Add hacktastic type parameter capturing

4 files changed, 67 insertions, 8 deletions

diff --git a/src/main/java/org/zwobble/couscous/frontends/java/FreeVariables.java b/src/main/java/org/zwobble/couscous/frontends/java/FreeVariables.java
index 00184b1..9e507dc 100644
--- a/src/main/java/org/zwobble/couscous/frontends/java/FreeVariables.java
+++ b/src/main/java/org/zwobble/couscous/frontends/java/FreeVariables.java
@@ -1,7 +1,10 @@
 package org.zwobble.couscous.frontends.java;
 
 import org.zwobble.couscous.ast.*;
+import org.zwobble.couscous.ast.visitors.NodeTransformer;
+import org.zwobble.couscous.types.*;
 
+import java.util.HashSet;
 import java.util.List;
 import java.util.Set;
 import java.util.stream.Collectors;
@@ -12,6 +15,41 @@ import static org.zwobble.couscous.util.Casts.tryCast;
 import static org.zwobble.couscous.util.ExtraStreams.toStream;
 
 public class FreeVariables {
+    public static Set<TypeParameter> findFreeTypeParameters(Node node) {
+        // TODO: this assumes that *all* type parameters are free, which is often but not always true in inner types
+        Set<TypeParameter> freeTypeParameters = new HashSet<>();
+
+        NodeTransformer.builder().transformType(type -> {
+            type.accept(new Type.Visitor<Void>() {
+                @Override
+                public Void visit(ScalarType type) {
+                    return null;
+                }
+
+                @Override
+                public Void visit(TypeParameter parameter) {
+                    freeTypeParameters.add(parameter);
+                    return null;
+                }
+
+                @Override
+                public Void visit(ParameterizedType type) {
+                    type.getParameters().forEach(parameter -> parameter.accept(this));
+                    return null;
+                }
+
+                @Override
+                public Void visit(BoundTypeParameter type) {
+                    type.getValue().accept(this);
+                    return null;
+                }
+            });
+            return type;
+        }).build().transform(node);
+
+        return freeTypeParameters;
+    }
+
     public static List<ReferenceNode> findFreeVariables(List<? extends Node> body) {
         Set<VariableDeclaration> declarations = body.stream()
             .flatMap(FreeVariables::findDeclarations)
diff --git a/src/main/java/org/zwobble/couscous/frontends/java/GeneratedClosure.java b/src/main/java/org/zwobble/couscous/frontends/java/GeneratedClosure.java
index b7059e2..9bad1d2 100644
--- a/src/main/java/org/zwobble/couscous/frontends/java/GeneratedClosure.java
+++ b/src/main/java/org/zwobble/couscous/frontends/java/GeneratedClosure.java
@@ -1,23 +1,28 @@
 package org.zwobble.couscous.frontends.java;
 
+import com.google.common.collect.ImmutableList;
 import org.zwobble.couscous.ast.ClassNode;
 import org.zwobble.couscous.ast.ConstructorCallNode;
 import org.zwobble.couscous.ast.ExpressionNode;
 import org.zwobble.couscous.ast.ReferenceNode;
 import org.zwobble.couscous.types.ScalarType;
+import org.zwobble.couscous.types.TypeParameter;
 import org.zwobble.couscous.util.InsertionOrderSet;
 
 import static org.zwobble.couscous.ast.ConstructorCallNode.constructorCall;
+import static org.zwobble.couscous.types.Types.addTypeParameters;
 import static org.zwobble.couscous.util.ExtraLists.concat;
 import static org.zwobble.couscous.util.ExtraLists.list;
 
 public class GeneratedClosure {
     private final ClassNode classNode;
-    private final InsertionOrderSet<ReferenceNode> captures;
+    private final InsertionOrderSet<TypeParameter> capturedTypes;
+    private final InsertionOrderSet<ReferenceNode> capturedVariables;
 
-    public GeneratedClosure(ClassNode classNode, InsertionOrderSet<ReferenceNode> captures) {
+    public GeneratedClosure(ClassNode classNode, InsertionOrderSet<TypeParameter> capturedTypes, InsertionOrderSet<ReferenceNode> capturedVariables) {
         this.classNode = classNode;
-        this.captures = captures;
+        this.capturedTypes = capturedTypes;
+        this.capturedVariables = capturedVariables;
     }
 
     public ClassNode getClassNode() {
@@ -30,8 +35,9 @@ public class GeneratedClosure {
 
     public ConstructorCallNode generateConstructor(Iterable<ExpressionNode> arguments) {
         return constructorCall(
-            getType(),
-            concat(captures, arguments));
+            // TODO: tidy up type parameters to avoid copy
+            addTypeParameters(getType(), ImmutableList.copyOf(capturedTypes.asList())),
+            concat(capturedVariables, arguments));
     }
 
     private ScalarType getType() {
diff --git a/src/main/java/org/zwobble/couscous/frontends/java/JavaReader.java b/src/main/java/org/zwobble/couscous/frontends/java/JavaReader.java
index 8353dac..e096429 100644
--- a/src/main/java/org/zwobble/couscous/frontends/java/JavaReader.java
+++ b/src/main/java/org/zwobble/couscous/frontends/java/JavaReader.java
@@ -11,7 +11,7 @@ import org.zwobble.couscous.ast.sugar.AnonymousClass;
 import org.zwobble.couscous.ast.sugar.Lambda;
 import org.zwobble.couscous.ast.sugar.TypeDeclarationBody;
 import org.zwobble.couscous.ast.visitors.NodeTransformer;
-import org.zwobble.couscous.types.ScalarType;
+import org.zwobble.couscous.types.*;
 import org.zwobble.couscous.types.Type;
 import org.zwobble.couscous.util.ExtraLists;
 import org.zwobble.couscous.util.InsertionOrderSet;
@@ -40,6 +40,7 @@ import static org.zwobble.couscous.ast.ReturnNode.returns;
 import static org.zwobble.couscous.ast.StaticReceiver.staticReceiver;
 import static org.zwobble.couscous.ast.ThisReferenceNode.thisReference;
 import static org.zwobble.couscous.ast.VariableReferenceNode.reference;
+import static org.zwobble.couscous.frontends.java.FreeVariables.findFreeTypeParameters;
 import static org.zwobble.couscous.frontends.java.FreeVariables.findFreeVariables;
 import static org.zwobble.couscous.frontends.java.JavaMethods.signature;
 import static org.zwobble.couscous.frontends.java.JavaTypes.*;
@@ -257,6 +258,9 @@ public class JavaReader {
         Scope scope,
         ClassNode classNode
     ) {
+        InsertionOrderSet<org.zwobble.couscous.types.TypeParameter> freeTypeParameters = InsertionOrderSet.copyOf(
+            findFreeTypeParameters(classNode));
+
         InsertionOrderSet<ReferenceNode> freeVariables = InsertionOrderSet.copyOf(Iterables.filter(
             findFreeVariables(ExtraLists.concat(
                 classNode.getFields(),
@@ -278,14 +282,15 @@ public class JavaReader {
 
         ClassNode generatedClass = new ClassNode(
             classNode.getName(),
-            classNode.getTypeParameters(),
+            // TODO: generate fresh type parameter and replace in body
+            ExtraLists.concat(lazyMap(freeTypeParameters, parameter -> formalTypeParameter(parameter)), classNode.getTypeParameters()),
             classNode.getSuperTypes(),
             fields,
             list(),
             buildConstructor(scope, classNode.getName(), capturedVariables, classNode.getConstructor()),
             eagerMap(classNode.getMethods(), method ->
                 method.mapBody(body -> replaceCaptureReferences(classNode.getName(), body, capturedVariables))));
-        return new GeneratedClosure(generatedClass, freeVariables);
+        return new GeneratedClosure(generatedClass, freeTypeParameters, freeVariables);
     }
 
     private boolean isThisReference(ScalarType name, ReferenceNode reference) {
diff --git a/src/main/java/org/zwobble/couscous/types/Types.java b/src/main/java/org/zwobble/couscous/types/Types.java
index 505d9a7..5338eb3 100644
--- a/src/main/java/org/zwobble/couscous/types/Types.java
+++ b/src/main/java/org/zwobble/couscous/types/Types.java
@@ -1,7 +1,9 @@
 package org.zwobble.couscous.types;
 
+import java.util.List;
 import java.util.Map;
 
+import static org.zwobble.couscous.types.ParameterizedType.parameterizedType;
 import static org.zwobble.couscous.util.ExtraLists.eagerMap;
 import static org.zwobble.couscous.util.ExtraLists.list;
 
@@ -16,6 +18,14 @@ public class Types {
     public static final ScalarType BOXED_BOOLEAN = ScalarType.of("java.lang.Boolean");
     public static final ScalarType ARRAY = ScalarType.of("array");
 
+    public static Type addTypeParameters(ScalarType rawType, List<Type> typeParameters) {
+        if (typeParameters.isEmpty()) {
+            return rawType;
+        } else {
+            return parameterizedType(rawType, typeParameters);
+        }
+    }
+
     public static Type array(Type elementType) {
         return new ParameterizedType(ARRAY, list(elementType));
     }