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, Punctuated)>, order: Vec, } 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() } }