/**
* Generates a cast from one row type to another
*
* @param rexBuilder RexBuilder to use for constructing casts
* @param lhsRowType target row type
* @param rhsRowType source row type; fields must be 1-to-1 with lhsRowType, in same order
* @return cast expressions
*/
public static RexNode[] generateCastExpressions(
RexBuilder rexBuilder, RelDataType lhsRowType, RelDataType rhsRowType) {
int n = rhsRowType.getFieldCount();
assert n == lhsRowType.getFieldCount()
: "field count: lhs [" + lhsRowType + "] rhs [" + rhsRowType + "]";
RexNode[] rhsExps = new RexNode[n];
for (int i = 0; i < n; ++i) {
rhsExps[i] = rexBuilder.makeInputRef(rhsRowType.getFields()[i].getType(), i);
}
return generateCastExpressions(rexBuilder, lhsRowType, rhsExps);
}
public Void visitInputRef(RexInputRef inputRef) {
super.visitInputRef(inputRef);
if (inputRef.getIndex() >= inputRowType.getFieldCount()) {
throw new IllegalForwardRefException();
}
return null;
}