implement Assert

fix-vm/src/dispatch_tailcall.rs

@@ -185,7 +185,7 @@ tail_fn!(op_coerce_to_string, (reader, mc));
 tail_fn!(op_concat_strings, (ctx, reader, mc));
 tail_fn!(op_resolve_path, (ctx));
 
-tail_fn!(op_assert, (reader));
+tail_fn!(op_assert, (ctx, reader, mc));
 
 tail_fn!(op_push_with, (ctx, reader, mc));
 tail_fn!(op_pop_with, ());

fix-vm/src/instructions/control.rs

@@ -1,5 +1,8 @@
+use fix_error::Error;
+use gc_arena::Mutation;
+
 use crate::value::*;
-use crate::{BytecodeReader, Step};
+use crate::{BytecodeReader, Step, VmRuntimeCtx};
 
 impl<'gc> crate::Vm<'gc> {
     #[inline(always)]
@@ -20,7 +23,7 @@ impl<'gc> crate::Vm<'gc> {
     pub(crate) fn op_jump_if_true(
         &mut self,
         reader: &mut BytecodeReader<'_>,
-        mc: &gc_arena::Mutation<'gc>,
+        mc: &Mutation<'gc>,
     ) -> Step {
         let offset = reader.read_i32();
         let cond = self.force_and_retry::<StrictValue>(reader, mc)?;
@@ -38,9 +41,20 @@ impl<'gc> crate::Vm<'gc> {
     }
 
     #[inline(always)]
-    pub(crate) fn op_assert(&mut self, reader: &mut BytecodeReader<'_>) -> Step {
-        let _raw_idx = reader.read_u32();
+    pub(crate) fn op_assert(
+        &mut self,
+        ctx: &mut impl VmRuntimeCtx,
+        reader: &mut BytecodeReader<'_>,
+        mc: &Mutation<'gc>,
+    ) -> Step {
+        let raw_id = reader.read_string_id();
+        let raw = ctx.resolve_string(raw_id);
         let _span_id = reader.read_u32();
-        todo!("implement Assert (force TOS)");
+        let assertion = self.force_and_retry::<bool>(reader, mc)?;
+        if !assertion {
+            // FIXME: use catchable error
+            return self.finish_err(Error::eval_error(format!("assertion '{raw}' failed")));
+        }
+        Step::Continue(())
     }
 }

fix-vm/src/lib.rs

@@ -697,7 +697,7 @@ impl<'gc> Vm<'gc> {
                 CoerceToString => self.op_coerce_to_string(&mut reader, mc),
                 ResolvePath => self.op_resolve_path(ctx),
 
-                Assert => self.op_assert(&mut reader),
+                Assert => self.op_assert(ctx, &mut reader, mc),
 
                 PushWith => self.op_push_with(ctx, &mut reader, mc),
                 PopWith => self.op_pop_with(),