From 58146e4a227c4cc4c49669a749dc04ee54d8f009 Mon Sep 17 00:00:00 2001
From: Shaopeng Wang <spxwang@gmail.com>
Date: Sat, 16 Nov 2019 21:10:07 +1300
Subject: [PATCH] LinkedList enumerator (#27)
* LinkedList iterator.
* Update naming.
* Default impl for LinkedItem.
* LinkList: add 'take_all' enumeration.
* Reuse Enumerator for take_all and enumerate fn.
* LinkedList: update take fn impl.
---
utilities/src/linked_item.rs | 131 ++++++++++++++++++++++++++++++-----
1 file changed, 115 insertions(+), 16 deletions(-)
diff --git a/utilities/src/linked_item.rs b/utilities/src/linked_item.rs
index 348fd82..0d8bf7a 100644
--- a/utilities/src/linked_item.rs
+++ b/utilities/src/linked_item.rs
@@ -1,4 +1,5 @@
use codec::{Decode, Encode};
+use rstd::{iter, marker};
use sr_primitives::{traits::Member, RuntimeDebug};
use support::{Parameter, StorageMap};
@@ -8,9 +9,15 @@ pub struct LinkedItem<Item> {
pub next: Option<Item>,
}
+impl<Item> Default for LinkedItem<Item> {
+ fn default() -> Self {
+ LinkedItem { prev: None, next: None }
+ }
+}
+
pub struct LinkedList<Storage, Key, Item>(rstd::marker::PhantomData<(Storage, Key, Item)>);
-impl<Storage, Key, Value> LinkedList<Storage, Key, Value>
+impl<'a, Storage, Key, Value> LinkedList<Storage, Key, Value>
where
Value: Parameter + Member + Copy,
Key: Parameter,
@@ -20,12 +27,18 @@ where
Self::read(key, None)
}
- fn write_head(account: &Key, item: LinkedItem<Value>) {
- Self::write(account, None, item);
+ fn write_head(key: &Key, item: LinkedItem<Value>) {
+ Self::write(key, None, item);
}
fn read(key: &Key, value: Option<Value>) -> LinkedItem<Value> {
- Storage::get(&(key.clone(), value)).unwrap_or_else(|| LinkedItem { prev: None, next: None })
+ Storage::get(&(key.clone(), value)).unwrap_or_else(|| Default::default())
+ }
+
+ fn take(key: &Key, value: Value) -> LinkedItem<Value> {
+ let item = Self::read(key, Some(value));
+ Self::remove(key, value);
+ item
}
fn write(key: &Key, value: Option<Value>, item: LinkedItem<Value>) {
@@ -74,8 +87,68 @@ where
Self::write(key, item.next, new_next);
}
}
+
+ pub fn enumerate(key: &'a Key) -> Enumerator<'a, Key, Value, Self> {
+ Enumerator::<'a, Key, Value, Self> {
+ key,
+ should_take: false,
+ linkage: Self::read_head(key),
+ _phantom: Default::default(),
+ }
+ }
+
+ pub fn take_all(key: &'a Key) -> Enumerator<'a, Key, Value, Self> {
+ Enumerator::<'a, Key, Value, Self> {
+ key,
+ should_take: true,
+ linkage: Self::read_head(key),
+ _phantom: Default::default(),
+ }
+ }
+}
+
+pub struct Enumerator<'a, Key, Value, LinkedList> {
+ key: &'a Key,
+ should_take: bool,
+ linkage: LinkedItem<Value>,
+ _phantom: marker::PhantomData<LinkedList>,
+}
+
+impl<'a, Key, Value, Storage> iter::Iterator for Enumerator<'a, Key, Value, LinkedList<Storage, Key, Value>>
+where
+ Key: Parameter,
+ Value: Parameter + Member + Copy,
+ Storage: StorageMap<(Key, Option<Value>), LinkedItem<Value>, Query = Option<LinkedItem<Value>>>,
+{
+ type Item = Value;
+
+ fn next(&mut self) -> Option<Self::Item> {
+ let next_value = self.linkage.next?;
+ if self.should_take {
+ self.linkage = <LinkedList<Storage, Key, Value>>::take(self.key, next_value);
+ } else {
+ self.linkage = <LinkedList<Storage, Key, Value>>::read(self.key, Some(next_value));
+ }
+ Some(next_value)
+ }
}
+// FIXME: error[E0366]: Implementations of Drop cannot be specialized
+// impl<'a, Key, Value, Storage> Drop for Enumerator<'a, Key, Value, LinkedList<Storage, Key, Value>>
+// where
+// Key: Parameter,
+// Value: Parameter + Member + Copy,
+// Storage: StorageMap<(Key, Option<Value>), LinkedItem<Value>, Query = Option<LinkedItem<Value>>>,
+// {
+// fn drop(&mut self) {
+// if !self.should_take {
+// return
+// }
+
+// while self.next() != None {}
+// }
+// }
+
#[cfg(test)]
mod tests {
use super::*;
@@ -152,10 +225,7 @@ mod tests {
})
);
- assert_eq!(
- TestItem::get(&(0, Some(1))),
- Some(TestLinkedItem { prev: None, next: None })
- );
+ assert_eq!(TestItem::get(&(0, Some(1))), Some(Default::default()));
TestLinkedList::append(&0, 2);
@@ -268,17 +338,11 @@ mod tests {
assert_eq!(TestItem::get(&(0, Some(2))), None);
- assert_eq!(
- TestItem::get(&(0, Some(3))),
- Some(TestLinkedItem { prev: None, next: None })
- );
+ assert_eq!(TestItem::get(&(0, Some(3))), Some(Default::default()));
TestLinkedList::remove(&0, 3);
- assert_eq!(
- TestItem::get(&(0, None)),
- Some(TestLinkedItem { prev: None, next: None })
- );
+ assert_eq!(TestItem::get(&(0, None)), Some(Default::default()));
assert_eq!(TestItem::get(&(0, Some(1))), None);
@@ -287,4 +351,39 @@ mod tests {
assert_eq!(TestItem::get(&(0, Some(2))), None);
});
}
+
+ #[test]
+ fn linked_list_can_enumerate() {
+ new_test_ext().execute_with(|| {
+ assert_eq!(TestLinkedList::enumerate(&0).collect::<Vec<_>>(), []);
+
+ TestLinkedList::append(&0, 1);
+ TestLinkedList::append(&0, 2);
+ TestLinkedList::append(&0, 3);
+
+ // iteration
+ assert_eq!(TestLinkedList::enumerate(&0).collect::<Vec<_>>(), [1, 2, 3]);
+
+ // should not take
+ assert_eq!(TestLinkedList::enumerate(&0).collect::<Vec<_>>(), [1, 2, 3]);
+ });
+ }
+
+ #[test]
+ fn linked_list_can_take_all() {
+ new_test_ext().execute_with(|| {
+ assert_eq!(TestLinkedList::take_all(&0).collect::<Vec<_>>(), []);
+
+ TestLinkedList::append(&0, 1);
+ TestLinkedList::append(&0, 2);
+ TestLinkedList::append(&0, 3);
+
+ assert_eq!(TestLinkedList::take_all(&0).collect::<Vec<_>>(), [1, 2, 3]);
+
+ assert_eq!(TestItem::get(&(0, Some(1))), None);
+ assert_eq!(TestItem::get(&(0, Some(2))), None);
+ assert_eq!(TestItem::get(&(0, Some(3))), None);
+ assert_eq!(TestLinkedList::enumerate(&0).collect::<Vec<_>>(), []);
+ });
+ }
}
--
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