Add VecMap to rustc_data_structures

compiler/rustc_data_structures/src/vec_map.rs

@@ -0,0 +1,137 @@
+use std::borrow::Borrow;
+use std::iter::FromIterator;
+use std::slice::{Iter, IterMut};
+use std::vec::IntoIter;
+
+use crate::stable_hasher::{HashStable, StableHasher};
+
+#[derive(Clone, Encodable, Decodable, Debug)]
+pub struct VecMap<K, V>(Vec<(K, V)>);
+
+impl<K, V> VecMap<K, V>
+where
+    K: PartialEq,
+{
+    pub fn new() -> Self {
+        VecMap(Default::default())
+    }
+
+    pub fn insert(&mut self, k: K, v: V) -> Option<V> {
+        if let Some(elem) = self.0.iter_mut().find(|(key, _)| *key == k) {
+            Some(std::mem::replace(&mut elem.1, v))
+        } else {
+            self.0.push((k, v));
+            None
+        }
+    }
+
+    pub fn get<Q: ?Sized>(&self, k: &Q) -> Option<&V>
+    where
+        K: Borrow<Q>,
+        Q: Eq,
+    {
+        self.0.iter().find(|(key, _)| k == key.borrow()).map(|elem| &elem.1)
+    }
+
+    pub fn contains_key<Q: ?Sized>(&self, k: &Q) -> bool
+    where
+        K: Borrow<Q>,
+        Q: Eq,
+    {
+        self.get(k).is_some()
+    }
+
+    pub fn is_empty(&self) -> bool {
+        self.0.is_empty()
+    }
+
+    pub fn iter(&self) -> Iter<'_, (K, V)> {
+        self.into_iter()
+    }
+
+    pub fn iter_mut(&mut self) -> IterMut<'_, (K, V)> {
+        self.into_iter()
+    }
+}
+
+impl<K, V> Default for VecMap<K, V> {
+    #[inline]
+    fn default() -> Self {
+        Self(Default::default())
+    }
+}
+
+impl<K, V> From<Vec<(K, V)>> for VecMap<K, V> {
+    fn from(vec: Vec<(K, V)>) -> Self {
+        Self(vec)
+    }
+}
+
+impl<K, V> Into<Vec<(K, V)>> for VecMap<K, V> {
+    fn into(self) -> Vec<(K, V)> {
+        self.0
+    }
+}
+
+impl<K, V> FromIterator<(K, V)> for VecMap<K, V> {
+    fn from_iter<I: IntoIterator<Item = (K, V)>>(iter: I) -> Self {
+        Self(iter.into_iter().collect())
+    }
+}
+
+impl<'a, K, V> IntoIterator for &'a VecMap<K, V> {
+    type Item = &'a (K, V);
+    type IntoIter = Iter<'a, (K, V)>;
+
+    #[inline]
+    fn into_iter(self) -> Self::IntoIter {
+        self.0.iter()
+    }
+}
+
+impl<'a, K, V> IntoIterator for &'a mut VecMap<K, V> {
+    type Item = &'a mut (K, V);
+    type IntoIter = IterMut<'a, (K, V)>;
+
+    #[inline]
+    fn into_iter(self) -> Self::IntoIter {
+        self.0.iter_mut()
+    }
+}
+
+impl<K, V> IntoIterator for VecMap<K, V> {
+    type Item = (K, V);
+    type IntoIter = IntoIter<(K, V)>;
+
+    #[inline]
+    fn into_iter(self) -> Self::IntoIter {
+        self.0.into_iter()
+    }
+}
+
+impl<K, V> Extend<(K, V)> for VecMap<K, V> {
+    fn extend<I: IntoIterator<Item = (K, V)>>(&mut self, iter: I) {
+        self.0.extend(iter);
+    }
+
+    fn extend_one(&mut self, item: (K, V)) {
+        self.0.extend_one(item);
+    }
+
+    fn extend_reserve(&mut self, additional: usize) {
+        self.0.extend_reserve(additional);
+    }
+}
+
+impl<K, V, CTX> HashStable<CTX> for VecMap<K, V>
+where
+    K: HashStable<CTX> + Eq,
+    V: HashStable<CTX>,
+{
+    fn hash_stable(&self, hcx: &mut CTX, hasher: &mut StableHasher) {
+        self.0.hash_stable(hcx, hasher)
+    }
+}
+
+#[cfg(test)]
+mod tests;