Make JS visitor generic

pmd-core/src/main/java/net/sourceforge/pmd/lang/ast/AstVisitorBase.java

@@ -10,29 +10,10 @@ package net.sourceforge.pmd.lang.ast;
  */
 public abstract class AstVisitorBase<P, R> implements AstVisitor<P, R> {
 
-    /** Initial value when combining values returned by children. */
-    protected R zero() {
-        return null;
-    }
-
-    /**
-     * Merge two values of type R, used to combine values returned by children.
-     *
-     * @param acc        Current accumulated value for the previous siblings
-     *                   (or {@link #zero()} if the child is the first child)
-     * @param childValue Value for the new child
-     *
-     * @return New accumulated value to use for the next sibling
-     */
-    protected R combine(R acc, R childValue) {
-        return acc;
-    }
-
     /**
      * Visit the children. By default the data parameter is passed unchanged
-     * to all descendants. The {@link #zero() zero} and {@link #combine(Object, Object) combine}
-     * functions should be implemented if this is to return something else
-     * than null.
+     * to all descendants, and null is returned. Override this method to customize
+     * this behavior.
      *
      * @param node Node whose children should be visited
      * @param data Parameter of the visit
@@ -41,12 +22,10 @@ public abstract class AstVisitorBase<P, R> implements AstVisitor<P, R> {
      */
     // kept separate from super.visit for clarity
     protected R visitChildren(Node node, P data) {
-        R result = zero();
         for (Node child : node.children()) {
-            R r1 = child.acceptVisitor(this, data);
-            result = combine(result, r1);
+            child.acceptVisitor(this, data);
         }
-        return result;
+        return null;
     }
 
     @Override

pmd-javascript/src/main/java/net/sourceforge/pmd/lang/ecmascript/ast/ASTArrayComprehension.java

@@ -12,7 +12,7 @@ public final class ASTArrayComprehension extends AbstractEcmascriptNode<ArrayCom
     }
 
     @Override
-    public Object jjtAccept(EcmascriptParserVisitor visitor, Object data) {
+    protected <P, R> R acceptJsVisitor(EcmascriptVisitor<? super P, ? extends R> visitor, P data) {
         return visitor.visit(this, data);
     }
 

pmd-javascript/src/main/java/net/sourceforge/pmd/lang/ecmascript/ast/ASTArrayComprehensionLoop.java

@@ -12,7 +12,7 @@ public final class ASTArrayComprehensionLoop extends AbstractEcmascriptNode<Arra
     }
 
     @Override
-    public Object jjtAccept(EcmascriptParserVisitor visitor, Object data) {
+    protected <P, R> R acceptJsVisitor(EcmascriptVisitor<? super P, ? extends R> visitor, P data) {
         return visitor.visit(this, data);
     }
 

pmd-javascript/src/main/java/net/sourceforge/pmd/lang/ecmascript/ast/ASTArrayLiteral.java

@@ -15,7 +15,7 @@ public final class ASTArrayLiteral extends AbstractEcmascriptNode<ArrayLiteral>
     }
 
     @Override
-    public Object jjtAccept(EcmascriptParserVisitor visitor, Object data) {
+    protected <P, R> R acceptJsVisitor(EcmascriptVisitor<? super P, ? extends R> visitor, P data) {
         return visitor.visit(this, data);
     }
 

pmd-javascript/src/main/java/net/sourceforge/pmd/lang/ecmascript/ast/ASTAssignment.java

@@ -12,7 +12,7 @@ public final class ASTAssignment extends AbstractInfixEcmascriptNode<Assignment>
     }
 
     @Override
-    public Object jjtAccept(EcmascriptParserVisitor visitor, Object data) {
+    protected <P, R> R acceptJsVisitor(EcmascriptVisitor<? super P, ? extends R> visitor, P data) {
         return visitor.visit(this, data);
     }
 }

pmd-javascript/src/main/java/net/sourceforge/pmd/lang/ecmascript/ast/ASTAstRoot.java

@@ -20,7 +20,7 @@ public final class ASTAstRoot extends AbstractEcmascriptNode<AstRoot> implements
     }
 
     @Override
-    public Object jjtAccept(EcmascriptParserVisitor visitor, Object data) {
+    protected <P, R> R acceptJsVisitor(EcmascriptVisitor<? super P, ? extends R> visitor, P data) {
         return visitor.visit(this, data);
     }
 

pmd-javascript/src/main/java/net/sourceforge/pmd/lang/ecmascript/ast/ASTBlock.java

@@ -12,7 +12,7 @@ public final class ASTBlock extends AbstractEcmascriptNode<Block> {
     }
 
     @Override
-    public Object jjtAccept(EcmascriptParserVisitor visitor, Object data) {
+    protected <P, R> R acceptJsVisitor(EcmascriptVisitor<? super P, ? extends R> visitor, P data) {
         return visitor.visit(this, data);
     }
 }

pmd-javascript/src/main/java/net/sourceforge/pmd/lang/ecmascript/ast/ASTBreakStatement.java

@@ -13,7 +13,7 @@ public final class ASTBreakStatement extends AbstractEcmascriptNode<BreakStateme
     }
 
     @Override
-    public Object jjtAccept(EcmascriptParserVisitor visitor, Object data) {
+    protected <P, R> R acceptJsVisitor(EcmascriptVisitor<? super P, ? extends R> visitor, P data) {
         return visitor.visit(this, data);
     }
 

pmd-javascript/src/main/java/net/sourceforge/pmd/lang/ecmascript/ast/ASTCatchClause.java

@@ -12,7 +12,7 @@ public final class ASTCatchClause extends AbstractEcmascriptNode<CatchClause> {
     }
 
     @Override
-    public Object jjtAccept(EcmascriptParserVisitor visitor, Object data) {
+    protected <P, R> R acceptJsVisitor(EcmascriptVisitor<? super P, ? extends R> visitor, P data) {
         return visitor.visit(this, data);
     }
 

pmd-javascript/src/main/java/net/sourceforge/pmd/lang/ecmascript/ast/ASTComment.java

@@ -12,7 +12,7 @@ public final class ASTComment extends AbstractEcmascriptNode<Comment> {
     }
 
     @Override
-    public Object jjtAccept(EcmascriptParserVisitor visitor, Object data) {
+    protected <P, R> R acceptJsVisitor(EcmascriptVisitor<? super P, ? extends R> visitor, P data) {
         return visitor.visit(this, data);
     }
 

pmd-javascript/src/main/java/net/sourceforge/pmd/lang/ecmascript/ast/ASTConditionalExpression.java

@@ -12,7 +12,7 @@ public final class ASTConditionalExpression extends AbstractEcmascriptNode<Condi
     }
 
     @Override
-    public Object jjtAccept(EcmascriptParserVisitor visitor, Object data) {
+    protected <P, R> R acceptJsVisitor(EcmascriptVisitor<? super P, ? extends R> visitor, P data) {
         return visitor.visit(this, data);
     }
 

pmd-javascript/src/main/java/net/sourceforge/pmd/lang/ecmascript/ast/ASTContinueStatement.java

@@ -13,7 +13,7 @@ public final class ASTContinueStatement extends AbstractEcmascriptNode<ContinueS
     }
 
     @Override
-    public Object jjtAccept(EcmascriptParserVisitor visitor, Object data) {
+    protected <P, R> R acceptJsVisitor(EcmascriptVisitor<? super P, ? extends R> visitor, P data) {
         return visitor.visit(this, data);
     }
 

pmd-javascript/src/main/java/net/sourceforge/pmd/lang/ecmascript/ast/ASTDoLoop.java

@@ -12,7 +12,7 @@ public final class ASTDoLoop extends AbstractEcmascriptNode<DoLoop> {
     }
 
     @Override
-    public Object jjtAccept(EcmascriptParserVisitor visitor, Object data) {
+    protected <P, R> R acceptJsVisitor(EcmascriptVisitor<? super P, ? extends R> visitor, P data) {
         return visitor.visit(this, data);
     }
 

pmd-javascript/src/main/java/net/sourceforge/pmd/lang/ecmascript/ast/ASTElementGet.java

@@ -12,7 +12,7 @@ public final class ASTElementGet extends AbstractEcmascriptNode<ElementGet> {
     }
 
     @Override
-    public Object jjtAccept(EcmascriptParserVisitor visitor, Object data) {
+    protected <P, R> R acceptJsVisitor(EcmascriptVisitor<? super P, ? extends R> visitor, P data) {
         return visitor.visit(this, data);
     }
 

pmd-javascript/src/main/java/net/sourceforge/pmd/lang/ecmascript/ast/ASTEmptyExpression.java

@@ -12,7 +12,7 @@ public final class ASTEmptyExpression extends AbstractEcmascriptNode<EmptyExpres
     }
 
     @Override
-    public Object jjtAccept(EcmascriptParserVisitor visitor, Object data) {
+    protected <P, R> R acceptJsVisitor(EcmascriptVisitor<? super P, ? extends R> visitor, P data) {
         return visitor.visit(this, data);
     }
 }

pmd-javascript/src/main/java/net/sourceforge/pmd/lang/ecmascript/ast/ASTEmptyStatement.java

@@ -12,7 +12,7 @@ public final class ASTEmptyStatement extends AbstractEcmascriptNode<EmptyStateme
     }
 
     @Override
-    public Object jjtAccept(EcmascriptParserVisitor visitor, Object data) {
+    protected <P, R> R acceptJsVisitor(EcmascriptVisitor<? super P, ? extends R> visitor, P data) {
         return visitor.visit(this, data);
     }
 }

pmd-javascript/src/main/java/net/sourceforge/pmd/lang/ecmascript/ast/ASTExpressionStatement.java

@@ -13,7 +13,7 @@ public final class ASTExpressionStatement extends AbstractEcmascriptNode<Express
     }
 
     @Override
-    public Object jjtAccept(EcmascriptParserVisitor visitor, Object data) {
+    protected <P, R> R acceptJsVisitor(EcmascriptVisitor<? super P, ? extends R> visitor, P data) {
         return visitor.visit(this, data);
     }
 

pmd-javascript/src/main/java/net/sourceforge/pmd/lang/ecmascript/ast/ASTForInLoop.java

@@ -12,7 +12,7 @@ public final class ASTForInLoop extends AbstractEcmascriptNode<ForInLoop> {
     }
 
     @Override
-    public Object jjtAccept(EcmascriptParserVisitor visitor, Object data) {
+    protected <P, R> R acceptJsVisitor(EcmascriptVisitor<? super P, ? extends R> visitor, P data) {
         return visitor.visit(this, data);
     }
 

pmd-javascript/src/main/java/net/sourceforge/pmd/lang/ecmascript/ast/ASTForLoop.java

@@ -12,7 +12,7 @@ public final class ASTForLoop extends AbstractEcmascriptNode<ForLoop> {
     }
 
     @Override
-    public Object jjtAccept(EcmascriptParserVisitor visitor, Object data) {
+    protected <P, R> R acceptJsVisitor(EcmascriptVisitor<? super P, ? extends R> visitor, P data) {
         return visitor.visit(this, data);
     }
 

pmd-javascript/src/main/java/net/sourceforge/pmd/lang/ecmascript/ast/ASTFunctionCall.java

@@ -12,7 +12,7 @@ public final class ASTFunctionCall extends AbstractEcmascriptNode<FunctionCall>
     }
 
     @Override
-    public Object jjtAccept(EcmascriptParserVisitor visitor, Object data) {
+    protected <P, R> R acceptJsVisitor(EcmascriptVisitor<? super P, ? extends R> visitor, P data) {
         return visitor.visit(this, data);
     }
 

pmd-javascript/src/main/java/net/sourceforge/pmd/lang/ecmascript/ast/ASTFunctionNode.java

@@ -13,7 +13,7 @@ public final class ASTFunctionNode extends AbstractEcmascriptNode<FunctionNode>
     }
 
     @Override
-    public Object jjtAccept(EcmascriptParserVisitor visitor, Object data) {
+    protected <P, R> R acceptJsVisitor(EcmascriptVisitor<? super P, ? extends R> visitor, P data) {
         return visitor.visit(this, data);
     }
 

pmd-javascript/src/main/java/net/sourceforge/pmd/lang/ecmascript/ast/ASTIfStatement.java

@@ -12,7 +12,7 @@ public final class ASTIfStatement extends AbstractEcmascriptNode<IfStatement> {
     }
 
     @Override
-    public Object jjtAccept(EcmascriptParserVisitor visitor, Object data) {
+    protected <P, R> R acceptJsVisitor(EcmascriptVisitor<? super P, ? extends R> visitor, P data) {
         return visitor.visit(this, data);
     }
 

pmd-javascript/src/main/java/net/sourceforge/pmd/lang/ecmascript/ast/ASTInfixExpression.java

@@ -12,7 +12,7 @@ public final class ASTInfixExpression extends AbstractInfixEcmascriptNode<InfixE
     }
 
     @Override
-    public Object jjtAccept(EcmascriptParserVisitor visitor, Object data) {
+    protected <P, R> R acceptJsVisitor(EcmascriptVisitor<? super P, ? extends R> visitor, P data) {
         return visitor.visit(this, data);
     }
 }

pmd-javascript/src/main/java/net/sourceforge/pmd/lang/ecmascript/ast/ASTKeywordLiteral.java

@@ -16,7 +16,7 @@ public final class ASTKeywordLiteral extends AbstractEcmascriptNode<KeywordLiter
     }
 
     @Override
-    public Object jjtAccept(EcmascriptParserVisitor visitor, Object data) {
+    protected <P, R> R acceptJsVisitor(EcmascriptVisitor<? super P, ? extends R> visitor, P data) {
         return visitor.visit(this, data);
     }
 

pmd-javascript/src/main/java/net/sourceforge/pmd/lang/ecmascript/ast/ASTLabel.java

@@ -13,7 +13,7 @@ public final class ASTLabel extends AbstractEcmascriptNode<Label> {
     }
 
     @Override
-    public Object jjtAccept(EcmascriptParserVisitor visitor, Object data) {
+    protected <P, R> R acceptJsVisitor(EcmascriptVisitor<? super P, ? extends R> visitor, P data) {
         return visitor.visit(this, data);
     }
 }

pmd-javascript/src/main/java/net/sourceforge/pmd/lang/ecmascript/ast/ASTLabeledStatement.java

@@ -12,7 +12,7 @@ public final class ASTLabeledStatement extends AbstractEcmascriptNode<LabeledSta
     }
 
     @Override
-    public Object jjtAccept(EcmascriptParserVisitor visitor, Object data) {
+    protected <P, R> R acceptJsVisitor(EcmascriptVisitor<? super P, ? extends R> visitor, P data) {
         return visitor.visit(this, data);
     }
 

pmd-javascript/src/main/java/net/sourceforge/pmd/lang/ecmascript/ast/ASTLetNode.java

@@ -12,7 +12,7 @@ public final class ASTLetNode extends AbstractEcmascriptNode<LetNode> {
     }
 
     @Override
-    public Object jjtAccept(EcmascriptParserVisitor visitor, Object data) {
+    protected <P, R> R acceptJsVisitor(EcmascriptVisitor<? super P, ? extends R> visitor, P data) {
         return visitor.visit(this, data);
     }
 

pmd-javascript/src/main/java/net/sourceforge/pmd/lang/ecmascript/ast/ASTName.java

@@ -13,7 +13,7 @@ public final class ASTName extends AbstractEcmascriptNode<Name> {
     }
 
     @Override
-    public Object jjtAccept(EcmascriptParserVisitor visitor, Object data) {
+    protected <P, R> R acceptJsVisitor(EcmascriptVisitor<? super P, ? extends R> visitor, P data) {
         return visitor.visit(this, data);
     }
 

pmd-javascript/src/main/java/net/sourceforge/pmd/lang/ecmascript/ast/ASTNewExpression.java

@@ -12,7 +12,7 @@ public final class ASTNewExpression extends AbstractEcmascriptNode<NewExpression
     }
 
     @Override
-    public Object jjtAccept(EcmascriptParserVisitor visitor, Object data) {
+    protected <P, R> R acceptJsVisitor(EcmascriptVisitor<? super P, ? extends R> visitor, P data) {
         return visitor.visit(this, data);
     }
 

pmd-javascript/src/main/java/net/sourceforge/pmd/lang/ecmascript/ast/ASTNumberLiteral.java

@@ -13,7 +13,7 @@ public final class ASTNumberLiteral extends AbstractEcmascriptNode<NumberLiteral
     }
 
     @Override
-    public Object jjtAccept(EcmascriptParserVisitor visitor, Object data) {
+    protected <P, R> R acceptJsVisitor(EcmascriptVisitor<? super P, ? extends R> visitor, P data) {
         return visitor.visit(this, data);
     }