private Expression translate0(RexNode expr) {
if (expr instanceof RexInputRef) {
// TODO: multiple inputs, e.g. joins
final Expression input = getInput(0);
final int index = ((RexInputRef) expr).getIndex();
final List<RelDataTypeField> fields = program.getInputRowType().getFieldList();
final RelDataTypeField field = fields.get(index);
if (fields.size() == 1) {
return input;
} else if (input.getType() == Object[].class) {
return Expressions.convert_(
Expressions.arrayIndex(input, Expressions.constant(field.getIndex())),
Types.box(JavaRules.EnumUtil.javaClass(typeFactory, field.getType())));
} else {
return Expressions.field(input, field.getName());
}
}
if (expr instanceof RexLocalRef) {
return translate(program.getExprList().get(((RexLocalRef) expr).getIndex()));
}
if (expr instanceof RexLiteral) {
return Expressions.constant(
((RexLiteral) expr).getValue(), typeFactory.getJavaClass(expr.getType()));
}
if (expr instanceof RexCall) {
final RexCall call = (RexCall) expr;
final SqlOperator operator = call.getOperator();
final ExpressionType expressionType = SQL_TO_LINQ_OPERATOR_MAP.get(operator);
if (expressionType != null) {
switch (operator.getSyntax()) {
case Binary:
return Expressions.makeBinary(
expressionType, translate(call.getOperands()[0]), translate(call.getOperands()[1]));
case Postfix:
case Prefix:
return Expressions.makeUnary(expressionType, translate(call.getOperands()[0]));
default:
throw new RuntimeException("unknown syntax " + operator.getSyntax());
}
}
Method method = SQL_OP_TO_JAVA_METHOD_MAP.get(operator);
if (method != null) {
List<Expression> exprs = translateList(Arrays.asList(call.operands));
return !Modifier.isStatic(method.getModifiers())
? Expressions.call(exprs.get(0), method, exprs.subList(1, exprs.size()))
: Expressions.call(method, exprs);
}
switch (expr.getKind()) {
default:
throw new RuntimeException("cannot translate expression " + expr);
}
}
throw new RuntimeException("cannot translate expression " + expr);
}
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;
}
static {
for (Map.Entry<Method, SqlOperator> entry : JAVA_TO_SQL_METHOD_MAP.entrySet()) {
SQL_OP_TO_JAVA_METHOD_MAP.put(entry.getValue(), entry.getKey());
}
}