Preliminary changes for Python

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

@@ -175,6 +175,7 @@ public class ActionTranslator implements ActionSplitterListener {
 				case RET: chunks.add(new RetValueRef(rf.ruleCtx, x.getText())); break;
 				case LOCAL: chunks.add(new LocalRef(nodeContext,x.getText())); break;
 				case PREDEFINED_RULE: chunks.add(getRulePropertyRef(x));	break;
+				default: // avoid warning
 			}
 		}
 		if ( node.resolver.resolvesToToken(x.getText(), node) ) {
@@ -229,6 +230,8 @@ public class ActionTranslator implements ActionSplitterListener {
 			case TOKEN:
 				chunks.add(getTokenPropertyRef(x, y));
 				break;
+			default:
+				// avoid warning
 		}
 	}
 

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

@@ -74,10 +74,12 @@ public class CodeGenPipeline {
 			writeRecognizer(parser, gen);
 			if ( g.tool.gen_listener ) {
 				gen.writeListener(gen.generateListener());
+				if (gen.getTarget().wantsBaseListener())
 					gen.writeBaseListener(gen.generateBaseListener());
 			}
 			if ( g.tool.gen_visitor ) {
 				gen.writeVisitor(gen.generateVisitor());
+				if (gen.getTarget().wantsBaseVisitor())
 					gen.writeBaseVisitor(gen.generateBaseVisitor());
 			}
 			gen.writeHeaderFile();

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

@@ -375,4 +375,16 @@ public abstract class Target {
 
 		return result;
 	}
+
+	public boolean wantsBaseListener() {
+		return true;
+	}
+
+	public boolean wantsBaseVisitor() {
+		return true;
+	}
+
+	public boolean supportsOverloadedMethods() {
+		return true;
+	}
 }

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

@@ -47,6 +47,7 @@ import org.antlr.v4.tool.ast.GrammarAST;
 import java.util.List;
 
 /** */
+@SuppressWarnings("unused")
 public class InvokeRule extends RuleElement implements LabeledOp {
 	public String name;
 	public OrderedHashSet<Decl> labels = new OrderedHashSet<Decl>(); // TODO: should need just 1

tool/src/org/antlr/v4/codegen/model/LL1StarBlockSingleAlt.java

@@ -38,6 +38,7 @@ import org.antlr.v4.tool.ast.GrammarAST;
 import java.util.List;
 
 /** */
+@SuppressWarnings("unused")
 public class LL1StarBlockSingleAlt extends LL1Loop {
 	public LL1StarBlockSingleAlt(OutputModelFactory factory, GrammarAST starRoot, List<CodeBlockForAlt> alts) {
 		super(factory, starRoot, alts);

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

@@ -41,6 +41,9 @@ public class LexerFile extends OutputFile {
 	public String genPackage; // from -package cmd-line
 	@ModelElement public Lexer lexer;
 	@ModelElement public Map<String, Action> namedActions;
+	public Boolean genListener = false;
+	public Boolean genVisitor = false;
+	public String grammarName;
 
 	public LexerFile(OutputModelFactory factory, String fileName) {
 		super(factory, fileName);
@@ -51,5 +54,9 @@ public class LexerFile extends OutputFile {
 			namedActions.put(name, new Action(factory, ast));
 		}
 		genPackage = factory.getGrammar().tool.genPackage;
+		// need the below members in the ST for Python
+		genListener = g.tool.gen_listener;
+		genVisitor = g.tool.gen_visitor;
+		grammarName = g.originalGrammar==null ? g.name : g.originalGrammar.name;
 	}
 }

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

@@ -52,6 +52,7 @@ public class Parser extends OutputModelObject {
 	public String grammarFileName;
 	public String grammarName;
 	@ModelElement public ActionChunk superClass;
+	public Boolean needsSuperClass = false;
 	public Map<String,Integer> tokens;
 	public String[] tokenNames;
 	public Set<String> ruleNames;
@@ -96,6 +97,7 @@ public class Parser extends OutputModelObject {
 		atn = new SerializedATN(factory, g.atn);
 		if (g.getOptionString("superClass") != null) {
 			superClass = new ActionText(null, g.getOptionString("superClass"));
+			needsSuperClass = true;
 		}
 		else {
 			superClass = new DefaultParserSuperClass();

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

@@ -42,6 +42,9 @@ public class ParserFile extends OutputFile {
 	public String genPackage; // from -package cmd-line
 	@ModelElement public Parser parser;
 	@ModelElement public Map<String, Action> namedActions;
+	public Boolean genListener = false;
+	public Boolean genVisitor = false;
+	public String grammarName;
 	
 	public ParserFile(OutputModelFactory factory, String fileName) {
 		super(factory, fileName);
@@ -51,6 +54,10 @@ public class ParserFile extends OutputFile {
 			ActionAST ast = g.namedActions.get(name);
 			namedActions.put(name, new Action(factory, ast));
 		}
-		genPackage = factory.getGrammar().tool.genPackage;
+		genPackage = g.tool.genPackage;
+		// need the below members in the ST for Python
+		genListener = g.tool.gen_listener;
+		genVisitor = g.tool.gen_visitor;
+		grammarName = g.name;
 	}
 }

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

@@ -248,6 +248,7 @@ public class RuleFunction extends OutputModelObject {
 			String ctxName = factory.getGenerator().getTarget()
 							 .getRuleFunctionContextStructName(rref);
 			if ( needList) {
+				if(factory.getGenerator().getTarget().supportsOverloadedMethods())
 					decls.add( new ContextRuleListGetterDecl(factory, refLabelName, ctxName) );
 				decls.add( new ContextRuleListIndexedGetterDecl(factory, refLabelName, ctxName) );
 			}
@@ -257,6 +258,7 @@ public class RuleFunction extends OutputModelObject {
 		}
 		else {
 			if ( needList ) {
+				if(factory.getGenerator().getTarget().supportsOverloadedMethods())
 					decls.add( new ContextTokenListGetterDecl(factory, refLabelName) );
 				decls.add( new ContextTokenListIndexedGetterDecl(factory, refLabelName) );
 			}