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|
//! Lowers a single complex use like `use foo::{bar, baz};` into a list of paths like
//! `foo::bar`, `foo::baz`;
use std::iter;
use either::Either;
use hir_expand::{
hygiene::Hygiene,
name::{AsName, Name},
};
use ra_syntax::ast::{self, NameOwner};
use crate::path::{ModPath, PathKind};
pub(crate) fn lower_use_tree(
prefix: Option<ModPath>,
tree: ast::UseTree,
hygiene: &Hygiene,
cb: &mut dyn FnMut(ModPath, &ast::UseTree, bool, Option<Name>),
) {
if let Some(use_tree_list) = tree.use_tree_list() {
let prefix = match tree.path() {
// E.g. use something::{{{inner}}};
None => prefix,
// E.g. `use something::{inner}` (prefix is `None`, path is `something`)
// or `use something::{path::{inner::{innerer}}}` (prefix is `something::path`, path is `inner`)
Some(path) => match convert_path(prefix, path, hygiene) {
Some(it) => Some(it),
None => return, // FIXME: report errors somewhere
},
};
for child_tree in use_tree_list.use_trees() {
lower_use_tree(prefix.clone(), child_tree, hygiene, cb);
}
} else {
let alias = tree.alias().and_then(|a| a.name()).map(|a| a.as_name());
if let Some(ast_path) = tree.path() {
// Handle self in a path.
// E.g. `use something::{self, <...>}`
if ast_path.qualifier().is_none() {
if let Some(segment) = ast_path.segment() {
if segment.kind() == Some(ast::PathSegmentKind::SelfKw) {
if let Some(prefix) = prefix {
cb(prefix, &tree, false, alias);
return;
}
}
}
}
if let Some(path) = convert_path(prefix, ast_path, hygiene) {
let is_glob = tree.has_star();
cb(path, &tree, is_glob, alias)
}
// FIXME: report errors somewhere
// We get here if we do
}
}
}
fn convert_path(prefix: Option<ModPath>, path: ast::Path, hygiene: &Hygiene) -> Option<ModPath> {
let prefix = if let Some(qual) = path.qualifier() {
Some(convert_path(prefix, qual, hygiene)?)
} else {
prefix
};
let segment = path.segment()?;
let res = match segment.kind()? {
ast::PathSegmentKind::Name(name_ref) => {
match hygiene.name_ref_to_name(name_ref) {
Either::Left(name) => {
// no type args in use
let mut res = prefix.unwrap_or_else(|| ModPath {
kind: PathKind::Plain,
segments: Vec::with_capacity(1),
});
res.segments.push(name);
res
}
Either::Right(crate_id) => {
return Some(ModPath::from_simple_segments(
PathKind::DollarCrate(crate_id),
iter::empty(),
))
}
}
}
ast::PathSegmentKind::CrateKw => {
if prefix.is_some() {
return None;
}
ModPath::from_simple_segments(PathKind::Crate, iter::empty())
}
ast::PathSegmentKind::SelfKw => {
if prefix.is_some() {
return None;
}
ModPath::from_simple_segments(PathKind::Super(0), iter::empty())
}
ast::PathSegmentKind::SuperKw => {
if prefix.is_some() {
return None;
}
ModPath::from_simple_segments(PathKind::Super(1), iter::empty())
}
ast::PathSegmentKind::Type { .. } => {
// not allowed in imports
return None;
}
};
Some(res)
}
|
