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//! FIXME: write short doc here
use super::*;
pub(super) fn use_(p: &mut Parser, m: Marker) {
assert!(p.at(T![use]));
p.bump(T![use]);
use_tree(p, true);
p.expect(T![;]);
m.complete(p, USE);
}
/// Parse a use 'tree', such as `some::path` in `use some::path;`
/// Note that this is called both by `use_item` and `use_tree_list`,
/// so handles both `some::path::{inner::path}` and `inner::path` in
/// `use some::path::{inner::path};`
fn use_tree(p: &mut Parser, top_level: bool) {
let m = p.start();
match p.current() {
// Finish the use_tree for cases of e.g.
// `use some::path::{self, *};` or `use *;`
// This does not handle cases such as `use some::path::*`
// N.B. in Rust 2015 `use *;` imports all from crate root
// however in Rust 2018 `use *;` errors: ('cannot glob-import all possible crates')
// FIXME: Add this error (if not out of scope)
// test use_star
// use *;
// use ::*;
// use some::path::{*};
// use some::path::{::*};
T![*] => p.bump(T![*]),
T![:] if p.at(T![::]) && p.nth(2) == T![*] => {
// Parse `use ::*;`, which imports all from the crate root in Rust 2015
// This is invalid inside a use_tree_list, (e.g. `use some::path::{::*}`)
// but still parses and errors later: ('crate root in paths can only be used in start position')
// FIXME: Add this error (if not out of scope)
// In Rust 2018, it is always invalid (see above)
p.bump(T![::]);
p.bump(T![*]);
}
// Open a use tree list
// Handles cases such as `use {some::path};` or `{inner::path}` in
// `use some::path::{{inner::path}, other::path}`
// test use_tree_list
// use {crate::path::from::root, or::path::from::crate_name}; // Rust 2018 (with a crate named `or`)
// use {path::from::root}; // Rust 2015
// use ::{some::arbritrary::path}; // Rust 2015
// use ::{{{root::export}}}; // Nonsensical but perfectly legal nesting
T!['{'] => {
use_tree_list(p);
}
T![:] if p.at(T![::]) && p.nth(2) == T!['{'] => {
p.bump(T![::]);
use_tree_list(p);
}
// Parse a 'standard' path.
// Also handles aliases (e.g. `use something as something_else`)
// test use_path
// use ::crate_name; // Rust 2018 - All flavours
// use crate_name; // Rust 2018 - Anchored paths
// use item_in_scope_or_crate_name; // Rust 2018 - Uniform Paths
//
// use self::module::Item;
// use crate::Item;
// use self::some::Struct;
// use crate_name::some_item;
_ if paths::is_use_path_start(p) => {
paths::use_path(p);
match p.current() {
T![as] => {
// test use_alias
// use some::path as some_name;
// use some::{
// other::path as some_other_name,
// different::path as different_name,
// yet::another::path,
// running::out::of::synonyms::for_::different::*
// };
// use Trait as _;
opt_rename(p);
}
T![:] if p.at(T![::]) => {
p.bump(T![::]);
match p.current() {
T![*] => {
p.bump(T![*]);
}
// test use_tree_list_after_path
// use crate::{Item};
// use self::{Item};
T!['{'] => use_tree_list(p),
_ => {
// is this unreachable?
p.error("expected `{` or `*`");
}
}
}
_ => (),
}
}
_ => {
m.abandon(p);
let msg = "expected one of `*`, `::`, `{`, `self`, `super` or an identifier";
if top_level {
p.err_recover(msg, ITEM_RECOVERY_SET);
} else {
// if we are parsing a nested tree, we have to eat a token to
// main balanced `{}`
p.err_and_bump(msg);
}
return;
}
}
m.complete(p, USE_TREE);
}
pub(crate) fn use_tree_list(p: &mut Parser) {
assert!(p.at(T!['{']));
let m = p.start();
p.bump(T!['{']);
while !p.at(EOF) && !p.at(T!['}']) {
use_tree(p, false);
if !p.at(T!['}']) {
p.expect(T![,]);
}
}
p.expect(T!['}']);
m.complete(p, USE_TREE_LIST);
}
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