1 files changed, 107 insertions, 0 deletions
diff --git a/container-search/src/main/java/com/yahoo/search/query/profile/ChainedMap.java b/container-search/src/main/java/com/yahoo/search/query/profile/ChainedMap.java
new file mode 100644
index 00000000000..3ec9a3c41b8
--- /dev/null
+++ b/container-search/src/main/java/com/yahoo/search/query/profile/ChainedMap.java
@@ -0,0 +1,107 @@
+// Copyright Yahoo. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+package com.yahoo.search.query.profile;
+
+import java.util.Collection;
+import java.util.HashSet;
+import java.util.Map;
+import java.util.Set;
+
+/**
+ * A read-only map which forwards lookups to a primary map, and then a secondary for
+ * keys not existing in the primary.
+ *
+ * @author bratseth
+ */
+class ChainedMap<K, V> implements Map<K, V> {
+
+    private final Map<K, V> primary, secondary;
+
+    ChainedMap(Map<K, V> primary, Map<K, V> secondary) {
+        this.primary = primary;
+        this.secondary = secondary;
+    }
+
+    @Override
+    public int size() {
+        return (primary.size() >= secondary.size())
+                ? countUnique(primary, secondary)
+                : countUnique(secondary, primary);
+    }
+
+    private int countUnique(Map<K, V> large, Map<K,V> small) {
+        int size = large.size();
+        for (K key : small.keySet()) {
+            if ( ! large.containsKey(key)) size++;
+        }
+        return size;
+    }
+
+    @Override
+    public boolean isEmpty() {
+        return primary.isEmpty() && secondary.isEmpty();
+    }
+
+    @Override
+    public boolean containsKey(Object key) {
+        return primary.containsKey(key) || secondary.containsKey(key);
+    }
+
+    @Override
+    public boolean containsValue(Object value) {
+        return primary.containsValue(value) || secondary.containsValue(value);
+    }
+
+    @Override
+    public V get(Object key) {
+        V value = primary.get(key);
+        return value != null ? value : secondary.get(key);
+    }
+
+    @Override
+    public V put(K key, V value) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public V remove(Object key) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public void putAll(Map<? extends K, ? extends V> m) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public void clear() {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public Set<K> keySet() {
+        var keys = new HashSet<>(secondary.keySet());
+        keys.addAll(primary.keySet());
+        return keys;
+    }
+
+    @Override
+    public Collection<V> values() {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public Set<Entry<K, V>> entrySet() {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public int hashCode() {
+        throw new UnsupportedOperationException();
+    }
+
+}