From 6c7a6c5219be516dd1a0369dc1a0e39e4c2600f1 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Cl=C3=A9ment=20Renault?= <renault.cle@gmail.com>
Date: Mon, 3 Dec 2018 16:18:01 +0100
Subject: [PATCH] feat: Implement DoubleEnded/ExactSizeIterator on DocumentIter

---
 src/database/database_view.rs | 23 ++++++++++++++++++++++-
 1 file changed, 22 insertions(+), 1 deletion(-)

diff --git a/src/database/database_view.rs b/src/database/database_view.rs
index 08d19b624..b72a24bbb 100644
--- a/src/database/database_view.rs
+++ b/src/database/database_view.rs
@@ -60,7 +60,7 @@ impl<'a> DatabaseView<'a> {
     }
 }
 
-// TODO impl ExactSizeIterator, DoubleEndedIterator
+// TODO this is just an iter::Map !!!
 pub struct DocumentIter<'a, D, I> {
     database_view: &'a DatabaseView<'a>,
     document_ids: I,
@@ -73,6 +73,10 @@ where D: DeserializeOwned,
 {
     type Item = Result<D, Box<Error>>;
 
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        self.document_ids.size_hint()
+    }
+
     fn next(&mut self) -> Option<Self::Item> {
         match self.document_ids.next() {
             Some(id) => Some(self.database_view.retrieve_document(id)),
@@ -80,3 +84,20 @@ where D: DeserializeOwned,
         }
     }
 }
+
+impl<'a, D, I> ExactSizeIterator for DocumentIter<'a, D, I>
+where D: DeserializeOwned,
+      I: ExactSizeIterator + Iterator<Item=DocumentId>,
+{ }
+
+impl<'a, D, I> DoubleEndedIterator for DocumentIter<'a, D, I>
+where D: DeserializeOwned,
+      I: DoubleEndedIterator + Iterator<Item=DocumentId>,
+{
+    fn next_back(&mut self) -> Option<Self::Item> {
+        match self.document_ids.next_back() {
+            Some(id) => Some(self.database_view.retrieve_document(id)),
+            None => None
+        }
+    }
+}