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use crate::prelude::*;
#[cfg(feature = "indexmap_1")]
use indexmap_1::IndexMap;
pub trait DuplicateInsertsFirstWinsMap<K, V> {
fn new(size_hint: Option<usize>) -> Self;
/// Insert the value into the map, if there is not already an existing value
fn insert(&mut self, key: K, value: V);
}
#[cfg(feature = "std")]
impl<K, V, S> DuplicateInsertsFirstWinsMap<K, V> for HashMap<K, V, S>
where
K: Eq + Hash,
S: BuildHasher + Default,
{
#[inline]
fn new(size_hint: Option<usize>) -> Self {
match size_hint {
Some(size) => Self::with_capacity_and_hasher(size, S::default()),
None => Self::with_hasher(S::default()),
}
}
#[inline]
fn insert(&mut self, key: K, value: V) {
use std::collections::hash_map::Entry;
match self.entry(key) {
// we want to keep the first value, so do nothing
Entry::Occupied(_) => {}
Entry::Vacant(vacant) => {
vacant.insert(value);
}
}
}
}
#[cfg(feature = "indexmap_1")]
impl<K, V, S> DuplicateInsertsFirstWinsMap<K, V> for IndexMap<K, V, S>
where
K: Eq + Hash,
S: BuildHasher + Default,
{
#[inline]
fn new(size_hint: Option<usize>) -> Self {
match size_hint {
Some(size) => Self::with_capacity_and_hasher(size, S::default()),
None => Self::with_hasher(S::default()),
}
}
#[inline]
fn insert(&mut self, key: K, value: V) {
use indexmap_1::map::Entry;
match self.entry(key) {
// we want to keep the first value, so do nothing
Entry::Occupied(_) => {}
Entry::Vacant(vacant) => {
vacant.insert(value);
}
}
}
}
impl<K, V> DuplicateInsertsFirstWinsMap<K, V> for BTreeMap<K, V>
where
K: Ord,
{
#[inline]
fn new(_size_hint: Option<usize>) -> Self {
Self::new()
}
#[inline]
fn insert(&mut self, key: K, value: V) {
use alloc::collections::btree_map::Entry;
match self.entry(key) {
// we want to keep the first value, so do nothing
Entry::Occupied(_) => {}
Entry::Vacant(vacant) => {
vacant.insert(value);
}
}
}
}