From df852b8a67f4b8f1c3e6f89d8c3630e678c49c14 Mon Sep 17 00:00:00 2001
From: bculkin2442 <bjculkin@mix.wvu.edu>
Date: Tue, 1 Mar 2016 20:43:09 -0500
Subject: Implemented support for lazy pairs

---
 .../main/java/bjc/utils/data/lazy/LazyHolder.java  | 101 +++++++++++++++++++++
 .../main/java/bjc/utils/data/lazy/LazyPair.java    |  31 +++++++
 2 files changed, 132 insertions(+)
 create mode 100644 BJC-Utils2/src/main/java/bjc/utils/data/lazy/LazyHolder.java
 create mode 100644 BJC-Utils2/src/main/java/bjc/utils/data/lazy/LazyPair.java

(limited to 'BJC-Utils2/src/main/java/bjc/utils/data/lazy')

diff --git a/BJC-Utils2/src/main/java/bjc/utils/data/lazy/LazyHolder.java b/BJC-Utils2/src/main/java/bjc/utils/data/lazy/LazyHolder.java
new file mode 100644
index 0000000..43dec86
--- /dev/null
+++ b/BJC-Utils2/src/main/java/bjc/utils/data/lazy/LazyHolder.java
@@ -0,0 +1,101 @@
+package bjc.utils.data.lazy;
+
+import java.util.function.Consumer;
+import java.util.function.Function;
+import java.util.function.Supplier;
+
+import bjc.utils.data.IHolder;
+import bjc.utils.funcdata.FunctionalList;
+
+/**
+ * Holds a single value of a specific type. This is used for indirect
+ * references to data, and more specifically for accessing non-final
+ * variables from a lambda. AKA the identity monad
+ * 
+ * This is a lazy variant of {@link IHolder}
+ * 
+ * @author ben
+ *
+ * @param <T>
+ *            The type of the data being held
+ */
+public class LazyHolder<T> implements IHolder<T> {
+	/**
+	 * The source for a value held by this lazy holder
+	 */
+	private Supplier<T>						heldSrc;
+
+	/**
+	 * The value internally held by this lazy holder
+	 */
+	private T								held;
+
+	/**
+	 * List of queued actions to be performed on realized values
+	 */
+	private FunctionalList<Function<T, T>>	actions;
+
+	/**
+	 * Create a new lazy holder with the given supplier
+	 * 
+	 * @param src
+	 *            The supplier for a value when it is neededs
+	 */
+	public LazyHolder(Supplier<T> src) {
+		heldSrc = src;
+
+		held = null;
+	}
+
+	/**
+	 * Create a new lazy holder with the given value
+	 * 
+	 * @param val
+	 *            The value held in the holder
+	 */
+	public LazyHolder(T val) {
+		held = val;
+	}
+
+	@Override
+	public <NewT> IHolder<NewT> map(Function<T, NewT> f) {
+		return new LazyHolder<NewT>(() -> {
+			if (held == null) {
+				return actions.reduceAux(heldSrc.get(),
+						Function<T, T>::apply, f::apply);
+			} else {
+				return actions.reduceAux(held, Function<T, T>::apply,
+						f::apply);
+			}
+		});
+	}
+
+	@Override
+	public IHolder<T> transform(Function<T, T> f) {
+		actions.add(f);
+
+		return this;
+	}
+
+	@Override
+	public <E> E unwrap(Function<T, E> f) {
+		// Actualize ourselves
+		if (held == null) {
+			held = heldSrc.get();
+		}
+
+		actions.forEach((act) -> held = act.apply(held));
+
+		return f.apply(held);
+	}
+
+	@Override
+	public void doWith(Consumer<T> f) {
+		transform((val) -> {
+			f.accept(val);
+
+			return val;
+		});
+	}
+
+}
diff --git a/BJC-Utils2/src/main/java/bjc/utils/data/lazy/LazyPair.java b/BJC-Utils2/src/main/java/bjc/utils/data/lazy/LazyPair.java
new file mode 100644
index 0000000..f680ed7
--- /dev/null
+++ b/BJC-Utils2/src/main/java/bjc/utils/data/lazy/LazyPair.java
@@ -0,0 +1,31 @@
+package bjc.utils.data.lazy;
+
+import java.util.function.BiConsumer;
+import java.util.function.BiFunction;
+import java.util.function.Function;
+
+import bjc.utils.data.IPair;
+import bjc.utils.data.Pair;
+
+public class LazyPair<L, R> implements IPair<L, R> {
+	private LazyHolder<Pair<L, R>> del;
+
+	@Override
+	public <L2, R2> IPair<L2, R2> apply(Function<L, L2> lf,
+			Function<R, R2> rf) {
+		return del.unwrap((par) -> par.apply(lf, rf));
+	}
+
+	@Override
+	public <E> E merge(BiFunction<L, R, E> bf) {
+		return del.unwrap((par) -> par.merge(bf));
+	}
+
+	@Override
+	public void doWith(BiConsumer<L, R> bc) {
+		del.doWith((par) -> {
+			par.doWith(bc);
+		});
+	}
+
+}
-- 
cgit v1.2.3