added a expression traversal

src/main/java/de/neemann/digital/hdl/model2/HDLNode.java

@@ -7,6 +7,7 @@ package de.neemann.digital.hdl.model2;
 
 import de.neemann.digital.core.element.ElementAttributes;
 import de.neemann.digital.hdl.model2.expression.Expression;
+import de.neemann.digital.hdl.model2.expression.Visitor;
 import de.neemann.digital.hdl.printer.CodePrinter;
 
 import java.io.IOException;
@@ -185,4 +186,13 @@ public abstract class HDLNode {
      * @param expression the expression to use instead
      */
     public abstract void replaceNetByExpression(HDLNet net, Expression expression);
+
+    /**
+     * Traverses all expressions
+     *
+     * @param visitor the visitor
+     * @param <V>     the type of the visitor
+     * @return the visitor for chained calls
+     */
+    public abstract <V extends Visitor> V traverseExpressions(V visitor);
 }

src/main/java/de/neemann/digital/hdl/model2/HDLNodeAssignment.java

@@ -9,6 +9,7 @@ package de.neemann.digital.hdl.model2;
 import de.neemann.digital.core.element.ElementAttributes;
 import de.neemann.digital.hdl.model2.expression.ExprVar;
 import de.neemann.digital.hdl.model2.expression.Expression;
+import de.neemann.digital.hdl.model2.expression.Visitor;
 import de.neemann.digital.hdl.printer.CodePrinter;
 
 import java.io.IOException;
@@ -61,6 +62,12 @@ public class HDLNodeAssignment extends HDLNode {
         expression.replace(oldNet, new ExprVar(newNet));
     }
 
+    @Override
+    public <V extends Visitor> V traverseExpressions(V visitor) {
+        expression.traverse(visitor);
+        return visitor;
+    }
+
     @Override
     public void replaceNetByExpression(HDLNet net, Expression expression) {
         expression.replace(net, expression);

src/main/java/de/neemann/digital/hdl/model2/HDLNodeBuildIn.java

@@ -8,6 +8,7 @@ package de.neemann.digital.hdl.model2;
 import de.neemann.digital.core.element.ElementAttributes;
 import de.neemann.digital.hdl.model2.expression.ExprVar;
 import de.neemann.digital.hdl.model2.expression.Expression;
+import de.neemann.digital.hdl.model2.expression.Visitor;
 
 import java.util.ArrayList;
 import java.util.Iterator;
@@ -36,6 +37,13 @@ public class HDLNodeBuildIn extends HDLNode implements Iterable<HDLNodeBuildIn.I
             ia.replaceNetByExpression(net, expression);
     }
 
+    @Override
+    public <V extends Visitor> V traverseExpressions(V visitor) {
+        for (InputAssignment ia : this)
+            ia.traverseExpressions(visitor);
+        return visitor;
+    }
+
     HDLNode createExpressions() {
         for (HDLPort in : getInputs())
             inputAssignement.add(new InputAssignment(in.getName(), new ExprVar(in.getNet())));
@@ -95,5 +103,9 @@ public class HDLNodeBuildIn extends HDLNode implements Iterable<HDLNodeBuildIn.I
         private void rename(HDLModel.Renaming renaming) {
             name = renaming.checkName(name);
         }
+
+        private  <V extends Visitor> void traverseExpressions(V visitor) {
+            expression.traverse(visitor);
+        }
     }
 }

src/main/java/de/neemann/digital/hdl/model2/HDLNodeSplitterManyToOne.java

@@ -8,6 +8,7 @@ package de.neemann.digital.hdl.model2;
 import de.neemann.digital.core.wiring.Splitter;
 import de.neemann.digital.hdl.model2.expression.ExprVar;
 import de.neemann.digital.hdl.model2.expression.Expression;
+import de.neemann.digital.hdl.model2.expression.Visitor;
 import de.neemann.digital.hdl.printer.CodePrinter;
 
 import java.io.IOException;
@@ -71,6 +72,13 @@ public class HDLNodeSplitterManyToOne extends HDLNode implements Iterable<HDLNod
             p.replace(net, expression);
     }
 
+    @Override
+    public <V extends Visitor> V traverseExpressions(V visitor) {
+        for (SplitterAssignment p : this)
+            p.traverseExpressions(visitor);
+        return visitor;
+    }
+
     @Override
     public Iterator<SplitterAssignment> iterator() {
         return outputs.iterator();
@@ -123,5 +131,9 @@ public class HDLNodeSplitterManyToOne extends HDLNode implements Iterable<HDLNod
             else
                 expression.replace(net, expr);
         }
+
+        private void traverseExpressions(Visitor visitor) {
+            expression.traverse(visitor);
+        }
     }
 }

src/main/java/de/neemann/digital/hdl/model2/HDLNodeSplitterOneToMany.java

@@ -7,6 +7,7 @@ package de.neemann.digital.hdl.model2;
 
 import de.neemann.digital.core.wiring.Splitter;
 import de.neemann.digital.hdl.model2.expression.Expression;
+import de.neemann.digital.hdl.model2.expression.Visitor;
 import de.neemann.digital.hdl.printer.CodePrinter;
 
 import java.io.IOException;
@@ -56,6 +57,11 @@ public class HDLNodeSplitterOneToMany extends HDLNode {
     public void replaceNetByExpression(HDLNet net, Expression expression) {
     }
 
+    @Override
+    public <V extends Visitor> V traverseExpressions(V visitor) {
+        throw new RuntimeException("HDLNodeSplitterOneToMany is not expression based!");
+    }
+
     /**
      * @return the source signals name
      */

src/main/java/de/neemann/digital/hdl/model2/expression/ExprNot.java

@@ -48,4 +48,9 @@ public class ExprNot implements Expression {
             expr.replace(net, expression);
     }
 
+    @Override
+    public void traverse(Visitor visitor) {
+        visitor.visit(this);
+        expr.traverse(visitor);
+    }
 }

src/main/java/de/neemann/digital/hdl/model2/expression/ExprOperate.java

@@ -87,4 +87,10 @@ public class ExprOperate implements Expression {
         }
     }
 
+    @Override
+    public void traverse(Visitor visitor) {
+        visitor.visit(this);
+        for (Expression o : operands)
+            o.traverse(visitor);
+    }
 }

src/main/java/de/neemann/digital/hdl/model2/expression/Expression.java

@@ -21,6 +21,15 @@ public interface Expression extends Printable {
      */
     void replace(HDLNet net, Expression expression);
 
+    /**
+     * Traverses all expressions
+     *
+     * @param visitor the visitor
+     */
+    default void traverse(Visitor visitor) {
+        visitor.visit(this);
+    }
+
     /**
      * Help er to check if a expression is a net reference
      *

src/main/java/de/neemann/digital/hdl/model2/expression/Visitor.java

@@ -0,0 +1,18 @@
+/*
+ * Copyright (c) 2018 Helmut Neemann.
+ * Use of this source code is governed by the GPL v3 license
+ * that can be found in the LICENSE file.
+ */
+package de.neemann.digital.hdl.model2.expression;
+
+/**
+ * Visitor to visit all expressions
+ */
+public interface Visitor {
+    /**
+     * Visited by all expressions
+     *
+     * @param expression the expression
+     */
+    void visit(Expression expression);
+}