Merge pull request RustPython#1970 from youknowone/sub-1962

non-subprocess stuff from RustPython#1962

Author: youknowone

vm/Cargo.toml

@@ -122,7 +122,7 @@ schannel = "0.1"
 
 [target.'cfg(windows)'.dependencies.winapi]
 version = "0.3"
-features = ["winsock2", "handleapi", "ws2def", "std", "winbase", "wincrypt", "fileapi"]
+features = ["winsock2", "handleapi", "ws2def", "std", "winbase", "wincrypt", "fileapi", "wincon"]
 
 [target.'cfg(target_arch = "wasm32")'.dependencies]
 wasm-bindgen = "0.2"

vm/src/function.rs

@@ -274,6 +274,11 @@ impl<T> From<HashMap<String, T>> for KwArgs<T> {
         KwArgs(map)
     }
 }
+impl<T> Default for KwArgs<T> {
+    fn default() -> Self {
+        KwArgs(HashMap::new())
+    }
+}
 
 impl<T> FromArgs for KwArgs<T>
 where

vm/src/obj/objdict.rs

@@ -10,7 +10,7 @@ use crate::exceptions::PyBaseExceptionRef;
 use crate::function::{KwArgs, OptionalArg, PyFuncArgs};
 use crate::pyobject::{
     IdProtocol, IntoPyObject, ItemProtocol, PyAttributes, PyClassImpl, PyContext, PyIterable,
-    PyObjectRef, PyRef, PyResult, PyValue,
+    PyObjectRef, PyRef, PyResult, PyValue, TryFromObject,
 };
 use crate::vm::{ReprGuard, VirtualMachine};
 
@@ -39,6 +39,7 @@ impl PyValue for PyDict {
 }
 
 // Python dict methods:
+#[allow(clippy::len_without_is_empty)]
 #[pyimpl(flags(BASETYPE))]
 impl PyDictRef {
     #[pyslot]
@@ -179,7 +180,7 @@ impl PyDictRef {
     }
 
     #[pymethod(magic)]
-    fn len(self) -> usize {
+    pub fn len(self) -> usize {
         self.entries.len()
     }
 
@@ -531,6 +532,11 @@ impl Iterator for DictIter {
             None => None,
         }
     }
+
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        let l = self.dict.entries.len_from_entry_index(self.position);
+        (l, Some(l))
+    }
 }
 
 macro_rules! dict_iterator {
@@ -675,3 +681,26 @@ pub(crate) fn init(context: &PyContext) {
     PyDictItems::extend_class(context, &context.types.dictitems_type);
     PyDictItemIterator::extend_class(context, &context.types.dictitemiterator_type);
 }
+
+pub struct PyMapping {
+    dict: PyDictRef,
+}
+
+impl TryFromObject for PyMapping {
+    fn try_from_object(vm: &VirtualMachine, obj: PyObjectRef) -> PyResult<Self> {
+        let dict = vm.ctx.new_dict();
+        PyDictRef::merge(
+            &dict.entries,
+            OptionalArg::Present(obj),
+            KwArgs::default(),
+            vm,
+        )?;
+        Ok(PyMapping { dict })
+    }
+}
+
+impl PyMapping {
+    pub fn into_dict(self) -> PyDictRef {
+        self.dict
+    }
+}

vm/src/pyobject.rs

@@ -980,9 +980,12 @@ impl<T> PyIterable<T> {
             },
         )?;
 
+        let lenhint = objiter::length_hint(vm, iter_obj.clone())?;
+
         Ok(PyIterator {
             vm,
             obj: iter_obj,
+            lenhint,
             _item: std::marker::PhantomData,
         })
     }
@@ -991,6 +994,7 @@ impl<T> PyIterable<T> {
 pub struct PyIterator<'a, T> {
     vm: &'a VirtualMachine,
     obj: PyObjectRef,
+    lenhint: Option<usize>,
     _item: std::marker::PhantomData<T>,
 }
 
@@ -1012,6 +1016,10 @@ where
             }
         }
     }
+
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        (self.lenhint.unwrap_or(0), self.lenhint)
+    }
 }
 
 impl<T> TryFromObject for PyIterable<T>