db abstraction: make .insert() and .remove() return the old value

1 files changed, 16 insertions, 14 deletions

diff --git a/src/db/lib.rs b/src/db/lib.rs
index 4543e53c..ed1bdb75 100644
--- a/src/db/lib.rs
+++ b/src/db/lib.rs
@@ -166,15 +166,18 @@ impl Tree {
 			.transpose()
 	}
 
-	/// True if item didn't exist before, false if item already existed
-	/// and was replaced.
+	/// Returns the old value if there was one
 	#[inline]
-	pub fn insert<T: AsRef<[u8]>, U: AsRef<[u8]>>(&self, key: T, value: U) -> Result<bool> {
+	pub fn insert<T: AsRef<[u8]>, U: AsRef<[u8]>>(
+		&self,
+		key: T,
+		value: U,
+	) -> Result<Option<Value>> {
 		self.0.insert(self.1, key.as_ref(), value.as_ref())
 	}
-	/// True if item was removed, false if item already didn't exist
+	/// Returns the old value if there was one
 	#[inline]
-	pub fn remove<T: AsRef<[u8]>>(&self, key: T) -> Result<bool> {
+	pub fn remove<T: AsRef<[u8]>>(&self, key: T) -> Result<Option<Value>> {
 		self.0.remove(self.1, key.as_ref())
 	}
 
@@ -220,20 +223,19 @@ impl<'a> Transaction<'a> {
 		self.0.len(tree.1)
 	}
 
-	/// True if item didn't exist before, false if item already existed
-	/// and was replaced.
+	/// Returns the old value if there was one
 	#[inline]
 	pub fn insert<T: AsRef<[u8]>, U: AsRef<[u8]>>(
 		&mut self,
 		tree: &Tree,
 		key: T,
 		value: U,
-	) -> Result<bool> {
+	) -> Result<Option<Value>> {
 		self.0.insert(tree.1, key.as_ref(), value.as_ref())
 	}
-	/// True if item was removed, false if item already didn't exist
+	/// Returns the old value if there was one
 	#[inline]
-	pub fn remove<T: AsRef<[u8]>>(&mut self, tree: &Tree, key: T) -> Result<bool> {
+	pub fn remove<T: AsRef<[u8]>>(&mut self, tree: &Tree, key: T) -> Result<Option<Value>> {
 		self.0.remove(tree.1, key.as_ref())
 	}
 
@@ -289,8 +291,8 @@ pub(crate) trait IDb: Send + Sync {
 	fn get(&self, tree: usize, key: &[u8]) -> Result<Option<Value>>;
 	fn len(&self, tree: usize) -> Result<usize>;
 
-	fn insert(&self, tree: usize, key: &[u8], value: &[u8]) -> Result<bool>;
-	fn remove(&self, tree: usize, key: &[u8]) -> Result<bool>;
+	fn insert(&self, tree: usize, key: &[u8], value: &[u8]) -> Result<Option<Value>>;
+	fn remove(&self, tree: usize, key: &[u8]) -> Result<Option<Value>>;
 
 	fn iter(&self, tree: usize) -> Result<ValueIter<'_>>;
 	fn iter_rev(&self, tree: usize) -> Result<ValueIter<'_>>;
@@ -315,8 +317,8 @@ pub(crate) trait ITx {
 	fn get(&self, tree: usize, key: &[u8]) -> Result<Option<Value>>;
 	fn len(&self, tree: usize) -> Result<usize>;
 
-	fn insert(&mut self, tree: usize, key: &[u8], value: &[u8]) -> Result<bool>;
-	fn remove(&mut self, tree: usize, key: &[u8]) -> Result<bool>;
+	fn insert(&mut self, tree: usize, key: &[u8], value: &[u8]) -> Result<Option<Value>>;
+	fn remove(&mut self, tree: usize, key: &[u8]) -> Result<Option<Value>>;
 
 	fn iter(&self, tree: usize) -> Result<ValueIter<'_>>;
 	fn iter_rev(&self, tree: usize) -> Result<ValueIter<'_>>;