1 files changed, 131 insertions, 0 deletions
diff --git a/chain/src/main/java/com/yahoo/component/chain/Chain.java b/chain/src/main/java/com/yahoo/component/chain/Chain.java
new file mode 100644
index 00000000000..e067b934f03
--- /dev/null
+++ b/chain/src/main/java/com/yahoo/component/chain/Chain.java
@@ -0,0 +1,131 @@
+// Copyright 2016 Yahoo Inc. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+package com.yahoo.component.chain;
+
+import com.google.common.collect.ImmutableList;
+import com.yahoo.component.ComponentId;
+import com.yahoo.component.chain.dependencies.ordering.ChainBuilder;
+
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.List;
+
+/**
+ * An immutable ordered list of components
+ *
+ * @author tonytv
+ */
+public class Chain<COMPONENT extends ChainedComponent> {
+    final private List<COMPONENT> componentList;
+    private final ComponentId id;
+
+    /** Create a chain directly. This will NOT order the chain by the ordering constraints. */
+    public Chain(String id, List<COMPONENT> componentList) {
+        this(new ComponentId(id), componentList);
+    }
+
+    /** Create a chain directly. This will NOT order the chain by the ordering constraints. */
+    public Chain(ComponentId id, List<COMPONENT> componentList) {
+        this.id = id;
+        this.componentList = ImmutableList.copyOf(componentList);
+    }
+
+    /** Create a chain directly. This will NOT order the chain by the ordering constraints. */
+    public Chain(List<COMPONENT> componentList) {
+        this(new ComponentId("anonymous chain"), componentList);
+    }
+
+    /** Create a chain directly. This will NOT order the chain by the ordering constraints. */
+    @SafeVarargs
+    public Chain(COMPONENT... components) {
+        this("anonymous chain", components);
+    }
+
+    /** Create a chain directly. This will NOT order the chain by the ordering constraints. */
+    @SafeVarargs
+    public Chain(String id, COMPONENT... components) {
+        this(new ComponentId(id), components);
+    }
+
+    /** Create a chain directly. This will NOT order the chain by the ordering constraints. */
+    @SafeVarargs
+    public Chain(ComponentId id, COMPONENT... components) {
+        this(id, Arrays.<COMPONENT>asList(components));
+    }
+
+    /** Create a chain by using a builder. This will order the chain by the ordering constraints. */
+    public Chain(ComponentId id, Collection<COMPONENT> components, Collection<Phase> phases) {
+        this(id, buildChain(
+                emptyListIfNull(components),
+                emptyListIfNull(phases)).components());
+
+    }
+
+    public ComponentId getId() {
+        return id;
+    }
+
+    private static <T> Collection<T> emptyListIfNull(Collection<T> collection) {
+        return collection == null ? Collections.<T>emptyList() : collection;
+    }
+
+    private static <T extends ChainedComponent> Chain<T> buildChain(Collection<T> components, Collection<Phase> phases) {
+        ChainBuilder<T> builder = new ChainBuilder<>(new ComponentId("temp"));
+        for (Phase phase : phases) {
+            builder.addPhase(phase);
+        }
+
+        for (T component : components) {
+            builder.addComponent(component);
+        }
+
+        return builder.orderNodes();
+    }
+
+    public List<COMPONENT> components() {
+        return componentList;
+    }
+
+    public
+    @Override
+    String toString() {
+        StringBuilder b = new StringBuilder("chain '");
+        b.append(getId().stringValue());
+        b.append("' [");
+        appendComponent(0, b);
+        appendComponent(1, b);
+        if (components().size() > 3)
+            b.append("... -> ");
+        if (components().size() > 2)
+            appendComponent(components().size() - 1, b);
+        b.append("]");
+        return b.toString();
+    }
+
+    private void appendComponent(int i, StringBuilder b) {
+        if (i >= components().size()) return;
+        b.append(components().get(i).getId().stringValue());
+        if (i < components().size() - 1)
+            b.append(" -> ");
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+
+        Chain chain = (Chain) o;
+
+        if (!componentList.equals(chain.componentList)) return false;
+        if (!id.equals(chain.id)) return false;
+
+        return true;
+    }
+
+    @Override
+    public int hashCode() {
+        int result = componentList.hashCode();
+        result = 31 * result + id.hashCode();
+        return result;
+    }
+}