/**
* Generates code to round an expression according to the Farrago convention. The Farrago
* convention is to round away from zero. Rounding is performed with the following algorithm.
*
* <pre>
* in = rhs;
* if (value < 0) {
* in = -in;
* out = Math.round(in);
* out = -out;
* } else {
* out = Math.round(in);
* }
* </pre>
*
* <p>PRECONDITION: rhsExp must be an unwrapped (not null) Java primitive
*
* <p>TODO: account for overflow in both unary minus and round.
*/
private Expression roundAway() {
// Get the primitive part of right hand side
RelDataType inType = translator.getTypeFactory().createTypeWithNullability(rhsType, false);
// TODO: is there any preference between stack and instance var?
OJClass inClass = getClass(inType);
Variable inTemp = translator.getRelImplementor().newVariable();
translator.addStatement(declareStackVar(inClass, inTemp, rhsExp));
OJClass outClass = getLhsClass();
Variable outTemp = translator.getRelImplementor().newVariable();
translator.addStatement(declareStackVar(outClass, outTemp, null));
boolean isLong =
translator.getFarragoTypeFactory().getClassForPrimitive(lhsType) == long.class;
addStatement(
new IfStatement(
new BinaryExpression(inTemp, BinaryExpression.LESS, Literal.constantZero()),
new StatementList(
assign(inTemp, minus(inClass, inTemp)),
assign(outTemp, round(lhsClass, inTemp, isLong)),
assign(outTemp, minus(outClass, outTemp))),
new StatementList(assign(outTemp, round(lhsClass, inTemp, isLong)))));
return outTemp;
}
/** Gets an expression for the current date */
private Expression getCurrentDate() {
// unfortunately, we hard code the method name here
return translator.convertVariable(
translator.getTypeFactory().createSqlType(SqlTypeName.DATE),
"getContextVariable_CURRENT_DATE",
new ExpressionList());
}
/** Creates a field access, as in expr.[value] */
private Expression getValue(RelDataType type, Expression expr) {
FarragoTypeFactory factory = (FarragoTypeFactory) translator.getTypeFactory();
return factory.getValueAccessExpression(type, expr);
}
