1 files changed, 98 insertions, 0 deletions
diff --git a/yolean/src/main/java/com/yahoo/yolean/chain/Chain.java b/yolean/src/main/java/com/yahoo/yolean/chain/Chain.java
new file mode 100644
index 00000000000..86ff0e07d00
--- /dev/null
+++ b/yolean/src/main/java/com/yahoo/yolean/chain/Chain.java
@@ -0,0 +1,98 @@
+// Copyright 2016 Yahoo Inc. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+package com.yahoo.yolean.chain;
+
+import com.google.common.collect.ImmutableList;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.Iterator;
+import java.util.List;
+
+import static java.util.Objects.requireNonNull;
+
+/**
+ * An immutable and ordered list of components
+ *
+ * @author tonytv
+ */
+public final class Chain<T> implements Iterable<T> {
+
+    private final String id;
+    private final Collection<T> components;
+
+    @SafeVarargs
+    public Chain(String id, T... components) {
+        this(id, Arrays.asList(components));
+    }
+
+    public Chain(String id, List<? extends T> components) {
+        requireNonNull(id, "id must be non-null.");
+        requireNonNull(components, "components must be non-null");
+
+        this.components = ImmutableList.copyOf(components);
+        this.id = id;
+    }
+
+    public String id() {
+        return id;
+    }
+
+    public boolean isEmpty() {
+        return components.isEmpty();
+    }
+
+    @Override
+    public Iterator<T> iterator() {
+        return components.iterator();
+    }
+
+    @Override
+    public String toString() {
+        StringBuilder b = new StringBuilder();
+        b.append("chain '").append(id).append("'{");
+        boolean first = true;
+        for (T component : components) {
+            if (!first) {
+                b.append("->");
+            } else {
+                first = false;
+            }
+            b.append(" ").append(component.getClass().getSimpleName()).append(" ");
+        }
+        b.append("}");
+        return b.toString();
+    }
+
+    @Override
+    public int hashCode() {
+        return id.hashCode();
+    }
+
+    @Override
+    public boolean equals(Object other) {
+        return other instanceof Chain && equals((Chain<?>)other);
+    }
+
+    public boolean equals(Chain<?> other) {
+        return id.equals(other.id) && componentsIdentical(components, other.components);
+    }
+
+    private boolean componentsIdentical(Collection<T> components1, Collection<?> components2) {
+        if (components1.size() != components2.size()) {
+            return false;
+        }
+        Iterator<T> iterator1 = components1.iterator();
+        Iterator<?> iterator2 = components2.iterator();
+        while (iterator1.hasNext()) {
+            T c1 = iterator1.next();
+            Object c2 = iterator2.next();
+
+            if (c1 != c2) {
+                return false;
+            }
+        }
+        return true;
+    }
+}