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]

1 files changed, 6 insertions, 6 deletions

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);