1 files changed, 58 insertions, 0 deletions
diff --git a/container-search/src/main/java/com/yahoo/search/grouping/request/PredefinedFunction.java b/container-search/src/main/java/com/yahoo/search/grouping/request/PredefinedFunction.java
new file mode 100644
index 00000000000..b00ee97452c
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+++ b/container-search/src/main/java/com/yahoo/search/grouping/request/PredefinedFunction.java
@@ -0,0 +1,58 @@
+// 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.Iterator;
+import java.util.LinkedList;
+import java.util.List;
+
+/**
+ * This class represents a predefined bucket-function in a {@link GroupingExpression}. It maps the input into one of the
+ * given buckets by the result of the argument expression.
+ *
+ * @author <a href="mailto:simon@yahoo-inc.com">Simon Thoresen</a>
+ */
+public abstract class PredefinedFunction extends FunctionNode {
+
+    protected PredefinedFunction(GroupingExpression exp, List<? extends BucketValue> args) {
+        super("predefined", asList(exp, args));
+        Iterator<? extends BucketValue> it = args.iterator();
+        BucketValue prev = it.next();
+        while (it.hasNext()) {
+            BucketValue arg = it.next();
+            if (prev.compareTo(arg) >= 0) {
+                throw new IllegalArgumentException("Buckets must be monotonically increasing, got " + prev +
+                                                   " before " + arg + ".");
+            }
+            prev = arg;
+        }
+    }
+
+    /**
+     * Returns the number of buckets to divide the result into.
+     *
+     * @return The bucket count.
+     */
+    public int getNumBuckets() {
+        return getNumArgs() - 1;
+    }
+
+    /**
+     * Returns the bucket at the given index.
+     *
+     * @param i The index of the bucket to return.
+     * @return The bucket at the given index.
+     * @throws IndexOutOfBoundsException If the index is out of range.
+     */
+    public BucketValue getBucket(int i) {
+        return (BucketValue)getArg(i + 1);
+    }
+
+    private static
+    List<GroupingExpression> asList(GroupingExpression exp, List<? extends BucketValue> args) {
+        List<GroupingExpression> ret = new LinkedList<>();
+        ret.add(exp);
+        ret.addAll(args);
+        return ret;
+    }
+}
+