refactor: move iterator trait to parent mod

Signed-off-by: Alex Chi <iskyzh@gmail.com>

mini-lsm-starter/src/iterators/impls.rs

@@ -1,15 +0,0 @@
-use anyhow::Result;
-
-pub trait StorageIterator {
-    /// Get the current value.
-    fn value(&self) -> &[u8];
-
-    /// Get the current key.
-    fn key(&self) -> &[u8];
-
-    /// Check if the current iterator is valid.
-    fn is_valid(&self) -> bool;
-
-    /// Move to the next position.
-    fn next(&mut self) -> Result<()>;
-}

mini-lsm-starter/src/iterators/merge_iterator.rs

@@ -6,7 +6,7 @@ use std::collections::BinaryHeap;
 
 use anyhow::Result;
 
-use super::impls::StorageIterator;
+use super::StorageIterator;
 
 struct HeapWrapper<I: StorageIterator>(pub usize, pub Box<I>);
 

mini-lsm-starter/src/iterators/two_merge_iterator.rs

@@ -3,7 +3,7 @@
 
 use anyhow::Result;
 
-use super::impls::StorageIterator;
+use super::StorageIterator;
 
 /// Merges two iterators of different types into one. If the two iterators have the same key, only
 /// produce the key once and prefer the entry from A.