From 800bd3a11c45ef62726b1c29c2c165e2dbf85ae2 Mon Sep 17 00:00:00 2001
From: Shivani Bhardwaj <shivanib134@gmail.com>
Date: Tue, 3 Sep 2019 15:42:54 +0530
Subject: [PATCH] data_structures: Add deterministic FxHashMap and FxHashSet
 wrappers

StableMap
A wrapper for FxHashMap that allows to insert, remove, get and get_mut
but no iteration support.

StableSet
A wrapper for FxHashSet that allows to insert, remove, get and create a
sorted vector from a hashset but no iteration support.
---
 src/librustc_data_structures/lib.rs        |  2 +
 src/librustc_data_structures/stable_map.rs | 99 ++++++++++++++++++++++
 src/librustc_data_structures/stable_set.rs | 77 +++++++++++++++++
 3 files changed, 178 insertions(+)
 create mode 100644 src/librustc_data_structures/stable_map.rs
 create mode 100644 src/librustc_data_structures/stable_set.rs

diff --git a/src/librustc_data_structures/lib.rs b/src/librustc_data_structures/lib.rs
index f7593501959c7..d6e9c479c9b8d 100644
--- a/src/librustc_data_structures/lib.rs
+++ b/src/librustc_data_structures/lib.rs
@@ -73,6 +73,7 @@ pub mod box_region;
 pub mod const_cstr;
 pub mod flock;
 pub mod fx;
+pub mod stable_map;
 pub mod graph;
 pub mod indexed_vec;
 pub mod jobserver;
@@ -84,6 +85,7 @@ pub mod small_c_str;
 pub mod snapshot_map;
 pub use ena::snapshot_vec;
 pub mod sorted_map;
+pub mod stable_set;
 #[macro_use] pub mod stable_hasher;
 pub mod sync;
 pub mod sharded;
diff --git a/src/librustc_data_structures/stable_map.rs b/src/librustc_data_structures/stable_map.rs
new file mode 100644
index 0000000000000..f69f28e14b2a1
--- /dev/null
+++ b/src/librustc_data_structures/stable_map.rs
@@ -0,0 +1,99 @@
+pub use rustc_hash::FxHashMap;
+use std::borrow::Borrow;
+use std::collections::hash_map::Entry;
+use std::fmt;
+use std::hash::Hash;
+
+/// A deterministic wrapper around FxHashMap that does not provide iteration support.
+///
+/// It supports insert, remove, get and get_mut functions from FxHashMap.
+/// It also allows to convert hashmap to a sorted vector with the method `into_sorted_vector()`.
+#[derive(Clone)]
+pub struct StableMap<K, V> {
+    base: FxHashMap<K, V>,
+}
+
+impl<K, V> Default for StableMap<K, V>
+where
+    K: Eq + Hash,
+{
+    fn default() -> StableMap<K, V> {
+        StableMap::new()
+    }
+}
+
+impl<K, V> fmt::Debug for StableMap<K, V>
+where
+    K: Eq + Hash + fmt::Debug,
+    V: fmt::Debug,
+{
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "{:?}", self.base)
+    }
+}
+
+impl<K, V> PartialEq for StableMap<K, V>
+where
+    K: Eq + Hash,
+    V: PartialEq,
+{
+    fn eq(&self, other: &StableMap<K, V>) -> bool {
+        self.base == other.base
+    }
+}
+
+impl<K, V> Eq for StableMap<K, V>
+where
+    K: Eq + Hash,
+    V: Eq,
+{}
+
+impl<K, V> StableMap<K, V>
+where
+    K: Eq + Hash,
+{
+    pub fn new() -> StableMap<K, V> {
+        StableMap { base: FxHashMap::default() }
+    }
+
+    pub fn into_sorted_vector(self) -> Vec<(K, V)>
+    where
+        K: Ord + Copy,
+    {
+        let mut vector = self.base.into_iter().collect::<Vec<_>>();
+        vector.sort_unstable_by_key(|pair| pair.0);
+        vector
+    }
+
+    pub fn entry(&mut self, k: K) -> Entry<'_, K, V> {
+        self.base.entry(k)
+    }
+
+    pub fn get<Q: ?Sized>(&self, k: &Q) -> Option<&V>
+    where
+        K: Borrow<Q>,
+        Q: Hash + Eq,
+    {
+        self.base.get(k)
+    }
+
+    pub fn get_mut<Q: ?Sized>(&mut self, k: &Q) -> Option<&mut V>
+    where
+        K: Borrow<Q>,
+        Q: Hash + Eq,
+    {
+        self.base.get_mut(k)
+    }
+
+    pub fn insert(&mut self, k: K, v: V) -> Option<V> {
+        self.base.insert(k, v)
+    }
+
+    pub fn remove<Q: ?Sized>(&mut self, k: &Q) -> Option<V>
+    where
+        K: Borrow<Q>,
+        Q: Hash + Eq,
+    {
+        self.base.remove(k)
+    }
+}
diff --git a/src/librustc_data_structures/stable_set.rs b/src/librustc_data_structures/stable_set.rs
new file mode 100644
index 0000000000000..c7ca74f5fbd9d
--- /dev/null
+++ b/src/librustc_data_structures/stable_set.rs
@@ -0,0 +1,77 @@
+pub use rustc_hash::FxHashSet;
+use std::borrow::Borrow;
+use std::fmt;
+use std::hash::Hash;
+
+/// A deterministic wrapper around FxHashSet that does not provide iteration support.
+///
+/// It supports insert, remove, get functions from FxHashSet.
+/// It also allows to convert hashset to a sorted vector with the method `into_sorted_vector()`.
+#[derive(Clone)]
+pub struct StableSet<T> {
+    base: FxHashSet<T>,
+}
+
+impl<T> Default for StableSet<T>
+where
+    T: Eq + Hash,
+{
+    fn default() -> StableSet<T> {
+        StableSet::new()
+    }
+}
+
+impl<T> fmt::Debug for StableSet<T>
+where
+    T: Eq + Hash + fmt::Debug,
+{
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "{:?}", self.base)
+    }
+}
+
+impl<T> PartialEq<StableSet<T>> for StableSet<T>
+where
+    T: Eq + Hash,
+{
+    fn eq(&self, other: &StableSet<T>) -> bool {
+        self.base == other.base
+    }
+}
+
+impl<T> Eq for StableSet<T> where T: Eq + Hash {}
+
+impl<T: Hash + Eq> StableSet<T> {
+    pub fn new() -> StableSet<T> {
+        StableSet { base: FxHashSet::default() }
+    }
+
+    pub fn into_sorted_vector(self) -> Vec<T>
+    where
+        T: Ord,
+    {
+        let mut vector = self.base.into_iter().collect::<Vec<_>>();
+        vector.sort_unstable();
+        vector
+    }
+
+    pub fn get<Q: ?Sized>(&self, value: &Q) -> Option<&T>
+    where
+        T: Borrow<Q>,
+        Q: Hash + Eq,
+    {
+        self.base.get(value)
+    }
+
+    pub fn insert(&mut self, value: T) -> bool {
+        self.base.insert(value)
+    }
+
+    pub fn remove<Q: ?Sized>(&mut self, value: &Q) -> bool
+    where
+        T: Borrow<Q>,
+        Q: Hash + Eq,
+    {
+        self.base.remove(value)
+    }
+}