snapshot

runtime/Java/src/org/antlr/v4/runtime/ParserRuleContext.java

@@ -136,7 +136,7 @@ public class ParserRuleContext<Symbol> extends RuleContext {
 
 	public void enterRule(ParseTreeListener<Symbol> listener) { }
 	public void exitRule(ParseTreeListener<Symbol> listener) { }
-	public <T,V extends ParseTreeVisitor<T>> T dispatch(V visitor) { visitor.visitChildren(this); return null; }
+	public <T> T dispatch(ParseTreeVisitor<? extends T> visitor) { visitor.visitChildren(this); return null; }
 
 	/** Does not set parent link; other add methods do */
 	public void addChild(TerminalNode<Symbol> t) {

tool/playground/AVisitor.java

@@ -7,5 +7,4 @@ public interface AVisitor<T> {
 	T visit(AParser.sContext ctx);
 	T visit(AParser.AddContext ctx);
 	T visit(AParser.IntContext ctx);
-//	T visit(Token t);
 }

tool/playground/TestVisitor.java

@@ -48,7 +48,8 @@ public class TestVisitor {
 
 		@Override
 		public Integer visit(AParser.MultContext ctx) {
-			return ctx.e(0).dispatch(this) * ctx.e(1).dispatch(this);
+//			return ctx.e(0).dispatch(this) * ctx.e(1).dispatch(this);
+			return visit(ctx.e(0)) * visit(ctx.e(1));
 		}
 
 		@Override
@@ -76,4 +77,3 @@ public class TestVisitor {
 		System.out.println("result from tree walk = " + result);
 	}
 }
-

tool/resources/org/antlr/v4/tool/templates/codegen/Java/Java.stg

@@ -533,7 +533,7 @@ ListLabelName(label)		  ::= "<label>"
 CaptureNextToken(d) ::= "<d.varName> = _input.LT(1);"
 CaptureNextTokenType(d) ::= "<d.varName> = _input.LA(1);"
 
-StructDecl(s,attrs,getters,visitorDispatchMethods,interfaces,extensionMembers,
+StructDecl(s,attrs,getters,dispatchMethods,interfaces,extensionMembers,
            superClass={ParserRuleContext\<<InputSymbolType()>>}) ::= <<
 public static class <s.name> extends <superClass><if(interfaces)> implements <interfaces; separator=", "><endif> {
 	<attrs:{a | <a>}; separator="\n">
@@ -550,29 +550,35 @@ public static class <s.name> extends <superClass><if(interfaces)> implements <in
 		<s.attrs:{a | this.<a.name> = ctx.<a.name>;}; separator="\n">
 	}
 <endif>
-	<visitorDispatchMethods; separator="\n">
+	<dispatchMethods; separator="\n">
-        public \<T, V extends <parser.grammarName>Visitor\<T>\> T dispatch(V visitor) { return visitor.visit(this); }
 	<extensionMembers; separator="\n">
 }
 >>
 
-AltLabelStructDecl(s,attrs,getters,visitorDispatchMethods) ::= <<
+AltLabelStructDecl(s,attrs,getters,dispatchMethods) ::= <<
 public static class <s.name> extends <currentRule.name>Context {
 	<attrs:{a | <a>}; separator="\n">
 	<getters:{g | <g>}; separator="\n">
 	public <s.name>(<currentRule.name>Context ctx) { copyFrom(ctx); }
-	<visitorDispatchMethods; separator="\n">
+	<dispatchMethods; separator="\n">
-        public \<T, V extends <parser.grammarName>Visitor\<T>\> T dispatch(V visitor) { return visitor.visit(this); }
 }
 >>
 
-VisitorDispatchMethod(method) ::= <<
+ListenerDispatchMethod(method) ::= <<
 @Override
 public void <if(method.isEnter)>enter<else>exit<endif>Rule(ParseTreeListener\<<InputSymbolType()>\> listener) {
 	if ( listener instanceof <parser.grammarName>Listener ) ((<parser.grammarName>Listener)listener).<if(method.isEnter)>enter<else>exit<endif>(this);
 }
 >>
 
+VisitorDispatchMethod() ::= <<
+@Override
+public \<T> T dispatch(ParseTreeVisitor\<? extends T> visitor) { 
+    if ( listener instanceof <parser.grammarName>Visitor ) return ((<parser.grammarName>Visitor\<T>)visitor).visit(this);
+    else return null;
+}
+>>
+
 AttributeDecl(d) ::= "public <d.decl>;"
 
 /** If we don't know location of label def x, use this template */

tool/src/org/antlr/v4/codegen/model/ListenerDispatchMethod.java

@@ -0,0 +1,20 @@
+package org.antlr.v4.codegen.model;
+
+import org.antlr.v4.codegen.OutputModelFactory;
+import org.antlr.v4.misc.Triple;
+import org.antlr.v4.tool.Rule;
+import org.antlr.v4.tool.ast.AltAST;
+
+import java.util.List;
+
+public class ListenerDispatchMethod extends OutputModelObject {
+	public String listenerName = "Rule";
+	public boolean isEnter;
+
+	public ListenerDispatchMethod(OutputModelFactory factory, Rule r, boolean isEnter) {
+		super(factory);
+		this.isEnter = isEnter;
+		List<Triple<Integer,AltAST,String>> label = r.getAltLabels();
+		if ( label!=null ) listenerName = label.get(0).c;
+	}
+}

tool/src/org/antlr/v4/codegen/model/decl/StructDecl.java

@@ -32,7 +32,7 @@ package org.antlr.v4.codegen.model.decl;
 import org.antlr.v4.codegen.OutputModelFactory;
 import org.antlr.v4.codegen.model.ModelElement;
 import org.antlr.v4.codegen.model.OutputModelObject;
-import org.antlr.v4.codegen.model.VisitorDispatchMethod;
+import org.antlr.v4.codegen.model.ListenerDispatchMethod;
 import org.antlr.v4.runtime.misc.OrderedHashSet;
 import org.antlr.v4.tool.Attribute;
 import org.antlr.v4.tool.Rule;
@@ -50,7 +50,7 @@ public class StructDecl extends Decl {
 	@ModelElement public OrderedHashSet<Decl> attrs = new OrderedHashSet<Decl>();
 	@ModelElement public OrderedHashSet<Decl> getters = new OrderedHashSet<Decl>();
 	@ModelElement public Collection<Attribute> ctorAttrs;
-	@ModelElement public List<VisitorDispatchMethod> visitorDispatchMethods;
+	@ModelElement public List<ListenerDispatchMethod> dispatchMethods;
 	@ModelElement public List<OutputModelObject> interfaces;
 	@ModelElement public List<OutputModelObject> extensionMembers;
 
@@ -61,9 +61,9 @@ public class StructDecl extends Decl {
 	}
 
 	public void addVisitorDispatchMethods(Rule r) {
-		visitorDispatchMethods = new ArrayList<VisitorDispatchMethod>();
+		dispatchMethods = new ArrayList<ListenerDispatchMethod>();
-		visitorDispatchMethods.add(new VisitorDispatchMethod(factory, r, true));
+		dispatchMethods.add(new ListenerDispatchMethod(factory, r, true));
-		visitorDispatchMethods.add(new VisitorDispatchMethod(factory, r, false));
+		dispatchMethods.add(new ListenerDispatchMethod(factory, r, false));
 	}
 
 	public void addDecl(Decl d) {