Provide a StorageVec datastructure (#1995)

Provide a vector like data structure, built on top of Mapping.

This allows to retrieve elements from the vector and grow the vector without loading and pushing all elements.

Author: xermicus

.config/cargo_spellcheck.dic

@@ -121,3 +121,10 @@ payability
 unpayable
 initializer
 WebSocket/S
+StorageVec
+KiB
+GB
+BufferTooSmall
+KeyNotFound
+ink_env
+^

CHANGELOG.md

@@ -15,6 +15,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Linter: `no_main` lint - [#2001](https://github.com/paritytech/ink/pull/2001)
 - Clean E2E configuration parsing - [#1922](https://github.com/paritytech/ink/pull/1922)
 - Make `set_code_hash` generic - [#1906](https://github.com/paritytech/ink/pull/1906)
+- Provide a `StorageVec` datastructure built on top of `Lazy` - [#1995](https://github.com/paritytech/ink/pull/1955)
 
 ### Changed
 - Messages return `TypeSpec` directly - #[1999](https://github.com/paritytech/ink/pull/1999)

crates/ink/src/lib.rs

@@ -57,6 +57,7 @@ pub mod storage {
     pub use ink_storage::{
         Lazy,
         Mapping,
+        StorageVec,
     };
 }
 

crates/storage/src/lazy/mod.rs

@@ -19,9 +19,11 @@
 //! extra care has to be taken when operating directly on them.
 
 mod mapping;
+mod vec;
 
 #[doc(inline)]
 pub use self::mapping::Mapping;
+pub use self::vec::StorageVec;
 
 use crate::traits::{
     AutoKey,
@@ -159,15 +161,15 @@ where
         let key_size = <Key as Storable>::encoded_size(&KeyType::KEY);
 
         if key_size >= ink_env::BUFFER_SIZE {
-            return Some(Err(ink_env::Error::BufferTooSmall))
+            return Some(Err(ink_env::Error::BufferTooSmall));
         }
 
         let value_size: usize = ink_env::contains_contract_storage(&KeyType::KEY)?
             .try_into()
             .expect("targets of less than 32bit pointer size are not supported; qed");
 
         if key_size.saturating_add(value_size) > ink_env::BUFFER_SIZE {
-            return Some(Err(ink_env::Error::BufferTooSmall))
+            return Some(Err(ink_env::Error::BufferTooSmall));
         }
 
         self.get().map(Ok)
@@ -191,7 +193,7 @@ where
         let value_size = <V as Storable>::encoded_size(value);
 
         if key_size.saturating_add(value_size) > ink_env::BUFFER_SIZE {
-            return Err(ink_env::Error::BufferTooSmall)
+            return Err(ink_env::Error::BufferTooSmall);
         };
 
         self.set(value);