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-rw-r--r--src/backend/parser/gram.y29
-rw-r--r--src/backend/parser/parse_clause.c17
-rw-r--r--src/backend/parser/parse_expr.c95
-rw-r--r--src/backend/parser/parse_target.c14
4 files changed, 120 insertions, 35 deletions
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 5a7dff919d8..c593196dfc8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -11,7 +11,7 @@
*
*
* IDENTIFICATION
- * $Header: /cvsroot/pgsql/src/backend/parser/gram.y,v 2.403 2003/02/13 05:25:24 momjian Exp $
+ * $Header: /cvsroot/pgsql/src/backend/parser/gram.y,v 2.404 2003/02/16 02:30:38 tgl Exp $
*
* HISTORY
* AUTHOR DATE MAJOR EVENT
@@ -6650,6 +6650,10 @@ in_expr: select_with_parens
* COALESCE(a,b,...)
* same as CASE WHEN a IS NOT NULL THEN a WHEN b IS NOT NULL THEN b ... END
* - thomas 1998-11-09
+ *
+ * NULLIF and COALESCE have become first class nodes to
+ * prevent double evaluation of arguments.
+ * - Kris Jurka 2003-02-11
*/
case_expr: CASE case_arg when_clause_list case_default END_P
{
@@ -6661,29 +6665,12 @@ case_expr: CASE case_arg when_clause_list case_default END_P
}
| NULLIF '(' a_expr ',' a_expr ')'
{
- CaseExpr *c = makeNode(CaseExpr);
- CaseWhen *w = makeNode(CaseWhen);
-
- w->expr = (Expr *) makeSimpleA_Expr(AEXPR_OP, "=", $3, $5);
- /* w->result is left NULL */
- c->args = makeList1(w);
- c->defresult = (Expr *) $3;
- $$ = (Node *)c;
+ $$ = (Node *) makeSimpleA_Expr(AEXPR_NULLIF, "=", $3, $5);
}
| COALESCE '(' expr_list ')'
{
- CaseExpr *c = makeNode(CaseExpr);
- List *l;
- foreach (l,$3)
- {
- CaseWhen *w = makeNode(CaseWhen);
- NullTest *n = makeNode(NullTest);
- n->arg = lfirst(l);
- n->nulltesttype = IS_NOT_NULL;
- w->expr = (Expr *) n;
- w->result = lfirst(l);
- c->args = lappend(c->args, w);
- }
+ CoalesceExpr *c = makeNode(CoalesceExpr);
+ c->args = $3;
$$ = (Node *)c;
}
;
diff --git a/src/backend/parser/parse_clause.c b/src/backend/parser/parse_clause.c
index d65df553acf..33e7cce4203 100644
--- a/src/backend/parser/parse_clause.c
+++ b/src/backend/parser/parse_clause.c
@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
- * $Header: /cvsroot/pgsql/src/backend/parser/parse_clause.c,v 1.109 2003/02/13 20:45:21 tgl Exp $
+ * $Header: /cvsroot/pgsql/src/backend/parser/parse_clause.c,v 1.110 2003/02/16 02:30:38 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -922,17 +922,10 @@ buildMergedJoinVar(JoinType jointype, Var *l_colvar, Var *r_colvar)
* Here we must build a COALESCE expression to ensure that
* the join output is non-null if either input is.
*/
- CaseExpr *c = makeNode(CaseExpr);
- CaseWhen *w = makeNode(CaseWhen);
- NullTest *n = makeNode(NullTest);
-
- n->arg = (Expr *) l_node;
- n->nulltesttype = IS_NOT_NULL;
- w->expr = (Expr *) n;
- w->result = (Expr *) l_node;
- c->casetype = outcoltype;
- c->args = makeList1(w);
- c->defresult = (Expr *) r_node;
+ CoalesceExpr *c = makeNode(CoalesceExpr);
+
+ c->coalescetype = outcoltype;
+ c->args = makeList2(l_node, r_node);
res_node = (Node *) c;
break;
}
diff --git a/src/backend/parser/parse_expr.c b/src/backend/parser/parse_expr.c
index f059a1db2c0..2ec65b52c21 100644
--- a/src/backend/parser/parse_expr.c
+++ b/src/backend/parser/parse_expr.c
@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
- * $Header: /cvsroot/pgsql/src/backend/parser/parse_expr.c,v 1.145 2003/02/13 18:29:07 tgl Exp $
+ * $Header: /cvsroot/pgsql/src/backend/parser/parse_expr.c,v 1.146 2003/02/16 02:30:38 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -277,6 +277,24 @@ transformExpr(ParseState *pstate, Node *expr)
NodeSetTag(result, T_DistinctExpr);
}
break;
+ case AEXPR_NULLIF:
+ {
+ Node *lexpr = transformExpr(pstate,
+ a->lexpr);
+ Node *rexpr = transformExpr(pstate,
+ a->rexpr);
+
+ result = (Node *) make_op(a->name,
+ lexpr,
+ rexpr);
+ if (((OpExpr *) result)->opresulttype != BOOLOID)
+ elog(ERROR, "NULLIF requires = operator to yield boolean");
+ /*
+ * We rely on NullIfExpr and OpExpr being same struct
+ */
+ NodeSetTag(result, T_NullIfExpr);
+ }
+ break;
case AEXPR_OF:
{
/*
@@ -615,6 +633,43 @@ transformExpr(ParseState *pstate, Node *expr)
break;
}
+ case T_CoalesceExpr:
+ {
+ CoalesceExpr *c = (CoalesceExpr *) expr;
+ CoalesceExpr *newc = makeNode(CoalesceExpr);
+ List *newargs = NIL;
+ List *newcoercedargs = NIL;
+ List *typeids = NIL;
+ List *args;
+
+ foreach(args, c->args)
+ {
+ Node *e = (Node *) lfirst(args);
+ Node *newe;
+
+ newe = transformExpr(pstate, e);
+ newargs = lappend(newargs, newe);
+ typeids = lappendo(typeids, exprType(newe));
+ }
+
+ newc->coalescetype = select_common_type(typeids, "COALESCE");
+
+ /* Convert arguments if necessary */
+ foreach(args, newargs)
+ {
+ Node *e = (Node *) lfirst(args);
+ Node *newe;
+
+ newe = coerce_to_common_type(e, newc->coalescetype,
+ "COALESCE");
+ newcoercedargs = lappend(newcoercedargs, newe);
+ }
+
+ newc->args = newcoercedargs;
+ result = (Node *) newc;
+ break;
+ }
+
case T_NullTest:
{
NullTest *n = (NullTest *) expr;
@@ -680,6 +735,7 @@ transformExpr(ParseState *pstate, Node *expr)
case T_FuncExpr:
case T_OpExpr:
case T_DistinctExpr:
+ case T_NullIfExpr:
case T_BoolExpr:
case T_FieldSelect:
case T_RelabelType:
@@ -1020,6 +1076,12 @@ exprType(Node *expr)
case T_CaseWhen:
type = exprType((Node *) ((CaseWhen *) expr)->result);
break;
+ case T_CoalesceExpr:
+ type = ((CoalesceExpr *) expr)->coalescetype;
+ break;
+ case T_NullIfExpr:
+ type = exprType((Node *) lfirst(((NullIfExpr *) expr)->args));
+ break;
case T_NullTest:
type = BOOLOID;
break;
@@ -1126,6 +1188,37 @@ exprTypmod(Node *expr)
return typmod;
}
break;
+ case T_CoalesceExpr:
+ {
+ /*
+ * If all the alternatives agree on type/typmod, return
+ * that typmod, else use -1
+ */
+ CoalesceExpr *cexpr = (CoalesceExpr *) expr;
+ Oid coalescetype = cexpr->coalescetype;
+ int32 typmod;
+ List *arg;
+
+ typmod = exprTypmod((Node *) lfirst(cexpr->args));
+ foreach(arg, cexpr->args)
+ {
+ Node *e = (Node *) lfirst(arg);
+
+ if (exprType(e) != coalescetype)
+ return -1;
+ if (exprTypmod(e) != typmod)
+ return -1;
+ }
+ return typmod;
+ }
+ break;
+ case T_NullIfExpr:
+ {
+ NullIfExpr *nexpr = (NullIfExpr *) expr;
+
+ return exprTypmod((Node *) lfirst(nexpr->args));
+ }
+ break;
case T_CoerceToDomain:
return ((CoerceToDomain *) expr)->resulttypmod;
case T_CoerceToDomainValue:
diff --git a/src/backend/parser/parse_target.c b/src/backend/parser/parse_target.c
index 70aaf18ef58..4108e7557da 100644
--- a/src/backend/parser/parse_target.c
+++ b/src/backend/parser/parse_target.c
@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
- * $Header: /cvsroot/pgsql/src/backend/parser/parse_target.c,v 1.97 2003/02/13 05:53:46 momjian Exp $
+ * $Header: /cvsroot/pgsql/src/backend/parser/parse_target.c,v 1.98 2003/02/16 02:30:38 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -482,6 +482,14 @@ FigureColnameInternal(Node *node, char **name)
case T_FuncCall:
*name = strVal(llast(((FuncCall *) node)->funcname));
return 2;
+ case T_A_Expr:
+ /* make nullif() act like a regular function */
+ if (((A_Expr *) node)->kind == AEXPR_NULLIF)
+ {
+ *name = "nullif";
+ return 2;
+ }
+ break;
case T_A_Const:
if (((A_Const *) node)->typename != NULL)
{
@@ -510,6 +518,10 @@ FigureColnameInternal(Node *node, char **name)
return 1;
}
break;
+ case T_CoalesceExpr:
+ /* make coalesce() act like a regular function */
+ *name = "coalesce";
+ return 2;
default:
break;
}
generated by cgit v1.2.3 (git 2.25.1) at 2025-08-07 15:30:30 +0000