1 //! Transforms syntax into `Path` objects, ideally with accounting for hygiene
5 use crate::intern::Interned;
9 use hir_expand::name::{name, AsName};
10 use syntax::ast::{self, AstNode, TypeBoundsOwner};
12 use super::AssociatedTypeBinding;
15 path::{GenericArg, GenericArgs, ModPath, Path, PathKind},
16 type_ref::{LifetimeRef, TypeBound, TypeRef},
19 pub(super) use lower_use::lower_use_tree;
21 /// Converts an `ast::Path` to `Path`. Works with use trees.
22 /// It correctly handles `$crate` based path from macro call.
23 pub(super) fn lower_path(mut path: ast::Path, ctx: &LowerCtx) -> Option<Path> {
24 let mut kind = PathKind::Plain;
25 let mut type_anchor = None;
26 let mut segments = Vec::new();
27 let mut generic_args = Vec::new();
28 let hygiene = ctx.hygiene();
30 let segment = path.segment()?;
32 if segment.coloncolon_token().is_some() {
36 match segment.kind()? {
37 ast::PathSegmentKind::Name(name_ref) => {
38 // FIXME: this should just return name
39 match hygiene.name_ref_to_name(name_ref) {
40 Either::Left(name) => {
43 .and_then(|it| lower_generic_args(ctx, it))
45 lower_generic_args_from_fn_path(
53 generic_args.push(args)
55 Either::Right(crate_id) => {
56 kind = PathKind::DollarCrate(crate_id);
61 ast::PathSegmentKind::Type { type_ref, trait_ref } => {
62 assert!(path.qualifier().is_none()); // this can only occur at the first segment
64 let self_type = TypeRef::from_ast(ctx, type_ref?);
69 type_anchor = Some(Interned::new(self_type));
70 kind = PathKind::Plain;
72 // <T as Trait<A>>::Foo desugars to Trait<Self=T, A>::Foo
74 let path = Path::from_src(trait_ref.path()?, ctx)?;
75 let mod_path = (*path.mod_path).clone();
76 let num_segments = path.mod_path.segments.len();
79 let mut prefix_segments = mod_path.segments;
80 prefix_segments.reverse();
81 segments.extend(prefix_segments);
83 let mut prefix_args = path.generic_args;
84 prefix_args.reverse();
85 generic_args.extend(prefix_args);
87 // Insert the type reference (T in the above example) as Self parameter for the trait
89 generic_args.iter_mut().rev().nth(num_segments.saturating_sub(1))?;
90 if last_segment.is_none() {
91 *last_segment = Some(Arc::new(GenericArgs::empty()));
93 let args = last_segment.as_mut().unwrap();
94 let mut args_inner = Arc::make_mut(args);
95 args_inner.has_self_type = true;
96 args_inner.args.insert(0, GenericArg::Type(self_type));
100 ast::PathSegmentKind::CrateKw => {
101 kind = PathKind::Crate;
104 ast::PathSegmentKind::SelfKw => {
105 // don't break out if `self` is the last segment of a path, this mean we got an
106 // use tree like `foo::{self}` which we want to resolve as `foo`
107 if !segments.is_empty() {
108 kind = PathKind::Super(0);
112 ast::PathSegmentKind::SuperKw => {
113 let nested_super_count = if let PathKind::Super(n) = kind { n } else { 0 };
114 kind = PathKind::Super(nested_super_count + 1);
117 path = match qualifier(&path) {
123 generic_args.reverse();
125 if segments.is_empty() && kind == PathKind::Plain && type_anchor.is_none() {
126 // plain empty paths don't exist, this means we got a single `self` segment as our path
127 kind = PathKind::Super(0);
130 // handle local_inner_macros :
131 // Basically, even in rustc it is quite hacky:
132 // https://github.com/rust-lang/rust/blob/614f273e9388ddd7804d5cbc80b8865068a3744e/src/librustc_resolve/macros.rs#L456
133 // We follow what it did anyway :)
134 if segments.len() == 1 && kind == PathKind::Plain {
135 if let Some(_macro_call) = path.syntax().parent().and_then(ast::MacroCall::cast) {
136 if let Some(crate_id) = hygiene.local_inner_macros(path) {
137 kind = PathKind::DollarCrate(crate_id);
142 let mod_path = Interned::new(ModPath::from_segments(kind, segments));
143 return Some(Path { type_anchor, mod_path, generic_args });
145 fn qualifier(path: &ast::Path) -> Option<ast::Path> {
146 if let Some(q) = path.qualifier() {
149 // FIXME: this bottom up traversal is not too precise.
150 // Should we handle do a top-down analysis, recording results?
151 let use_tree_list = path.syntax().ancestors().find_map(ast::UseTreeList::cast)?;
152 let use_tree = use_tree_list.parent_use_tree();
157 pub(super) fn lower_generic_args(
158 lower_ctx: &LowerCtx,
159 node: ast::GenericArgList,
160 ) -> Option<GenericArgs> {
161 let mut args = Vec::new();
162 let mut bindings = Vec::new();
163 for generic_arg in node.generic_args() {
165 ast::GenericArg::TypeArg(type_arg) => {
166 let type_ref = TypeRef::from_ast_opt(lower_ctx, type_arg.ty());
167 args.push(GenericArg::Type(type_ref));
169 ast::GenericArg::AssocTypeArg(assoc_type_arg) => {
170 if let Some(name_ref) = assoc_type_arg.name_ref() {
171 let name = name_ref.as_name();
172 let type_ref = assoc_type_arg.ty().map(|it| TypeRef::from_ast(lower_ctx, it));
173 let bounds = if let Some(l) = assoc_type_arg.type_bound_list() {
174 l.bounds().map(|it| TypeBound::from_ast(lower_ctx, it)).collect()
178 bindings.push(AssociatedTypeBinding { name, type_ref, bounds });
181 ast::GenericArg::LifetimeArg(lifetime_arg) => {
182 if let Some(lifetime) = lifetime_arg.lifetime() {
183 let lifetime_ref = LifetimeRef::new(&lifetime);
184 args.push(GenericArg::Lifetime(lifetime_ref))
187 // constants are ignored for now.
188 ast::GenericArg::ConstArg(_) => (),
192 if args.is_empty() && bindings.is_empty() {
195 Some(GenericArgs { args, has_self_type: false, bindings })
198 /// Collect `GenericArgs` from the parts of a fn-like path, i.e. `Fn(X, Y)
199 /// -> Z` (which desugars to `Fn<(X, Y), Output=Z>`).
200 fn lower_generic_args_from_fn_path(
202 params: Option<ast::ParamList>,
203 ret_type: Option<ast::RetType>,
204 ) -> Option<GenericArgs> {
205 let mut args = Vec::new();
206 let mut bindings = Vec::new();
207 if let Some(params) = params {
208 let mut param_types = Vec::new();
209 for param in params.params() {
210 let type_ref = TypeRef::from_ast_opt(&ctx, param.ty());
211 param_types.push(type_ref);
213 let arg = GenericArg::Type(TypeRef::Tuple(param_types));
216 if let Some(ret_type) = ret_type {
217 let type_ref = TypeRef::from_ast_opt(&ctx, ret_type.ty());
218 bindings.push(AssociatedTypeBinding {
220 type_ref: Some(type_ref),
224 if args.is_empty() && bindings.is_empty() {
227 Some(GenericArgs { args, has_self_type: false, bindings })