use super::*; pub(super) fn use_item(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_ITEM); } /// 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 ::{{{crate::export}}}; // Nonsensical but perfectly legal nestnig 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_alias(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); }