From f8215c428f0b46b459c59d0783b4bc4dadfc38a3 Mon Sep 17 00:00:00 2001
From: bculkin2442 <bjculkin@mix.wvu.edu>
Date: Mon, 28 Sep 2015 22:41:55 -0400
Subject: Basic data structure code.

Still importing things from the old project.
---
 .../src/main/java/bjc/utils/data/GenHolder.java    | 66 ++++++++++++++++++++++
 1 file changed, 66 insertions(+)
 create mode 100644 BJC-Utils2/src/main/java/bjc/utils/data/GenHolder.java

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

diff --git a/BJC-Utils2/src/main/java/bjc/utils/data/GenHolder.java b/BJC-Utils2/src/main/java/bjc/utils/data/GenHolder.java
new file mode 100644
index 0000000..f969960
--- /dev/null
+++ b/BJC-Utils2/src/main/java/bjc/utils/data/GenHolder.java
@@ -0,0 +1,66 @@
+package bjc.utils.data;
+
+import java.util.function.Function;
+
+/**
+ * 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
+ * @author ben
+ *
+ * @param <T> The type of the data being held
+ */
+public class GenHolder<T> {
+	/**
+	 * The state this holder is responsible for.
+	 */
+	public T held;
+	
+	/**
+	 * Creates a new empty holder, with its state set to null
+	 */
+	public GenHolder() {
+		held = null;
+	}
+	
+	/**
+	 * Creates a new holder, with its state initialized to the provided value
+	 * 
+	 * @param held The state to initialize this holder to.
+	 */
+	public GenHolder(T hld) {
+		held = hld;
+	}
+	
+	/**
+	 * Apply the given transformation to the held value.
+	 * 	Returns the holder for allowing chaining of transforms
+	 * @param f The transform to apply to the value
+	 * @return The holder
+	 */
+	public GenHolder<T> transform(Function<T, T> f) {
+		held = f.apply(held);
+		
+		return this;
+	}
+	
+	/**
+	 * Return the result of applying the given transformation to the held value
+	 * 	Doesn't change the held value
+	 * @param f The transformation to apply
+	 * @return A holder with the transformed value
+	 */
+	public <NewT> GenHolder<NewT> map(Function<T, NewT> f) {
+		return new GenHolder<NewT>(f.apply(held));
+	}
+	
+	/**
+	 * Returns a raw mapped value, not contained in a GenHolder
+	 * @param f The function to use for mapping the value
+	 * @return The mapped value outside of a GenHolder
+	 */
+	public <E> E unwrap(Function<T, E> f) {
+		return f.apply(held);
+	}
+}
-- 
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