From fefd6eb2917b9a0856c247353545cc13876b6eda Mon Sep 17 00:00:00 2001
From: Ben Culkin <scorpress@gmail.com>
Date: Tue, 1 Dec 2020 20:19:34 -0500
Subject: An assortment of changes/new things

---
 .../java/bjc/utils/funcutils/ChainIterator.java    | 54 ++++++++++++++++++++++
 1 file changed, 54 insertions(+)
 create mode 100644 base/src/main/java/bjc/utils/funcutils/ChainIterator.java

(limited to 'base/src/main/java/bjc/utils/funcutils/ChainIterator.java')

diff --git a/base/src/main/java/bjc/utils/funcutils/ChainIterator.java b/base/src/main/java/bjc/utils/funcutils/ChainIterator.java
new file mode 100644
index 0000000..36f94e5
--- /dev/null
+++ b/base/src/main/java/bjc/utils/funcutils/ChainIterator.java
@@ -0,0 +1,54 @@
+package bjc.utils.funcutils;
+
+import java.util.*;
+import java.util.function.*;
+
+/**
+ * A chain iterator. This is essentially flatMap in iterator form.
+ * 
+ * @author bjculkin
+ *
+ * @param <T1>
+ *             The type of the input values.
+ *
+ * @param <T2>
+ *             The type of the output values.
+ */
+public class ChainIterator<T1, T2> implements Iterator<T2> {
+	private Iterator<T1> mainItr;
+	private Function<T1, Iterator<T2>> trans;
+
+	private Iterator<T2> curItr;
+
+	/**
+	 * Create a new chain iterator.
+	 *
+	 * @param mainItr
+	 *                The main iterator for input.
+	 *
+	 * @param trans
+	 *                The transformation to use to produce the outputs.
+	 */
+	public ChainIterator(Iterator<T1> mainItr, Function<T1, Iterator<T2>> trans) {
+		this.mainItr = mainItr;
+		this.trans = trans;
+	}
+
+	@Override
+	public boolean hasNext() {
+		if (curItr != null) {
+			return curItr.hasNext() ? true : mainItr.hasNext();
+		}
+
+		return mainItr.hasNext();
+	}
+
+	@Override
+	public T2 next() {
+		if (curItr == null || !curItr.hasNext()) {
+			curItr = trans.apply(mainItr.next());
+		}
+
+		return curItr.next();
+	}
+}
\ No newline at end of file
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