Implement checkcast

Author: dlunch

java_runtime/src/classes/java/lang.rs

@@ -1,6 +1,7 @@
 mod arithmetic_exception;
 mod array_index_out_of_bounds_exception;
 mod class;
+mod class_cast_exception;
 mod class_loader;
 mod clone_not_supported_exception;
 mod cloneable;
@@ -33,12 +34,12 @@ mod unsupported_operation_exception;
 
 pub use self::{
     arithmetic_exception::ArithmeticException, array_index_out_of_bounds_exception::ArrayIndexOutOfBoundsException, class::Class,
-    class_loader::ClassLoader, clone_not_supported_exception::CloneNotSupportedException, cloneable::Cloneable, comparable::Comparable, error::Error,
-    exception::Exception, illegal_argument_exception::IllegalArgumentException, incompatible_class_change_error::IncompatibleClassChangeError,
-    index_out_of_bounds_exception::IndexOutOfBoundsException, instantiation_error::InstantiationError, integer::Integer,
-    interrupted_exception::InterruptedException, linkage_error::LinkageError, math::Math, no_class_def_found_error::NoClassDefFoundError,
-    no_such_field_error::NoSuchFieldError, no_such_method_error::NoSuchMethodError, null_pointer_exception::NullPointerException, object::Object,
-    runnable::Runnable, runtime::Runtime, runtime_exception::RuntimeException, security_exception::SecurityException, string::String,
-    string_buffer::StringBuffer, system::System, thread::Thread, throwable::Throwable,
+    class_cast_exception::ClassCastException, class_loader::ClassLoader, clone_not_supported_exception::CloneNotSupportedException,
+    cloneable::Cloneable, comparable::Comparable, error::Error, exception::Exception, illegal_argument_exception::IllegalArgumentException,
+    incompatible_class_change_error::IncompatibleClassChangeError, index_out_of_bounds_exception::IndexOutOfBoundsException,
+    instantiation_error::InstantiationError, integer::Integer, interrupted_exception::InterruptedException, linkage_error::LinkageError, math::Math,
+    no_class_def_found_error::NoClassDefFoundError, no_such_field_error::NoSuchFieldError, no_such_method_error::NoSuchMethodError,
+    null_pointer_exception::NullPointerException, object::Object, runnable::Runnable, runtime::Runtime, runtime_exception::RuntimeException,
+    security_exception::SecurityException, string::String, string_buffer::StringBuffer, system::System, thread::Thread, throwable::Throwable,
     unsupported_operation_exception::UnsupportedOperationException,
 };

java_runtime/src/classes/java/lang/class_cast_exception.rs

@@ -0,0 +1,43 @@
+use alloc::vec;
+
+use java_class_proto::JavaMethodProto;
+use jvm::{ClassInstanceRef, Jvm, Result};
+
+use crate::{RuntimeClassProto, RuntimeContext, classes::java::lang::String};
+
+// class java.lang.ClassCastException
+pub struct ClassCastException;
+
+impl ClassCastException {
+    pub fn as_proto() -> RuntimeClassProto {
+        RuntimeClassProto {
+            name: "java/lang/ClassCastException",
+            parent_class: Some("java/lang/Exception"),
+            interfaces: vec![],
+            methods: vec![
+                JavaMethodProto::new("<init>", "()V", Self::init, Default::default()),
+                JavaMethodProto::new("<init>", "(Ljava/lang/String;)V", Self::init_with_message, Default::default()),
+            ],
+            fields: vec![],
+            access_flags: Default::default(),
+        }
+    }
+
+    async fn init(jvm: &Jvm, _: &mut RuntimeContext, this: ClassInstanceRef<Self>) -> Result<()> {
+        tracing::debug!("java.lang.ClassCastException::<init>({:?})", &this);
+
+        let _: () = jvm.invoke_special(&this, "java/lang/Exception", "<init>", "()V", ()).await?;
+
+        Ok(())
+    }
+
+    async fn init_with_message(jvm: &Jvm, _: &mut RuntimeContext, this: ClassInstanceRef<Self>, message: ClassInstanceRef<String>) -> Result<()> {
+        tracing::debug!("java.lang.ClassCastException::<init>({:?}, {:?})", &this, &message);
+
+        let _: () = jvm
+            .invoke_special(&this, "java/lang/Exception", "<init>", "(Ljava/lang/String;)V", (message,))
+            .await?;
+
+        Ok(())
+    }
+}

java_runtime/src/loader.rs

@@ -34,6 +34,7 @@ pub fn get_runtime_class_proto(name: &str) -> Option<RuntimeClassProto> {
         crate::classes::java::io::Writer::as_proto(),
         crate::classes::java::lang::ArrayIndexOutOfBoundsException::as_proto(),
         crate::classes::java::lang::Class::as_proto(),
+        crate::classes::java::lang::ClassCastException::as_proto(),
         crate::classes::java::lang::ClassLoader::as_proto(),
         crate::classes::java::lang::Cloneable::as_proto(),
         crate::classes::java::lang::CloneNotSupportedException::as_proto(),

jvm/src/value.rs

@@ -90,6 +90,15 @@ impl From<JavaValue> for f64 {
     }
 }
 
+impl<'a> From<&'a JavaValue> for &'a Option<Box<dyn ClassInstance>> {
+    fn from(x: &'a JavaValue) -> Self {
+        match x {
+            JavaValue::Object(x) => x,
+            _ => panic!("Expected object, got {:?}", x),
+        }
+    }
+}
+
 impl From<JavaValue> for Option<Box<dyn ClassInstance>> {
     fn from(x: JavaValue) -> Self {
         match x {

jvm_rust/src/interpreter.rs

@@ -153,9 +153,11 @@ impl Interpreter {
             }
             Opcode::Bipush(x) => stack_frame.operand_stack.push(JavaValue::Int(*x as i32)),
             Opcode::Checkcast(x) => {
-                let top_stack = stack_frame.operand_stack.last().unwrap();
+                let top_stack: &Option<Box<dyn ClassInstance>> = stack_frame.operand_stack.last().unwrap().into();
 
-                tracing::warn!("Unimplemented checkcast: {:?} {:?}", top_stack, x);
+                if !top_stack.is_none() && !jvm.is_instance(&**top_stack.as_ref().unwrap(), x.as_class()) {
+                    return Err(jvm.exception("java/lang/ClassCastException", "Invalid cast").await);
+                }
             }
             Opcode::D2f => {
                 let value: f64 = stack_frame.operand_stack.pop().unwrap().into();

test_data/CheckCast.class

@@ -0,0 +1,2 @@
+Successfully cast to String
+Failed to cast to Integer

test_data/CheckCast.txt

@@ -0,0 +1,19 @@
+public class CheckCast {
+    public static void main(String[] args) {
+        Object obj = "This is a string";
+
+        try {
+            String str = (String) obj; // This should succeed
+            System.out.println("Successfully cast to String");
+        } catch (ClassCastException e) {
+            System.out.println("Failed to cast to String");
+        }
+
+        try {
+            Integer num = (Integer) obj; // This should fail
+            System.out.println("Successfully cast to Integer");
+        } catch (ClassCastException e) {
+            System.out.println("Failed to cast to Integer");
+        }
+    }
+}