Add transformation pass to C# backend

27 files changed, 440 insertions, 69 deletions

diff --git a/src/main/java/org/zwobble/couscous/ast/AnnotationNode.java b/src/main/java/org/zwobble/couscous/ast/AnnotationNode.java
index 0d135ba..e102af7 100644
--- a/src/main/java/org/zwobble/couscous/ast/AnnotationNode.java
+++ b/src/main/java/org/zwobble/couscous/ast/AnnotationNode.java
@@ -1,6 +1,7 @@
 package org.zwobble.couscous.ast;
 
 import org.zwobble.couscous.ast.visitors.NodeMapper;
+import org.zwobble.couscous.ast.visitors.NodeTransformer;
 
 public class AnnotationNode implements Node {
     public static AnnotationNode annotation(TypeName type) {
@@ -22,6 +23,10 @@ public class AnnotationNode implements Node {
         return visitor.visit(this);
     }
 
+    public AnnotationNode transform(NodeTransformer transformer) {
+        return new AnnotationNode(transformer.transform(type));
+    }
+
     @Override
     public String toString() {
         return "AnnotationNode(type=" + type + ")";
diff --git a/src/main/java/org/zwobble/couscous/ast/AssignmentNode.java b/src/main/java/org/zwobble/couscous/ast/AssignmentNode.java
index 15ecf8f..dd1a9f3 100644
--- a/src/main/java/org/zwobble/couscous/ast/AssignmentNode.java
+++ b/src/main/java/org/zwobble/couscous/ast/AssignmentNode.java
@@ -1,6 +1,7 @@
 package org.zwobble.couscous.ast;
 
 import org.zwobble.couscous.ast.visitors.ExpressionNodeMapper;
+import org.zwobble.couscous.ast.visitors.NodeTransformer;
 
 import java.util.function.Function;
 
@@ -52,6 +53,12 @@ public class AssignmentNode implements ExpressionNode {
             replace.apply(value));
     }
 
+    public ExpressionNode transform(NodeTransformer transformer) {
+        return new AssignmentNode(
+            (AssignableExpressionNode) transformer.visit(target),
+            transformer.visit(value));
+    }
+
     @Override
     public TypeName getType() {
         return value.getType();
diff --git a/src/main/java/org/zwobble/couscous/ast/CastNode.java b/src/main/java/org/zwobble/couscous/ast/CastNode.java
index e81cd94..1f61941 100644
--- a/src/main/java/org/zwobble/couscous/ast/CastNode.java
+++ b/src/main/java/org/zwobble/couscous/ast/CastNode.java
@@ -1,6 +1,7 @@
 package org.zwobble.couscous.ast;
 
 import org.zwobble.couscous.ast.visitors.ExpressionNodeMapper;
+import org.zwobble.couscous.ast.visitors.NodeTransformer;
 
 import java.util.function.Function;
 
@@ -36,6 +37,10 @@ public class CastNode implements ExpressionNode {
         return new CastNode(replace.apply(expression), type);
     }
 
+    public ExpressionNode transform(NodeTransformer transformer) {
+        return new CastNode(transformer.visit(expression), transformer.transform(type));
+    }
+
     @Override
     public String toString() {
         return "CastNode(" +
diff --git a/src/main/java/org/zwobble/couscous/ast/ClassNode.java b/src/main/java/org/zwobble/couscous/ast/ClassNode.java
index 3545084..8b54be6 100644
--- a/src/main/java/org/zwobble/couscous/ast/ClassNode.java
+++ b/src/main/java/org/zwobble/couscous/ast/ClassNode.java
@@ -1,6 +1,7 @@
 package org.zwobble.couscous.ast;
 
 import org.zwobble.couscous.ast.visitors.NodeMapper;
+import org.zwobble.couscous.ast.visitors.NodeTransformer;
 
 import java.util.List;
 import java.util.Set;
@@ -66,6 +67,15 @@ public class ClassNode implements Node {
         return visitor.visit(this);
     }
 
+    public ClassNode transform(NodeTransformer transformer) {
+        return new ClassNode(
+            transformer.transform(name),
+            transformer.transformTypes(superTypes),
+            transformer.transformFields(fields),
+            transformer.visit(constructor),
+            transformer.transformMethods(methods));
+    }
+
     @Override
     public String toString() {
         return "ClassNode(" +
diff --git a/src/main/java/org/zwobble/couscous/ast/ConstructorCallNode.java b/src/main/java/org/zwobble/couscous/ast/ConstructorCallNode.java
index cad359d..ecbdc00 100644
--- a/src/main/java/org/zwobble/couscous/ast/ConstructorCallNode.java
+++ b/src/main/java/org/zwobble/couscous/ast/ConstructorCallNode.java
@@ -1,10 +1,11 @@
 package org.zwobble.couscous.ast;
 
+import org.zwobble.couscous.ast.visitors.ExpressionNodeMapper;
+import org.zwobble.couscous.ast.visitors.NodeTransformer;
+
 import java.util.List;
 import java.util.function.Function;
 
-import org.zwobble.couscous.ast.visitors.ExpressionNodeMapper;
-
 import static org.zwobble.couscous.util.ExtraLists.eagerMap;
 
 public class ConstructorCallNode implements ExpressionNode {
@@ -43,6 +44,12 @@ public class ConstructorCallNode implements ExpressionNode {
         return new ConstructorCallNode(type, eagerMap(arguments, replace::apply));
     }
 
+    public ExpressionNode transform(NodeTransformer transformer) {
+        return new ConstructorCallNode(
+            transformer.transform(type),
+            transformer.transformExpressions(arguments));
+    }
+
     @Override
     public String toString() {
         return "ConstructorCallNode(type=" + type + ", arguments=" + arguments
diff --git a/src/main/java/org/zwobble/couscous/ast/ConstructorNode.java b/src/main/java/org/zwobble/couscous/ast/ConstructorNode.java
index 0d4bad8..fab931b 100644
--- a/src/main/java/org/zwobble/couscous/ast/ConstructorNode.java
+++ b/src/main/java/org/zwobble/couscous/ast/ConstructorNode.java
@@ -1,6 +1,7 @@
 package org.zwobble.couscous.ast;
 
 import org.zwobble.couscous.ast.visitors.NodeMapper;
+import org.zwobble.couscous.ast.visitors.NodeTransformer;
 
 import java.util.Collections;
 import java.util.List;
@@ -17,7 +18,7 @@ public class ConstructorNode implements CallableNode {
     private final List<FormalArgumentNode> arguments;
     private final List<StatementNode> body;
     
-    public ConstructorNode(
+    private ConstructorNode(
             List<FormalArgumentNode> arguments,
             List<StatementNode> body) {
         this.arguments = arguments;
@@ -37,6 +38,12 @@ public class ConstructorNode implements CallableNode {
         return visitor.visit(this);
     }
 
+    public ConstructorNode transform(NodeTransformer transformer) {
+        return new ConstructorNode(
+            transformer.transformFormalArguments(arguments),
+            transformer.transformStatements(body));
+    }
+
     @Override
     public String toString() {
         return "ConstructorNode(arguments=" + arguments + ", body=" + body
diff --git a/src/main/java/org/zwobble/couscous/ast/ExpressionStatementNode.java b/src/main/java/org/zwobble/couscous/ast/ExpressionStatementNode.java
index 0ac7381..68acedb 100644
--- a/src/main/java/org/zwobble/couscous/ast/ExpressionStatementNode.java
+++ b/src/main/java/org/zwobble/couscous/ast/ExpressionStatementNode.java
@@ -1,5 +1,6 @@
 package org.zwobble.couscous.ast;
 
+import org.zwobble.couscous.ast.visitors.NodeTransformer;
 import org.zwobble.couscous.ast.visitors.StatementNodeMapper;
 
 import java.util.function.Function;
@@ -29,6 +30,10 @@ public class ExpressionStatementNode implements StatementNode {
         return new ExpressionStatementNode(replace.apply(expression));
     }
 
+    public StatementNode transform(NodeTransformer transformer) {
+        return new ExpressionStatementNode(transformer.visit(expression));
+    }
+
     @Override
     public String toString() {
         return "ExpressionStatementNode(expression=" + expression + ")";
diff --git a/src/main/java/org/zwobble/couscous/ast/FieldAccessNode.java b/src/main/java/org/zwobble/couscous/ast/FieldAccessNode.java
index 9f881b4..3224b5d 100644
--- a/src/main/java/org/zwobble/couscous/ast/FieldAccessNode.java
+++ b/src/main/java/org/zwobble/couscous/ast/FieldAccessNode.java
@@ -2,6 +2,7 @@ package org.zwobble.couscous.ast;
 
 import org.zwobble.couscous.ast.visitors.AssignableExpressionNodeVisitor;
 import org.zwobble.couscous.ast.visitors.ExpressionNodeMapper;
+import org.zwobble.couscous.ast.visitors.NodeTransformer;
 
 import java.util.function.Function;
 
@@ -48,6 +49,13 @@ public class FieldAccessNode implements AssignableExpressionNode {
         return new FieldAccessNode(replace.apply(left), fieldName, type);
     }
 
+    public ExpressionNode transform(NodeTransformer transformer) {
+        return new FieldAccessNode(
+            transformer.visit(left),
+            fieldName,
+            transformer.transform(type));
+    }
+
     @Override
     public void accept(AssignableExpressionNodeVisitor mapper) {
         mapper.visit(this);
diff --git a/src/main/java/org/zwobble/couscous/ast/FieldDeclarationNode.java b/src/main/java/org/zwobble/couscous/ast/FieldDeclarationNode.java
index 7fea43c..3b27b9e 100644
--- a/src/main/java/org/zwobble/couscous/ast/FieldDeclarationNode.java
+++ b/src/main/java/org/zwobble/couscous/ast/FieldDeclarationNode.java
@@ -1,7 +1,7 @@
 package org.zwobble.couscous.ast;
 
 import org.zwobble.couscous.ast.visitors.NodeMapper;
-import org.zwobble.couscous.ast.visitors.NodeVisitor;
+import org.zwobble.couscous.ast.visitors.NodeTransformer;
 
 public class FieldDeclarationNode implements Node {
     public static FieldDeclarationNode field(String name, TypeName type) {
@@ -29,6 +29,12 @@ public class FieldDeclarationNode implements Node {
         return visitor.visit(this);
     }
 
+    public FieldDeclarationNode transform(NodeTransformer transformer) {
+        return new FieldDeclarationNode(
+            name,
+            transformer.transform(type));
+    }
+
     @Override
     public String toString() {
         return "FieldDeclarationNode(name=" + name + ", type=" + type + ")";
diff --git a/src/main/java/org/zwobble/couscous/ast/FormalArgumentNode.java b/src/main/java/org/zwobble/couscous/ast/FormalArgumentNode.java
index 41fb982..f7d7f42 100644
--- a/src/main/java/org/zwobble/couscous/ast/FormalArgumentNode.java
+++ b/src/main/java/org/zwobble/couscous/ast/FormalArgumentNode.java
@@ -1,6 +1,7 @@
 package org.zwobble.couscous.ast;
 
 import org.zwobble.couscous.ast.visitors.NodeMapper;
+import org.zwobble.couscous.ast.visitors.NodeTransformer;
 
 public class FormalArgumentNode implements VariableNode, Node {
     public static FormalArgumentNode formalArg(VariableDeclaration declaration) {
@@ -30,6 +31,10 @@ public class FormalArgumentNode implements VariableNode, Node {
         return visitor.visit(this);
     }
 
+    public FormalArgumentNode transform(NodeTransformer transformer) {
+        return new FormalArgumentNode(transformer.transform(declaration));
+    }
+
     @Override
     public String toString() {
         return "FormalArgumentNode(declaration=" + declaration + ")";
diff --git a/src/main/java/org/zwobble/couscous/ast/IfStatementNode.java b/src/main/java/org/zwobble/couscous/ast/IfStatementNode.java
index 8b4709a..972f0a4 100644
--- a/src/main/java/org/zwobble/couscous/ast/IfStatementNode.java
+++ b/src/main/java/org/zwobble/couscous/ast/IfStatementNode.java
@@ -1,5 +1,6 @@
 package org.zwobble.couscous.ast;
 
+import org.zwobble.couscous.ast.visitors.NodeTransformer;
 import org.zwobble.couscous.ast.visitors.StatementNodeMapper;
 
 import java.util.List;
@@ -53,6 +54,13 @@ public class IfStatementNode implements StatementNode {
             eagerMap(falseBranch, statement -> statement.replaceExpressions(replace)));
     }
 
+    public StatementNode transform(NodeTransformer transformer) {
+        return new IfStatementNode(
+            transformer.visit(condition),
+            transformer.transformStatements(trueBranch),
+            transformer.transformStatements(falseBranch));
+    }
+
     @Override
     public String toString() {
         return "IfStatementNode(condition=" + condition + ", trueBranch="
diff --git a/src/main/java/org/zwobble/couscous/ast/InstanceReceiver.java b/src/main/java/org/zwobble/couscous/ast/InstanceReceiver.java
index 926af5d..ed32dc4 100644
--- a/src/main/java/org/zwobble/couscous/ast/InstanceReceiver.java
+++ b/src/main/java/org/zwobble/couscous/ast/InstanceReceiver.java
@@ -1,6 +1,7 @@
 package org.zwobble.couscous.ast;
 
 import org.zwobble.couscous.ast.visitors.NodeMapper;
+import org.zwobble.couscous.ast.visitors.NodeTransformer;
 
 import java.util.function.Function;
 
@@ -29,6 +30,10 @@ public class InstanceReceiver implements Receiver {
         return visitor.visit(expression);
     }
 
+    public Receiver transform(NodeTransformer transformer) {
+        return new InstanceReceiver(transformer.visit(expression));
+    }
+
     @Override
     public <T> T accept(NodeMapper<T> visitor) {
         return visitor.visit(this);
diff --git a/src/main/java/org/zwobble/couscous/ast/LiteralNode.java b/src/main/java/org/zwobble/couscous/ast/LiteralNode.java
index ed2aaf0..5753650 100644
--- a/src/main/java/org/zwobble/couscous/ast/LiteralNode.java
+++ b/src/main/java/org/zwobble/couscous/ast/LiteralNode.java
@@ -1,6 +1,7 @@
 package org.zwobble.couscous.ast;
 
 import org.zwobble.couscous.ast.visitors.ExpressionNodeMapper;
+import org.zwobble.couscous.ast.visitors.NodeTransformer;
 import org.zwobble.couscous.values.*;
 
 import java.util.function.Function;
@@ -58,6 +59,18 @@ public class LiteralNode implements ExpressionNode {
         return this;
     }
 
+    public ExpressionNode transform(NodeTransformer transformer) {
+        return new LiteralNode(transformValue(transformer), transformer.transform(type));
+    }
+
+    private PrimitiveValue transformValue(NodeTransformer transformer) {
+        if (value instanceof TypeValue) {
+            return new TypeValue(transformer.transform(((TypeValue)value).getValue()));
+        } else {
+            return value;
+        }
+    }
+
     @Override
     public String toString() {
         return "LiteralNode(value=" + value + ", type=" + type + ")";
diff --git a/src/main/java/org/zwobble/couscous/ast/LocalVariableDeclarationNode.java b/src/main/java/org/zwobble/couscous/ast/LocalVariableDeclarationNode.java
index a165070..4ee0e97 100644
--- a/src/main/java/org/zwobble/couscous/ast/LocalVariableDeclarationNode.java
+++ b/src/main/java/org/zwobble/couscous/ast/LocalVariableDeclarationNode.java
@@ -1,6 +1,7 @@
 package org.zwobble.couscous.ast;
 
 import org.zwobble.couscous.ast.identifiers.Identifier;
+import org.zwobble.couscous.ast.visitors.NodeTransformer;
 import org.zwobble.couscous.ast.visitors.StatementNodeMapper;
 
 import java.util.function.Function;
@@ -58,6 +59,12 @@ public class LocalVariableDeclarationNode implements VariableNode, StatementNode
         return new LocalVariableDeclarationNode(declaration, replace.apply(initialValue));
     }
 
+    public StatementNode transform(NodeTransformer transformer) {
+        return new LocalVariableDeclarationNode(
+            transformer.transform(declaration),
+            transformer.visit(initialValue));
+    }
+
     @Override
     public String toString() {
         return "LocalVariableDeclarationNode(declaration=" + declaration
diff --git a/src/main/java/org/zwobble/couscous/ast/MethodCallNode.java b/src/main/java/org/zwobble/couscous/ast/MethodCallNode.java
index b50250d..5a67bc2 100644
--- a/src/main/java/org/zwobble/couscous/ast/MethodCallNode.java
+++ b/src/main/java/org/zwobble/couscous/ast/MethodCallNode.java
@@ -1,6 +1,7 @@
 package org.zwobble.couscous.ast;
 
 import org.zwobble.couscous.ast.visitors.ExpressionNodeMapper;
+import org.zwobble.couscous.ast.visitors.NodeTransformer;
 
 import java.util.List;
 import java.util.function.Function;
@@ -95,6 +96,14 @@ public class MethodCallNode implements ExpressionNode {
             type);
     }
 
+    public ExpressionNode transform(NodeTransformer transformer) {
+        return new MethodCallNode(
+            transformer.visit(receiver),
+            methodName,
+            transformer.transformExpressions(arguments),
+            transformer.transform(type));
+    }
+
     @Override
     public String toString() {
         return "MethodCallNode(receiver=" + receiver + ", methodName="
diff --git a/src/main/java/org/zwobble/couscous/ast/MethodNode.java b/src/main/java/org/zwobble/couscous/ast/MethodNode.java
index 5ee3a7d..b5dfd39 100644
--- a/src/main/java/org/zwobble/couscous/ast/MethodNode.java
+++ b/src/main/java/org/zwobble/couscous/ast/MethodNode.java
@@ -2,6 +2,7 @@ package org.zwobble.couscous.ast;
 
 import com.google.common.collect.ImmutableList;
 import org.zwobble.couscous.ast.visitors.NodeMapper;
+import org.zwobble.couscous.ast.visitors.NodeTransformer;
 import org.zwobble.couscous.values.UnitValue;
 
 import java.util.List;
@@ -151,6 +152,16 @@ public class MethodNode implements CallableNode {
         return visitor.visit(this);
     }
 
+    public MethodNode transform(NodeTransformer transformer) {
+        return new MethodNode(
+            transformer.transformAnnotations(annotations),
+            isStatic,
+            name,
+            transformer.transformFormalArguments(arguments),
+            transformer.transform(returnType),
+            transformer.transformStatements(body));
+    }
+
     @Override
     public String toString() {
         return "MethodNode(" +
diff --git a/src/main/java/org/zwobble/couscous/ast/ReturnNode.java b/src/main/java/org/zwobble/couscous/ast/ReturnNode.java
index 68330af..5bd5987 100644
--- a/src/main/java/org/zwobble/couscous/ast/ReturnNode.java
+++ b/src/main/java/org/zwobble/couscous/ast/ReturnNode.java
@@ -1,5 +1,6 @@
 package org.zwobble.couscous.ast;
 
+import org.zwobble.couscous.ast.visitors.NodeTransformer;
 import org.zwobble.couscous.ast.visitors.StatementNodeMapper;
 
 import java.util.function.Function;
@@ -29,6 +30,12 @@ public class ReturnNode implements StatementNode {
         return new ReturnNode(replace.apply(value));
     }
 
+    public StatementNode transform(NodeTransformer transformer) {
+        // TODO: remove duplication with replaceExpressions
+        // (can probably implement replaceExpressions with transform)
+        return new ReturnNode(transformer.visit(value));
+    }
+
     @Override
     public String toString() {
         return "ReturnNode(value=" + value + ")";
diff --git a/src/main/java/org/zwobble/couscous/ast/StaticReceiver.java b/src/main/java/org/zwobble/couscous/ast/StaticReceiver.java
index 4d35376..7814108 100644
--- a/src/main/java/org/zwobble/couscous/ast/StaticReceiver.java
+++ b/src/main/java/org/zwobble/couscous/ast/StaticReceiver.java
@@ -1,6 +1,7 @@
 package org.zwobble.couscous.ast;
 
 import org.zwobble.couscous.ast.visitors.NodeMapper;
+import org.zwobble.couscous.ast.visitors.NodeTransformer;
 
 import java.util.function.Function;
 
@@ -34,6 +35,10 @@ public class StaticReceiver implements Receiver {
         return visitor.visit(this);
     }
 
+    public Receiver transform(NodeTransformer transformer) {
+        return new StaticReceiver(transformer.transform(type));
+    }
+
     @Override
     public String toString() {
         return "StaticReceiver(" +
diff --git a/src/main/java/org/zwobble/couscous/ast/TernaryConditionalNode.java b/src/main/java/org/zwobble/couscous/ast/TernaryConditionalNode.java
index f370b0a..c49bbc5 100644
--- a/src/main/java/org/zwobble/couscous/ast/TernaryConditionalNode.java
+++ b/src/main/java/org/zwobble/couscous/ast/TernaryConditionalNode.java
@@ -1,6 +1,7 @@
 package org.zwobble.couscous.ast;
 
 import org.zwobble.couscous.ast.visitors.ExpressionNodeMapper;
+import org.zwobble.couscous.ast.visitors.NodeTransformer;
 
 import java.util.function.Function;
 
@@ -50,6 +51,13 @@ public class TernaryConditionalNode implements ExpressionNode {
             replace.apply(ifFalse));
     }
 
+    public ExpressionNode transform(NodeTransformer transformer) {
+        return new TernaryConditionalNode(
+            transformer.visit(condition),
+            transformer.visit(ifTrue),
+            transformer.visit(ifFalse));
+    }
+
     @Override
     public TypeName getType() {
         return ifTrue.getType();
diff --git a/src/main/java/org/zwobble/couscous/ast/ThisReferenceNode.java b/src/main/java/org/zwobble/couscous/ast/ThisReferenceNode.java
index a4851c8..6056abd 100644
--- a/src/main/java/org/zwobble/couscous/ast/ThisReferenceNode.java
+++ b/src/main/java/org/zwobble/couscous/ast/ThisReferenceNode.java
@@ -1,6 +1,7 @@
 package org.zwobble.couscous.ast;
 
 import org.zwobble.couscous.ast.visitors.ExpressionNodeMapper;
+import org.zwobble.couscous.ast.visitors.NodeTransformer;
 
 import java.util.function.Function;
 
@@ -34,6 +35,10 @@ public class ThisReferenceNode implements ExpressionNode, ReferenceNode {
         return visitor.visit(this);
     }
 
+    public ExpressionNode transform(NodeTransformer transformer) {
+        return new ThisReferenceNode(transformer.transform(type));
+    }
+
     @Override
     public String toString() {
         return "ThisReferenceNode(type=" + type + ")";
diff --git a/src/main/java/org/zwobble/couscous/ast/TypeCoercionNode.java b/src/main/java/org/zwobble/couscous/ast/TypeCoercionNode.java
index 1ffdd95..04ba7d1 100644
--- a/src/main/java/org/zwobble/couscous/ast/TypeCoercionNode.java
+++ b/src/main/java/org/zwobble/couscous/ast/TypeCoercionNode.java
@@ -1,6 +1,7 @@
 package org.zwobble.couscous.ast;
 
 import org.zwobble.couscous.ast.visitors.ExpressionNodeMapper;
+import org.zwobble.couscous.ast.visitors.NodeTransformer;
 
 import java.util.function.Function;
 
@@ -36,6 +37,12 @@ public class TypeCoercionNode implements ExpressionNode {
         return new TypeCoercionNode(replace.apply(expression), type);
     }
 
+    public ExpressionNode transform(NodeTransformer transformer) {
+        return new TypeCoercionNode(
+            transformer.visit(expression),
+            transformer.transform(type));
+    }
+
     @Override
     public String toString() {
         return "TypeCoercionNode(" +
diff --git a/src/main/java/org/zwobble/couscous/ast/VariableReferenceNode.java b/src/main/java/org/zwobble/couscous/ast/VariableReferenceNode.java
index c1b022a..b907c6d 100644
--- a/src/main/java/org/zwobble/couscous/ast/VariableReferenceNode.java
+++ b/src/main/java/org/zwobble/couscous/ast/VariableReferenceNode.java
@@ -3,6 +3,7 @@ package org.zwobble.couscous.ast;
 import org.zwobble.couscous.ast.identifiers.Identifier;
 import org.zwobble.couscous.ast.visitors.AssignableExpressionNodeVisitor;
 import org.zwobble.couscous.ast.visitors.ExpressionNodeMapper;
+import org.zwobble.couscous.ast.visitors.NodeTransformer;
 
 import java.util.function.Function;
 
@@ -54,6 +55,10 @@ public class VariableReferenceNode implements AssignableExpressionNode, Referenc
         return visitor.visit(this);
     }
 
+    public ExpressionNode transform(NodeTransformer transformer) {
+        return new VariableReferenceNode(transformer.transform(referent));
+    }
+
     @Override
     public String toString() {
         return "VariableReferenceNode(referent=" + referent + ")";
diff --git a/src/main/java/org/zwobble/couscous/ast/WhileNode.java b/src/main/java/org/zwobble/couscous/ast/WhileNode.java
index 6462821..34d1883 100644
--- a/src/main/java/org/zwobble/couscous/ast/WhileNode.java
+++ b/src/main/java/org/zwobble/couscous/ast/WhileNode.java
@@ -1,6 +1,7 @@
 package org.zwobble.couscous.ast;
 
 import com.google.common.base.Objects;
+import org.zwobble.couscous.ast.visitors.NodeTransformer;
 import org.zwobble.couscous.ast.visitors.StatementNodeMapper;
 
 import java.util.List;
@@ -41,6 +42,12 @@ public class WhileNode implements StatementNode {
             eagerMap(body, statement -> statement.replaceExpressions(replace)));
     }
 
+    public StatementNode transform(NodeTransformer transformer) {
+        return new WhileNode(
+            transformer.visit(condition),
+            transformer.transformStatements(body));
+    }
+
     @Override
     public boolean equals(Object o) {
         if (this == o) return true;
diff --git a/src/main/java/org/zwobble/couscous/ast/visitors/NodeTransformer.java b/src/main/java/org/zwobble/couscous/ast/visitors/NodeTransformer.java
new file mode 100644
index 0000000..539acd0
--- /dev/null
+++ b/src/main/java/org/zwobble/couscous/ast/visitors/NodeTransformer.java
@@ -0,0 +1,185 @@
+package org.zwobble.couscous.ast.visitors;
+
+import com.google.common.base.Function;
+import com.google.common.collect.ImmutableList;
+import com.google.common.collect.ImmutableSet;
+import com.google.common.collect.Iterables;
+import org.zwobble.couscous.ast.*;
+
+import java.util.List;
+import java.util.Set;
+
+public class NodeTransformer implements ExpressionNodeMapper<ExpressionNode>, StatementNodeMapper<StatementNode>, NodeMapper<Node> {
+    // TODO: tidy up transform vs visit
+    public TypeName transform(TypeName type) {
+        return type;
+    }
+
+    public ExpressionNode visit(ExpressionNode value) {
+        return value.accept((ExpressionNodeMapper<ExpressionNode>)this);
+    }
+
+    @Override
+    public ExpressionNode visit(LiteralNode literal) {
+        return literal.transform(this);
+    }
+
+    @Override
+    public ExpressionNode visit(VariableReferenceNode variableReference) {
+        return variableReference.transform(this);
+    }
+
+    @Override
+    public ExpressionNode visit(ThisReferenceNode reference) {
+        return reference.transform(this);
+    }
+
+    @Override
+    public ExpressionNode visit(AssignmentNode assignment) {
+        return assignment.transform(this);
+    }
+
+    @Override
+    public ExpressionNode visit(TernaryConditionalNode ternaryConditional) {
+        return ternaryConditional.transform(this);
+    }
+
+    @Override
+    public ExpressionNode visit(MethodCallNode methodCall) {
+        return methodCall.transform(this);
+    }
+
+    @Override
+    public ExpressionNode visit(ConstructorCallNode call) {
+        return call.transform(this);
+    }
+
+    @Override
+    public ExpressionNode visit(FieldAccessNode fieldAccess) {
+        return fieldAccess.transform(this);
+    }
+
+    @Override
+    public ExpressionNode visit(TypeCoercionNode typeCoercion) {
+        return typeCoercion.transform(this);
+    }
+
+    @Override
+    public ExpressionNode visit(CastNode cast) {
+        return cast.transform(this);
+    }
+
+    public Receiver visit(Receiver receiver) {
+        // TODO: remove cast
+        return (Receiver) receiver.accept(this);
+    }
+
+    @Override
+    public Node visit(InstanceReceiver receiver) {
+        return receiver.transform(this);
+    }
+
+    @Override
+    public Node visit(StaticReceiver receiver) {
+        return receiver.transform(this);
+    }
+
+    public VariableDeclaration transform(VariableDeclaration declaration) {
+        return VariableDeclaration.var(declaration.getId(), declaration.getName(), transform(declaration.getType()));
+    }
+
+    public StatementNode visit(StatementNode statement) {
+        return statement.accept((StatementNodeMapper<StatementNode>)this);
+    }
+
+    @Override
+    public StatementNode visit(ReturnNode returnNode) {
+        return returnNode.transform(this);
+    }
+
+    @Override
+    public StatementNode visit(ExpressionStatementNode expressionStatement) {
+        return expressionStatement.transform(this);
+    }
+
+    @Override
+    public StatementNode visit(LocalVariableDeclarationNode localVariableDeclaration) {
+        return localVariableDeclaration.transform(this);
+    }
+
+    @Override
+    public StatementNode visit(IfStatementNode ifStatement) {
+        return ifStatement.transform(this);
+    }
+
+    @Override
+    public StatementNode visit(WhileNode whileLoop) {
+        return whileLoop.transform(this);
+    }
+
+    @Override
+    public FormalArgumentNode visit(FormalArgumentNode formalArgumentNode) {
+        return formalArgumentNode.transform(this);
+    }
+
+    @Override
+    public AnnotationNode visit(AnnotationNode annotation) {
+        return annotation.transform(this);
+    }
+
+    @Override
+    public MethodNode visit(MethodNode method) {
+        return method.transform(this);
+    }
+
+    @Override
+    public ConstructorNode visit(ConstructorNode constructor) {
+        return constructor.transform(this);
+    }
+
+    @Override
+    public FieldDeclarationNode visit(FieldDeclarationNode field) {
+        return field.transform(this);
+    }
+
+    @Override
+    public ClassNode visit(ClassNode classNode) {
+        return classNode.transform(this);
+    }
+
+    public List<AnnotationNode> transformAnnotations(List<AnnotationNode> annotations) {
+        return transformList(annotations, this::visit);
+    }
+
+    public Set<TypeName> transformTypes(Set<TypeName> superTypes) {
+        return transformSet(superTypes, this::transform);
+    }
+
+    public List<FieldDeclarationNode> transformFields(List<FieldDeclarationNode> fields) {
+        return transformList(fields, this::visit);
+    }
+
+    public List<MethodNode> transformMethods(List<MethodNode> methods) {
+        return transformList(methods, this::visit);
+    }
+
+    public List<StatementNode> transformStatements(List<StatementNode> body) {
+        return transformList(body, this::visit);
+    }
+
+    public List<ExpressionNode> transformExpressions(List<? extends ExpressionNode> expressions) {
+        return transformList(expressions, this::visit);
+    }
+
+    public List<FormalArgumentNode> transformFormalArguments(List<FormalArgumentNode> arguments) {
+        return transformList(arguments, this::visit);
+    }
+
+    private <T> Set<T> transformSet(Set<T> values, Function<T, T> function) {
+        return ImmutableSet.copyOf(Iterables.transform(values, function));
+    }
+
+    private <T> List<T> transformList(List<? extends T> values, Function<T, T> function) {
+        return ImmutableList.copyOf(Iterables.transform(values, function));
+    }
+}
diff --git a/src/main/java/org/zwobble/couscous/backends/csharp/CsharpCodeGenerator.java b/src/main/java/org/zwobble/couscous/backends/csharp/CsharpCodeGenerator.java
new file mode 100644
index 0000000..9e48e9a
--- /dev/null
+++ b/src/main/java/org/zwobble/couscous/backends/csharp/CsharpCodeGenerator.java
@@ -0,0 +1,68 @@
+package org.zwobble.couscous.backends.csharp;
+
+import com.google.common.collect.ImmutableMap;
+import org.zwobble.couscous.ast.*;
+import org.zwobble.couscous.ast.visitors.NodeTransformer;
+import org.zwobble.couscous.values.*;
+
+import java.util.Map;
+import java.util.Optional;
+
+public class CsharpCodeGenerator extends NodeTransformer {
+    private final static Map<TypeName, TypeName> PRIMITIVES = ImmutableMap.<TypeName, TypeName>builder()
+        .put(IntegerValue.REF, TypeName.of("int"))
+        .put(StringValue.REF, TypeName.of("string"))
+        .put(BooleanValue.REF, TypeName.of("bool"))
+        .put(ObjectValues.OBJECT, TypeName.of("object"))
+        .put(ObjectValues.CLASS, TypeName.of("System.Type"))
+        .put(UnitValue.REF, TypeName.of("void"))
+        .build();
+
+    private final String namespace;
+
+    public static Node generateCode(Node node, String namespace) {
+        return new CsharpCodeGenerator(namespace).generateCode(node);
+    }
+
+    private CsharpCodeGenerator(String namespace) {
+        this.namespace = namespace;
+    }
+
+    private Node generateCode(Node node) {
+        return node.accept(this);
+    }
+
+    @Override
+    public TypeName transform(TypeName type) {
+        if (PRIMITIVES.containsKey(type)) {
+            return PRIMITIVES.get(type);
+        } else {
+            return addPrefix(type, namespace);
+        }
+    }
+
+    @Override
+    public ExpressionNode visit(MethodCallNode call) {
+        return toPrimitiveMethod(call).orElseGet(() -> super.visit(call));
+    }
+
+    private Optional<ExpressionNode> toPrimitiveMethod(MethodCallNode call) {
+        return call.getReceiver().accept(new Receiver.Mapper<Optional<ExpressionNode>>() {
+            @Override
+            public Optional<ExpressionNode> visit(ExpressionNode receiver) {
+                return Optional.empty();
+            }
+
+            @Override
+            public Optional<ExpressionNode> visit(TypeName receiver) {
+                return CsharpPrimitiveMethods.getPrimitiveStaticMethod(receiver, call.getMethodName())
+                    .map(generator -> generator.generate(call.getArguments()));
+            }
+        });
+
+    }
+
+    private TypeName addPrefix(TypeName name, String namespace) {
+        return TypeName.of(namespace + "." + name.getQualifiedName());
+    }
+}
diff --git a/src/main/java/org/zwobble/couscous/backends/csharp/CsharpPrimitiveMethods.java b/src/main/java/org/zwobble/couscous/backends/csharp/CsharpPrimitiveMethods.java
index b53560d..9424b2d 100644
--- a/src/main/java/org/zwobble/couscous/backends/csharp/CsharpPrimitiveMethods.java
+++ b/src/main/java/org/zwobble/couscous/backends/csharp/CsharpPrimitiveMethods.java
@@ -3,25 +3,24 @@ package org.zwobble.couscous.backends.csharp;
 import com.google.common.collect.ImmutableMap;
 import org.zwobble.couscous.ast.ExpressionNode;
 import org.zwobble.couscous.ast.TypeName;
-import org.zwobble.couscous.backends.SourceCodeWriter;
 import org.zwobble.couscous.values.ObjectValues;
 
 import java.util.List;
 import java.util.Map;
 import java.util.Optional;
 
+import static org.zwobble.couscous.ast.MethodCallNode.staticMethodCall;
+import static org.zwobble.couscous.util.ExtraLists.list;
+
 public class CsharpPrimitiveMethods {
     private static final Map<String, PrimitiveStaticMethodGenerator> STATIC_INT_METHODS =
         ImmutableMap.<String, PrimitiveStaticMethodGenerator>builder()
 
-            .put("parseInt", (arguments, writer) -> {
-                writer.writeIdentifier("int");
-                writer.writeSymbol(".");
-                writer.writeIdentifier("Parse");
-                writer.writeSymbol("(");
-                writer.writeIdentifier(CsharpSerializer.serialize(arguments.get(0), ""));
-                writer.writeSymbol(")");
-            })
+            .put("parseInt", arguments -> staticMethodCall(
+                TypeName.of("int"),
+                "Parse",
+                list(arguments.get(0)),
+                TypeName.of("int")))
 
             .build();
 
@@ -37,6 +36,6 @@ public class CsharpPrimitiveMethods {
 
     @FunctionalInterface
     public interface PrimitiveStaticMethodGenerator {
-        void generate(List<ExpressionNode> arguments, SourceCodeWriter writer);
+        ExpressionNode generate(List<ExpressionNode> arguments);
     }
 }
diff --git a/src/main/java/org/zwobble/couscous/backends/csharp/CsharpSerializer.java b/src/main/java/org/zwobble/couscous/backends/csharp/CsharpSerializer.java
index 275ae13..ffd2f02 100644
--- a/src/main/java/org/zwobble/couscous/backends/csharp/CsharpSerializer.java
+++ b/src/main/java/org/zwobble/couscous/backends/csharp/CsharpSerializer.java
@@ -1,24 +1,13 @@
 package org.zwobble.couscous.backends.csharp;
 
-import com.google.common.collect.ImmutableMap;
 import org.zwobble.couscous.ast.*;
 import org.zwobble.couscous.ast.visitors.NodeVisitor;
 import org.zwobble.couscous.backends.SourceCodeWriter;
-import org.zwobble.couscous.values.*;
+import org.zwobble.couscous.values.PrimitiveValueVisitor;
 
 import java.util.List;
-import java.util.Map;
 
 public class CsharpSerializer implements NodeVisitor {
-    private final static Map<TypeName, String> PRIMITIVES = ImmutableMap.<TypeName, String>builder()
-        .put(IntegerValue.REF, "int")
-        .put(StringValue.REF, "string")
-        .put(BooleanValue.REF, "bool")
-        .put(ObjectValues.OBJECT, "object")
-        .put(ObjectValues.CLASS, "System.Type")
-        .put(UnitValue.REF, "void")
-        .build();
-
     public static String serialize(Node node, String namespace) {
         SourceCodeWriter writer = new SourceCodeWriter(
             (writer2) -> {
@@ -29,17 +18,16 @@ public class CsharpSerializer implements NodeVisitor {
                 writer2.writeStatement(() -> writer2.writeSymbol("}"));
             }
         );
-        CsharpSerializer serializer = new CsharpSerializer(writer, namespace);
-        serializer.write(node);
+        CsharpSerializer serializer = new CsharpSerializer(writer);
+
+        serializer.write(CsharpCodeGenerator.generateCode(node, namespace));
         return writer.asString();
     }
 
     private final SourceCodeWriter writer;
-    private final String namespace;
 
-    private CsharpSerializer(SourceCodeWriter writer, String namespace) {
+    private CsharpSerializer(SourceCodeWriter writer) {
         this.writer = writer;
-        this.namespace = namespace;
     }
 
     private void write(Node node) {
@@ -117,32 +105,10 @@ public class CsharpSerializer implements NodeVisitor {
 
     @Override
     public void visit(MethodCallNode methodCall) {
-        if (!writePrimitiveMethod(methodCall)) {
-            write(methodCall.getReceiver());
-            writer.writeSymbol(".");
-            writer.writeIdentifier(methodCall.getMethodName());
-            writeArguments(methodCall.getArguments());
-        }
-    }
-
-    private boolean writePrimitiveMethod(MethodCallNode methodCall) {
-        return methodCall.getReceiver().accept(new Receiver.Mapper<Boolean>() {
-            @Override
-            public Boolean visit(ExpressionNode receiver) {
-                return false;
-            }
-
-            @Override
-            public Boolean visit(TypeName receiver) {
-                // TODO: transform AST before serialisation instead of exposing write to CsharpPrimitiveMethods
-                return CsharpPrimitiveMethods.getPrimitiveStaticMethod(receiver, methodCall.getMethodName())
-                    .map(generator -> {
-                        generator.generate(methodCall.getArguments(), writer);
-                        return true;
-                    })
-                    .orElse(false);
-            }
-        });
+        write(methodCall.getReceiver());
+        writer.writeSymbol(".");
+        writer.writeIdentifier(methodCall.getMethodName());
+        writeArguments(methodCall.getArguments());
     }
 
     @Override
@@ -278,13 +244,9 @@ public class CsharpSerializer implements NodeVisitor {
 
     @Override
     public void visit(ClassNode classNode) {
-        String namespace = this.namespace +
-            classNode.getName().getPackage()
-                .map(packageName -> "." + packageName)
-                .orElse("");
         writer.writeKeyword("namespace");
         writer.writeSpace();
-        writer.writeIdentifier(namespace);
+        writer.writeIdentifier(classNode.getName().getPackage().get());
         writer.startBlock();
         writer.writeStatement(() -> {
             writer.writeKeyword("internal");
@@ -323,15 +285,10 @@ public class CsharpSerializer implements NodeVisitor {
     }
 
     private void writeTypeReference(TypeName value) {
-        // TODO: process the nodes before serialization
-        if (PRIMITIVES.containsKey(value)) {
-            writer.writeIdentifier(PRIMITIVES.get(value));
-        } else {
-            writer.writeIdentifier(typeReference(value));
-        }
+        writer.writeIdentifier(typeReference(value));
     }
 
     private String typeReference(TypeName value) {
-        return namespace + "." + value.getQualifiedName();
+        return value.getQualifiedName();
     }
 }