From 8d9b4dd153c6436bf0b9b8daacd799f40a0a8eed Mon Sep 17 00:00:00 2001
From: kngwyu <yuji.kngw.80s.revive@gmail.com>
Date: Mon, 18 Feb 2019 16:05:48 +0900
Subject: [PATCH] Introduce PyDictItem

---
 src/instance.rs   |  2 +-
 src/types/dict.rs | 99 ++++++++++++++++++++++++++++++++---------------
 2 files changed, 68 insertions(+), 33 deletions(-)

diff --git a/src/instance.rs b/src/instance.rs
index 44093442..83c474d7 100644
--- a/src/instance.rs
+++ b/src/instance.rs
@@ -53,7 +53,7 @@ pub trait PyNativeType: PyObjectWithGIL {}
 /// let gil = Python::acquire_gil();
 /// let py = gil.python();
 /// let obj = PyRef::new(gil.python(), Point { x: 3, y: 4 }).unwrap();
-/// let d = vec![("p", obj)].into_py_dict(py);
+/// let d = [("p", obj)].into_py_dict(py);
 /// py.run("assert p.length() == 12", None, Some(d)).unwrap();
 /// ```
 #[derive(Debug)]
diff --git a/src/types/dict.rs b/src/types/dict.rs
index a6e6a755..aa63f918 100644
--- a/src/types/dict.rs
+++ b/src/types/dict.rs
@@ -196,12 +196,7 @@ where
     H: hash::BuildHasher,
 {
     fn to_object(&self, py: Python) -> PyObject {
-        let dict = PyDict::new(py);
-        for (key, value) in self {
-            dict.set_item(key, value)
-                .expect("Failed to set_item on dict");
-        }
-        dict.into()
+        IntoPyDict::into_py_dict(self, py).into()
     }
 }
 
@@ -211,12 +206,7 @@ where
     V: ToPyObject,
 {
     fn to_object(&self, py: Python) -> PyObject {
-        let dict = PyDict::new(py);
-        for (key, value) in self {
-            dict.set_item(key, value)
-                .expect("Failed to set_item on dict");
-        }
-        dict.into()
+        IntoPyDict::into_py_dict(self, py).into()
     }
 }
 
@@ -227,27 +217,23 @@ where
     H: hash::BuildHasher,
 {
     fn into_object(self, py: Python) -> PyObject {
-        let dict = PyDict::new(py);
-        for (key, value) in self {
-            dict.set_item(key.into_object(py), value.into_object(py))
-                .expect("Failed to set_item on dict");
-        }
-        dict.into()
+        let iter = self
+            .into_iter()
+            .map(|(k, v)| (k.into_object(py), v.into_object(py)));
+        IntoPyDict::into_py_dict(iter, py).into()
     }
 }
 
 impl<K, V> IntoPyObject for collections::BTreeMap<K, V>
 where
-    K: cmp::Eq + ToPyObject,
-    V: ToPyObject,
+    K: cmp::Eq + IntoPyObject,
+    V: IntoPyObject,
 {
     fn into_object(self, py: Python) -> PyObject {
-        let dict = PyDict::new(py);
-        for (key, value) in self {
-            dict.set_item(key, value)
-                .expect("Failed to set_item on dict");
-        }
-        dict.into()
+        let iter = self
+            .into_iter()
+            .map(|(k, v)| (k.into_object(py), v.into_object(py)));
+        IntoPyDict::into_py_dict(iter, py).into()
     }
 }
 
@@ -259,22 +245,59 @@ pub trait IntoPyDict {
     fn into_py_dict(self, py: Python) -> &PyDict;
 }
 
-impl<K, V, I> IntoPyDict for I
+impl<T, I> IntoPyDict for I
 where
-    K: ToPyObject,
-    V: ToPyObject,
-    I: IntoIterator<Item = (K, V)>,
+    T: PyDictItem,
+    I: IntoIterator<Item = T>,
 {
     fn into_py_dict(self, py: Python) -> &PyDict {
         let dict = PyDict::new(py);
-        for (key, value) in self {
-            dict.set_item(key, value)
+        for item in self {
+            dict.set_item(item.key(), item.value())
                 .expect("Failed to set_item on dict");
         }
         dict
     }
 }
 
+/// Represents a tuple which can be used as a PyDict item.
+pub trait PyDictItem {
+    type K: ToPyObject;
+    type V: ToPyObject;
+    fn key(&self) -> &Self::K;
+    fn value(&self) -> &Self::V;
+}
+
+impl<K, V> PyDictItem for (K, V)
+where
+    K: ToPyObject,
+    V: ToPyObject,
+{
+    type K = K;
+    type V = V;
+    fn key(&self) -> &Self::K {
+        &self.0
+    }
+    fn value(&self) -> &Self::V {
+        &self.1
+    }
+}
+
+impl<K, V> PyDictItem for &(K, V)
+where
+    K: ToPyObject,
+    V: ToPyObject,
+{
+    type K = K;
+    type V = V;
+    fn key(&self) -> &Self::K {
+        &self.0
+    }
+    fn value(&self) -> &Self::V {
+        &self.1
+    }
+}
+
 #[cfg(test)]
 mod test {
     use crate::conversion::{IntoPyObject, PyTryFrom, ToPyObject};
@@ -637,4 +660,16 @@ mod test {
         assert_eq!(py_map.len(), 3);
         assert_eq!(py_map.get_item("b").unwrap().extract::<i32>().unwrap(), 2);
     }
+
+    #[test]
+    fn test_slice_into_dict() {
+        let gil = Python::acquire_gil();
+        let py = gil.python();
+
+        let arr = [("a", 1), ("b", 2), ("c", 3)];
+        let py_map = arr.into_py_dict(py);
+
+        assert_eq!(py_map.len(), 3);
+        assert_eq!(py_map.get_item("b").unwrap().extract::<i32>().unwrap(), 2);
+    }
 }