Refactor subtype field of AlterDomainStmt

AlterDomainStmt.subtype used characters for its subtypes of commands,
SET|DROP DEFAULT|NOT NULL and ADD|DROP|VALIDATE CONSTRAINT, which were
hardcoded in a couple of places of the code.  The code is improved by
using an enum instead, with the same character values as the original
code.

Note that the field was documented in parsenodes.h and that it forgot to
mention 'V' (VALIDATE CONSTRAINT).

Author: Quan Zongliang <[email protected]>
Reviewed-by: Peter Eisentraut <[email protected]>
Reviewed-by: wenhui qiu <[email protected]>
Reviewed-by: Tender Wang <[email protected]>
Discussion: https://postgr.es/m/[email protected]

5 files changed, 26 insertions, 22 deletions

diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index f9f594b44cf..6c5cb068013 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -15726,7 +15726,7 @@ ATPostAlterTypeParse(Oid oldId, Oid oldRelId, Oid refRelId, char *cmd,
 		{
 			AlterDomainStmt *stmt = (AlterDomainStmt *) stm;
 
-			if (stmt->subtype == 'C')	/* ADD CONSTRAINT */
+			if (stmt->subtype == AD_AddConstraint)
 			{
 				Constraint *con = castNode(Constraint, stmt->def);
 				AlterTableCmd *cmd = makeNode(AlterTableCmd);
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index a2e084b8f64..a751bf0d531 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -11665,7 +11665,7 @@ AlterDomainStmt:
 				{
 					AlterDomainStmt *n = makeNode(AlterDomainStmt);
 
-					n->subtype = 'T';
+					n->subtype = AD_AlterDefault;
 					n->typeName = $3;
 					n->def = $4;
 					$$ = (Node *) n;
@@ -11675,7 +11675,7 @@ AlterDomainStmt:
 				{
 					AlterDomainStmt *n = makeNode(AlterDomainStmt);
 
-					n->subtype = 'N';
+					n->subtype = AD_DropNotNull;
 					n->typeName = $3;
 					$$ = (Node *) n;
 				}
@@ -11684,7 +11684,7 @@ AlterDomainStmt:
 				{
 					AlterDomainStmt *n = makeNode(AlterDomainStmt);
 
-					n->subtype = 'O';
+					n->subtype = AD_SetNotNull;
 					n->typeName = $3;
 					$$ = (Node *) n;
 				}
@@ -11693,7 +11693,7 @@ AlterDomainStmt:
 				{
 					AlterDomainStmt *n = makeNode(AlterDomainStmt);
 
-					n->subtype = 'C';
+					n->subtype = AD_AddConstraint;
 					n->typeName = $3;
 					n->def = $5;
 					$$ = (Node *) n;
@@ -11703,7 +11703,7 @@ AlterDomainStmt:
 				{
 					AlterDomainStmt *n = makeNode(AlterDomainStmt);
 
-					n->subtype = 'X';
+					n->subtype = AD_DropConstraint;
 					n->typeName = $3;
 					n->name = $6;
 					n->behavior = $7;
@@ -11715,7 +11715,7 @@ AlterDomainStmt:
 				{
 					AlterDomainStmt *n = makeNode(AlterDomainStmt);
 
-					n->subtype = 'X';
+					n->subtype = AD_DropConstraint;
 					n->typeName = $3;
 					n->name = $8;
 					n->behavior = $9;
@@ -11727,7 +11727,7 @@ AlterDomainStmt:
 				{
 					AlterDomainStmt *n = makeNode(AlterDomainStmt);
 
-					n->subtype = 'V';
+					n->subtype = AD_ValidateConstraint;
 					n->typeName = $3;
 					n->name = $6;
 					$$ = (Node *) n;
diff --git a/src/backend/tcop/utility.c b/src/backend/tcop/utility.c
index 25fe3d58016..aff8510755f 100644
--- a/src/backend/tcop/utility.c
+++ b/src/backend/tcop/utility.c
@@ -1343,7 +1343,7 @@ ProcessUtilitySlow(ParseState *pstate,
 					 */
 					switch (stmt->subtype)
 					{
-						case 'T':	/* ALTER DOMAIN DEFAULT */
+						case AD_AlterDefault:
 
 							/*
 							 * Recursively alter column default for table and,
@@ -1353,30 +1353,30 @@ ProcessUtilitySlow(ParseState *pstate,
 								AlterDomainDefault(stmt->typeName,
 												   stmt->def);
 							break;
-						case 'N':	/* ALTER DOMAIN DROP NOT NULL */
+						case AD_DropNotNull:
 							address =
 								AlterDomainNotNull(stmt->typeName,
 												   false);
 							break;
-						case 'O':	/* ALTER DOMAIN SET NOT NULL */
+						case AD_SetNotNull:
 							address =
 								AlterDomainNotNull(stmt->typeName,
 												   true);
 							break;
-						case 'C':	/* ADD CONSTRAINT */
+						case AD_AddConstraint:
 							address =
 								AlterDomainAddConstraint(stmt->typeName,
 														 stmt->def,
 														 &secondaryObject);
 							break;
-						case 'X':	/* DROP CONSTRAINT */
+						case AD_DropConstraint:
 							address =
 								AlterDomainDropConstraint(stmt->typeName,
 														  stmt->name,
 														  stmt->behavior,
 														  stmt->missing_ok);
 							break;
-						case 'V':	/* VALIDATE CONSTRAINT */
+						case AD_ValidateConstraint:
 							address =
 								AlterDomainValidateConstraint(stmt->typeName,
 															  stmt->name);
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index daa285ca62f..28e2e8dc0fd 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2536,17 +2536,20 @@ typedef struct AlterCollationStmt
  * this command.
  * ----------------------
  */
+typedef enum AlterDomainType
+{
+	AD_AlterDefault = 'T',		/* SET|DROP DEFAULT */
+	AD_DropNotNull = 'N',		/* DROP NOT NULL */
+	AD_SetNotNull = 'O',		/* SET NOT NULL */
+	AD_AddConstraint = 'C',		/* ADD CONSTRAINT */
+	AD_DropConstraint = 'X',	/* DROP CONSTRAINT */
+	AD_ValidateConstraint = 'V',	/* VALIDATE CONSTRAINT */
+} AlterDomainType;
+
 typedef struct AlterDomainStmt
 {
 	NodeTag		type;
-	char		subtype;		/*------------
-								 *	T = alter column default
-								 *	N = alter column drop not null
-								 *	O = alter column set not null
-								 *	C = add constraint
-								 *	X = drop constraint
-								 *------------
-								 */
+	AlterDomainType subtype;	/* subtype of command */
 	List	   *typeName;		/* domain to work on */
 	char	   *name;			/* column or constraint name to act on */
 	Node	   *def;			/* definition of default or constraint */
diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list
index e7d1c48e1f2..7544e7c5073 100644
--- a/src/tools/pgindent/typedefs.list
+++ b/src/tools/pgindent/typedefs.list
@@ -74,6 +74,7 @@ AlterDatabaseSetStmt
 AlterDatabaseStmt
 AlterDefaultPrivilegesStmt
 AlterDomainStmt
+AlterDomainType
 AlterEnumStmt
 AlterEventTrigStmt
 AlterExtensionContentsStmt