1 //! This is the actual "grammar" of the Rust language.
3 //! Each function in this module and its children corresponds
4 //! to a production of the formal grammar. Submodules roughly
5 //! correspond to different *areas* of the grammar. By convention,
6 //! each submodule starts with `use super::*` import and exports
7 //! "public" productions via `pub(super)`.
9 //! See docs for [`Parser`](super::parser::Parser) to learn about API,
10 //! available to the grammar, and see docs for [`Event`](super::event::Event)
11 //! to learn how this actually manages to produce parse trees.
13 //! Code in this module also contains inline tests, which start with
14 //! `// test name-of-the-test` comment and look like this:
17 //! // test function_with_zero_parameters
21 //! After adding a new inline-test, run `cargo test -p xtask` to
22 //! extract it as a standalone text-fixture into
23 //! `crates/syntax/test_data/parser/`, and run `cargo test` once to
24 //! create the "gold" value.
26 //! Coding convention: rules like `where_clause` always produce either a
27 //! node or an error, rules like `opt_where_clause` may produce nothing.
28 //! Non-opt rules typically start with `assert!(p.at(FIRST_TOKEN))`, the
29 //! caller is responsible for branching on the first token.
42 parser::{CompletedMarker, Marker, Parser},
43 SyntaxKind::{self, *},
47 pub(crate) mod entry {
50 pub(crate) mod prefix {
53 pub(crate) fn vis(p: &mut Parser) {
54 let _ = opt_visibility(p, false);
57 pub(crate) fn block(p: &mut Parser) {
58 expressions::block_expr(p);
61 pub(crate) fn stmt(p: &mut Parser) {
62 expressions::stmt(p, expressions::StmtWithSemi::No, true);
67 pub(crate) mod entry_points {
70 pub(crate) fn source_file(p: &mut Parser) {
73 items::mod_contents(p, false);
74 m.complete(p, SOURCE_FILE);
77 pub(crate) use paths::type_path as path;
79 pub(crate) use patterns::pattern_single as pattern;
81 pub(crate) use types::type_;
83 pub(crate) fn expr(p: &mut Parser) {
84 let _ = expressions::expr(p);
87 pub(crate) fn stmt_optional_semi(p: &mut Parser) {
88 expressions::stmt(p, expressions::StmtWithSemi::Optional, false);
91 // Parse a meta item , which excluded [], e.g : #[ MetaItem ]
92 pub(crate) fn meta_item(p: &mut Parser) {
96 pub(crate) fn item(p: &mut Parser) {
97 items::item_or_macro(p, true);
100 pub(crate) fn macro_items(p: &mut Parser) {
102 items::mod_contents(p, false);
103 m.complete(p, MACRO_ITEMS);
106 pub(crate) fn macro_stmts(p: &mut Parser) {
115 expressions::stmt(p, expressions::StmtWithSemi::Optional, true);
118 m.complete(p, MACRO_STMTS);
121 pub(crate) fn attr(p: &mut Parser) {
122 attributes::outer_attrs(p);
126 pub(crate) fn reparser(
128 first_child: Option<SyntaxKind>,
129 parent: Option<SyntaxKind>,
130 ) -> Option<fn(&mut Parser)> {
131 let res = match node {
132 BLOCK_EXPR => expressions::block_expr,
133 RECORD_FIELD_LIST => items::record_field_list,
134 RECORD_EXPR_FIELD_LIST => items::record_expr_field_list,
135 VARIANT_LIST => items::variant_list,
136 MATCH_ARM_LIST => items::match_arm_list,
137 USE_TREE_LIST => items::use_tree_list,
138 EXTERN_ITEM_LIST => items::extern_item_list,
139 TOKEN_TREE if first_child? == T!['{'] => items::token_tree,
140 ASSOC_ITEM_LIST => match parent? {
141 IMPL | TRAIT => items::assoc_item_list,
144 ITEM_LIST => items::item_list,
150 #[derive(Clone, Copy, PartialEq, Eq)]
157 fn is_block(self) -> bool {
158 self == BlockLike::Block
162 fn opt_visibility(p: &mut Parser, in_tuple_field: bool) -> bool {
169 // test crate_visibility
170 // pub(crate) struct S;
171 // pub(self) struct S;
172 // pub(super) struct S;
174 // test pub_parens_typepath
175 // struct B(pub (super::A));
176 // struct B(pub (crate::A,));
177 T![crate] | T![self] | T![super] | T![ident] if p.nth(2) != T![:] => {
178 // If we are in a tuple struct, then the parens following `pub`
179 // might be an tuple field, not part of the visibility. So in that
180 // case we don't want to consume an identifier.
182 // test pub_tuple_field
183 // struct MyStruct(pub (u32, u32));
184 if !(in_tuple_field && matches!(p.nth(1), T![ident])) {
190 // test crate_visibility_in
191 // pub(in super::A) struct S;
192 // pub(in crate) struct S;
202 m.complete(p, VISIBILITY);
205 // test crate_keyword_vis
206 // crate fn main() { }
207 // struct S { crate field: u32 }
208 // struct T(crate u32);
210 if p.nth_at(1, T![::]) {
211 // test crate_keyword_path
212 // fn foo() { crate::foo(); }
217 m.complete(p, VISIBILITY);
224 fn opt_rename(p: &mut Parser) {
231 m.complete(p, RENAME);
235 fn abi(p: &mut Parser) {
236 assert!(p.at(T![extern]));
240 abi.complete(p, ABI);
243 fn opt_ret_type(p: &mut Parser) -> bool {
247 types::type_no_bounds(p);
248 m.complete(p, RET_TYPE);
255 fn name_r(p: &mut Parser, recovery: TokenSet) {
261 p.err_recover("expected a name", recovery);
265 fn name(p: &mut Parser) {
266 name_r(p, TokenSet::EMPTY);
269 fn name_ref(p: &mut Parser) {
273 m.complete(p, NAME_REF);
275 p.err_and_bump("expected identifier");
279 fn name_ref_or_index(p: &mut Parser) {
280 assert!(p.at(IDENT) || p.at(INT_NUMBER));
283 m.complete(p, NAME_REF);
286 fn lifetime(p: &mut Parser) {
287 assert!(p.at(LIFETIME_IDENT));
289 p.bump(LIFETIME_IDENT);
290 m.complete(p, LIFETIME);
293 fn error_block(p: &mut Parser, message: &str) {
294 assert!(p.at(T!['{']));
298 expressions::expr_block_contents(p);
300 m.complete(p, ERROR);