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