From cc045fbaf31ebc8ef678c726f40c4770ea80f608 Mon Sep 17 00:00:00 2001
From: Sam Harwell <sam@tunnelvisionlabs.com>
Date: Thu, 23 Jan 2014 07:23:55 -0600
Subject: [PATCH] Improve CommonToken cloning performance, and update
 documentation

---
 .../Java/src/org/antlr/v4/runtime/CommonToken.java    | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/runtime/Java/src/org/antlr/v4/runtime/CommonToken.java b/runtime/Java/src/org/antlr/v4/runtime/CommonToken.java
index 050255caf..9c63393ec 100644
--- a/runtime/Java/src/org/antlr/v4/runtime/CommonToken.java
+++ b/runtime/Java/src/org/antlr/v4/runtime/CommonToken.java
@@ -139,10 +139,17 @@ public class CommonToken implements WritableToken, Serializable {
 	/**
 	 * Constructs a new {@link CommonToken} as a copy of another {@link Token}.
 	 *
+	 * <p>
+	 * If {@code oldToken} is also a {@link CommonToken} instance, the newly
+	 * constructed token will share a reference to the {@link #text} field and
+	 * the {@link Pair} stored in {@link #source}. Otherwise, {@link #text} will
+	 * be assigned the result of calling {@link #getText}, and {@link #source}
+	 * will be constructed from the result of {@link Token#getTokenSource} and
+	 * {@link Token#getInputStream}.</p>
+	 *
 	 * @param oldToken The token to copy.
 	 */
 	public CommonToken(@NotNull Token oldToken) {
-		text = oldToken.getText();
 		type = oldToken.getType();
 		line = oldToken.getLine();
 		index = oldToken.getTokenIndex();
@@ -152,9 +159,11 @@ public class CommonToken implements WritableToken, Serializable {
 		stop = oldToken.getStopIndex();
 
 		if (oldToken instanceof CommonToken) {
+			text = ((CommonToken)oldToken).text;
 			source = ((CommonToken)oldToken).source;
 		}
 		else {
+			text = oldToken.getText();
 			source = new Pair<TokenSource, CharStream>(oldToken.getTokenSource(), oldToken.getInputStream());
 		}
 	}