/**
* Implement the cast expression.
*
* <p>TODO: check for overflow
*
* @return the rhs expression casted as the lhs type
*/
public Expression implement() {
// Check for invalid null assignment. Code generated afterwards
// can assume null will never be assigned to a not null value.
checkNotNull();
// Check for an explicit rhs null value. Code generated
// afterwards need never check for an explicit null.
if (rhsType.getSqlTypeName() == SqlTypeName.NULL) {
if (lhsType.isNullable()) {
return castFromNull();
} else {
// NOTE jvs 27-Jan-2005: this code will never actually
// be executed do to previous checkNotNull test, but
// it still has to compile!
return rhsAsValue();
}
}
// Case when left hand side is a nullable primitive
if (translator.isNullablePrimitive(lhsType)) {
if (SqlTypeUtil.isJavaPrimitive(rhsType)
&& (!rhsType.isNullable() || translator.isNullablePrimitive(rhsType))) {
return castPrimitiveToNullablePrimitive();
}
return castToAssignableValue();
}
// Case when left hand side is a not nullable primitive
if (SqlTypeUtil.isJavaPrimitive(lhsType)) {
return castToNotNullPrimitive();
}
// Case when left hand side is a structure
if (lhsType.isStruct()) {
assert (rhsType.isStruct());
// TODO jvs 27-May-2004: relax this assert and deal with
// conversions, null checks, etc.
assert (lhsType.equals(rhsType));
return getDirectAssignment();
}
// Default is to treat non-primitives as AssignableValue
return castToAssignableValue();
}
/**
* Generates a cast for a row type.
*
* @param rexBuilder RexBuilder to use for constructing casts
* @param lhsRowType target row type
* @param rhsExps expressions to be cast
* @return cast expressions
*/
public static RexNode[] generateCastExpressions(
RexBuilder rexBuilder, RelDataType lhsRowType, RexNode[] rhsExps) {
RelDataTypeField[] lhsFields = lhsRowType.getFields();
final int fieldCount = lhsFields.length;
RexNode[] castExps = new RexNode[fieldCount];
assert fieldCount == rhsExps.length;
for (int i = 0; i < fieldCount; ++i) {
RelDataTypeField lhsField = lhsFields[i];
RelDataType lhsType = lhsField.getType();
RelDataType rhsType = rhsExps[i].getType();
if (lhsType.equals(rhsType)) {
castExps[i] = rhsExps[i];
} else {
castExps[i] = rexBuilder.makeCast(lhsType, rhsExps[i]);
}
}
return castExps;
}
