Change method bodies to be optional

8 files changed, 48 insertions, 23 deletions

diff --git a/src/main/java/org/zwobble/couscous/ast/CallableNode.java b/src/main/java/org/zwobble/couscous/ast/CallableNode.java
deleted file mode 100644
index 6d6fc7b..0000000
--- a/src/main/java/org/zwobble/couscous/ast/CallableNode.java
+++ /dev/null
@@ -1,8 +0,0 @@
-package org.zwobble.couscous.ast;
-
-import java.util.List;
-
-public interface CallableNode extends Node {
-    List<FormalArgumentNode> getArguments();
-    List<StatementNode> getBody();
-}
diff --git a/src/main/java/org/zwobble/couscous/ast/ConstructorNode.java b/src/main/java/org/zwobble/couscous/ast/ConstructorNode.java
index fab931b..a25a993 100644
--- a/src/main/java/org/zwobble/couscous/ast/ConstructorNode.java
+++ b/src/main/java/org/zwobble/couscous/ast/ConstructorNode.java
@@ -6,7 +6,7 @@ import org.zwobble.couscous.ast.visitors.NodeTransformer;
 import java.util.Collections;
 import java.util.List;
 
-public class ConstructorNode implements CallableNode {
+public class ConstructorNode implements Node {
     public static final ConstructorNode DEFAULT = constructor(Collections.emptyList(), Collections.emptyList());
 
     public static ConstructorNode constructor(
diff --git a/src/main/java/org/zwobble/couscous/ast/MethodNode.java b/src/main/java/org/zwobble/couscous/ast/MethodNode.java
index 967b2b1..c201047 100644
--- a/src/main/java/org/zwobble/couscous/ast/MethodNode.java
+++ b/src/main/java/org/zwobble/couscous/ast/MethodNode.java
@@ -11,7 +11,7 @@ import java.util.function.Function;
 
 import static org.zwobble.couscous.util.ExtraLists.eagerMap;
 
-public class MethodNode implements CallableNode {
+public class MethodNode implements Node {
     public static Builder staticMethod(String name) {
         return builder(name).isStatic(true);
     }
@@ -140,8 +140,8 @@ public class MethodNode implements CallableNode {
         return returnType;
     }
     
-    public List<StatementNode> getBody() {
-        return body.get();
+    public Optional<List<StatementNode>> getBody() {
+        return body;
     }
 
     public MethodSignature signature() {
diff --git a/src/main/java/org/zwobble/couscous/ast/structure/NodeStructure.java b/src/main/java/org/zwobble/couscous/ast/structure/NodeStructure.java
index 2424bbe..f1f37a6 100644
--- a/src/main/java/org/zwobble/couscous/ast/structure/NodeStructure.java
+++ b/src/main/java/org/zwobble/couscous/ast/structure/NodeStructure.java
@@ -3,6 +3,7 @@ package org.zwobble.couscous.ast.structure;
 import org.zwobble.couscous.ast.*;
 import org.zwobble.couscous.ast.visitors.NodeMapper;
 
+import java.util.Collection;
 import java.util.function.Predicate;
 import java.util.stream.Stream;
 
@@ -158,7 +159,7 @@ public class NodeStructure {
                 return concatStreams(
                     methodNode.getAnnotations().stream(),
                     methodNode.getArguments().stream(),
-                    methodNode.getBody().stream());
+                    methodNode.getBody().map(Collection::stream).orElse(Stream.empty()));
             }
 
             @Override
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 37147ed..3cfcd33 100644
--- a/src/main/java/org/zwobble/couscous/backends/csharp/CsharpSerializer.java
+++ b/src/main/java/org/zwobble/couscous/backends/csharp/CsharpSerializer.java
@@ -265,7 +265,7 @@ public class CsharpSerializer implements NodeVisitor {
             writer.writeSpace();
             writer.writeIdentifier(method.getName());
             writeFormalArguments(method.getArguments());
-            writeBlock(method.getBody());
+            writeBlock(method.getBody().get());
         });
     }
 
diff --git a/src/main/java/org/zwobble/couscous/backends/python/PythonCodeGenerator.java b/src/main/java/org/zwobble/couscous/backends/python/PythonCodeGenerator.java
index 2aafcca..08ecba4 100644
--- a/src/main/java/org/zwobble/couscous/backends/python/PythonCodeGenerator.java
+++ b/src/main/java/org/zwobble/couscous/backends/python/PythonCodeGenerator.java
@@ -166,7 +166,7 @@ public class PythonCodeGenerator {
         Iterable<String> argumentNames = Iterables.concat(
             method.isStatic() ? Collections.<String>emptyList() : list("self"),
             explicitArgumentNames);
-        List<PythonStatementNode> pythonBody = generateStatements(method.getBody());
+        List<PythonStatementNode> pythonBody = generateStatements(method.getBody().get());
         return pythonFunctionDefinition(Names.toUniqueName(method.signature()), ImmutableList.copyOf(argumentNames), new PythonBlock(pythonBody));
     }
 
diff --git a/src/main/java/org/zwobble/couscous/interpreter/Executor.java b/src/main/java/org/zwobble/couscous/interpreter/Executor.java
index 60f7d9c..8ba263c 100644
--- a/src/main/java/org/zwobble/couscous/interpreter/Executor.java
+++ b/src/main/java/org/zwobble/couscous/interpreter/Executor.java
@@ -15,18 +15,50 @@ import static org.zwobble.couscous.interpreter.Evaluator.eval;
 import static org.zwobble.couscous.interpreter.Evaluator.evalCondition;
 
 public class Executor implements StatementNodeMapper<Optional<InterpreterValue>> {
-    public static InterpreterValue callMethod(Environment environment, CallableNode method, Optional<InterpreterValue> thisValue, PositionalArguments arguments) {
-        Environment innerEnvironment = buildEnvironment(environment, method, thisValue, arguments);
-        return exec(innerEnvironment, method.getBody())
+    public static InterpreterValue callMethod(
+        Environment environment,
+        MethodNode method,
+        Optional<InterpreterValue> thisValue,
+        PositionalArguments actualArguments)
+    {
+        List<StatementNode> body = method.getBody().orElseThrow(() -> new RuntimeException("Cannot call abstract method"));
+        return callMethod(environment, method.getArguments(), body, thisValue, actualArguments);
+    }
+
+    public static InterpreterValue callConstructor(
+        Environment environment,
+        ConstructorNode constructor,
+        Optional<InterpreterValue> thisValue,
+        PositionalArguments actualArguments)
+    {
+        return callMethod(environment, constructor.getArguments(), constructor.getBody(), thisValue, actualArguments);
+    }
+
+    private static InterpreterValue callMethod(
+        Environment environment,
+        List<FormalArgumentNode> formalArguments,
+        List<StatementNode> statements,
+        Optional<InterpreterValue> thisValue,
+        PositionalArguments actualArguments)
+    {
+        Environment innerEnvironment = buildEnvironment(environment, formalArguments, statements, thisValue, actualArguments);
+        return exec(innerEnvironment, statements)
             .orElse(UnitInterpreterValue.UNIT);
     }
 
-    private static Environment buildEnvironment(final Environment environment, final CallableNode method, Optional<InterpreterValue> thisValue, PositionalArguments arguments) {
+    private static Environment buildEnvironment(
+        Environment environment,
+        List<FormalArgumentNode> formalArguments,
+        List<StatementNode> statements,
+        Optional<InterpreterValue> thisValue,
+        PositionalArguments arguments)
+    {
+        // TODO use map with multiple iterables
         final org.zwobble.couscous.interpreter.StackFrameBuilder stackFrame = new StackFrameBuilder();
-        for (int index = 0; index < method.getArguments().size(); index++) {
-            stackFrame.declare(method.getArguments().get(index), arguments.get(index));
+        for (int index = 0; index < formalArguments.size(); index++) {
+            stackFrame.declare(formalArguments.get(index), arguments.get(index));
         }
-        findDeclarations(method.getBody()).forEach(declaration -> stackFrame.declare(declaration));
+        findDeclarations(statements).forEach(declaration -> stackFrame.declare(declaration));
         return environment.withStackFrame(thisValue, stackFrame.build());
     }
 
diff --git a/src/main/java/org/zwobble/couscous/interpreter/values/ConcreteType.java b/src/main/java/org/zwobble/couscous/interpreter/values/ConcreteType.java
index 98036f1..19a6039 100644
--- a/src/main/java/org/zwobble/couscous/interpreter/values/ConcreteType.java
+++ b/src/main/java/org/zwobble/couscous/interpreter/values/ConcreteType.java
@@ -99,7 +99,7 @@ public class ConcreteType {
                 field -> field));
         MethodValue constructor = new MethodValue(
             getArgumentTypes(classNode.getConstructor().getArguments()),
-            (environment, arguments) -> Executor.callMethod(
+            (environment, arguments) -> Executor.callConstructor(
                 environment,
                 classNode.getConstructor(),
                 Optional.of(arguments.getReceiver()),