private List<Expression> translate(List<Statement> list, List<RexLocalRef> rexList) {
// First pass. Count how many times each sub-expression is used.
this.list = null;
for (RexNode rexExpr : rexList) {
translate(rexExpr);
}
// Mark expressions as inline if they are not used more than once.
for (Map.Entry<RexNode, Slot> entry : map.entrySet()) {
if (entry.getValue().count < 2 || entry.getKey() instanceof RexLiteral) {
inlineRexSet.add(entry.getKey());
}
}
// Second pass. When translating each expression, if it is used more
// than once, the first time it is encountered, add a declaration to the
// list and set its usage count to 0.
this.list = list;
this.map.clear();
List<Expression> translateds = new ArrayList<Expression>();
for (RexNode rexExpr : rexList) {
translateds.add(translate(rexExpr));
}
return translateds;
}
private Expression translate(RexNode expr) {
Slot slot = map.get(expr);
if (slot == null) {
Expression expression = translate0(expr);
assert expression != null;
final ParameterExpression parameter;
if (!inlineRexSet.contains(expr) && !(expr instanceof RexLocalRef)) {
parameter = Expressions.parameter(expression.getType(), "v" + map.size());
} else {
parameter = null;
}
slot = new Slot(parameter, expression);
if (parameter != null && list != null) {
list.add(Expressions.declare(Modifier.FINAL, slot.parameterExpression, slot.expression));
}
map.put(expr, slot);
}
slot.count++;
return slot.parameterExpression != null ? slot.parameterExpression : slot.expression;
}