Merge pull request #3367 from DimitrisJim/length_hint_opt

vm.length_hint into vm.length_hint_opt

vm/src/builtins/map.rs

@@ -37,7 +37,7 @@ impl PyMap {
     #[pymethod(magic)]
     fn length_hint(&self, vm: &VirtualMachine) -> PyResult<usize> {
         self.iterators.iter().try_fold(0, |prev, cur| {
-            let cur = vm.length_hint(cur.as_ref().to_owned())?.unwrap_or(0);
+            let cur = cur.as_ref().to_owned().length_hint(0, vm)?;
             let max = std::cmp::max(prev, cur);
             Ok(max)
         })

vm/src/protocol/iter.rs

@@ -50,7 +50,7 @@ where
         &'b self,
         vm: &'a VirtualMachine,
     ) -> PyResult<PyIterIter<'a, U, &'b PyObject>> {
-        let length_hint = vm.length_hint(self.as_ref().to_owned())?;
+        let length_hint = vm.length_hint_opt(self.as_ref().to_owned())?;
         Ok(PyIterIter::new(vm, self.0.borrow(), length_hint))
     }
 
@@ -65,7 +65,7 @@ where
 impl PyIter<PyObjectRef> {
     /// Returns an iterator over this sequence of objects.
     pub fn into_iter<U>(self, vm: &VirtualMachine) -> PyResult<PyIterIter<U, PyObjectRef>> {
-        let length_hint = vm.length_hint(self.as_object().to_owned())?;
+        let length_hint = vm.length_hint_opt(self.as_object().to_owned())?;
         Ok(PyIterIter::new(vm, self.0, length_hint))
     }
 }

vm/src/protocol/object.rs

@@ -73,12 +73,8 @@ impl PyObjectRef {
         self.is_true(vm).map(|x| !x)
     }
 
-    pub fn length_hint(
-        self,
-        defaultvalue: Option<usize>,
-        vm: &VirtualMachine,
-    ) -> PyResult<Option<usize>> {
-        Ok(vm.length_hint(self)?.or(defaultvalue))
+    pub fn length_hint(self, defaultvalue: usize, vm: &VirtualMachine) -> PyResult<usize> {
+        Ok(vm.length_hint_opt(self)?.unwrap_or(defaultvalue))
     }
 
     // item protocol

vm/src/stdlib/operator.rs

@@ -282,7 +282,7 @@ mod _operator {
                 v.payload::<PyInt>().unwrap().try_to_primitive(vm)
             })
             .unwrap_or(Ok(0))?;
-        vm.length_hint(obj).map(|v| v.unwrap_or(default))
+        obj.length_hint(default, vm)
     }
 
     // Inplace Operators

vm/src/vm.rs

@@ -1201,7 +1201,7 @@ impl VirtualMachine {
         F: FnMut(PyObjectRef) -> PyResult<R>,
     {
         let iter = value.to_owned().get_iter(self)?;
-        let cap = match self.length_hint(value.to_owned()) {
+        let cap = match self.length_hint_opt(value.to_owned()) {
             Err(e) if e.class().is(&self.ctx.exceptions.runtime_error) => return Err(e),
             Ok(Some(value)) => Some(value),
             // Use a power of 2 as a default capacity.
@@ -1681,7 +1681,7 @@ impl VirtualMachine {
             })
     }
 
-    pub fn length_hint(&self, iter: PyObjectRef) -> PyResult<Option<usize>> {
+    pub fn length_hint_opt(&self, iter: PyObjectRef) -> PyResult<Option<usize>> {
         if let Some(len) = self.obj_len_opt(&iter) {
             match len {
                 Ok(len) => return Ok(Some(len)),