Add typedefs for storage types (#4654)

* Add typedefs for storage types

* Fix after merge

substrate/primitives/state-machine/src/overlayed_changes.rs

@@ -33,6 +33,18 @@ use std::{mem, ops};
 
 use hash_db::Hasher;
 
+/// Storage key.
+pub type StorageKey = Vec<u8>;
+
+/// Storage value.
+pub type StorageValue = Vec<u8>;
+
+/// In memory array of storage values.
+pub type StorageCollection = Vec<(StorageKey, Option<StorageValue>)>;
+
+/// In memory arrays of storage values for multiple child tries.
+pub type ChildStorageCollection = Vec<(StorageKey, StorageCollection)>;
+
 /// The overlayed changes to state to be queried on top of the backend.
 ///
 /// A transaction shares all prospective changes within an inner overlay
@@ -52,7 +64,7 @@ pub struct OverlayedChanges {
 #[cfg_attr(test, derive(PartialEq))]
 pub struct OverlayedValue {
 	/// Current value. None if value has been deleted.
-	pub value: Option<Vec<u8>>,
+	pub value: Option<StorageValue>,
 	/// The set of extinsic indices where the values has been changed.
 	/// Is filled only if runtime has announced changes trie support.
 	pub extrinsics: Option<BTreeSet<u32>>,
@@ -63,9 +75,9 @@ pub struct OverlayedValue {
 #[cfg_attr(test, derive(PartialEq))]
 pub struct OverlayedChangeSet {
 	/// Top level storage changes.
-	pub top: BTreeMap<Vec<u8>, OverlayedValue>,
+	pub top: BTreeMap<StorageKey, OverlayedValue>,
 	/// Child storage changes.
-	pub children: HashMap<Vec<u8>, (BTreeMap<Vec<u8>, OverlayedValue>, OwnedChildInfo)>,
+	pub children: HashMap<StorageKey, (BTreeMap<StorageKey, OverlayedValue>, OwnedChildInfo)>,
 }
 
 /// A storage changes structure that can be generated by the data collected in [`OverlayedChanges`].
@@ -76,9 +88,9 @@ pub struct StorageChanges<Transaction, H: Hasher, N: BlockNumber> {
 	/// All changes to the main storage.
 	///
 	/// A value of `None` means that it was deleted.
-	pub main_storage_changes: Vec<(Vec<u8>, Option<Vec<u8>>)>,
+	pub main_storage_changes: StorageCollection,
 	/// All changes to the child storages.
-	pub child_storage_changes: Vec<(Vec<u8>, Vec<(Vec<u8>, Option<Vec<u8>>)>)>,
+	pub child_storage_changes: ChildStorageCollection,
 	/// A transaction for the backend that contains all changes from
 	/// [`main_storage_changes`](Self::main_storage_changes) and from
 	/// [`child_storage_changes`](Self::child_storage_changes).
@@ -94,8 +106,8 @@ pub struct StorageChanges<Transaction, H: Hasher, N: BlockNumber> {
 impl<Transaction, H: Hasher, N: BlockNumber> StorageChanges<Transaction, H, N> {
 	/// Deconstruct into the inner values
 	pub fn into_inner(self) -> (
-		Vec<(Vec<u8>, Option<Vec<u8>>)>,
-		Vec<(Vec<u8>, Vec<(Vec<u8>, Option<Vec<u8>>)>)>,
+		StorageCollection,
+		ChildStorageCollection,
 		Transaction,
 		H::Out,
 		Option<ChangesTrieTransaction<H, N>>,
@@ -155,8 +167,8 @@ impl<Transaction: Default, H: Hasher, N: BlockNumber> Default for StorageChanges
 }
 
 #[cfg(test)]
-impl FromIterator<(Vec<u8>, OverlayedValue)> for OverlayedChangeSet {
-	fn from_iter<T: IntoIterator<Item = (Vec<u8>, OverlayedValue)>>(iter: T) -> Self {
+impl FromIterator<(StorageKey, OverlayedValue)> for OverlayedChangeSet {
+	fn from_iter<T: IntoIterator<Item = (StorageKey, OverlayedValue)>>(iter: T) -> Self {
 		Self {
 			top: iter.into_iter().collect(),
 			children: Default::default(),
@@ -219,7 +231,7 @@ impl OverlayedChanges {
 	/// Inserts the given key-value pair into the prospective change set.
 	///
 	/// `None` can be used to delete a value specified by the given key.
-	pub(crate) fn set_storage(&mut self, key: Vec<u8>, val: Option<Vec<u8>>) {
+	pub(crate) fn set_storage(&mut self, key: StorageKey, val: Option<StorageValue>) {
 		let extrinsic_index = self.extrinsic_index();
 		let entry = self.prospective.top.entry(key).or_default();
 		entry.value = val;
@@ -235,10 +247,10 @@ impl OverlayedChanges {
 	/// `None` can be used to delete a value specified by the given key.
 	pub(crate) fn set_child_storage(
 		&mut self,
-		storage_key: Vec<u8>,
+		storage_key: StorageKey,
 		child_info: ChildInfo,
-		key: Vec<u8>,
-		val: Option<Vec<u8>>,
+		key: StorageKey,
+		val: Option<StorageValue>,
 	) {
 		let extrinsic_index = self.extrinsic_index();
 		let map_entry = self.prospective.children.entry(storage_key)
@@ -417,8 +429,8 @@ impl OverlayedChanges {
 	/// Panics:
 	/// Will panic if there are any uncommitted prospective changes.
 	pub fn into_committed(self) -> (
-		impl Iterator<Item=(Vec<u8>, Option<Vec<u8>>)>,
-		impl Iterator<Item=(Vec<u8>, (impl Iterator<Item=(Vec<u8>, Option<Vec<u8>>)>, OwnedChildInfo))>,
+		impl Iterator<Item=(StorageKey, Option<StorageValue>)>,
+		impl Iterator<Item=(StorageKey, (impl Iterator<Item=(StorageKey, Option<StorageValue>)>, OwnedChildInfo))>,
 	){
 		assert!(self.prospective.is_empty());
 		(
@@ -631,8 +643,8 @@ impl OverlayedChanges {
 }
 
 #[cfg(test)]
-impl From<Option<Vec<u8>>> for OverlayedValue {
-	fn from(value: Option<Vec<u8>>) -> OverlayedValue {
+impl From<Option<StorageValue>> for OverlayedValue {
+	fn from(value: Option<StorageValue>) -> OverlayedValue {
 		OverlayedValue { value, ..Default::default() }
 	}
 }
@@ -647,8 +659,8 @@ mod tests {
 	use crate::ext::Ext;
 	use super::*;
 
-	fn strip_extrinsic_index(map: &BTreeMap<Vec<u8>, OverlayedValue>)
-		-> BTreeMap<Vec<u8>, OverlayedValue>
+	fn strip_extrinsic_index(map: &BTreeMap<StorageKey, OverlayedValue>)
+		-> BTreeMap<StorageKey, OverlayedValue>
 	{
 		let mut clone = map.clone();
 		clone.remove(&EXTRINSIC_INDEX.to_vec());