/**
* Determines whether a {@link RexCall} requires decimal expansion. It usually requires expansion
* if it has decimal operands.
*
* <p>Exceptions to this rule are:
*
* <ul>
* <li>isNull doesn't require expansion
* <li>It's okay to cast decimals to and from char types
* <li>It's okay to cast nulls as decimals
* <li>Casts require expansion if their return type is decimal
* <li>Reinterpret casts can handle a decimal operand
* </ul>
*
* @param expr expression possibly in need of expansion
* @param recurse whether to check nested calls
* @return whether the expression requires expansion
*/
public static boolean requiresDecimalExpansion(RexNode expr, boolean recurse) {
if (!(expr instanceof RexCall)) {
return false;
}
RexCall call = (RexCall) expr;
boolean localCheck = true;
switch (call.getKind()) {
case Reinterpret:
case IsNull:
localCheck = false;
break;
case Cast:
RelDataType lhsType = call.getType();
RelDataType rhsType = call.operands[0].getType();
if (rhsType.getSqlTypeName() == SqlTypeName.NULL) {
return false;
}
if (SqlTypeUtil.inCharFamily(lhsType) || SqlTypeUtil.inCharFamily(rhsType)) {
localCheck = false;
} else if (SqlTypeUtil.isDecimal(lhsType) && (lhsType != rhsType)) {
return true;
}
break;
default:
localCheck = call.getOperator().requiresDecimalExpansion();
}
if (localCheck) {
if (SqlTypeUtil.isDecimal(call.getType())) {
// NOTE jvs 27-Mar-2007: Depending on the type factory, the
// result of a division may be decimal, even though both inputs
// are integer.
return true;
}
for (int i = 0; i < call.operands.length; i++) {
if (SqlTypeUtil.isDecimal(call.operands[i].getType())) {
return true;
}
}
}
return (recurse && requiresDecimalExpansion(call.operands, recurse));
}
// override RexShuttle
public RexNode visitCall(final RexCall call) {
int i = reducibleExps.indexOf(call);
if (i == -1) {
return super.visitCall(call);
}
RexNode replacement = reducedValues.get(i);
if (addCasts.get(i) && (replacement.getType() != call.getType())) {
// Handle change from nullable to NOT NULL by claiming
// that the result is still nullable, even though
// we know it isn't.
//
// Also, we cannot reduce CAST('abc' AS VARCHAR(4)) to 'abc'.
// If we make 'abc' of type VARCHAR(4), we may later encounter
// the same expression in a ProjectRel's digest where it has
// type VARCHAR(3), and that's wrong.
replacement = rexBuilder.makeCast(call.getType(), replacement);
}
return replacement;
}
/**
* Replaces the operands of a call. The new operands' types must match the old operands' types.
*/
public static RexCall replaceOperands(RexCall call, RexNode[] operands) {
if (call.operands == operands) {
return call;
}
for (int i = 0; i < operands.length; i++) {
RelDataType oldType = call.operands[i].getType();
RelDataType newType = operands[i].getType();
if (!oldType.isNullable() && newType.isNullable()) {
throw Util.newInternal("invalid nullability");
}
assert (oldType.toString().equals(newType.toString()));
}
return new RexCall(call.getType(), call.getOperator(), operands);
}
public RexNode visitCall(RexCall call) {
List<RexNode> normalizedOperands = new ArrayList<RexNode>();
int diffCount = 0;
for (RexNode operand : call.getOperands()) {
operand.accept(this);
final RexNode normalizedOperand = lookup(operand);
normalizedOperands.add(normalizedOperand);
if (normalizedOperand != operand) {
++diffCount;
}
}
if (diffCount > 0) {
call = call.clone(call.getType(), normalizedOperands);
}
return register(call);
}
private void reduceCasts(RexCall outerCast) {
RexNode[] operands = outerCast.getOperands();
if (operands.length != 1) {
return;
}
RelDataType outerCastType = outerCast.getType();
RelDataType operandType = operands[0].getType();
if (operandType.equals(outerCastType)) {
removableCasts.add(outerCast);
return;
}
// See if the reduction
// CAST((CAST x AS type) AS type NOT NULL)
// -> CAST(x AS type NOT NULL)
// applies. TODO jvs 15-Dec-2008: consider
// similar cases for precision changes.
if (!(operands[0] instanceof RexCall)) {
return;
}
RexCall innerCast = (RexCall) operands[0];
if (innerCast.getOperator() != SqlStdOperatorTable.castFunc) {
return;
}
if (innerCast.getOperands().length != 1) {
return;
}
RelDataTypeFactory typeFactory = preparingStmt.getFarragoTypeFactory();
RelDataType outerTypeNullable = typeFactory.createTypeWithNullability(outerCastType, true);
RelDataType innerTypeNullable = typeFactory.createTypeWithNullability(operandType, true);
if (outerTypeNullable != innerTypeNullable) {
return;
}
if (operandType.isNullable()) {
removableCasts.add(innerCast);
}
}
