@Override
public LogicalExpression visitFunctionCall(
FunctionCall call, FunctionImplementationRegistry registry) {
List<LogicalExpression> args = Lists.newArrayList();
for (int i = 0; i < call.args.size(); ++i) {
LogicalExpression newExpr = call.args.get(i).accept(this, registry);
args.add(newExpr);
}
// replace with a new function call, since its argument could be changed.
call = new FunctionCall(call.getDefinition(), args, call.getPosition());
// call function resolver, get the best match.
FunctionResolver resolver = FunctionResolverFactory.getResolver(call);
DrillFuncHolder matchedFuncHolder =
resolver.getBestMatch(registry.getMethods().get(call.getDefinition().getName()), call);
// new arg lists, possible with implicit cast inserted.
List<LogicalExpression> argsWithCast = Lists.newArrayList();
if (matchedFuncHolder == null) {
// TODO: found no matched funcholder. Raise exception here?
return validateNewExpr(call);
} else {
// Compare parm type against arg type. Insert cast on top of arg, whenever necessary.
for (int i = 0; i < call.args.size(); ++i) {
MajorType parmType = matchedFuncHolder.getParmMajorType(i);
// Case 1: If 1) the argument is NullExpression
// 2) the parameter of matchedFuncHolder allows null input, or func's
// null_handling is NULL_IF_NULL (means null and non-null are exchangable).
// then replace NullExpression with a TypedNullConstant
if (call.args.get(i).equals(NullExpression.INSTANCE)
&& (parmType.getMode().equals(DataMode.OPTIONAL)
|| matchedFuncHolder.getNullHandling() == NullHandling.NULL_IF_NULL)) {
argsWithCast.add(new TypedNullConstant(parmType));
} else if (Types.softEquals(
parmType,
call.args.get(i).getMajorType(),
matchedFuncHolder.getNullHandling() == NullHandling.NULL_IF_NULL)) {
// Case 2: argument and parameter matches. Do nothing.
argsWithCast.add(call.args.get(i));
} else {
// Case 3: insert cast if param type is different from arg type.
FunctionDefinition castFuncDef =
CastFunctionDefs.getCastFuncDef(parmType.getMinorType());
List<LogicalExpression> castArgs = Lists.newArrayList();
castArgs.add(call.args.get(i)); // input_expr
argsWithCast.add(new FunctionCall(castFuncDef, castArgs, ExpressionPosition.UNKNOWN));
}
}
}
return validateNewExpr(
new FunctionCall(call.getDefinition(), argsWithCast, call.getPosition()));
}
public void resolveHash(
DrillConfig config,
LogicalExpression arg,
TypeProtos.MajorType expectedArg,
TypeProtos.MajorType expectedOut,
TypeProtos.DataMode expectedBestInputMode,
FunctionImplementationRegistry registry)
throws JClassAlreadyExistsException, IOException {
List<LogicalExpression> args = new ArrayList<>();
args.add(arg);
String[] registeredNames = {"hash"};
FunctionCall call = new FunctionCall("hash", args, ExpressionPosition.UNKNOWN);
FunctionResolver resolver = FunctionResolverFactory.getResolver(call);
DrillFuncHolder matchedFuncHolder = registry.findDrillFunction(resolver, call);
assertEquals(expectedBestInputMode, matchedFuncHolder.getParmMajorType(0).getMode());
}