edit

Author: usfalami

src/main/java/org/usf/jquery/core/CombinedOperator.java

@@ -11,7 +11,7 @@ public interface CombinedOperator extends Operator {
 	OperationColumn args(Object... args);
 
 	@Override
-	default OperationColumn args(JDBCType type, Object... args) {
+	default OperationColumn operation(JDBCType type, Object... args) {
 		var c = args(args);
 		if(type == c.getType()) {
 			return c;

src/main/java/org/usf/jquery/core/Comparator.java

@@ -25,6 +25,10 @@ default ColumnSingleFilter filter(Object... args) {
 		return new ColumnSingleFilter(args[0], 
 				expression(copyOfRange(args, 1, args.length))); // no type
 	}
+	
+	default boolean is(Class<? extends Comparator> type) { 
+		return type.isInstance(this);
+	}
 
 	//basic comparator
 

src/main/java/org/usf/jquery/core/OperationColumn.java

@@ -35,7 +35,7 @@ public JDBCType getType() {
 
 	@Override
 	public boolean isAggregation() {
-		return operator instanceof AggregateFunction || 
+		return operator.is(AggregateFunction.class) || 
 				(!isOverFunction() && Stream.of(args).anyMatch(Nested::aggregation)); //can do better
 	}
 
@@ -44,7 +44,7 @@ public Stream<DBColumn> groupKeys() {
 		if(isOverFunction()) {
 			return ((Partition)args[1]).groupKeys();
 		}
-		return operator instanceof AggregateFunction || operator instanceof ConstantOperator
+		return operator.is(AggregateFunction.class) || operator.is(ConstantOperator.class)
 				? Stream.empty() 
 				: DBColumn.super.groupKeys();
 	}

src/main/java/org/usf/jquery/core/Operator.java

@@ -31,10 +31,14 @@ public interface Operator extends DBProcessor {
 
 	String id(); //nullable
 
-	default OperationColumn args(JDBCType type, Object... args) {
+	default OperationColumn operation(JDBCType type, Object... args) {
 		return new OperationColumn(this, args, type);
 	}
 
+	default boolean is(Class<? extends Operator> type) {
+		return type.isInstance(this);
+	}
+	
 	//Arithmetic operations
 
 	static TypedOperator plus() {

src/main/java/org/usf/jquery/core/ParameterSet.java

@@ -28,20 +28,16 @@ public final class ParameterSet { //there is no Singleton implementation, dummy
 	private final Parameter[] parameters;
 
 	public Object[] assertArguments(Object... args) {
-		return assertArgumentsFrom(0, args);
-	}
-	
-	public Object[] assertArgumentsFrom(int idx, Object... args) { //partial assert
 		var arr = isNull(args) ? new Object[0] : args;
-		forEach(arr.length+idx, (p,i)-> {
-			if(i>=idx && !p.accept(i-idx, arr)) {
-				throw badArgumentTypeException(arr[i-idx], p.types(arr));
+		eachParameter(arr.length, (p,i)-> {
+			if(!p.accept(i, arr)) {
+				throw badArgumentTypeException(arr[i], p.types(arr));
 			}
 		});
 		return arr;
 	}
 
-	public void forEach(int nArgs, ObjIntConsumer<Parameter> cons) {
+	public void eachParameter(int nArgs, ObjIntConsumer<Parameter> cons) {
 		if(nArgs < nReqArgs || (nArgs > parameters.length && !isVarags())) {
 			throw badArgumentCountException(nArgs, nReqArgs);
 		}

src/main/java/org/usf/jquery/core/QueryBuilder.java

@@ -69,9 +69,11 @@ public QueryView overView(DBView view, Supplier<QueryView> supp) {
 	}
 
 	public QueryBuilder columns(@NonNull NamedColumn... columns) {
-		for(var col : columns) {
-			if(this.columns.stream().anyMatch(nc-> nc.getTag().equals(col.getTag()))) {
-				throw resourceAlreadyExistsException(col.getTag());
+		for(var col : columns) { //optional tag
+			if(nonNull(col.getTag()) && this.columns.stream()
+					.filter(c-> nonNull(c.getTag()))
+					.anyMatch(nc-> nc.getTag().equals(col.getTag()))) {
+					throw resourceAlreadyExistsException(col.getTag());
 			}
 			this.columns.add(col);
 		}

src/main/java/org/usf/jquery/core/TypedComparator.java

@@ -11,34 +11,33 @@
  *
  */
 @Getter
-public final class TypedComparator {
+public final class TypedComparator implements Comparator {
 
-	private final Comparator comparator;
+	private final Comparator comparator; // do not delegate
 	private final ParameterSet parameterSet;
 
 	public TypedComparator(Comparator comparator, Parameter... parameters) {
 		this.comparator = comparator;
 		this.parameterSet = ofParameters(parameters);
 	}
 
-	public ComparisonExpression expression(Object... right) {
-		try {
-			return comparator.expression(parameterSet.assertArgumentsFrom(1, right)); //no left 
-		} catch (BadArgumentException e) {
-			throw badArgumentsException("comparator", comparator.id(), right, e);
-		}
+	@Override
+	public String id() {
+		return comparator.id();
 	}
 
-	public ColumnSingleFilter filter(Object... args) {
+	@Override
+	public String sql(QueryVariables builder, Object[] args) {
 		try {
-			return comparator.filter(parameterSet.assertArguments(args));
+			return comparator.sql(builder, parameterSet.assertArguments(args));
 		} catch (BadArgumentException e) {
 			throw badArgumentsException("comparator", comparator.id(), args, e);
 		}
 	}
-
-	public Comparator unwrap() {
-		return comparator;
+	
+	@Override
+	public boolean is(Class<? extends Comparator> type) {
+		return comparator.is(type);
 	}
 
 	@Override

src/main/java/org/usf/jquery/core/TypedOperator.java

@@ -11,9 +11,9 @@
  *
  */
 @Getter
-public class TypedOperator {
+public class TypedOperator implements Operator {
 
-	private final Operator operator;
+	private final Operator operator; // do not delegate
 	private final ArgTypeRef typeFn;
 	private final ParameterSet parameterSet;
 
@@ -26,22 +26,37 @@ public TypedOperator(ArgTypeRef typeFn, Operator function, Parameter... paramete
 		this.typeFn = typeFn;
 		this.parameterSet = ofParameters(parameter);
 	}
-
-	public OperationColumn operation(Object... args) {
+	
+	@Override
+	public String id() {
+		return operator.id();
+	}
+	
+	@Override
+	public String sql(QueryVariables builder, Object[] args) {
 		try {
-			args = parameterSet.assertArguments(args);
-			return operator.args(typeFn.apply(args), args);
-		} catch (BadArgumentException e) {
+			return operator.sql(builder, parameterSet.assertArguments(args));
+		}
+		catch (BadArgumentException e) {
 			throw badArgumentsException("operator", operator.id(), args, e);
 		}
 	}
+	
+	@Override
+	public boolean is(Class<? extends Operator> type) {
+		return operator.is(type);
+	}
 
-	public boolean isCountFunction() {
-		return "COUNT".equals(operator.id());
+	public OperationColumn operation(Object... args) {
+		return Operator.super.operation(typeFn.apply(args), args);
 	}
-	
+
 	public boolean isWindowFunction() {
-		return operator instanceof WindowFunction;
+		return operator.is(WindowFunction.class);
+	}
+	
+	public boolean isCountFunction() {
+		return "COUNT".equals(operator.id());
 	}
 
 	@Override

src/main/java/org/usf/jquery/core/Utils.java

@@ -46,7 +46,7 @@ public static <T> String joinArray(String delemiter, T... args) {
 	@SuppressWarnings("unchecked")
 	public static <T> String joinAndDelemitArray(String delemiter, String before, String after, T... args) {
 		return isNull(args) 
-				? null 
+				? before + after 
 				: joinAndDelemit(delemiter, before, after, Stream.of(args));
 	}
 

src/main/java/org/usf/jquery/web/RequestEntryChain.java

@@ -11,6 +11,7 @@
 import static java.util.Optional.empty;
 import static java.util.Optional.ofNullable;
 import static java.util.stream.Collectors.joining;
+import static org.usf.jquery.core.BadArgumentException.badArgumentsFormat;
 import static org.usf.jquery.core.Comparator.eq;
 import static org.usf.jquery.core.Comparator.in;
 import static org.usf.jquery.core.Comparator.lookupComparator;
@@ -44,6 +45,7 @@
 import java.util.function.IntFunction;
 import java.util.stream.Stream;
 
+import org.usf.jquery.core.BadArgumentException;
 import org.usf.jquery.core.ComparisonExpression;
 import org.usf.jquery.core.DBColumn;
 import org.usf.jquery.core.DBFilter;
@@ -250,7 +252,7 @@ else if(nonNull(rc.col)) {
 			if(rc.entry.isLast()) { // no criteria, no comparator
 				if(!isEmpty(values)) {
 					var fn = values.size() == 1 ? eq() : in(); //non empty
-					var e = new RequestEntryChain(fn.unwrap().id(), false, null, values, null); 
+					var e = new RequestEntryChain(fn.id(), false, null, values, null); 
 					return fn.filter(e.toArgs(vd, ctx, rc.col, fn.getParameterSet())); //no chain
 				}
 				throw badEntrySyntaxException(this.toString(), FILTER);
@@ -429,7 +431,7 @@ private Object[] toArgs(ViewDecorator td, QueryContext ctx, DBObject col, Parame
 			arr[0] = col;
 		}
 		try {
-			ps.forEach(arr.length, (p,i)-> {
+			ps.eachParameter(arr.length, (p,i)-> {
 				if(i>=inc) { //arg0 already parsed
 					var e = args.get(i-inc);
 					arr[i] = isNull(e.value) || e.text
@@ -439,8 +441,8 @@ private Object[] toArgs(ViewDecorator td, QueryContext ctx, DBObject col, Parame
 			});
 		}
 		catch (Exception e) {
-			throw new EntrySyntaxException(format("bad entry arguments : %s[(%s)]", 
-					value, isNull(args) ? "" : joinArray(", ", args.toArray())), e);
+			throw new EntrySyntaxException("bad entry arguments: " +
+					badArgumentsFormat(value, nonNull(args) ? args.toArray() : null), e);
 		}
 		return arr;
 	}

src/main/java/org/usf/jquery/web/RequestParameterResolver.java

@@ -55,6 +55,10 @@ public QueryBuilder requestQuery(@NonNull RequestQueryParam ant, @NonNull Map<St
 			}
 			throw new ResourceAccessException("non-aggregate query");
 		}
+		catch (Exception e) {
+			e.printStackTrace();
+			throw e;
+		}
 		finally {
 			releaseContext();
 		}