1 files changed, 157 insertions, 0 deletions
diff --git a/src/main/java/bjc/funcdata/ExtendedMap.java b/src/main/java/bjc/funcdata/ExtendedMap.java
new file mode 100644
index 0000000..76fac01
--- /dev/null
+++ b/src/main/java/bjc/funcdata/ExtendedMap.java
@@ -0,0 +1,157 @@
+package bjc.funcdata;
+
+import java.util.function.BiConsumer;
+import java.util.function.Consumer;
+import java.util.function.Function;
+
+/**
+ * An extended version of a map, that stores values into a map, but can look
+ * into a different one for others.
+ *
+ * @author Ben Culkin
+ *
+ * @param <KeyType>
+ *        The type of the keys of the map.
+ *
+ * @param <ValueType>
+ *        The type of the values of the map.
+ */
+class ExtendedMap<KeyType, ValueType> implements IMap<KeyType, ValueType> {
+	/* The map we delegate lookups to. */
+	private final IMap<KeyType, ValueType> delegate;
+	/* The map we store things in. */
+	private final IMap<KeyType, ValueType> store;
+
+	/**
+	 * Create a new extended map.
+	 *
+	 * @param delegate
+	 *        The map to lookup things in.
+	 * 
+	 * @param store
+	 *        The map to store things in.
+	 */
+	public ExtendedMap(final IMap<KeyType, ValueType> delegate, final IMap<KeyType, ValueType> store) {
+		this.delegate = delegate;
+		this.store = store;
+	}
+
+	@Override
+	public void clear() {
+		store.clear();
+	}
+
+	@Override
+	public boolean containsKey(final KeyType key) {
+		if(store.containsKey(key)) return true;
+
+		return delegate.containsKey(key);
+	}
+
+	@Override
+	public IMap<KeyType, ValueType> extend() {
+		return new ExtendedMap<>(this, new FunctionalMap<>());
+	}
+
+	@Override
+	public void forEach(final BiConsumer<KeyType, ValueType> action) {
+		store.forEach(action);
+
+		delegate.forEach(action);
+	}
+
+	@Override
+	public void forEachKey(final Consumer<KeyType> action) {
+		store.forEachKey(action);
+
+		delegate.forEachKey(action);
+	}
+
+	@Override
+	public void forEachValue(final Consumer<ValueType> action) {
+		store.forEachValue(action);
+
+		delegate.forEachValue(action);
+	}
+
+	@Override
+	public ValueType get(final KeyType key) {
+		if(store.containsKey(key)) return store.get(key);
+
+		return delegate.get(key);
+	}
+
+	@Override
+	public int size() {
+		return store.size() + delegate.size();
+	}
+
+	@Override
+	public IList<KeyType> keyList() {
+		IList<KeyType> ilst = new FunctionalList<>();
+
+		ilst.addAll(store.keyList());
+		ilst.addAll(delegate.keyList());
+
+		return ilst;
+	}
+
+	@Override
+	public <MappedValue> IMap<KeyType, MappedValue> transform(final Function<ValueType, MappedValue> transformer) {
+		return new TransformedValueMap<>(this, transformer);
+	}
+
+	@Override
+	public ValueType put(final KeyType key, final ValueType val) {
+		return store.put(key, val);
+	}
+
+	@Override
+	public ValueType remove(final KeyType key) {
+		if(!store.containsKey(key)) return delegate.remove(key);
+
+		return store.remove(key);
+	}
+
+	@Override
+	public IList<ValueType> valueList() {
+		IList<ValueType> ilst = new FunctionalList<>();
+
+		ilst.addAll(store.valueList());
+		ilst.addAll(delegate.valueList());
+
+		return ilst;
+	}
+
+	@Override
+	public int hashCode() {
+		final int prime = 31;
+		int result = 1;
+		result = prime * result + (delegate == null ? 0 : delegate.hashCode());
+		result = prime * result + (store == null ? 0 : store.hashCode());
+		return result;
+	}
+
+	@Override
+	public boolean equals(final Object obj) {
+		if(this == obj) return true;
+		if(obj == null) return false;
+		if(!(obj instanceof ExtendedMap)) return false;
+
+		final ExtendedMap<?, ?> other = (ExtendedMap<?, ?>) obj;
+
+		if(delegate == null) {
+			if(other.delegate != null) return false;
+		} else if(!delegate.equals(other.delegate)) return false;
+		if(store == null) {
+			if(other.store != null) return false;
+		} else if(!store.equals(other.store)) return false;
+
+		return true;
+	}
+
+	@Override
+	public String toString() {
+		return String.format("ExtendedMap [delegate=%s, store=%s]", delegate, store);
+	}
+}