopt_tab[3].offset = offsetof(DummyIndexOptions,
+	di_relopt_tab[4].optname = "option_string_val";
+	di_relopt_tab[4].opttype = RELOPT_TYPE_STRING;
+	di_relopt_tab[4].offset = offsetof(DummyIndexOptions,
 									   option_string_val_offset);
 
 	/*
@@ -102,9 +125,9 @@ create_reloptions_table(void)
 						 NULL,	/* description */
 						 NULL, &validate_string_option,
 						 AccessExclusiveLock);
-	di_relopt_tab[4].optname = "option_string_null";
-	di_relopt_tab[4].opttype = RELOPT_TYPE_STRING;
-	di_relopt_tab[4].offset = offsetof(DummyIndexOptions,
+	di_relopt_tab[5].optname = "option_string_null";
+	di_relopt_tab[5].opttype = RELOPT_TYPE_STRING;
+	di_relopt_tab[5].offset = offsetof(DummyIndexOptions,
 									   option_string_null_offset);
 }
 
diff --git a/src/test/modules/dummy_index_am/sql/reloptions.sql b/src/test/modules/dummy_index_am/sql/reloptions.sql
index be3457562f1..0172cf094e6 100644
--- a/src/test/modules/dummy_index_am/sql/reloptions.sql
+++ b/src/test/modules/dummy_index_am/sql/reloptions.sql
@@ -32,12 +32,15 @@ ALTER INDEX dummy_test_idx SET (option_bool = true);
 ALTER INDEX dummy_test_idx SET (option_real = 3.2);
 ALTER INDEX dummy_test_idx SET (option_string_val = 'val2');
 ALTER INDEX dummy_test_idx SET (option_string_null = NULL);
+ALTER INDEX dummy_test_idx SET (option_enum = 'one');
+ALTER INDEX dummy_test_idx SET (option_enum = 'three');
 SELECT unnest(reloptions) FROM pg_class WHERE relname = 'dummy_test_idx';
 
 -- ALTER INDEX .. RESET
 ALTER INDEX dummy_test_idx RESET (option_int);
 ALTER INDEX dummy_test_idx RESET (option_bool);
 ALTER INDEX dummy_test_idx RESET (option_real);
+ALTER INDEX dummy_test_idx RESET (option_enum);
 ALTER INDEX dummy_test_idx RESET (option_string_val);
 ALTER INDEX dummy_test_idx RESET (option_string_null);
 SELECT unnest(reloptions) FROM pg_class WHERE relname = 'dummy_test_idx';
@@ -62,6 +65,13 @@ ALTER INDEX dummy_test_idx SET (option_real = true); -- error
 ALTER INDEX dummy_test_idx SET (option_real = 'val5'); -- error
 SELECT unnest(reloptions) FROM pg_class WHERE relname = 'dummy_test_idx';
 ALTER INDEX dummy_test_idx RESET (option_real);
+-- Enum
+ALTER INDEX dummy_test_idx SET (option_enum = 'one'); -- ok
+ALTER INDEX dummy_test_idx SET (option_enum = 0); -- error
+ALTER INDEX dummy_test_idx SET (option_enum = true); -- error
+ALTER INDEX dummy_test_idx SET (option_enum = 'three'); -- error
+SELECT unnest(reloptions) FROM pg_class WHERE relname = 'dummy_test_idx';
+ALTER INDEX dummy_test_idx RESET (option_enum);
 -- String
 ALTER INDEX dummy_test_idx SET (option_string_val = 4); -- ok
 ALTER INDEX dummy_test_idx SET (option_string_val = 3.5); -- ok