| use proc_macro2::TokenStream; |
| use quote::ToTokens; |
| use std::collections::btree_map::Entry; |
| use std::collections::{BTreeMap as Map, BTreeSet as Set}; |
| use syn::punctuated::Punctuated; |
| use syn::{parse_quote, GenericArgument, Generics, Ident, PathArguments, Token, Type, WhereClause}; |
| |
| pub struct ParamsInScope<'a> { |
| names: Set<&'a Ident>, |
| } |
| |
| impl<'a> ParamsInScope<'a> { |
| pub fn new(generics: &'a Generics) -> Self { |
| ParamsInScope { |
| names: generics.type_params().map(|param| ¶m.ident).collect(), |
| } |
| } |
| |
| pub fn intersects(&self, ty: &Type) -> bool { |
| let mut found = false; |
| crawl(self, ty, &mut found); |
| found |
| } |
| } |
| |
| fn crawl(in_scope: &ParamsInScope, ty: &Type, found: &mut bool) { |
| if let Type::Path(ty) = ty { |
| if ty.qself.is_none() { |
| if let Some(ident) = ty.path.get_ident() { |
| if in_scope.names.contains(ident) { |
| *found = true; |
| } |
| } |
| } |
| for segment in &ty.path.segments { |
| if let PathArguments::AngleBracketed(arguments) = &segment.arguments { |
| for arg in &arguments.args { |
| if let GenericArgument::Type(ty) = arg { |
| crawl(in_scope, ty, found); |
| } |
| } |
| } |
| } |
| } |
| } |
| |
| pub struct InferredBounds { |
| bounds: Map<String, (Set<String>, Punctuated<TokenStream, Token![+]>)>, |
| order: Vec<TokenStream>, |
| } |
| |
| impl InferredBounds { |
| pub fn new() -> Self { |
| InferredBounds { |
| bounds: Map::new(), |
| order: Vec::new(), |
| } |
| } |
| |
| #[allow(clippy::type_repetition_in_bounds, clippy::trait_duplication_in_bounds)] // clippy bug: https://github.com/rust-lang/rust-clippy/issues/8771 |
| pub fn insert(&mut self, ty: impl ToTokens, bound: impl ToTokens) { |
| let ty = ty.to_token_stream(); |
| let bound = bound.to_token_stream(); |
| let entry = self.bounds.entry(ty.to_string()); |
| if let Entry::Vacant(_) = entry { |
| self.order.push(ty); |
| } |
| let (set, tokens) = entry.or_default(); |
| if set.insert(bound.to_string()) { |
| tokens.push(bound); |
| } |
| } |
| |
| pub fn augment_where_clause(&self, generics: &Generics) -> WhereClause { |
| let mut generics = generics.clone(); |
| let where_clause = generics.make_where_clause(); |
| for ty in &self.order { |
| let (_set, bounds) = &self.bounds[&ty.to_string()]; |
| where_clause.predicates.push(parse_quote!(#ty: #bounds)); |
| } |
| generics.where_clause.unwrap() |
| } |
| } |