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 List<Expression> translateList(List<RexNode> operandList) {
final List<Expression> list = new ArrayList<Expression>();
for (RexNode rex : operandList) {
list.add(translate(rex));
}
return list;
}
private RexToLixTranslator(
RexProgram program, JavaTypeFactory typeFactory, List<Expression> inputs) {
this.program = program;
this.typeFactory = typeFactory;
for (Expression input : inputs) {
inputSlots.add(new Slot(null, input));
}
}
/**
* Gets the expression for an input and counts it.
*
* @param index Input ordinal
* @return Expression to which an input should be translated
*/
private Expression getInput(int index) {
Slot slot = inputSlots.get(index);
if (list == null) {
slot.count++;
} else {
if (slot.count > 1 && slot.parameterExpression == null) {
slot.parameterExpression = Expressions.parameter(slot.expression.type, "current" + index);
list.add(Expressions.declare(Modifier.FINAL, slot.parameterExpression, slot.expression));
}
}
return slot.parameterExpression != null ? slot.parameterExpression : slot.expression;
}
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;
}