Add shards_mut() and into_shards() to DashMap and shards() to…

… `ReadOnlyView` (#237)

src/lib.rs

@@ -318,11 +318,51 @@ impl<'a, K: 'a + Eq + Hash, V: 'a, S: BuildHasher + Clone> DashMap<K, V, S> {
             pub fn shards(&self) -> &[RwLock<HashMap<K, V, S>>] {
                 &self.shards
             }
+
+            /// Provides mutable access to the inner shards that store your data.
+            /// You should probably not use this unless you know what you are doing.
+            ///
+            /// Requires the `raw-api` feature to be enabled.
+            ///
+            /// # Examples
+            ///
+            /// ```
+            /// use dashmap::DashMap;
+            /// use dashmap::SharedValue;
+            ///
+            /// let mut map = DashMap::<i32, &'static str>::new();
+            /// let shard_ind = map.determine_map(&42); 
+            /// map.shards_mut()[shard_ind].get_mut().insert(42, SharedValue::new("forty two"));
+            /// assert_eq!(*map.get(&42).unwrap(), "forty two");
+            /// ```
+            pub fn shards_mut(&mut self) -> &mut [RwLock<HashMap<K, V, S>>] {
+                &mut self.shards
+            }
+
+            /// Consumes this `DashMap` and returns the inner shards.
+            /// You should probably not use this unless you know what you are doing.
+            /// 
+            /// Requires the `raw-api` feature to be enabled.
+            /// 
+            /// See [`DashMap::shards()`] and [`DashMap::shards_mut()`] for more information.
+            pub fn into_shards(self) -> Box<[RwLock<HashMap<K, V, S>>]> {
+                self.shards
+            }
         } else {
             #[allow(dead_code)]
             pub(crate) fn shards(&self) -> &[RwLock<HashMap<K, V, S>>] {
                 &self.shards
             }
+
+            #[allow(dead_code)]
+            pub(crate) fn shards_mut(&mut self) -> &mut [RwLock<HashMap<K, V, S>>] {
+                &mut self.shards
+            }
+
+            #[allow(dead_code)]
+            pub(crate) fn into_shards(self) -> Box<[RwLock<HashMap<K, V, S>>]> {
+                self.shards
+            }
         }
     }
 

src/read_only.rs

@@ -1,5 +1,7 @@
+use crate::lock::RwLock;
 use crate::t::Map;
 use crate::{DashMap, HashMap};
+use cfg_if::cfg_if;
 use core::borrow::Borrow;
 use core::fmt;
 use core::hash::{BuildHasher, Hash};
@@ -121,6 +123,32 @@ impl<'a, K: 'a + Eq + Hash, V: 'a, S: BuildHasher + Clone> ReadOnlyView<K, V, S>
             .flat_map(|shard| shard.values())
             .map(|v| v.get())
     }
+
+    cfg_if! {
+        if #[cfg(feature = "raw-api")] {
+            /// Allows you to peek at the inner shards that store your data.
+            /// You should probably not use this unless you know what you are doing.
+            ///
+            /// Requires the `raw-api` feature to be enabled.
+            ///
+            /// # Examples
+            ///
+            /// ```
+            /// use dashmap::DashMap;
+            ///
+            /// let map = DashMap::<(), ()>::new().into_read_only();
+            /// println!("Amount of shards: {}", map.shards().len());
+            /// ```
+            pub fn shards(&self) -> &[RwLock<HashMap<K, V, S>>] {
+                &self.map.shards
+            }
+        } else {
+            #[allow(dead_code)]
+            pub(crate) fn shards(&self) -> &[RwLock<HashMap<K, V, S>>] {
+                &self.map.shards
+            }
+        }
+    }
 }
 
 #[cfg(test)]