From f278d3b45334e44f6c0277d89b4988cac9d7469c Mon Sep 17 00:00:00 2001
From: Terence Parr <parrt@antlr.org>
Date: Sat, 11 Feb 2012 11:35:27 -0800
Subject: [PATCH] add unit test for left-recur grammars

---
 .../Java/src/org/antlr/v4/runtime/Lexer.java  |  9 +++----
 .../org/antlr/v4/test/TestLeftRecursion.java  | 27 +++++++++++++++++++
 2 files changed, 30 insertions(+), 6 deletions(-)

diff --git a/runtime/Java/src/org/antlr/v4/runtime/Lexer.java b/runtime/Java/src/org/antlr/v4/runtime/Lexer.java
index aada783d8..6d4132782 100644
--- a/runtime/Java/src/org/antlr/v4/runtime/Lexer.java
+++ b/runtime/Java/src/org/antlr/v4/runtime/Lexer.java
@@ -88,7 +88,7 @@ public abstract class Lexer extends Recognizer<Integer, LexerATNSimulator>
 	/** The token type for the current token */
 	public int _type;
 
-	public ArrayDeque<Integer> _modeStack;
+	public ArrayDeque<Integer> _modeStack = new ArrayDeque<Integer>();
 	public int _mode = Lexer.DEFAULT_MODE;
 
 	/** You can set the text for the current token to override what is in
@@ -115,9 +115,7 @@ public abstract class Lexer extends Recognizer<Integer, LexerATNSimulator>
 
 		_hitEOF = false;
 		_mode = Lexer.DEFAULT_MODE;
-		if (_modeStack != null) {
-			_modeStack.clear();
-		}
+		_modeStack.clear();
 
 		getInterpreter().reset();
 	}
@@ -184,14 +182,13 @@ public abstract class Lexer extends Recognizer<Integer, LexerATNSimulator>
 
 	public void pushMode(int m) {
 		if ( LexerATNSimulator.debug ) System.out.println("pushMode "+m);
-		if ( _modeStack ==null ) _modeStack = new ArrayDeque<Integer>();
 		getInterpreter().tracePushMode(m);
 		_modeStack.push(_mode);
 		mode(m);
 	}
 
 	public int popMode() {
-		if ( _modeStack ==null ) throw new EmptyStackException();
+		if ( _modeStack.isEmpty() ) throw new EmptyStackException();
 		if ( LexerATNSimulator.debug ) System.out.println("popMode back to "+ _modeStack.peek());
 		getInterpreter().tracePopMode();
 		mode( _modeStack.pop() );
diff --git a/tool/test/org/antlr/v4/test/TestLeftRecursion.java b/tool/test/org/antlr/v4/test/TestLeftRecursion.java
index 4a4c12a22..ffdb45941 100644
--- a/tool/test/org/antlr/v4/test/TestLeftRecursion.java
+++ b/tool/test/org/antlr/v4/test/TestLeftRecursion.java
@@ -228,6 +228,33 @@ public class TestLeftRecursion extends BaseTest {
 		runTests(grammar, tests, "s");
 	}
 
+	@Test public void testReturnValueAndActionsAndLabels() throws Exception {
+		String grammar =
+			"grammar T;\n" +
+			"s : q=e {System.out.println($e.v);} ;\n" +
+			"\n" +
+			"e returns [int v]\n" +
+			"  : a=e op='*' b=e {$v = $a.v * $b.v;}  -> mult\n" +
+			"  | a=e '+' b=e {$v = $a.v + $b.v;}     -> add\n" +
+			"  | INT         {$v = $INT.int;}\n" +
+			"  | '(' x=e ')' {$v = $x.v;}\n" +
+			"  | x=e '++'    {$v = $x.v+1;}          -> inc\n" +
+			"  | e '--'\n" +
+			"  | ID          {$v = 3;}               -> anID\n" +
+			"  ; \n" +
+			"\n" +
+			"ID : 'a'..'z'+ ;\n" +
+			"INT : '0'..'9'+ ;\n" +
+			"WS : (' '|'\\n') {skip();} ;\n";
+		String[] tests = {
+			"4",			"4",
+			"1+2",			"3",
+			"1+2*3",		"7",
+			"i++*3",		"12",
+		};
+		runTests(grammar, tests, "s");
+	}
+
 	public void runTests(String grammar, String[] tests, String startRule) {
 		rawGenerateAndBuildRecognizer("T.g", grammar, "TParser", "TLexer");
 		writeRecognizerAndCompile("TParser",