From a100f2a0d71f37320fe0f73be0d6d65094b60eb0 Mon Sep 17 00:00:00 2001
From: bculkin2442 <bjculkin@mix.wvu.edu>
Date: Thu, 28 Jul 2016 16:22:31 -0400
Subject: Ensure supplier don't materialize more than once

---
 .../main/java/bjc/utils/data/SingleSupplier.java   | 34 ++++++++++++++++++++++
 1 file changed, 34 insertions(+)
 create mode 100644 BJC-Utils2/src/main/java/bjc/utils/data/SingleSupplier.java

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

diff --git a/BJC-Utils2/src/main/java/bjc/utils/data/SingleSupplier.java b/BJC-Utils2/src/main/java/bjc/utils/data/SingleSupplier.java
new file mode 100644
index 0000000..016f492
--- /dev/null
+++ b/BJC-Utils2/src/main/java/bjc/utils/data/SingleSupplier.java
@@ -0,0 +1,34 @@
+package bjc.utils.data;
+
+import java.util.function.Supplier;
+
+public class SingleSupplier<T> implements Supplier<T> {
+	private Supplier<T>	source;
+
+	private boolean		gotten;
+
+	private long		id;
+
+	private static long	nextID	= 0;
+
+	public SingleSupplier(Supplier<T> supp) {
+		source = supp;
+
+		gotten = false;
+
+		id = nextID++;
+	}
+
+	@Override
+	public T get() {
+		if (gotten == true) {
+			throw new IllegalStateException(
+					"Attempted to get value more than once"
+							+ " from single supplier #" + id);
+		}
+
+		gotten = true;
+
+		return source.get();
+	}
+}
-- 
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