parse_expr.c

来自「PostgreSQL7.4.6 for Linux」· C语言 代码 · 共 1,537 行 · 第 1/3 页

					sublink->useOr = FALSE;
				}
				else
				{
					/* ALL, ANY, or MULTIEXPR: generate operator list */
					List	   *left_list = sublink->lefthand;
					List	   *right_list = qtree->targetList;
					int			row_length = length(left_list);
					bool		needNot = false;
					List	   *op = sublink->operName;
					char	   *opname = strVal(llast(op));
					List	   *elist;

					/* transform lefthand expressions */
					foreach(elist, left_list)
						lfirst(elist) = transformExpr(pstate, lfirst(elist));

					/*
					 * If the expression is "<> ALL" (with unqualified
					 * opname) then convert it to "NOT IN".  This is a
					 * hack to improve efficiency of expressions output by
					 * pre-7.4 Postgres.
					 */
					if (sublink->subLinkType == ALL_SUBLINK &&
						length(op) == 1 && strcmp(opname, "<>") == 0)
					{
						sublink->subLinkType = ANY_SUBLINK;
						opname = pstrdup("=");
						op = makeList1(makeString(opname));
						sublink->operName = op;
						needNot = true;
					}

					/* Set useOr if op is "<>" (possibly qualified) */
					if (strcmp(opname, "<>") == 0)
						sublink->useOr = TRUE;
					else
						sublink->useOr = FALSE;

					/* Combining operators other than =/<> is dubious... */
					if (row_length != 1 &&
						strcmp(opname, "=") != 0 &&
						strcmp(opname, "<>") != 0)
						ereport(ERROR,
								(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
						  errmsg("row comparison cannot use operator %s",
								 opname)));

					/*
					 * To build the list of combining operator OIDs, we
					 * must scan subquery's targetlist to find values that
					 * will be matched against lefthand values.  We need
					 * to ignore resjunk targets, so doing the outer
					 * iteration over right_list is easier than doing it
					 * over left_list.
					 */
					sublink->operOids = NIL;

					while (right_list != NIL)
					{
						TargetEntry *tent = (TargetEntry *) lfirst(right_list);
						Node	   *lexpr;
						Operator	optup;
						Form_pg_operator opform;

						right_list = lnext(right_list);
						if (tent->resdom->resjunk)
							continue;

						if (left_list == NIL)
							ereport(ERROR,
									(errcode(ERRCODE_SYNTAX_ERROR),
							 errmsg("subquery has too many columns")));
						lexpr = lfirst(left_list);
						left_list = lnext(left_list);

						/*
						 * It's OK to use oper() not compatible_oper()
						 * here, because make_subplan() will insert type
						 * coercion calls if needed.
						 */
						optup = oper(op,
									 exprType(lexpr),
									 exprType((Node *) tent->expr),
									 false);
						opform = (Form_pg_operator) GETSTRUCT(optup);

						if (opform->oprresult != BOOLOID)
							ereport(ERROR,
									(errcode(ERRCODE_DATATYPE_MISMATCH),
									 errmsg("operator %s must return type boolean, not type %s",
											opname,
									  format_type_be(opform->oprresult)),
									 errhint("The operator of a quantified predicate subquery must return type boolean.")));

						if (get_func_retset(opform->oprcode))
							ereport(ERROR,
									(errcode(ERRCODE_DATATYPE_MISMATCH),
							  errmsg("operator %s must not return a set",
									 opname),
									 errhint("The operator of a quantified predicate subquery must return type boolean.")));

						sublink->operOids = lappendo(sublink->operOids,
													 oprid(optup));

						ReleaseSysCache(optup);
					}
					if (left_list != NIL)
						ereport(ERROR,
								(errcode(ERRCODE_SYNTAX_ERROR),
							  errmsg("subquery has too few columns")));

					if (needNot)
					{
						expr = coerce_to_boolean(pstate, expr, "NOT");
						expr = (Node *) makeBoolExpr(NOT_EXPR,
													 makeList1(expr));
					}
				}
				result = (Node *) expr;
				break;
			}

		case T_CaseExpr:
			{
				CaseExpr   *c = (CaseExpr *) expr;
				CaseExpr   *newc = makeNode(CaseExpr);
				List	   *newargs = NIL;
				List	   *typeids = NIL;
				List	   *args;
				Node	   *defresult;
				Oid			ptype;

				/* transform the list of arguments */
				foreach(args, c->args)
				{
					CaseWhen   *w = (CaseWhen *) lfirst(args);
					CaseWhen   *neww = makeNode(CaseWhen);
					Node	   *warg;

					Assert(IsA(w, CaseWhen));

					warg = (Node *) w->expr;
					if (c->arg != NULL)
					{
						/* shorthand form was specified, so expand... */
						warg = (Node *) makeSimpleA_Expr(AEXPR_OP, "=",
														 (Node *) c->arg,
														 warg);
					}
					neww->expr = (Expr *) transformExpr(pstate, warg);

					neww->expr = (Expr *) coerce_to_boolean(pstate,
													 (Node *) neww->expr,
															"CASE/WHEN");

					/*
					 * result is NULL for NULLIF() construct - thomas
					 * 1998-11-11
					 */
					warg = (Node *) w->result;
					if (warg == NULL)
					{
						A_Const    *n = makeNode(A_Const);

						n->val.type = T_Null;
						warg = (Node *) n;
					}
					neww->result = (Expr *) transformExpr(pstate, warg);

					newargs = lappend(newargs, neww);
					typeids = lappendo(typeids, exprType((Node *) neww->result));
				}

				newc->args = newargs;

				/*
				 * It's not shorthand anymore, so drop the implicit
				 * argument. This is necessary to keep any re-application
				 * of transformExpr from doing the wrong thing.
				 */
				newc->arg = NULL;

				/* transform the default clause */
				defresult = (Node *) c->defresult;
				if (defresult == NULL)
				{
					A_Const    *n = makeNode(A_Const);

					n->val.type = T_Null;
					defresult = (Node *) n;
				}
				newc->defresult = (Expr *) transformExpr(pstate, defresult);

				/*
				 * Note: default result is considered the most significant
				 * type in determining preferred type.	This is how the
				 * code worked before, but it seems a little bogus to me
				 * --- tgl
				 */
				typeids = lconso(exprType((Node *) newc->defresult), typeids);

				ptype = select_common_type(typeids, "CASE");
				newc->casetype = ptype;

				/* Convert default result clause, if necessary */
				newc->defresult = (Expr *)
					coerce_to_common_type(pstate,
										  (Node *) newc->defresult,
										  ptype,
										  "CASE/ELSE");

				/* Convert when-clause results, if necessary */
				foreach(args, newc->args)
				{
					CaseWhen   *w = (CaseWhen *) lfirst(args);

					w->result = (Expr *)
						coerce_to_common_type(pstate,
											  (Node *) w->result,
											  ptype,
											  "CASE/WHEN");
				}

				result = (Node *) newc;
				break;
			}

		case T_ArrayExpr:
			{
				ArrayExpr  *a = (ArrayExpr *) expr;
				ArrayExpr  *newa = makeNode(ArrayExpr);
				List	   *newelems = NIL;
				List	   *newcoercedelems = NIL;
				List	   *typeids = NIL;
				List	   *element;
				Oid			array_type;
				Oid			element_type;

				/* Transform the element expressions */
				foreach(element, a->elements)
				{
					Node	   *e = (Node *) lfirst(element);
					Node	   *newe;

					newe = transformExpr(pstate, e);
					newelems = lappend(newelems, newe);
					typeids = lappendo(typeids, exprType(newe));
				}

				/* Select a common type for the elements */
				element_type = select_common_type(typeids, "ARRAY");

				/* Coerce arguments to common type if necessary */
				foreach(element, newelems)
				{
					Node	   *e = (Node *) lfirst(element);
					Node	   *newe;

					newe = coerce_to_common_type(pstate, e,
												 element_type,
												 "ARRAY");
					newcoercedelems = lappend(newcoercedelems, newe);
				}

				/* Do we have an array type to use? */
				array_type = get_array_type(element_type);
				if (array_type != InvalidOid)
				{
					/* Elements are presumably of scalar type */
					newa->multidims = false;
				}
				else
				{
					/* Must be nested array expressions */
					newa->multidims = true;

					array_type = element_type;
					element_type = get_element_type(array_type);
					if (!OidIsValid(element_type))
						ereport(ERROR,
								(errcode(ERRCODE_UNDEFINED_OBJECT),
								 errmsg("could not find array type for data type %s",
										format_type_be(array_type))));
				}

				newa->array_typeid = array_type;
				newa->element_typeid = element_type;
				newa->elements = newcoercedelems;

				result = (Node *) newa;
				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(pstate, e,
												 newc->coalescetype,
												 "COALESCE");
					newcoercedargs = lappend(newcoercedargs, newe);
				}

				newc->args = newcoercedargs;
				result = (Node *) newc;
				break;
			}

		case T_NullTest:
			{
				NullTest   *n = (NullTest *) expr;

				n->arg = (Expr *) transformExpr(pstate, (Node *) n->arg);
				/* the argument can be any type, so don't coerce it */
				result = expr;
				break;
			}

		case T_BooleanTest:
			{
				BooleanTest *b = (BooleanTest *) expr;
				const char *clausename;

				switch (b->booltesttype)
				{
					case IS_TRUE:
						clausename = "IS TRUE";
						break;
					case IS_NOT_TRUE:
						clausename = "IS NOT TRUE";
						break;
					case IS_FALSE:
						clausename = "IS FALSE";
						break;
					case IS_NOT_FALSE:
						clausename = "IS NOT FALSE";
						break;
					case IS_UNKNOWN:
						clausename = "IS UNKNOWN";
						break;
					case IS_NOT_UNKNOWN:
						clausename = "IS NOT UNKNOWN";
						break;
					default:
						elog(ERROR, "unrecognized booltesttype: %d",
							 (int) b->booltesttype);
						clausename = NULL;		/* keep compiler quiet */
				}

				b->arg = (Expr *) transformExpr(pstate, (Node *) b->arg);

				b->arg = (Expr *) coerce_to_boolean(pstate,
													(Node *) b->arg,
													clausename);

				result = expr;
				break;
			}

			/*********************************************
			 * Quietly accept node types that may be presented when we are
			 * called on an already-transformed tree.
			 *
			 * Do any other node types need to be accepted?  For now we are
			 * taking a conservative approach, and only accepting node
			 * types that are demonstrably necessary to accept.
			 *********************************************/
		case T_Var:
		case T_Const:
		case T_Param:
		case T_Aggref:
		case T_ArrayRef:
		case T_FuncExpr:
		case T_OpExpr:
		case T_DistinctExpr:
		case T_ScalarArrayOpExpr:
		case T_NullIfExpr:
		case T_BoolExpr:
		case T_FieldSelect:
		case T_RelabelType:
		case T_CoerceToDomain:
		case T_CoerceToDomainValue:
		case T_SetToDefault:
			{
				result = (Node *) expr;
				break;
			}

		default:
			/* should not reach here */
			elog(ERROR, "unrecognized node type: %d", (int) nodeTag(expr));
			break;
	}

	expr_depth_counter--;

	return result;
}

static Node *
transformIndirection(ParseState *pstate, Node *basenode, List *indirection)
{
	if (indirection == NIL)
		return basenode;
	return (Node *) transformArraySubscripts(pstate,
											 basenode,
											 exprType(basenode),
											 exprTypmod(basenode),
											 indirection,
											 false,
											 NULL);
}

static Node *
transformColumnRef(ParseState *pstate, ColumnRef *cref)
{
	int			numnames = length(cref->fields);
	Node	   *node;
	RangeVar   *rv;
	int			levels_up;

	/*----------
	 * The allowed syntaxes are:
	 *
	 * A		First try to resolve as unqualified column name;
	 *			if no luck, try to resolve as unqual. table name (A.*).
	 * A.B		A is an unqual. table name; B is either a
	 *			column or function name (trying column name first).
	 * A.B.C	schema A, table B, col or func name C.
	 * A.B.C.D	catalog A, schema B, table C, col or func D.
	 * A.*		A is an unqual. table name; means whole-row value.
	 * A.B.*	whole-row value of table B in schema A.
	 * A.B.C.*	whole-row value of table C in schema B in catalog A.
	 *
	 * We do not need to cope with bare "*"; that will only be accepted by
	 * the grammar at the top level of a SELECT list, and transformTargetList
	 * will take care of it before it ever gets here.
	 *
	 * Currently, if a catalog name is given then it must equal the current
	 * database name; we check it here and then discard it.
	 *
	 * For whole-row references, the result is an untransformed RangeVar,
	 * which will work as the argument to a function call, but not in any
	 * other context at present.  (We could instead coerce to a whole-row Var,
	 * but that will fail for subselect and join RTEs, because there is no
	 * pg_type entry for their rowtypes.)
	 *----------
	 */
	switch (numnames)
	{
		case 1:
			{
				char	   *name = strVal(lfirst(cref->fields));

				/* Try to identify as an unqualified column */
				node = colNameToVar(pstate, name, false);

				if (node == NULL)
				{
					/*
					 * Not known as a column of any range-table entry.
					 *
					 * Consider the possibility that it's VALUE in a domain
					 * check expression.  (We handle VALUE as a name, not
					 * a keyword, to avoid breaking a lot of applications
					 * that have used VALUE as a column name in the past.)
					 */
					if (pstate->p_value_substitute != NULL &&
						strcmp(name, "value") == 0)
					{
						node = (Node *) copyObject(pstate->p_value_substitute);
						break;
					}

					/*
					 * Try to find the name as a relation ... but not if
					 * subscripts appear.  Note also that only relations
					 * already entered into the rangetable will be
					 * recognized.
					 *
					 * This is a hack for backwards compatibility with
					 * PostQUEL-inspired syntax.  The preferred form now
					 * is "rel.*".
					 */
					if (cref->indirection == NIL &&
						refnameRangeTblEntry(pstate, NULL, name,
											 &levels_up) != NULL)
					{
						rv = makeNode(RangeVar);