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//! Implementations of `serde::Serialize` and `serde::Deserialize` for //! `BiHashMap` and `BiBTreeMap`. //! //! You do not need to import anything from this module to use this //! functionality, simply enable the `serde` feature in your dependency //! manifest. Note that currently, this requires the `std` feature to also be //! enabled, and thus cannot be used in `no_std` enviroments. //! //! # Examples //! //! You can easily serialize and deserialize bimaps with any serde-compatbile //! serializer or deserializer. //! //! Serializing and deserializing a [`BiHashMap`]: //! //! ``` //! # use bimap::BiHashMap; //! // create a new bimap //! let mut map = BiHashMap::new(); //! //! // insert some pairs //! map.insert('A', 1); //! map.insert('B', 2); //! map.insert('C', 3); //! //! // convert the bimap to json //! let json = serde_json::to_string(&map).unwrap(); //! //! // convert the json back into a bimap //! let map2 = serde_json::from_str(&json).unwrap(); //! //! // check that the two bimaps are equal //! assert_eq!(map, map2); //! ``` //! //! Serializing and deserializing a [`BiBTreeMap`]: //! ``` //! # use bimap::BiBTreeMap; //! // create a new bimap //! let mut map = BiBTreeMap::new(); //! //! // insert some pairs //! map.insert('A', 3); //! map.insert('B', 2); //! map.insert('C', 1); //! //! // convert the bimap to json //! let json = serde_json::to_string(&map).unwrap(); //! //! // convert the json back into a bimap //! let map2 = serde_json::from_str(&json).unwrap(); //! //! // check that the two bimaps are equal //! assert_eq!(map, map2); //! ``` //! //! Of course, this is only possible for bimaps where the values also implement //! `Serialize` and `Deserialize` respectively: //! //! ```compile_fail //! # use bimap::BiHashMap; //! // this type doesn't implement Serialize or Deserialize! //! #[derive(PartialEq, Eq, Hash)] //! enum MyEnum { A, B, C } //! //! // create a bimap and add some pairs //! let mut map = BiHashMap::new(); //! map.insert(MyEnum::A, 1); //! map.insert(MyEnum::B, 2); //! map.insert(MyEnum::C, 3); //! //! // this line will cause the code to fail to compile //! let json = serde_json::to_string(&map).unwrap(); //! ``` //! //! # Implementation details //! //! Bimaps are serialized and deserialized as a map data type in serde. //! Consequentially, it is possible to serialize and deserialize bimaps to/from //! other types that are represented the same way. *This is considered an //! implementation detail and should not be relied upon.* //! //! For example, a bimap can be deserialized from the serialized form of a //! standard [`HashMap`]. However, *deserializing a bimap silently overwrites //! any conflicting pairs*, leading to non-deterministic results. //! ``` //! # use std::collections::HashMap; //! # use bimap::BiHashMap; //! // construct a regular map //! let mut map = HashMap::new(); //! //! // insert some entries //! // note that both 'B' and 'C' are associated with the value 2 here //! map.insert('A', 1); //! map.insert('B', 2); //! map.insert('C', 2); //! //! // serialize the map //! let json = serde_json::to_string(&map).unwrap(); //! //! // deserialize it into a bimap //! let bimap: BiHashMap<char, i32> = serde_json::from_str(&json).unwrap(); //! //! // deserialization succeeds, but the bimap is now in a non-deterministic //! // state - either ('B', 2) or ('C', 2) will have been overwritten while //! // deserializing, but this depends on the iteration order of the original //! // HashMap that was serialized. //! //! // we can still demonstrate that certain properties of the bimap are still //! // in a known state, but this shouldn't be relied upon //! assert_eq!(bimap.len(), 2); //! assert_eq!(bimap.get_by_left(&'A'), Some(&1)); //! assert!(bimap.get_by_left(&'B') == Some(&2) || bimap.get_by_left(&'C') == Some(&2)) //! ``` //! //! The reverse is also possible: bimaps may be serialized and then //! deserialized as other compatible types, such as a [`HashMap`]. //! //! ``` //! # use std::collections::HashMap; //! # use bimap::BiHashMap; //! // construct a bimap //! let mut bimap = BiHashMap::new(); //! //! // insert some pairs //! bimap.insert('A', 1); //! bimap.insert('B', 2); //! bimap.insert('C', 3); //! //! // serialize the bimap //! let json = serde_json::to_string(&bimap).unwrap(); //! //! // deserialize it as a regular map //! let map: HashMap<char, i32> = serde_json::from_str(&json).unwrap(); //! //! // this succeeds and the result is sensible, but this is still an //! // implementation detail and shouldn't be relied upon. //! assert_eq!(map.len(), 3); //! assert_eq!(map[&'A'], 1); //! assert_eq!(map[&'B'], 2); //! assert_eq!(map[&'C'], 3); //! ``` //! [`BiHashMap`]: crate::BiHashMap //! [`BiBTreeMap`]: crate::BiBTreeMap //! [`HashMap`]: https://doc.rust-lang.org/std/collections/struct.HashMap.html use crate::{BiBTreeMap, BiHashMap}; use serde::{ de::{MapAccess, Visitor}, Deserialize, Deserializer, Serialize, Serializer, }; use std::{ default::Default, fmt::{Formatter, Result as FmtResult}, hash::{BuildHasher, Hash}, marker::PhantomData, }; /// Serializer for `BiHashMap` impl<L, R, LS, RS> Serialize for BiHashMap<L, R, LS, RS> where L: Serialize + Eq + Hash, R: Serialize + Eq + Hash, LS: BuildHasher + Default, RS: BuildHasher + Default, { fn serialize<S: Serializer>(&self, ser: S) -> Result<S::Ok, S::Error> { ser.collect_map(self.iter()) } } /// Visitor to construct `BiHashMap` from serialized map entries struct BiHashMapVisitor<L, R, LS, RS> { marker: PhantomData<BiHashMap<L, R, LS, RS>>, } impl<'de, L, R, LS, RS> Visitor<'de> for BiHashMapVisitor<L, R, LS, RS> where L: Deserialize<'de> + Eq + Hash, R: Deserialize<'de> + Eq + Hash, LS: BuildHasher + Default, RS: BuildHasher + Default, { fn expecting(&self, f: &mut Formatter) -> FmtResult { write!(f, "a map") } type Value = BiHashMap<L, R, LS, RS>; fn visit_map<A: MapAccess<'de>>(self, mut entries: A) -> Result<Self::Value, A::Error> { let mut map = match entries.size_hint() { Some(s) => BiHashMap::<L, R, LS, RS>::with_capacity_and_hashers( s, LS::default(), RS::default(), ), None => BiHashMap::<L, R, LS, RS>::with_hashers(LS::default(), RS::default()), }; while let Some((l, r)) = entries.next_entry()? { map.insert(l, r); } Ok(map) } } /// Deserializer for `BiHashMap` impl<'de, L, R, LS, RS> Deserialize<'de> for BiHashMap<L, R, LS, RS> where L: Deserialize<'de> + Eq + Hash, R: Deserialize<'de> + Eq + Hash, LS: BuildHasher + Default, RS: BuildHasher + Default, { fn deserialize<D: Deserializer<'de>>(de: D) -> Result<Self, D::Error> { de.deserialize_map(BiHashMapVisitor::<L, R, LS, RS> { marker: PhantomData::default(), }) } } /// Serializer for `BiBTreeMap` impl<L, R> Serialize for BiBTreeMap<L, R> where L: Serialize + Ord, R: Serialize + Ord, { fn serialize<S: Serializer>(&self, ser: S) -> Result<S::Ok, S::Error> { ser.collect_map(self.iter()) } } /// Visitor to construct `BiBTreeMap` from serialized map entries struct BiBTreeMapVisitor<L, R> { marker: PhantomData<BiBTreeMap<L, R>>, } impl<'de, L, R> Visitor<'de> for BiBTreeMapVisitor<L, R> where L: Deserialize<'de> + Ord, R: Deserialize<'de> + Ord, { fn expecting(&self, f: &mut Formatter) -> FmtResult { write!(f, "a map") } type Value = BiBTreeMap<L, R>; fn visit_map<A: MapAccess<'de>>(self, mut entries: A) -> Result<Self::Value, A::Error> { let mut map = BiBTreeMap::new(); while let Some((l, r)) = entries.next_entry()? { map.insert(l, r); } Ok(map) } } /// Deserializer for `BiBTreeMap` impl<'de, L, R> Deserialize<'de> for BiBTreeMap<L, R> where L: Deserialize<'de> + Ord, R: Deserialize<'de> + Ord, { fn deserialize<D: Deserializer<'de>>(de: D) -> Result<Self, D::Error> { de.deserialize_map(BiBTreeMapVisitor { marker: PhantomData::default(), }) } } #[cfg(test)] mod tests { use super::*; use serde::de::value::Error; use std::hash::BuildHasherDefault; #[test] fn serde_hash() { let mut bimap = BiHashMap::new(); bimap.insert('a', 1); bimap.insert('b', 2); bimap.insert('c', 3); let json = serde_json::to_string(&bimap).unwrap(); let bimap2 = serde_json::from_str(&json).unwrap(); assert_eq!(bimap, bimap2); } #[test] fn serde_hash_w_fnv_hasher() { let hasher_builder = BuildHasherDefault::<fnv::FnvHasher>::default(); let mut bimap = BiHashMap::< char, u8, BuildHasherDefault<fnv::FnvHasher>, BuildHasherDefault<fnv::FnvHasher>, >::with_capacity_and_hashers( 4, hasher_builder.clone(), hasher_builder.clone() ); bimap.insert('f', 1); bimap.insert('g', 2); bimap.insert('h', 3); let json = serde_json::to_string(&bimap).unwrap(); let bimap2 = serde_json::from_str(&json).unwrap(); assert_eq!(bimap, bimap2); } #[test] fn serde_hash_w_hashbrown_hasher() { let hasher_builder = hashbrown::hash_map::DefaultHashBuilder::default(); let mut bimap = BiHashMap::< char, u8, hashbrown::hash_map::DefaultHashBuilder, hashbrown::hash_map::DefaultHashBuilder, >::with_capacity_and_hashers( 4, hasher_builder.clone(), hasher_builder.clone() ); bimap.insert('x', 1); bimap.insert('y', 2); bimap.insert('z', 3); let json = serde_json::to_string(&bimap).unwrap(); let bimap2 = serde_json::from_str(&json).unwrap(); assert_eq!(bimap, bimap2); } #[test] fn serde_btree() { let mut bimap = BiBTreeMap::new(); bimap.insert('a', 1); bimap.insert('b', 2); bimap.insert('c', 3); let json = serde_json::to_string(&bimap).unwrap(); let bimap2 = serde_json::from_str(&json).unwrap(); assert_eq!(bimap, bimap2); } #[test] fn expecting_btree() { let visitor = BiBTreeMapVisitor { marker: PhantomData::<BiBTreeMap<char, i32>>, }; let error_str = format!("{:?}", visitor.visit_bool::<Error>(true)); let expected = "Err(Error(\"invalid type: boolean `true`, expected a map\"))"; assert_eq!(error_str, expected); } #[test] fn expecting_hash() { let visitor = BiHashMapVisitor { marker: PhantomData::<BiHashMap<char, i32>>, }; let error_str = format!("{:?}", visitor.visit_bool::<Error>(true)); let expected = "Err(Error(\"invalid type: boolean `true`, expected a map\"))"; assert_eq!(error_str, expected); } }