1 files changed, 78 insertions, 0 deletions
diff --git a/container-search/src/main/java/com/yahoo/search/grouping/request/FunctionNode.java b/container-search/src/main/java/com/yahoo/search/grouping/request/FunctionNode.java
new file mode 100644
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+++ b/container-search/src/main/java/com/yahoo/search/grouping/request/FunctionNode.java
@@ -0,0 +1,78 @@
+// Copyright 2016 Yahoo Inc. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+package com.yahoo.search.grouping.request;
+
+import java.util.*;
+
+/**
+ * This class represents a function in a {@link GroupingExpression}. Because it operate on other expressions (as opposed
+ * to {@link AggregatorNode} and {@link DocumentValue} that operate on inputs), this expression type can be used at any
+ * input level (see {@link GroupingExpression#resolveLevel(int)}).
+ *
+ * @author <a href="mailto:simon@yahoo-inc.com">Simon Thoresen</a>
+ */
+public abstract class FunctionNode extends GroupingExpression implements Iterable<GroupingExpression> {
+
+    private final List<GroupingExpression> args = new ArrayList<>();
+
+    protected FunctionNode(String image, List<GroupingExpression> args) {
+        super(image + "(" + asString(args) + ")");
+        this.args.addAll(args);
+    }
+
+    /**
+     * Returns the number of arguments that were given to this function at construction.
+     *
+     * @return The argument count.
+     */
+    public int getNumArgs() {
+        return args.size();
+    }
+
+    /**
+     * Returns the argument at the given index.
+     *
+     * @param i The index of the argument to return.
+     * @return The argument at the given index.
+     * @throws IndexOutOfBoundsException If the index is out of range.
+     */
+    public GroupingExpression getArg(int i) {
+        return args.get(i);
+    }
+
+    @Override
+    public Iterator<GroupingExpression> iterator() {
+        return Collections.unmodifiableList(args).iterator();
+    }
+
+    @Override
+    public void resolveLevel(int level) {
+        super.resolveLevel(level);
+        for (GroupingExpression arg : args) {
+            arg.resolveLevel(level);
+        }
+    }
+
+    @Override
+    public void visit(ExpressionVisitor visitor) {
+        super.visit(visitor);
+        for (GroupingExpression arg : args) {
+            arg.visit(visitor);
+        }
+    }
+
+    @SuppressWarnings("unchecked")
+    protected static <T> List<T> asList(T arg1, T... argN) {
+        return asList(Arrays.asList(arg1), Arrays.asList(argN));
+    }
+
+    @SuppressWarnings("unchecked")
+    protected static <T> List<T> asList(T arg1, T arg2, T... argN) {
+        return asList(Arrays.asList(arg1, arg2), Arrays.asList(argN));
+    }
+
+    protected static <T> List<T> asList(List<T> foo, List<T> bar) {
+        List<T> ret = new LinkedList<>(foo);
+        ret.addAll(bar);
+        return ret;
+    }
+}