parse_expr.c

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

						rv->relname = name;
						rv->inhOpt = INH_DEFAULT;
						node = (Node *) rv;
					}
					else
						ereport(ERROR,
								(errcode(ERRCODE_UNDEFINED_COLUMN),
							errmsg("column \"%s\" does not exist", name)));
				}
				break;
			}
		case 2:
			{
				char	   *name1 = strVal(lfirst(cref->fields));
				char	   *name2 = strVal(lsecond(cref->fields));

				/* Whole-row reference? */
				if (strcmp(name2, "*") == 0)
				{
					rv = makeNode(RangeVar);
					rv->relname = name1;
					rv->inhOpt = INH_DEFAULT;
					node = (Node *) rv;
					break;
				}

				/* Try to identify as a once-qualified column */
				node = qualifiedNameToVar(pstate, NULL, name1, name2, true);
				if (node == NULL)
				{
					/*
					 * Not known as a column of any range-table entry, so
					 * try it as a function call.  Here, we will create an
					 * implicit RTE for tables not already entered.
					 */
					rv = makeNode(RangeVar);
					rv->relname = name1;
					rv->inhOpt = INH_DEFAULT;
					node = ParseFuncOrColumn(pstate,
											 makeList1(makeString(name2)),
											 makeList1(rv),
											 false, false, true);
				}
				break;
			}
		case 3:
			{
				char	   *name1 = strVal(lfirst(cref->fields));
				char	   *name2 = strVal(lsecond(cref->fields));
				char	   *name3 = strVal(lthird(cref->fields));

				/* Whole-row reference? */
				if (strcmp(name3, "*") == 0)
				{
					rv = makeNode(RangeVar);
					rv->schemaname = name1;
					rv->relname = name2;
					rv->inhOpt = INH_DEFAULT;
					node = (Node *) rv;
					break;
				}

				/* Try to identify as a twice-qualified column */
				node = qualifiedNameToVar(pstate, name1, name2, name3, true);
				if (node == NULL)
				{
					/* Try it as a function call */
					rv = makeNode(RangeVar);
					rv->schemaname = name1;
					rv->relname = name2;
					rv->inhOpt = INH_DEFAULT;
					node = ParseFuncOrColumn(pstate,
											 makeList1(makeString(name3)),
											 makeList1(rv),
											 false, false, true);
				}
				break;
			}
		case 4:
			{
				char	   *name1 = strVal(lfirst(cref->fields));
				char	   *name2 = strVal(lsecond(cref->fields));
				char	   *name3 = strVal(lthird(cref->fields));
				char	   *name4 = strVal(lfourth(cref->fields));

				/*
				 * We check the catalog name and then ignore it.
				 */
				if (strcmp(name1, get_database_name(MyDatabaseId)) != 0)
					ereport(ERROR,
							(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
							 errmsg("cross-database references are not implemented")));

				/* Whole-row reference? */
				if (strcmp(name4, "*") == 0)
				{
					rv = makeNode(RangeVar);
					rv->schemaname = name2;
					rv->relname = name3;
					rv->inhOpt = INH_DEFAULT;
					node = (Node *) rv;
					break;
				}

				/* Try to identify as a twice-qualified column */
				node = qualifiedNameToVar(pstate, name2, name3, name4, true);
				if (node == NULL)
				{
					/* Try it as a function call */
					rv = makeNode(RangeVar);
					rv->schemaname = name2;
					rv->relname = name3;
					rv->inhOpt = INH_DEFAULT;
					node = ParseFuncOrColumn(pstate,
											 makeList1(makeString(name4)),
											 makeList1(rv),
											 false, false, true);
				}
				break;
			}
		default:
			ereport(ERROR,
					(errcode(ERRCODE_SYNTAX_ERROR),
			errmsg("improper qualified name (too many dotted names): %s",
				   NameListToString(cref->fields))));
			node = NULL;		/* keep compiler quiet */
			break;
	}

	return transformIndirection(pstate, node, cref->indirection);
}

/*
 *	exprType -
 *	  returns the Oid of the type of the expression. (Used for typechecking.)
 */
Oid
exprType(Node *expr)
{
	Oid			type;

	if (!expr)
		return InvalidOid;

	switch (nodeTag(expr))
	{
		case T_Var:
			type = ((Var *) expr)->vartype;
			break;
		case T_Const:
			type = ((Const *) expr)->consttype;
			break;
		case T_Param:
			type = ((Param *) expr)->paramtype;
			break;
		case T_Aggref:
			type = ((Aggref *) expr)->aggtype;
			break;
		case T_ArrayRef:
			type = ((ArrayRef *) expr)->refrestype;
			break;
		case T_FuncExpr:
			type = ((FuncExpr *) expr)->funcresulttype;
			break;
		case T_OpExpr:
			type = ((OpExpr *) expr)->opresulttype;
			break;
		case T_DistinctExpr:
			type = ((DistinctExpr *) expr)->opresulttype;
			break;
		case T_ScalarArrayOpExpr:
			type = BOOLOID;
			break;
		case T_BoolExpr:
			type = BOOLOID;
			break;
		case T_SubLink:
			{
				SubLink    *sublink = (SubLink *) expr;

				if (sublink->subLinkType == EXPR_SUBLINK ||
					sublink->subLinkType == ARRAY_SUBLINK)
				{
					/* get the type of the subselect's first target column */
					Query	   *qtree = (Query *) sublink->subselect;
					TargetEntry *tent;

					if (!qtree || !IsA(qtree, Query))
						elog(ERROR, "cannot get type for untransformed sublink");
					tent = (TargetEntry *) lfirst(qtree->targetList);
					Assert(IsA(tent, TargetEntry));
					Assert(!tent->resdom->resjunk);
					if (sublink->subLinkType == EXPR_SUBLINK)
						type = tent->resdom->restype;
					else
/* ARRAY_SUBLINK */
					{
						type = get_array_type(tent->resdom->restype);
						if (!OidIsValid(type))
							ereport(ERROR,
									(errcode(ERRCODE_UNDEFINED_OBJECT),
									 errmsg("could not find array type for data type %s",
								format_type_be(tent->resdom->restype))));
					}
				}
				else
				{
					/* for all other sublink types, result is boolean */
					type = BOOLOID;
				}
			}
			break;
		case T_SubPlan:
			{
				/*
				 * Although the parser does not ever deal with
				 * already-planned expression trees, we support SubPlan
				 * nodes in this routine for the convenience of
				 * ruleutils.c.
				 */
				SubPlan    *subplan = (SubPlan *) expr;

				if (subplan->subLinkType == EXPR_SUBLINK ||
					subplan->subLinkType == ARRAY_SUBLINK)
				{
					/* get the type of the subselect's first target column */
					TargetEntry *tent;

					tent = (TargetEntry *) lfirst(subplan->plan->targetlist);
					Assert(IsA(tent, TargetEntry));
					Assert(!tent->resdom->resjunk);
					if (subplan->subLinkType == EXPR_SUBLINK)
						type = tent->resdom->restype;
					else
/* ARRAY_SUBLINK */
					{
						type = get_array_type(tent->resdom->restype);
						if (!OidIsValid(type))
							ereport(ERROR,
									(errcode(ERRCODE_UNDEFINED_OBJECT),
									 errmsg("could not find array type for data type %s",
								format_type_be(tent->resdom->restype))));
					}
				}
				else
				{
					/* for all other subplan types, result is boolean */
					type = BOOLOID;
				}
			}
			break;
		case T_FieldSelect:
			type = ((FieldSelect *) expr)->resulttype;
			break;
		case T_RelabelType:
			type = ((RelabelType *) expr)->resulttype;
			break;
		case T_CaseExpr:
			type = ((CaseExpr *) expr)->casetype;
			break;
		case T_CaseWhen:
			type = exprType((Node *) ((CaseWhen *) expr)->result);
			break;
		case T_ArrayExpr:
			type = ((ArrayExpr *) expr)->array_typeid;
			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;
		case T_BooleanTest:
			type = BOOLOID;
			break;
		case T_CoerceToDomain:
			type = ((CoerceToDomain *) expr)->resulttype;
			break;
		case T_CoerceToDomainValue:
			type = ((CoerceToDomainValue *) expr)->typeId;
			break;
		case T_SetToDefault:
			type = ((SetToDefault *) expr)->typeId;
			break;
		case T_RangeVar:

			/*
			 * If someone uses a bare relation name in an expression, we
			 * will likely first notice a problem here (see comments in
			 * transformColumnRef()).  Issue an appropriate error message.
			 */
			ereport(ERROR,
					(errcode(ERRCODE_SYNTAX_ERROR),
					 errmsg("relation reference \"%s\" cannot be used in an expression",
							((RangeVar *) expr)->relname)));
			type = InvalidOid;	/* keep compiler quiet */
			break;
		default:
			elog(ERROR, "unrecognized node type: %d", (int) nodeTag(expr));
			type = InvalidOid;	/* keep compiler quiet */
			break;
	}
	return type;
}

/*
 *	exprTypmod -
 *	  returns the type-specific attrmod of the expression, if it can be
 *	  determined.  In most cases, it can't and we return -1.
 */
int32
exprTypmod(Node *expr)
{
	if (!expr)
		return -1;

	switch (nodeTag(expr))
	{
		case T_Var:
			return ((Var *) expr)->vartypmod;
		case T_Const:
			{
				/* Be smart about string constants... */
				Const	   *con = (Const *) expr;

				switch (con->consttype)
				{
					case BPCHAROID:
						if (!con->constisnull)
							return VARSIZE(DatumGetPointer(con->constvalue));
						break;
					default:
						break;
				}
			}
			break;
		case T_FuncExpr:
			{
				int32		coercedTypmod;

				/* Be smart about length-coercion functions... */
				if (exprIsLengthCoercion(expr, &coercedTypmod))
					return coercedTypmod;
			}
			break;
		case T_FieldSelect:
			return ((FieldSelect *) expr)->resulttypmod;
		case T_RelabelType:
			return ((RelabelType *) expr)->resulttypmod;
		case T_CaseExpr:
			{
				/*
				 * If all the alternatives agree on type/typmod, return
				 * that typmod, else use -1
				 */
				CaseExpr   *cexpr = (CaseExpr *) expr;
				Oid			casetype = cexpr->casetype;
				int32		typmod;
				List	   *arg;

				if (!cexpr->defresult)
					return -1;
				if (exprType((Node *) cexpr->defresult) != casetype)
					return -1;
				typmod = exprTypmod((Node *) cexpr->defresult);
				if (typmod < 0)
					return -1;	/* no point in trying harder */
				foreach(arg, cexpr->args)
				{
					CaseWhen   *w = (CaseWhen *) lfirst(arg);

					Assert(IsA(w, CaseWhen));
					if (exprType((Node *) w->result) != casetype)
						return -1;
					if (exprTypmod((Node *) w->result) != typmod)
						return -1;
				}
				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:
			return ((CoerceToDomainValue *) expr)->typeMod;
		case T_SetToDefault:
			return ((SetToDefault *) expr)->typeMod;
		default:
			break;
	}
	return -1;
}

/*
 * exprIsLengthCoercion
 *		Detect whether an expression tree is an application of a datatype's
 *		typmod-coercion function.  Optionally extract the result's typmod.
 *
 * If coercedTypmod is not NULL, the typmod is stored there if the expression
 * is a length-coercion function, else -1 is stored there.
 */
bool
exprIsLengthCoercion(Node *expr, int32 *coercedTypmod)
{
	FuncExpr   *func;
	int			nargs;
	Const	   *second_arg;

	if (coercedTypmod != NULL)
		*coercedTypmod = -1;	/* default result on failure */

	/* Is it a function-call at all? */
	if (expr == NULL || !IsA(expr, FuncExpr))
		return false;
	func = (FuncExpr *) expr;

	/*
	 * If it didn't come from a coercion context, reject.
	 */
	if (func->funcformat != COERCE_EXPLICIT_CAST &&
		func->funcformat != COERCE_IMPLICIT_CAST)
		return false;

	/*
	 * If it's not a two-argument or three-argument function with the
	 * second argument being an int4 constant, it can't have been created
	 * from a length coercion (it must be a type coercion, instead).
	 */
	nargs = length(func->args);
	if (nargs < 2 || nargs > 3)
		return false;

	second_arg = (Const *) lsecond(func->args);
	if (!IsA(second_arg, Const) ||
		second_arg->consttype != INT4OID ||
		second_arg->constisnull)
		return false;

	/*
	 * OK, it is indeed a length-coercion function.
	 */
	if (coercedTypmod != NULL)
		*coercedTypmod = DatumGetInt32(second_arg->constvalue);

	return true;
}

/*
 * Handle an explicit CAST construct.
 *
 * The given expr has already been transformed, but we need to lookup
 * the type name and then apply any necessary coercion function(s).
 */
static Node *
typecast_expression(ParseState *pstate, Node *expr, TypeName *typename)
{
	Oid			inputType = exprType(expr);
	Oid			targetType;

	targetType = typenameTypeId(typename);

	if (inputType == InvalidOid)
		return expr;			/* do nothing if NULL input */

	expr = coerce_to_target_type(pstate, expr, inputType,
								 targetType, typename->typmod,
								 COERCION_EXPLICIT,
								 COERCE_EXPLICIT_CAST);
	if (expr == NULL)
		ereport(ERROR,
				(errcode(ERRCODE_CANNOT_COERCE),
				 errmsg("cannot cast type %s to %s",
						format_type_be(inputType),
						format_type_be(targetType))));

	return expr;
}