Got the visitor thing cleaned up enough for a small example

[git-p4: depot-paths = "//depot/code/antlr4/main/": change = 9059]

runtime/Java/src/org/antlr/v4/runtime/tree/ParseTreeListener.java

@@ -29,10 +29,11 @@
 
 package org.antlr.v4.runtime.tree;
 
-import org.antlr.v4.runtime.*;
+import org.antlr.v4.runtime.ParserRuleContext;
+import org.antlr.v4.runtime.Token;
 
 public interface ParseTreeListener {
     void visitToken(Token token);
-    void discoverRule(ParserRuleContext ctx);
+    void enterEveryRule(ParserRuleContext ctx);
-    void finishRule(ParserRuleContext ctx);
+    void exitEveryRule(ParserRuleContext ctx);
-}
+}

runtime/Java/src/org/antlr/v4/runtime/tree/ParseTreeVisitor.java

@@ -57,55 +57,13 @@ public class ParseTreeVisitor {
 	 */
     protected void enterRule(ParseTreeListener listener, ParseTree.RuleNode r) {
 		ParserRuleContext ctx = (ParserRuleContext)r.getRuleContext();
-		listener.discoverRule((ParserRuleContext)r.getRuleContext());
+		listener.enterEveryRule((ParserRuleContext) r.getRuleContext());
 		ctx.enterRule(listener);
     }
 
     protected void exitRule(ParseTreeListener listener, ParseTree.RuleNode r) {
 		ParserRuleContext ctx = (ParserRuleContext)r.getRuleContext();
 		ctx.exitRule(listener);
-		listener.finishRule(ctx);
+		listener.exitEveryRule(ctx);
     }
-
-	/*
-	public static void main(String[] args) {
-		TListener listener = new TListener() {
-			public void discover_s(s_ctx ctx) {
-			}
-			public void finish_s(s_ctx ctx) {
-			}
-			public void discover_ifstat(ParserRuleContext ctx) {
-			}
-			public void finish_ifstat(ParserRuleContext ctx) {
-			}
-			public void visitToken(Token token) {
-			}
-			public void discoverRule(ParserRuleContext ctx) {
-			}
-			public void finishRule(ParserRuleContext ctx) {
-			}
-		};
-		ParserRuleContext ctx = new ParserRuleContext();
-		ParseTreeVisitor visitor = new ParseTreeVisitor();
-		visitor.visit(listener, ctx);
-	}
-	*/
 }
-
-/*
-interface TListener extends ParseTreeListener {
-	void discover_s(s_ctx ctx);
-	void finish_s(s_ctx ctx);
-	void discover_ifstat(ParserRuleContext ctx); // no labels
-	void finish_ifstat(ParserRuleContext ctx); // no labels
-}
-
-class s_ctx extends ParserRuleContext {
-    public ParserRuleContext i;
-    public s_ctx(RuleContext parent, int state) {
-            super(parent, state);
-    }
-	public void discover(TListener listener) { listener.discover_s(this); }
-	public void finish(TListener listener) { listener.discover_s(this); }
-}
-*/

tool/playground/TestT.java

@@ -1,5 +1,7 @@
 import org.antlr.v4.runtime.ANTLRFileStream;
 import org.antlr.v4.runtime.CommonTokenStream;
+import org.antlr.v4.runtime.ParserRuleContext;
+import org.antlr.v4.runtime.tree.ParseTreeVisitor;
 
 public class TestT {
 	public static void main(String[] args) throws Exception {
@@ -11,7 +13,18 @@ public class TestT {
 //		}
 		TParser p = new TParser(tokens);
 		p.setBuildParseTrees(true);
-		TParser.sContext ret = p.s();
+		TParser.sContext tree = p.s();
-		System.out.println(ret.toStringTree(p));
+		System.out.println(tree.toStringTree(p));
+
+		ParseTreeVisitor visitor = new ParseTreeVisitor();
+		TListener listener = new BlankTListener() {
+			public void enterEveryRule(ParserRuleContext ctx) {
+				System.out.println("enter rule "+TParser.ruleNames[ctx.ruleIndex]);
+			}
+			public void exitRule(TParser.sContext ctx) { // specific to rule s
+				System.out.println("exit rule s");
+			}
+		};
+		visitor.visit(listener, tree);
 	}
 }

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

@@ -35,15 +35,36 @@ import java.util.ArrayList;
 <parser>
 >>
 
-ListenerFile(listener) ::= <<
+ListenerFile(listener, header) ::= <<
+<header>
+import org.antlr.v4.runtime.tree.ParseTreeListener;
+
 @SuppressWarnings({"all", "warnings", "unchecked", "unused"})
-public interface <listener.grammarName>Listener {
+public interface <listener.grammarName>Listener extends ParseTreeListener {
     <listener.rules:{r |
 void enterRule(<listener.parserName>.<r.name>Context ctx);
 void exitRule(<listener.parserName>.<r.name>Context ctx);}; separator="\n">
 }
 >>
 
+BlankListenerFile(listener, header) ::= <<
+<header>
+
+import org.antlr.v4.runtime.ParserRuleContext;
+import org.antlr.v4.runtime.Token;
+
+@SuppressWarnings({"all", "warnings", "unchecked", "unused"})
+public class Blank<listener.grammarName>Listener implements <listener.grammarName>Listener {
+    <listener.rules:{r |
+public void enterRule(<listener.parserName>.<r.name>Context ctx) { \}
+public void exitRule(<listener.parserName>.<r.name>Context ctx) { \}}; separator="\n">
+
+	public void enterEveryRule(ParserRuleContext ctx) { }
+	public void exitEveryRule(ParserRuleContext ctx) { }
+	public void visitToken(Token token) { }
+}
+>>
+
 Parser(parser, scopes, funcs, atn, sempredFuncs) ::= <<
 @SuppressWarnings({"all", "warnings", "unchecked", "unused"})
 public class <parser.name> extends Parser {
@@ -429,8 +450,8 @@ public static class <s.name> extends ParserRuleContext {
     	super(parent, state);
         <s.ctorAttrs:{a | this.<a.name> = <a.name>;}; separator="\n">
     }
-	public void enterRule(<parser.grammarName>Listener listener) { listener.enterRule(this); }
+	public void enterRule(ParseTreeListener listener) { ((<parser.grammarName>Listener)listener).enterRule(this); }
-	public void exitRule(<parser.grammarName>Listener listener) { listener.exitRule(this); }
+	public void exitRule(ParseTreeListener listener) { ((<parser.grammarName>Listener)listener).exitRule(this); }
 }
 >>
 

tool/src/org/antlr/v4/codegen/CodeGenPipeline.java

@@ -47,6 +47,7 @@ public class CodeGenPipeline {
 		else {
 			gen.writeRecognizer(gen.generateParser());
 			gen.writeListener(gen.generateListener());
+			gen.writeBlankListener(gen.generateBlankListener());
 			gen.writeHeaderFile();
 		}
 		gen.writeVocabFile();

tool/src/org/antlr/v4/codegen/CodeGenerator.java

@@ -52,8 +52,6 @@ public class CodeGenerator {
 		"<tokens.keys:{t | <t>=<tokens.(t)>\n}>" +
 		"<literals.keys:{t | <t>=<literals.(t)>\n}>";
 
-	public OutputModelObject outputModel;
-
 	public Grammar g;
 	public Tool tool;
 	public Target target;
@@ -118,9 +116,6 @@ public class CodeGenerator {
 //		OutputModelFactory factory;
 //		if ( g.isLexer() ) factory = new LexerFactory(this);
 //		else factory = new ParserFactory(this);
-//
-//		// TODO: let someone add their own factory?
-//
 //		// CREATE OUTPUT MODEL FROM GRAMMAR OBJ AND AST WITHIN RULES
 //		OutputModelController controller = new OutputModelController(factory);
 //		if ( g.hasASTOption() ) {
@@ -140,7 +135,7 @@ public class CodeGenerator {
 		OutputModelController controller = new OutputModelController(factory);
 		factory.setController(controller);
 
-		outputModel = controller.buildLexerOutputModel();
+		OutputModelObject outputModel = controller.buildLexerOutputModel();
 
 		OutputModelWalker walker = new OutputModelWalker(tool, templates);
 		ST st = walker.walk(outputModel);
@@ -156,8 +151,6 @@ public class CodeGenerator {
 	public ST generateParser() {
 		OutputModelFactory factory = new ParserFactory(this);
 
-		// TODO: let someone add their own factory?
-
 		// CREATE OUTPUT MODEL FROM GRAMMAR OBJ AND AST WITHIN RULES
 		OutputModelController controller = new OutputModelController(factory);
 		if ( g.hasASTOption() ) {
@@ -165,7 +158,7 @@ public class CodeGenerator {
 		}
 		factory.setController(controller);
 
-		outputModel = controller.buildParserOutputModel();
+		OutputModelObject outputModel = controller.buildParserOutputModel();
 
 		OutputModelWalker walker = new OutputModelWalker(tool, templates);
 		ST st = walker.walk(outputModel);
@@ -181,25 +174,26 @@ public class CodeGenerator {
 	public ST generateListener() {
 		OutputModelFactory factory = new ParserFactory(this);
 
-		// TODO: let someone add their own factory?
-
-		// CREATE OUTPUT MODEL FROM GRAMMAR OBJ AND AST WITHIN RULES
 		OutputModelController controller = new OutputModelController(factory);
-		if ( g.hasASTOption() ) {
-			controller.addExtension( new ParserASTExtension(factory) );
-		}
 		factory.setController(controller);
 
-		outputModel = controller.buildListenerOutputModel();
+		OutputModelObject listenerModel = controller.buildListenerOutputModel();
 
 		OutputModelWalker walker = new OutputModelWalker(tool, templates);
-		ST st = walker.walk(outputModel);
+		ST st = walker.walk(listenerModel);
+		return st;
+	}
 
-		if ( tool.launch_ST_inspector ) {
+	public ST generateBlankListener() {
-			st.inspect();
+		OutputModelFactory factory = new ParserFactory(this);
-			//if ( templates.isDefined("headerFile") ) headerFileST.inspect();
-		}
 
+		OutputModelController controller = new OutputModelController(factory);
+		factory.setController(controller);
+
+		OutputModelObject blankModel = controller.buildBlankListenerOutputModel();
+
+		OutputModelWalker walker = new OutputModelWalker(tool, templates);
+		ST st = walker.walk(blankModel);
 		return st;
 	}
 
@@ -240,7 +234,11 @@ public class CodeGenerator {
 	}
 
 	public void writeListener(ST outputFileST) {
-		target.genFile(g,outputFileST,getListenerFileName());
+		target.genFile(g,outputFileST, getListenerFileName());
+	}
+
+	public void writeBlankListener(ST outputFileST) {
+		target.genFile(g,outputFileST, getBlankListenerFileName());
 	}
 
 	public void writeHeaderFile() {
@@ -322,6 +320,15 @@ public class CodeGenerator {
 		return listenerName+extST.render();
 	}
 
+	/** A given grammar T, return a blank listener implementation
+	 *  such as BlankTListener.java, if we're using the Java target.
+ 	 */
+	public String getBlankListenerFileName() {
+		ST extST = templates.getInstanceOf("codeFileExtension");
+		String listenerName = "Blank" + g.name + "Listener";
+		return listenerName+extST.render();
+	}
+
 	/** What is the name of the vocab file generated for this grammar?
 	 *  Returns null if no .tokens file should be generated.
 	 */

tool/src/org/antlr/v4/codegen/OutputModelController.java

@@ -110,6 +110,11 @@ public class OutputModelController {
 		return new ListenerFile(delegate, gen.getListenerFileName());
 	}
 
+	public OutputModelObject buildBlankListenerOutputModel() {
+		CodeGenerator gen = delegate.getGenerator();
+		return new BlankListenerFile(delegate, gen.getBlankListenerFileName());
+	}
+
 	public ParserFile parserFile(String fileName) {
 		ParserFile f = delegate.parserFile(fileName);
 		for (CodeGeneratorExtension ext : extensions) f = ext.parserFile(f);

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

@@ -0,0 +1,9 @@
+package org.antlr.v4.codegen.model;
+
+import org.antlr.v4.codegen.OutputModelFactory;
+
+public class BlankListenerFile extends ListenerFile {
+	public BlankListenerFile(OutputModelFactory factory, String fileName) {
+		super(factory, fileName);
+	}
+}

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

@@ -1,6 +1,7 @@
 package org.antlr.v4.codegen.model;
 
 import org.antlr.v4.codegen.OutputModelFactory;
+import org.antlr.v4.tool.ActionAST;
 import org.antlr.v4.tool.Grammar;
 import org.antlr.v4.tool.Rule;
 
@@ -15,6 +16,8 @@ public class ListenerFile extends OutputModelObject {
 	public String parserName;
 	public Collection<Rule> rules;
 
+	@ModelElement public Action header;
+
 	public ListenerFile(OutputModelFactory factory, String fileName) {
 		super(factory);
 		this.fileName = fileName;
@@ -22,5 +25,7 @@ public class ListenerFile extends OutputModelObject {
 		parserName = g.getRecognizerName();
 		grammarName = g.name;
 		rules = g.rules.values();
+		ActionAST ast = g.namedActions.get("header");
+		if ( ast!=null ) header = new Action(factory, ast);
 	}
 }