Both In() and IsNull() will work on general expressions, not just columns.

src/java/com/samskivert/depot/expression/ColumnExp.java

@@ -26,7 +26,6 @@ import com.samskivert.depot.PersistentRecord;
 import com.samskivert.depot.clause.Join;
 import com.samskivert.depot.impl.FragmentVisitor;
 import com.samskivert.depot.impl.operator.In;
-import com.samskivert.depot.impl.operator.IsNull;
 import com.samskivert.depot.impl.operator.Like;
 
 /**
@@ -55,18 +54,6 @@ public class ColumnExp extends FluentExp
         return new ColumnExp(oClass, name);
     }
 
-    /** Returns an {@link IsNull} with this column as its target. */
-    public IsNull isNull ()
-    {
-        return new IsNull(this);
-    }
-
-    /** Returns an {@link In} with this column and the supplied values. */
-    public In in (Comparable<?>... values)
-    {
-        return new In(this, values);
-    }
-
     /** Returns an {@link In} with this column and the supplied values. */
     public In in (Collection<? extends Comparable<?>> values)
     {

src/java/com/samskivert/depot/expression/FluentExp.java

@@ -28,6 +28,8 @@ import com.samskivert.depot.impl.operator.Div;
 import com.samskivert.depot.impl.operator.Equals;
 import com.samskivert.depot.impl.operator.GreaterThan;
 import com.samskivert.depot.impl.operator.GreaterThanEquals;
+import com.samskivert.depot.impl.operator.In;
+import com.samskivert.depot.impl.operator.IsNull;
 import com.samskivert.depot.impl.operator.LessThan;
 import com.samskivert.depot.impl.operator.LessThanEquals;
 import com.samskivert.depot.impl.operator.Mul;
@@ -64,6 +66,18 @@ public abstract class FluentExp
         return new NotEquals(this, expr);
     }
 
+    /** Returns an {@link IsNull} with this expression as its target. */
+    public IsNull isNull ()
+    {
+        return new IsNull(this);
+    }
+
+    /** Returns an {@link In} with this expression and the supplied values. */
+    public In in (Comparable<?>... values)
+    {
+        return new In(this, values);
+    }
+
     /** Returns a {@link GreaterThan} with this expression and the supplied target. */
     public FluentExp greaterThan (Comparable<?> value)
     {

src/java/com/samskivert/depot/impl/BuildVisitor.java

@@ -197,7 +197,7 @@ public abstract class BuildVisitor implements FragmentVisitor<Void>
 
     public Void visit (IsNull isNull)
     {
-        isNull.getColumn().accept(this);
+        isNull.getExpression().accept(this);
         _builder.append(" is null");
         return null;
     }
@@ -209,7 +209,7 @@ public abstract class BuildVisitor implements FragmentVisitor<Void>
             new ValueExp(false).accept(this);
             return null;
         }
-        in.getColumn().accept(this);
+        in.getExpression().accept(this);
         _builder.append(" in (");
         Comparable<?>[] values = in.getValues();
         for (int ii = 0; ii < values.length; ii ++) {

src/java/com/samskivert/depot/impl/ExpressionEvaluator.java

@@ -137,13 +137,13 @@ public class ExpressionEvaluator
 
     public Object visit (IsNull isNull)
     {
-        Object operand = isNull.getColumn().accept(this);
+        Object operand = isNull.getExpression().accept(this);
         return (operand instanceof NoValue) ? operand : operand != null;
     }
 
     public Object visit (In in)
     {
-        Object operand = in.getColumn().accept(this);
+        Object operand = in.getExpression().accept(this);
         return (operand instanceof NoValue) ? operand :
             -1 != ArrayUtil.indexOf(in.getValues(), operand);
     }

src/java/com/samskivert/depot/impl/PostgreSQL4Builder.java

@@ -45,7 +45,7 @@ public class PostgreSQL4Builder extends PostgreSQLBuilder
                 new ValueExp(false).accept(this);
                 return null;
             }
-            in.getColumn().accept(this);
+            in.getExpression().accept(this);
             _builder.append(" = any (?)");
             _bindables.add(new Bindable() {
                 public void doBind (Connection conn, PreparedStatement stmt, int argIdx)

src/java/com/samskivert/depot/impl/operator/In.java

@@ -23,7 +23,6 @@ package com.samskivert.depot.impl.operator;
 import java.util.Collection;
 
 import com.samskivert.depot.PersistentRecord;
-import com.samskivert.depot.expression.ColumnExp;
 import com.samskivert.depot.expression.SQLExpression;
 import com.samskivert.depot.impl.FragmentVisitor;
 
@@ -36,20 +35,20 @@ public class In
     /** The maximum number of keys allowed in an IN() clause. */
     public static final int MAX_KEYS = Short.MAX_VALUE;
 
-    public In (ColumnExp column, Comparable<?>... values)
+    public In (SQLExpression expression, Comparable<?>... values)
     {
-        _column = column;
+        _expression = expression;
         _values = values;
     }
 
-    public In (ColumnExp pColumn, Collection<? extends Comparable<?>> values)
+    public In (SQLExpression pColumn, Collection<? extends Comparable<?>> values)
     {
         this(pColumn, values.toArray(new Comparable<?>[values.size()]));
     }
 
-    public ColumnExp getColumn ()
+    public SQLExpression getExpression ()
     {
-        return _column;
+        return _expression;
     }
 
     public Comparable<?>[] getValues ()
@@ -66,14 +65,14 @@ public class In
     // from SQLFragment
     public void addClasses (Collection<Class<? extends PersistentRecord>> classSet)
     {
-        _column.addClasses(classSet);
+        _expression.addClasses(classSet);
     }
 
     @Override // from Object
     public String toString ()
     {
         StringBuilder builder = new StringBuilder();
-        builder.append(_column).append(" in (");
+        builder.append(_expression).append(" in (");
         for (int ii = 0; ii < _values.length; ii++) {
             if (ii > 0) {
                 builder.append(", ");
@@ -84,6 +83,6 @@ public class In
         return builder.append(")").toString();
     }
 
-    protected ColumnExp _column;
+    protected SQLExpression _expression;
     protected Comparable<?>[] _values;
 }

src/java/com/samskivert/depot/impl/operator/IsNull.java

@@ -23,7 +23,6 @@ package com.samskivert.depot.impl.operator;
 import java.util.Collection;
 
 import com.samskivert.depot.PersistentRecord;
-import com.samskivert.depot.expression.ColumnExp;
 import com.samskivert.depot.expression.SQLExpression;
 import com.samskivert.depot.impl.FragmentVisitor;
 
@@ -33,14 +32,14 @@ import com.samskivert.depot.impl.FragmentVisitor;
 public class IsNull
     implements SQLExpression
 {
-    public IsNull (ColumnExp column)
+    public IsNull (SQLExpression expression)
     {
-        _column = column;
+        _expression = expression;
     }
 
-    public ColumnExp getColumn()
+    public SQLExpression getExpression ()
     {
-        return _column;
+        return _expression;
     }
 
     // from SQLFragment
@@ -57,8 +56,8 @@ public class IsNull
     @Override // from Object
     public String toString ()
     {
-        return "IsNull(" + _column + ")";
+        return "IsNull(" + _expression + ")";
     }
 
-    protected ColumnExp _column;
+    protected SQLExpression _expression;
 }