borsh_derive/internals/attributes/field/
bounds.rs

Help
1use std::collections::BTreeMap;
2
3use syn::{meta::ParseNestedMeta, WherePredicate};
4
5use crate::internals::attributes::{parsing::parse_lit_into_vec, Symbol, DESERIALIZE, SERIALIZE};
6use once_cell::sync::Lazy;
7
8pub enum Variants {
9    Serialize(Vec<WherePredicate>),
10    Deserialize(Vec<WherePredicate>),
11}
12
13type ParseFn = dyn Fn(Symbol, Symbol, &ParseNestedMeta) -> syn::Result<Variants> + Send + Sync;
14
15pub static BOUNDS_FIELD_PARSE_MAP: Lazy<BTreeMap<Symbol, Box<ParseFn>>> = Lazy::new(|| {
16    let mut m = BTreeMap::new();
17    // assigning closure `let f = |args| {...};` and boxing closure `let f: Box<ParseFn> = Box::new(f);`
18    // on 2 separate lines doesn't work
19    let f_serialize: Box<ParseFn> = Box::new(|attr_name, meta_item_name, meta| {
20        parse_lit_into_vec::<WherePredicate>(attr_name, meta_item_name, meta)
21            .map(Variants::Serialize)
22    });
23    let f_deserialize: Box<ParseFn> = Box::new(|attr_name, meta_item_name, meta| {
24        parse_lit_into_vec::<WherePredicate>(attr_name, meta_item_name, meta)
25            .map(Variants::Deserialize)
26    });
27    m.insert(SERIALIZE, f_serialize);
28    m.insert(DESERIALIZE, f_deserialize);
29    m
30});
31
32#[derive(Default, Clone)]
33pub struct Bounds {
34    pub serialize: Option<Vec<WherePredicate>>,
35    pub deserialize: Option<Vec<WherePredicate>>,
36}
37
38impl From<BTreeMap<Symbol, Variants>> for Bounds {
39    fn from(mut map: BTreeMap<Symbol, Variants>) -> Self {
40        let serialize = map.remove(&SERIALIZE);
41        let deserialize = map.remove(&DESERIALIZE);
42        let serialize = serialize.map(|variant| match variant {
43            Variants::Serialize(ser) => ser,
44            _ => unreachable!("only one enum variant is expected to correspond to given map key"),
45        });
46        let deserialize = deserialize.map(|variant| match variant {
47            Variants::Deserialize(de) => de,
48            _ => unreachable!("only one enum variant is expected to correspond to given map key"),
49        });
50        Self {
51            serialize,
52            deserialize,
53        }
54    }
55}
borsh_derive/internals/attributes/field/bounds.rs

borsh_derive/internals/attributes/field/
bounds.rs
