Merge pull request #60 from CosmWasm/try-get

Implement {ItemAccess, ColumnAccess}::try_get

packages/storey/src/containers/column.rs

@@ -7,6 +7,7 @@ use crate::encoding::{DecodableWith, EncodableWith};
 use crate::storage::{IterableStorage, StorageBranch};
 use crate::storage::{Storage, StorageMut};
 
+use super::common::TryGetError;
 use super::{BoundFor, BoundedIterableAccessor, IterableAccessor, NonTerminal, Storable};
 
 const META_LAST_IX: &[u8] = &[0];
@@ -158,6 +159,8 @@ where
 {
     /// Get the value associated with the given key.
     ///
+    /// Returns `Ok(None)` if the entry doesn't exist (has not been set yet).
+    ///
     /// # Example
     /// ```
     /// # use mocks::encoding::TestEncoding;
@@ -179,6 +182,33 @@ where
             .transpose()
     }
 
+    /// Get the value associated with the given key.
+    ///
+    /// Returns [`TryGetError::Empty`] if the entry doesn't exist (has not been
+    /// set yet).
+    ///
+    /// This is similar to [`get`](Self::get), but removes one level of nesting
+    /// so that you can get to your data faster, without having to unpack the
+    /// [`Option`].
+    ///
+    /// # Example
+    /// ```
+    /// # use mocks::encoding::TestEncoding;
+    /// # use mocks::backend::TestStorage;
+    /// use storey::containers::Column;
+    ///
+    /// let mut storage = TestStorage::new();
+    /// let column = Column::<u64, TestEncoding>::new(0);
+    /// let mut access = column.access(&mut storage);
+    ///
+    /// access.push(&1337).unwrap();
+    /// assert_eq!(access.try_get(0).unwrap(), 1337);
+    /// assert!(access.try_get(1).is_err());
+    /// ```
+    pub fn try_get(&self, key: u32) -> Result<T, TryGetError<E::DecodeError>> {
+        self.get(key)?.ok_or(TryGetError::Empty)
+    }
+
     /// Get the length of the column. This is the number of elements actually stored,
     /// taking the possibility of removed elements into account.
     ///

packages/storey/src/containers/common.rs

@@ -0,0 +1,7 @@
+#[derive(Debug, PartialEq, Eq, Clone, Copy, thiserror::Error)]
+pub enum TryGetError<E> {
+    #[error("item is empty")]
+    Empty,
+    #[error(transparent)]
+    DecodeError(#[from] E),
+}

packages/storey/src/containers/item.rs

@@ -4,6 +4,7 @@ use crate::encoding::{DecodableWith, EncodableWith, Encoding};
 use crate::storage::StorageBranch;
 use crate::storage::{Storage, StorageMut};
 
+use super::common::TryGetError;
 use super::{Storable, Terminal};
 
 /// A single item in the storage.
@@ -117,7 +118,7 @@ where
 {
     /// Get the value of the item.
     ///
-    /// Returns `None` if the item doesn't exist (has not been set yet).
+    /// Returns `Ok(None)` if the item doesn't exist (has not been set yet).
     ///
     /// # Examples
     /// ```
@@ -149,6 +150,43 @@ where
             .map(|bytes| T::decode(&bytes))
             .transpose()
     }
+
+    /// Get the value of the item.
+    ///
+    /// Returns [`TryGetError::Empty`] if the item doesn't exist (has not been
+    /// set yet).
+    ///
+    /// This is similar to [`get`](Self::get), but removes one level of nesting
+    /// so that you can get to your data faster, without having to unpack the
+    /// [`Option`].
+    ///
+    /// # Examples
+    /// ```
+    /// # use mocks::encoding::TestEncoding;
+    /// # use mocks::backend::TestStorage;
+    /// use storey::containers::Item;
+    ///
+    /// let mut storage = TestStorage::new();
+    /// let item = Item::<u64, TestEncoding>::new(0);
+    ///
+    /// item.access(&mut storage).set(&42).unwrap();
+    /// assert_eq!(item.access(&storage).try_get().unwrap(), 42);
+    /// ```
+    ///
+    /// ```
+    /// # use mocks::encoding::TestEncoding;
+    /// # use mocks::backend::TestStorage;
+    /// use storey::containers::Item;
+    ///
+    /// let storage = TestStorage::new();
+    /// let item = Item::<u64, TestEncoding>::new(0);
+    /// let access = item.access(&storage);
+    ///
+    /// assert!(access.try_get().is_err());
+    /// ```
+    pub fn try_get(&self) -> Result<T, TryGetError<E::DecodeError>> {
+        self.get()?.ok_or_else(|| TryGetError::Empty)
+    }
 }
 
 impl<E, T, S> ItemAccess<E, T, S>

packages/storey/src/containers/mod.rs

@@ -2,6 +2,7 @@
 //! few fundamental collections/containers themselves.
 
 mod column;
+pub mod common;
 mod item;
 pub mod map;