From f2037af115d8459aeaed003bb7c4aa0557a040b9 Mon Sep 17 00:00:00 2001
From: Ben Culkin <scorpress@gmail.com>
Date: Wed, 25 Oct 2023 19:33:51 -0400
Subject: Tweak

---
 .../java/bjc/pratt/tokens/SimpleTokenStream.java   | 82 ++++++++++++++++++++++
 1 file changed, 82 insertions(+)
 create mode 100644 JPratt/src/main/java/bjc/pratt/tokens/SimpleTokenStream.java

(limited to 'JPratt/src/main/java/bjc/pratt/tokens/SimpleTokenStream.java')

diff --git a/JPratt/src/main/java/bjc/pratt/tokens/SimpleTokenStream.java b/JPratt/src/main/java/bjc/pratt/tokens/SimpleTokenStream.java
new file mode 100644
index 0000000..fba38bb
--- /dev/null
+++ b/JPratt/src/main/java/bjc/pratt/tokens/SimpleTokenStream.java
@@ -0,0 +1,82 @@
+package bjc.pratt.tokens;
+
+import java.util.Iterator;
+
+import bjc.data.MarkListIterator;
+
+/**
+ * Simple token stream implementation
+ * @author bjcul
+ *
+ * @param <K> The key type
+ * @param <V> The value type
+ */
+public class SimpleTokenStream<K, V> extends TokenStream<K, V> {
+	private final MarkListIterator<Token<K, V>> iter;
+
+	private Token<K, V> curr;
+
+	private Token<K, V> terminal;
+	/**
+	 * Create a new token stream from a iterator.
+	 *
+	 * @param itr The iterator to use.
+	 * @param terminal The terminal token to use for end-of-stream
+	 *
+	 */
+	public SimpleTokenStream(final Iterator<Token<K, V>> itr, Token<K, V> terminal) {
+		this.iter = new MarkListIterator<>(itr);
+		this.terminal = terminal;
+	}
+
+	@Override
+	public Token<K, V> current() {
+		// Prime stream if necessary
+		if (curr == null)
+			return next();
+		return curr;
+	}
+
+	@Override
+	public Token<K, V> next() {
+		if (iter.hasNext()) {
+			curr = iter.next();
+		} else {
+			curr = terminal;
+		}
+
+		return curr;
+	}
+
+	@Override
+	public boolean hasNext() {
+		return iter.hasNext();
+	}
+
+	@Override
+	public void mark() {
+		iter.mark();
+	}
+
+	@Override
+	public void commit() {
+		iter.commit();
+
+		if (!iter.hasMark()) {
+			// No marks outstanding; we can release the previous state
+			iter.reset();
+		}
+	}
+
+	@Override
+	public void rollback() {
+		iter.rollback();
+
+		curr = iter.current();
+	}
+
+	@Override
+	public boolean hasMark() {
+		return iter.hasMark();
+	}
+}
-- 
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