Only allow declared fields to be set

6 files changed, 53 insertions, 2 deletions

diff --git a/src/main/java/org/zwobble/couscous/ast/ClassNode.java b/src/main/java/org/zwobble/couscous/ast/ClassNode.java
index 674e347..d0598d8 100644
--- a/src/main/java/org/zwobble/couscous/ast/ClassNode.java
+++ b/src/main/java/org/zwobble/couscous/ast/ClassNode.java
@@ -13,6 +13,7 @@ public class ClassNode implements Node {
     }
     
     TypeName name;
+    List<FieldDeclarationNode> fields;
     ConstructorNode constructor;
     List<MethodNode> methods;
     
diff --git a/src/main/java/org/zwobble/couscous/ast/ClassNodeBuilder.java b/src/main/java/org/zwobble/couscous/ast/ClassNodeBuilder.java
index 2a0d967..b4ddad9 100644
--- a/src/main/java/org/zwobble/couscous/ast/ClassNodeBuilder.java
+++ b/src/main/java/org/zwobble/couscous/ast/ClassNodeBuilder.java
@@ -65,6 +65,7 @@ public class ClassNodeBuilder {
     public ClassNode build() {
         return new ClassNode(
             name,
+            fields.build(),
             constructor.orElse(constructorBuilder().build()),
             methods.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 6d0f3e5..93dd651 100644
--- a/src/main/java/org/zwobble/couscous/interpreter/values/ConcreteType.java
+++ b/src/main/java/org/zwobble/couscous/interpreter/values/ConcreteType.java
@@ -9,10 +9,10 @@ import java.util.stream.Collectors;
 import org.zwobble.couscous.ast.ClassNode;
 import org.zwobble.couscous.ast.FormalArgumentNode;
 import org.zwobble.couscous.ast.TypeName;
-import org.zwobble.couscous.interpreter.PositionalArguments;
 import org.zwobble.couscous.interpreter.Environment;
 import org.zwobble.couscous.interpreter.Executor;
 import org.zwobble.couscous.interpreter.NoSuchMethod;
+import org.zwobble.couscous.interpreter.PositionalArguments;
 import org.zwobble.couscous.interpreter.UnexpectedValueType;
 import org.zwobble.couscous.interpreter.WrongNumberOfArguments;
 import org.zwobble.couscous.util.Casts;
@@ -62,6 +62,7 @@ public class ConcreteType {
         public ConcreteType build() {
             return new ConcreteType(
                 name,
+                ImmutableMap.of(),
                 new MethodValue(
                     ImmutableList.of(),
                     (environment, arguments) -> InterpreterValues.UNIT),
@@ -71,6 +72,11 @@ public class ConcreteType {
     }
     
     public static ConcreteType fromNode(ClassNode classNode) {
+        val fields = classNode.getFields().stream()
+            .collect(toMap(
+                field -> field.getName(),
+                field -> new FieldValue(field.getName(), field.getType())));
+        
         val constructor = new MethodValue(
             getArgumentTypes(classNode.getConstructor().getArguments()),
             (environment, arguments) -> Executor.callMethod(
@@ -113,6 +119,7 @@ public class ConcreteType {
                 }));
         return new ConcreteType(
             classNode.getName(),
+            fields,
             constructor,
             methods,
             staticMethods);
@@ -126,16 +133,19 @@ public class ConcreteType {
     }
 
     private final TypeName name;
+    private final Map<String, FieldValue> fields;
     private final MethodValue constructor;
     private final Map<String, MethodValue> methods;
     private final Map<String, StaticMethodValue> staticMethods;
 
     public ConcreteType(
             TypeName name,
+            Map<String, FieldValue> fields,
             MethodValue constructor,
             Map<String, MethodValue> methods,
             Map<String, StaticMethodValue> staticMethods) {
         this.name = name;
+        this.fields = fields;
         this.constructor = constructor;
         this.methods = methods;
         this.staticMethods = staticMethods;
@@ -144,6 +154,10 @@ public class ConcreteType {
     public TypeName getName() {
         return name;
     }
+    
+    public Optional<FieldValue> getField(String fieldName) {
+        return Optional.ofNullable(fields.get(fieldName));
+    }
 
     public static <T> ConcreteType.Builder<T> builder(Class<T> interpreterValueType, TypeName reference) {
         return new Builder<>(interpreterValueType, reference);
diff --git a/src/main/java/org/zwobble/couscous/interpreter/values/FieldValue.java b/src/main/java/org/zwobble/couscous/interpreter/values/FieldValue.java
new file mode 100644
index 0000000..d778144
--- /dev/null
+++ b/src/main/java/org/zwobble/couscous/interpreter/values/FieldValue.java
@@ -0,0 +1,11 @@
+package org.zwobble.couscous.interpreter.values;
+
+import org.zwobble.couscous.ast.TypeName;
+
+import lombok.Value;
+
+@Value
+public class FieldValue {
+    String name;
+    TypeName type;
+}
diff --git a/src/main/java/org/zwobble/couscous/interpreter/values/ObjectInterpreterValue.java b/src/main/java/org/zwobble/couscous/interpreter/values/ObjectInterpreterValue.java
index acb6ef7..7ff8bb1 100644
--- a/src/main/java/org/zwobble/couscous/interpreter/values/ObjectInterpreterValue.java
+++ b/src/main/java/org/zwobble/couscous/interpreter/values/ObjectInterpreterValue.java
@@ -4,6 +4,7 @@ import java.util.HashMap;
 import java.util.Map;
 import java.util.Optional;
 
+import org.zwobble.couscous.interpreter.NoSuchField;
 import org.zwobble.couscous.values.PrimitiveValue;
 
 public class ObjectInterpreterValue implements InterpreterValue {
@@ -35,6 +36,7 @@ public class ObjectInterpreterValue implements InterpreterValue {
     }
 
     public void setField(String fieldName, InterpreterValue value) {
-        fields.put(fieldName, value);
+        type.getField(fieldName).orElseThrow(() -> new NoSuchField(fieldName));
+        fields.put(fieldName, value);   
     }
 }
diff --git a/src/test/java/org/zwobble/couscous/tests/interpreter/EvaluatorTests.java b/src/test/java/org/zwobble/couscous/tests/interpreter/EvaluatorTests.java
index 2cec753..7c5594a 100644
--- a/src/test/java/org/zwobble/couscous/tests/interpreter/EvaluatorTests.java
+++ b/src/test/java/org/zwobble/couscous/tests/interpreter/EvaluatorTests.java
@@ -11,6 +11,7 @@ import org.zwobble.couscous.ast.ExpressionNode;
 import org.zwobble.couscous.ast.TernaryConditionalNode;
 import org.zwobble.couscous.interpreter.ConditionMustBeBoolean;
 import org.zwobble.couscous.interpreter.Environment;
+import org.zwobble.couscous.interpreter.NoSuchField;
 import org.zwobble.couscous.interpreter.NoSuchMethod;
 import org.zwobble.couscous.interpreter.StackFrameBuilder;
 import org.zwobble.couscous.interpreter.UnexpectedValueType;
@@ -27,7 +28,9 @@ import com.google.common.collect.ImmutableMap;
 import static java.util.Arrays.asList;
 import static org.junit.Assert.assertEquals;
 import static org.zwobble.couscous.ast.AssignmentNode.assign;
+import static org.zwobble.couscous.ast.AssignmentNode.assignStatement;
 import static org.zwobble.couscous.ast.ConstructorCallNode.constructorCall;
+import static org.zwobble.couscous.ast.FieldAccessNode.fieldAccess;
 import static org.zwobble.couscous.ast.FormalArgumentNode.formalArg;
 import static org.zwobble.couscous.ast.LiteralNode.literal;
 import static org.zwobble.couscous.ast.MethodCallNode.methodCall;
@@ -112,6 +115,25 @@ public class EvaluatorTests extends BackendEvalTests {
         assertEquals(new UnexpectedValueType(IntegerValue.REF, StringValue.REF), exception);
     }
     
+    @Test
+    public void cannotSetValueOfUndeclaredField() {
+        val classNode = ClassNode.builder("com.example.Example")
+            .constructor(constructor -> constructor
+                .statement(assignStatement(
+                    fieldAccess(constructor.thisReference(), "value", IntegerValue.REF),
+                    literal(42))))
+            .build();
+        
+        val exception = assertThrows(NoSuchField.class,
+            () -> evalExpression(
+                asList(classNode),
+                constructorCall(
+                    classNode.getName(),
+                    asList())));
+        
+        assertEquals(new NoSuchField("value"), exception);
+    }
+    
     private static Environment emptyEnvironment() {
         return new Environment(
             JavaProject.builder().build(),