// traversing origin, find ExprNodeDesc in sources and replaces it with ExprNodeDesc
// in targets having same index.
// return null if failed to find
public static ExprNodeDesc replace(
ExprNodeDesc origin, List<ExprNodeDesc> sources, List<ExprNodeDesc> targets) {
int index = indexOf(origin, sources);
if (index >= 0) {
return targets.get(index);
}
// encountered column or field which cannot be found in sources
if (origin instanceof ExprNodeColumnDesc || origin instanceof ExprNodeFieldDesc) {
return null;
}
// for ExprNodeGenericFuncDesc, it should be deterministic and stateless
if (origin instanceof ExprNodeGenericFuncDesc) {
ExprNodeGenericFuncDesc func = (ExprNodeGenericFuncDesc) origin;
if (!FunctionRegistry.isDeterministic(func.getGenericUDF())
|| FunctionRegistry.isStateful(func.getGenericUDF())) {
return null;
}
List<ExprNodeDesc> children = new ArrayList<ExprNodeDesc>();
for (int i = 0; i < origin.getChildren().size(); i++) {
ExprNodeDesc child = replace(origin.getChildren().get(i), sources, targets);
if (child == null) {
return null;
}
children.add(child);
}
// duplicate function with possibly replaced children
ExprNodeGenericFuncDesc clone = (ExprNodeGenericFuncDesc) func.clone();
clone.setChildren(children);
return clone;
}
// constant or null, just return it
return origin;
}
/** Return false if the expression has any non deterministic function */
public static boolean isDeterministic(ExprNodeDesc desc) {
if (desc instanceof ExprNodeGenericFuncDesc) {
if (!FunctionRegistry.isDeterministic(((ExprNodeGenericFuncDesc) desc).getGenericUDF())) {
return false;
}
}
if (desc.getChildren() != null) {
for (ExprNodeDesc child : desc.getChildren()) {
if (!isDeterministic(child)) {
return false;
}
}
}
return true;
}
public static boolean isConstant(ExprNodeDesc value) {
if (value instanceof ExprNodeConstantDesc) {
return true;
}
if (value instanceof ExprNodeGenericFuncDesc) {
ExprNodeGenericFuncDesc func = (ExprNodeGenericFuncDesc) value;
if (!FunctionRegistry.isDeterministic(func.getGenericUDF())) {
return false;
}
for (ExprNodeDesc child : func.getChildren()) {
if (!isConstant(child)) {
return false;
}
}
return true;
}
return false;
}
private static ExprNodeConstantDesc foldConstant(ExprNodeGenericFuncDesc func) {
GenericUDF udf = func.getGenericUDF();
if (!FunctionRegistry.isDeterministic(udf) || FunctionRegistry.isStateful(udf)) {
return null;
}
try {
// If the UDF depends on any external resources, we can't fold because the
// resources may not be available at compile time.
if (udf instanceof GenericUDFBridge) {
UDF internal = ReflectionUtils.newInstance(((GenericUDFBridge) udf).getUdfClass(), null);
if (internal.getRequiredFiles() != null || internal.getRequiredJars() != null) {
return null;
}
} else {
if (udf.getRequiredFiles() != null || udf.getRequiredJars() != null) {
return null;
}
}
if (func.getChildren() != null) {
for (ExprNodeDesc child : func.getChildren()) {
if (child instanceof ExprNodeConstantDesc) {
continue;
}
if (child instanceof ExprNodeGenericFuncDesc) {
if (foldConstant((ExprNodeGenericFuncDesc) child) != null) {
continue;
}
}
return null;
}
}
ExprNodeEvaluator evaluator = ExprNodeEvaluatorFactory.get(func);
ObjectInspector output = evaluator.initialize(null);
Object constant = evaluator.evaluate(null);
Object java = ObjectInspectorUtils.copyToStandardJavaObject(constant, output);
return new ExprNodeConstantDesc(java);
} catch (Exception e) {
return null;
}
}
