Now outputs headers a bit as well as code.

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

@@ -1046,4 +1046,25 @@ initValue(typeName) ::= <<
 <cppTypeInitMap.(typeName)>
 >>
 
+headerFile(file, parser, namedActions) ::= <<
+FOOM1
+>>
+
+parserHeaderFile(file, parser, namedActions) ::= <<
+FOOM2
+>>
+
+visitorHeaderFile(file, parser, namedActions) ::= <<
+FOOM3
+>>
+
+ParserHeaderFile(file, parser, namedActions) ::= <<
+FOOM4
+>>
+
+VisitorHeaderFile(file, parser, namedActions) ::= <<
+FOOM5
+>>
+
 codeFileExtension() ::= ".cpp"
+headerFileExtension() ::= ".h"

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

@@ -203,7 +203,7 @@ public class CodeGenerator {
 		if ( fileName==null ) return;
 		if ( getTemplates().isDefined("headerFile") ) {
 			ST extST = getTemplates().getInstanceOf("headerFileExtension");
-			ST headerFileST = null;
+			ST headerFileST = getTemplates().getInstanceOf("headerFile");
 			// TODO:  don't hide this header file generation here!
 			getTarget().genRecognizerHeaderFile(g,headerFileST,extST.render(lineWidth));
 		}
@@ -298,4 +298,39 @@ public class CodeGenerator {
 		String recognizerName = g.getRecognizerName();
 		return recognizerName+extST.render();
 	}
+
+	public String getRecognizerHeaderFileName() {
+		ST extST = getTemplates().getInstanceOf("headerFileExtension");
+		if ( extST==null ) return null;
+		String recognizerName = g.getRecognizerName();
+		return recognizerName+extST.render();
+	}
+
+	public String getListenerHeaderFileName() {
+		ST extST = getTemplates().getInstanceOf("headerFileExtension");
+		if ( extST==null ) return null;
+		String listenerName = g.name + "Listener";
+		return listenerName+extST.render();
+	}
+
+	public String getVisitorHeaderFileName() {
+		ST extST = getTemplates().getInstanceOf("headerFileExtension");
+		if ( extST==null ) return null;
+		String visitorName = g.name + "Visitor";
+		return visitorName+extST.render();
+	}
+
+	public String getBaseListenerHeaderFileName() {
+		assert g.name != null;
+		ST extST = getTemplates().getInstanceOf("headerFileExtension");
+		String visitorName = g.name + "BaseListener";
+		return visitorName+extST.render();
+	}
+
+	public String getBaseVisitorHeaderFileName() {
+		assert g.name != null;
+		ST extST = getTemplates().getInstanceOf("headerFileExtension");
+		String visitorName = g.name + "BaseVisitor";
+		return visitorName+extST.render();
+	}
 }

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

@@ -30,7 +30,9 @@
 
 package org.antlr.v4.codegen;
 
+import org.antlr.v4.tool.Grammar;
 import org.antlr.v4.tool.ast.GrammarAST;
+import org.stringtemplate.v4.ST;
 import org.stringtemplate.v4.STGroup;
 import org.stringtemplate.v4.StringRenderer;
 
@@ -70,6 +72,10 @@ public class CppTarget extends Target {
 		super(gen, "Cpp");
 	}
 
+	public String getVersion() {
+		return "4.1";
+	}
+
 	public Set<String> getBadWords() {
 		if (badWords.isEmpty()) {
 			addBadWords();
@@ -200,4 +206,11 @@ public class CppTarget extends Target {
 		result.registerRenderer(String.class, new StringRenderer(), true);
 		return result;
 	}
+
+// MEGAHACK -- Make it so we can have different header filenames for the three types of files -- recognizer, listener, visitor.
+        @Override
+        protected void genRecognizerHeaderFile(Grammar grammar, ST headerFileST,  String extName) {
+ 		String fileName = getCodeGenerator().getRecognizerHeaderFileName();
+ 		getCodeGenerator().write(headerFileST, fileName);
+ 	}
 }