Implement CASE expression.

src/backend/optimizer/plan/createplan.c

@@ -7,7 +7,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/optimizer/plan/createplan.c,v 1.33 1998/11/22 10:48:43 vadim Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/optimizer/plan/createplan.c,v 1.34 1998/12/04 15:34:05 thomas Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -437,7 +437,7 @@ create_nestloop_node(JoinPath *best_path,
 		 * used in the inner scan path, so we need only consider the first
 		 * set of qualifications in indxqual.
 		 *
-		 * But there may be more than one clauses in this "first set" in the
+		 * But there may be more than one clause in this "first set" in the
 		 * case of multi-column indices. - vadim 03/18/97
 		 */
 
@@ -735,6 +735,11 @@ fix_indxqual_references(Node *clause, Path *index_path)
 		else
 			return clause;
 	}
+	else if (IsA(clause, CaseExpr))
+	{
+		elog(NOTICE,"optimizer: fix_indxqual_references sees CaseExpr");
+		return clause;
+	}
 	else
 	{
 		List	   *oldclauses = (List *) clause;

src/backend/optimizer/util/clauses.c

@@ -7,7 +7,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/optimizer/util/clauses.c,v 1.25 1998/11/27 19:52:07 vadim Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/optimizer/util/clauses.c,v 1.26 1998/12/04 15:34:14 thomas Exp $
  *
  * HISTORY
  *	  AUTHOR			DATE			MAJOR EVENT
@@ -306,6 +306,26 @@ make_andclause(List *andclauses)
 	return expr;
 }
 
+
+/*****************************************************************************
+ *		CASE clause functions
+ *****************************************************************************/
+
+
+/*
+ * case_clause--
+ *
+ * Returns t iff its argument is a 'case' clause: (CASE { expr }).
+ *
+ */
+bool
+case_clause(Node *clause)
+{
+	return
+	(clause != NULL &&
+	 nodeTag(clause) == T_CaseExpr);
+}
+
 /*****************************************************************************
  *																			 *
  *																			 *
@@ -540,6 +560,19 @@ fix_opid(Node *clause)
 			fix_opid((Node *) get_leftop((Expr *) lfirst(lst)));
 		}
 	}
+	else if (case_clause(clause))
+	{
+		List	   *lst;
+
+		fix_opid(((CaseExpr *) clause)->defresult);
+
+		/* Run through the WHEN clauses... */
+		foreach(lst, ((CaseExpr *) clause)->args)
+		{
+			fix_opid(((CaseWhen *) lfirst(lst))->expr);
+			fix_opid(((CaseWhen *) lfirst(lst))->result);
+		}
+	}
 
 }
 
@@ -577,13 +610,12 @@ fix_opids(List *clauses)
  *		returned for the value if it is unknown or null.
  * END OF OLD OBSOLETE COMMENT.
  * NEW COMMENT:
- * when defining rules one of the attibutes of the operator can
+ * when defining rules one of the attributes of the operator can
  * be a Param node (which is supposed to be treated as a constant).
  * However as there is no value specified for a parameter until run time
- * this routine used to return "" as value, which made 'compute_selec'
+ * this routine used to return "" as value, which caused 'compute_selec'
  * to bomb (because it was expecting a lisp integer and got back a lisp
  * string). Now the code returns a plain old good "lispInteger(0)".
- *
  */
 void
 get_relattval(Node *clause,
@@ -787,3 +819,4 @@ CommuteClause(Node *clause)
 	lfirst(((Expr *) clause)->args) = lsecond(((Expr *) clause)->args);
 	lsecond(((Expr *) clause)->args) = temp;
 }
+

src/backend/optimizer/util/tlist.c

@@ -7,7 +7,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/optimizer/util/tlist.c,v 1.20 1998/09/22 21:48:27 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/optimizer/util/tlist.c,v 1.21 1998/12/04 15:34:15 thomas Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -482,7 +482,6 @@ flatten_tlistentry(Node *tlistentry, List *flat_tlist)
 							flatten_tlistentry(lfirst(elt), flat_tlist));
 
 		return ((Node *) make_funcclause((Func *) expr->oper, temp_result));
-
 	}
 	else if (IsA(tlistentry, Aggreg))
 	{
@@ -509,19 +508,36 @@ flatten_tlistentry(Node *tlistentry, List *flat_tlist)
 
 		return tlistentry;
 	}
+	else if (case_clause(tlistentry))
+	{
+		CaseExpr   *cexpr = (CaseExpr *) tlistentry;
+		CaseWhen   *cwhen;
+		List	   *elt = NIL;
+
+		foreach(elt, cexpr->args)
+			cwhen = (CaseWhen *)lfirst(elt);
+			cwhen->result = flatten_tlistentry(cwhen->result, flat_tlist);
+		cexpr->defresult = flatten_tlistentry(cexpr->defresult, flat_tlist);
+
+		return ((Node *) cexpr);
+	}
 	else
 	{
-		Expr	   *expr = (Expr *) tlistentry;
-
-		Var 	   *left = (Var *) flatten_tlistentry((Node *) get_leftop(expr),
-								   flat_tlist);
-		Var		   *right = (Var *) flatten_tlistentry((Node *) get_rightop(expr),
-								   flat_tlist);
-		Expr	   *final = make_opclause((Oper *) expr->oper, left, right);
+		Expr	   *expr, *final;
+		Var 	   *left, *right;
 
 		Assert(IsA(tlistentry, Expr));
+
+		expr = (Expr *) tlistentry;
+		left = (Var *) flatten_tlistentry((Node *) get_leftop(expr),
+								   flat_tlist);
+		right = (Var *) flatten_tlistentry((Node *) get_rightop(expr),
+								   flat_tlist);
+
+		final = make_opclause((Oper *) expr->oper, left, right);
 		final->opType = expr->opType;
 		final->typeOid = expr->typeOid;
+
 		return (Node *)final;
 	}
 }

src/backend/optimizer/util/var.c

@@ -7,7 +7,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/optimizer/util/var.c,v 1.13 1998/09/01 03:24:00 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/optimizer/util/var.c,v 1.14 1998/12/04 15:34:15 thomas Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -137,6 +137,21 @@ contain_var_clause(Node *clause)
 	else if (is_opclause(clause))
 		return (contain_var_clause((Node *) get_leftop((Expr *) clause)) ||
 			  contain_var_clause((Node *) get_rightop((Expr *) clause)));
+	else if (case_clause(clause))
+	{
+		List	   *args;
+		CaseWhen   *when;
+
+		foreach(args, ((CaseExpr *) clause)->args)
+		{
+			when = lfirst(args);
+			if (contain_var_clause(when->expr))
+				return TRUE;
+			if (contain_var_clause(when->result))
+				return TRUE;
+		}
+		return (contain_var_clause(((CaseExpr *) clause)->defresult));
+	}
 
 	return FALSE;
 }
@@ -199,6 +214,18 @@ pull_var_clause(Node *clause)
 	else if (is_opclause(clause))
 		retval = nconc(pull_var_clause((Node *) get_leftop((Expr *) clause)),
 				 pull_var_clause((Node *) get_rightop((Expr *) clause)));
+	else if (case_clause(clause))
+	{
+		List	   *temp;
+
+		foreach(temp, ((CaseExpr *) clause)->args)
+		{
+			retval = nconc(retval, pull_var_clause(((CaseWhen *) lfirst(temp))->expr));
+			retval = nconc(retval, pull_var_clause(((CaseWhen *) lfirst(temp))->result));
+		}
+
+		retval = nconc(retval, pull_var_clause(((CaseExpr *) clause)->defresult));
+	}
 	else
 		retval = NIL;