feat: Add support for HashMap<K, V, S> (for other S)

This makes the implementations for Serialize and JsonSerialize
accept different S values instead of the default RandomState
specified by `std::collections::HashMap`.

It also adds an example with the ahash crate.

Closes #87

.github/workflows/test.yml

@@ -28,7 +28,7 @@ jobs:
           pushd merde
           EXAMPLES=($(cd examples && for i in *; do echo "${i%.rs}"; done))
           for example in "${EXAMPLES[@]}"; do
-            cargo run --features full --example "$example"
+            cargo run --features full,json --example "$example"
           done
           popd
       - name: Test zerodeps-example

Justfile

@@ -15,6 +15,6 @@ check:
     pushd merde
     EXAMPLES=($(cd examples && for i in *; do echo "${i%.rs}"; done))
     for example in "${EXAMPLES[@]}"; do
-      cargo run --features full --example "$example"
+      cargo run --features full,ahash --example "$example"
     done
     popd

merde/Cargo.toml

@@ -40,6 +40,11 @@ name = "yaml"
 path = "examples/yaml.rs"
 required-features = ["yaml"]
 
+[[example]]
+name = "ahash"
+path = "examples/ahash.rs"
+required-features = ["json", "ahash"]
+
 [dependencies]
 merde_core = { version = "6.0.2", path = "../merde_core", optional = true }
 merde_json = { version = "6.0.3", path = "../merde_json", optional = true }
@@ -48,6 +53,7 @@ merde_time = { version = "4.0.14", path = "../merde_time", optional = true, feat
     "merde",
     "deserialize",
 ] }
+ahash = { version = "0.8.11", optional = true }
 
 [features]
 default = ["core", "deserialize"]
@@ -71,3 +77,6 @@ rusqlite = ["merde_core/rusqlite"]
 json = ["dep:merde_json", "merde_time/json"]
 yaml = ["dep:merde_yaml"]
 time = ["dep:merde_time"]
+
+# others
+ahash = ["dep:ahash"]

merde/examples/ahash.rs

@@ -0,0 +1,26 @@
+#[cfg(feature = "ahash")]
+fn main() {
+    use ahash::HashMap;
+    use merde::json;
+
+    let mut h = HashMap::default();
+    h.insert("street".to_string(), "123 Main St".to_string());
+    h.insert("city".to_string(), "Anytown".to_string());
+    h.insert("state".to_string(), "CA".to_string());
+    h.insert("zip".to_string(), "12345".to_string());
+
+    println!("h: {:#?}", h);
+
+    let serialized = json::to_string(&h);
+    println!("serialized: {}", serialized);
+
+    let deserialized: HashMap<String, String> = json::from_str(&serialized).unwrap();
+    println!("deserialized: {:#?}", deserialized);
+
+    assert_eq!(h, deserialized);
+
+    assert_eq!(deserialized.get("street"), Some(&"123 Main St".to_string()));
+    assert_eq!(deserialized.get("city"), Some(&"Anytown".to_string()));
+    assert_eq!(deserialized.get("state"), Some(&"CA".to_string()));
+    assert_eq!(deserialized.get("zip"), Some(&"12345".to_string()));
+}

merde_core/src/deserialize.rs

@@ -1,6 +1,8 @@
 use std::{
     borrow::Cow,
+    collections::HashMap,
     future::Future,
+    hash::{BuildHasher, Hash},
     pin::Pin,
     task::{Context, Poll, RawWaker, RawWakerVTable, Waker},
 };
@@ -470,17 +472,18 @@ impl<'s, T: Deserialize<'s>> Deserialize<'s> for Vec<T> {
     }
 }
 
-impl<'s, K, V> Deserialize<'s> for std::collections::HashMap<K, V>
+impl<'s, K, V, S> Deserialize<'s> for HashMap<K, V, S>
 where
-    K: Deserialize<'s> + Eq + std::hash::Hash,
+    K: Deserialize<'s> + Eq + Hash,
     V: Deserialize<'s>,
+    S: Default + BuildHasher + 's,
 {
     async fn deserialize<D>(de: &mut D) -> Result<Self, D::Error<'s>>
     where
         D: Deserializer<'s> + ?Sized,
     {
         de.next()?.into_map_start()?;
-        let mut map = std::collections::HashMap::new();
+        let mut map = HashMap::<K, V, S>::default();
 
         loop {
             match de.next()? {

merde_core/src/into_static.rs

@@ -2,6 +2,7 @@ use std::borrow::Cow;
 use std::collections::HashMap;
 use std::collections::HashSet;
 use std::collections::VecDeque;
+use std::hash::BuildHasher;
 use std::hash::Hash;
 
 /// Allow turning a value into an "owned" variant, which can then be
@@ -83,13 +84,14 @@ impl<T: IntoStatic> IntoStatic for Vec<T> {
     }
 }
 
-impl<K, V> IntoStatic for HashMap<K, V>
+impl<K, V, S> IntoStatic for HashMap<K, V, S>
 where
+    S: BuildHasher + Default + 'static,
     K: IntoStatic + Eq + Hash,
     V: IntoStatic,
     K::Output: Eq + Hash,
 {
-    type Output = HashMap<K::Output, V::Output>;
+    type Output = HashMap<K::Output, V::Output, S>;
 
     fn into_static(self) -> Self::Output {
         self.into_iter()

merde_core/src/with_lifetime.rs

@@ -90,12 +90,13 @@ where
     type Lifetimed = HashSet<T::Lifetimed>;
 }
 
-impl<'s, K, V> WithLifetime<'s> for HashMap<K, V>
+impl<'s, K, V, S> WithLifetime<'s> for HashMap<K, V, S>
 where
+    S: 's,
     K: WithLifetime<'s>,
     V: WithLifetime<'s>,
 {
-    type Lifetimed = HashMap<K::Lifetimed, V::Lifetimed>;
+    type Lifetimed = HashMap<K::Lifetimed, V::Lifetimed, S>;
 }
 
 impl<'s, T1: WithLifetime<'s>> WithLifetime<'s> for (T1,) {

merde_json/src/lib.rs

@@ -349,7 +349,7 @@ impl JsonSerialize for bool {
     }
 }
 
-impl<K: AsRef<str>, V: JsonSerialize> JsonSerialize for HashMap<K, V> {
+impl<K: AsRef<str>, V: JsonSerialize, S> JsonSerialize for HashMap<K, V, S> {
     fn json_serialize(&self, serializer: &mut JsonSerializer) {
         let mut guard = serializer.write_obj();
         for (key, value) in self {