Add QList for List typed projections

Add multi argument creation for GroupBy ResultTransformer #473

querydsl-core/src/main/java/com/mysema/query/group/GroupBy.java

@@ -29,6 +29,7 @@
 import com.mysema.query.types.FactoryExpressionUtils;
 import com.mysema.query.types.Operation;
 import com.mysema.query.types.Ops;
+import com.mysema.query.types.QList;
 import com.mysema.query.types.QTuple;
 import com.mysema.query.types.Visitor;
 
@@ -79,6 +80,16 @@ public static <K> GroupByBuilder<K> groupBy(Expression<K> key) {
         return new GroupByBuilder<K>(key);
     }
 
+    /**
+     * Create a new GroupByBuilder for the given key expressions
+     *
+     * @param keys
+     * @return
+     */
+    public static GroupByBuilder<List<?>> groupBy(Expression<?>... keys) {
+        return new GroupByBuilder<List<?>>(new QList(keys));
+    }
+
     /**
      * Create a new aggregating min expression
      *

querydsl-core/src/main/java/com/mysema/query/types/QList.java

@@ -0,0 +1,97 @@
+/*
+ * Copyright 2013, Mysema Ltd
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ * http://www.apache.org/licenses/LICENSE-2.0
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.mysema.query.types;
+
+import java.util.List;
+
+import javax.annotation.Nullable;
+
+import com.google.common.collect.ImmutableList;
+
+/**
+ * QList represents a projection of type List
+ *
+ * @author tiwe
+ *
+ */
+public class QList extends ExpressionBase<List<?>> implements FactoryExpression<List<?>> {
+
+    private static final long serialVersionUID = -7545994090073480810L;
+
+    private final ImmutableList<Expression<?>> args;
+
+    /**
+     * Create a new QList instance
+     *
+     * @param args
+     */
+    public QList(Expression<?>... args) {
+        super((Class)List.class);
+        this.args = ImmutableList.copyOf(args);
+    }
+
+    /**
+     * Create a new QList instance
+     *
+     * @param args
+     */
+    public QList(ImmutableList<Expression<?>> args) {
+        super((Class)List.class);
+        this.args = args;
+    }
+
+    /**
+     * Create a new QMap instance
+     *
+     * @param args
+     */
+    public QList(Expression<?>[]... args) {
+        super((Class)List.class);
+        ImmutableList.Builder<Expression<?>> builder = ImmutableList.builder();
+        for (Expression<?>[] exprs: args) {
+            builder.add(exprs);
+        }
+        this.args = builder.build();
+    }
+
+    @Override
+    @Nullable
+    public <R, C> R accept(Visitor<R, C> v, C context) {
+        return v.visit(this, context);
+    }
+
+    @Override
+    public List<Expression<?>> getArgs() {
+        return args;
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (obj == this) {
+            return true;
+        } else if (obj instanceof FactoryExpression) {
+            FactoryExpression<?> c = (FactoryExpression<?>)obj;
+            return args.equals(c.getArgs()) && getType().equals(c.getType());
+        } else {
+            return false;
+        }
+    }
+
+    @Override
+    @Nullable
+    public List<?> newInstance(Object... args) {
+        return ImmutableList.copyOf(args);
+    }
+
+}