thiserror_impl/
generics.rs

1use proc_macro2::TokenStream;
2use quote::ToTokens;
3use std::collections::btree_map::Entry;
4use std::collections::{BTreeMap as Map, BTreeSet as Set};
5use syn::punctuated::Punctuated;
6use syn::{parse_quote, GenericArgument, Generics, Ident, PathArguments, Token, Type, WhereClause};
7
8pub struct ParamsInScope<'a> {
9    names: Set<&'a Ident>,
10}
11
12impl<'a> ParamsInScope<'a> {
13    pub fn new(generics: &'a Generics) -> Self {
14        ParamsInScope {
15            names: generics.type_params().map(|param| &param.ident).collect(),
16        }
17    }
18
19    pub fn intersects(&self, ty: &Type) -> bool {
20        let mut found = false;
21        crawl(self, ty, &mut found);
22        found
23    }
24}
25
26fn crawl(in_scope: &ParamsInScope, ty: &Type, found: &mut bool) {
27    if let Type::Path(ty) = ty {
28        if let Some(qself) = &ty.qself {
29            crawl(in_scope, &qself.ty, found);
30        } else {
31            let front = ty.path.segments.first().unwrap();
32            if front.arguments.is_none() && in_scope.names.contains(&front.ident) {
33                *found = true;
34            }
35        }
36        for segment in &ty.path.segments {
37            if let PathArguments::AngleBracketed(arguments) = &segment.arguments {
38                for arg in &arguments.args {
39                    if let GenericArgument::Type(ty) = arg {
40                        crawl(in_scope, ty, found);
41                    }
42                }
43            }
44        }
45    }
46}
47
48pub struct InferredBounds {
49    bounds: Map<String, (Set<String>, Punctuated<TokenStream, Token![+]>)>,
50    order: Vec<TokenStream>,
51}
52
53impl InferredBounds {
54    pub fn new() -> Self {
55        InferredBounds {
56            bounds: Map::new(),
57            order: Vec::new(),
58        }
59    }
60
61    pub fn insert(&mut self, ty: impl ToTokens, bound: impl ToTokens) {
62        let ty = ty.to_token_stream();
63        let bound = bound.to_token_stream();
64        let entry = self.bounds.entry(ty.to_string());
65        if let Entry::Vacant(_) = entry {
66            self.order.push(ty);
67        }
68        let (set, tokens) = entry.or_default();
69        if set.insert(bound.to_string()) {
70            tokens.push(bound);
71        }
72    }
73
74    pub fn augment_where_clause(&self, generics: &Generics) -> WhereClause {
75        let mut generics = generics.clone();
76        let where_clause = generics.make_where_clause();
77        for ty in &self.order {
78            let (_set, bounds) = &self.bounds[&ty.to_string()];
79            where_clause.predicates.push(parse_quote!(#ty: #bounds));
80        }
81        generics.where_clause.unwrap()
82    }
83}
thiserror_impl/generics.rs

thiserror_impl/
generics.rs
