refactor primops

fix-vm/src/primops/list.rs

@@ -0,0 +1,73 @@
+use fix_builtins::PrimOpPhase;
+use gc_arena::Mutation;
+
+use crate::bytecode_reader::BytecodeReader;
+use crate::value::*;
+use crate::{Step, Vm};
+
+impl<'gc> Vm<'gc> {
+    pub(crate) fn primop_filter_force_list(
+        &mut self,
+        reader: &mut BytecodeReader<'_>,
+        mc: &Mutation<'gc>,
+    ) -> Step {
+        self.force_slot(0, reader, mc)?;
+        let list = match self.peek_forced(0).expect_gc::<List>() {
+            Ok(list) => list,
+            Err(got) => return self.finish_type_err(NixType::List, got),
+        };
+        if list.inner.borrow().is_empty() {
+            let val = self.pop();
+            return self.return_from_primop(val, reader);
+        }
+        // prepare stack layout: [ pred list idx acc ]
+        self.push(Value::new_inline(0));
+        self.push(Value::new_gc(List::new_gc(mc)));
+        reader.set_pc(PrimOpPhase::FilterCallPred.ip() as usize);
+        Step::Continue(())
+    }
+
+    pub(crate) fn primop_filter_call_pred(
+        &mut self,
+        reader: &mut BytecodeReader<'_>,
+        mc: &Mutation<'gc>,
+    ) -> Step {
+        self.force_slot(3, reader, mc)?;
+        let pred = self.peek_forced(3);
+        #[allow(clippy::unwrap_used)]
+        let idx = self.peek(1).as_inline::<i32>().unwrap();
+        #[allow(clippy::unwrap_used)]
+        let elem = self.peek_forced(2).as_gc::<List>().unwrap().inner.borrow()[idx as usize];
+        self.push(pred.relax());
+        self.call(reader, mc, elem, PrimOpPhase::FilterCheck.ip() as usize)
+    }
+
+    pub(crate) fn primop_filter_check(
+        &mut self,
+        reader: &mut BytecodeReader<'_>,
+        mc: &Mutation<'gc>,
+    ) -> Step {
+        let ret = self.force_and_retry::<bool>(reader, mc)?;
+        #[allow(clippy::unwrap_used)]
+        let idx = self.peek(1).as_inline::<i32>().unwrap();
+        #[allow(clippy::unwrap_used)]
+        let list = self.peek_forced(2).as_gc::<List>().unwrap();
+        let list = list.inner.borrow();
+        #[allow(clippy::unwrap_used)]
+        let acc = self.peek_forced(0).as_gc::<List>().unwrap();
+        if ret {
+            let mut acc = acc.unlock(mc).borrow_mut();
+            acc.push(list[idx as usize]);
+        }
+        if idx as usize == list.len() - 1 {
+            let acc = self.pop();
+            let _ = self.pop(); // idx
+            let _ = self.pop(); // list
+            let _ = self.pop(); // pred
+            return self.return_from_primop(acc, reader);
+        }
+        self.replace(1, Value::new_inline(idx + 1));
+        reader.set_pc(PrimOpPhase::FilterCallPred.ip() as usize);
+        Step::Continue(())
+    }
+}