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` to learn about API, available to the grammar,
10 //! and see docs for `Event` to learn how this actually manages to
11 //! 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 xtask codegen` 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.
41 parser::{CompletedMarker, Marker, Parser},
42 SyntaxKind::{self, *},
46 pub(crate) fn root(p: &mut Parser) {
49 items::mod_contents(p, false);
50 m.complete(p, SOURCE_FILE);
53 /// Various pieces of syntax that can be parsed by macros by example
54 pub(crate) mod fragments {
57 pub(crate) use super::{
58 expressions::block_expr, paths::type_path as path, patterns::pattern_single, types::type_,
61 pub(crate) fn expr(p: &mut Parser) {
62 let _ = expressions::expr_with_attrs(p);
65 pub(crate) fn stmt(p: &mut Parser) {
66 expressions::stmt(p, expressions::StmtWithSemi::No)
69 pub(crate) fn stmt_optional_semi(p: &mut Parser) {
70 expressions::stmt(p, expressions::StmtWithSemi::Optional)
73 pub(crate) fn opt_visibility(p: &mut Parser) {
74 let _ = super::opt_visibility(p);
77 // Parse a meta item , which excluded [], e.g : #[ MetaItem ]
78 pub(crate) fn meta_item(p: &mut Parser) {
79 fn is_delimiter(p: &mut Parser) -> bool {
80 matches!(p.current(), T!['{'] | T!['('] | T!['['])
94 // https://doc.rust-lang.org/reference/attributes.html
95 // https://doc.rust-lang.org/reference/paths.html#simple-paths
96 // The start of an meta must be a simple path
98 IDENT | T![::] | T![super] | T![self] | T![crate] => p.bump_any(),
102 c if c.is_literal() => p.bump_any(),
103 T![true] | T![false] => p.bump_any(),
113 m.complete(p, TOKEN_TREE);
116 pub(crate) fn item(p: &mut Parser) {
117 items::item_or_macro(p, true)
120 pub(crate) fn macro_items(p: &mut Parser) {
122 items::mod_contents(p, false);
123 m.complete(p, MACRO_ITEMS);
126 pub(crate) fn macro_stmts(p: &mut Parser) {
135 expressions::stmt(p, expressions::StmtWithSemi::Optional);
138 m.complete(p, MACRO_STMTS);
141 pub(crate) fn attr(p: &mut Parser) {
142 attributes::outer_attrs(p)
146 pub(crate) fn reparser(
148 first_child: Option<SyntaxKind>,
149 parent: Option<SyntaxKind>,
150 ) -> Option<fn(&mut Parser)> {
151 let res = match node {
152 BLOCK_EXPR => expressions::block_expr,
153 RECORD_FIELD_LIST => items::record_field_list,
154 RECORD_EXPR_FIELD_LIST => items::record_expr_field_list,
155 VARIANT_LIST => items::variant_list,
156 MATCH_ARM_LIST => items::match_arm_list,
157 USE_TREE_LIST => items::use_tree_list,
158 EXTERN_ITEM_LIST => items::extern_item_list,
159 TOKEN_TREE if first_child? == T!['{'] => items::token_tree,
160 ASSOC_ITEM_LIST => match parent? {
161 IMPL => items::assoc_item_list,
162 TRAIT => items::assoc_item_list,
165 ITEM_LIST => items::item_list,
171 #[derive(Clone, Copy, PartialEq, Eq)]
178 fn is_block(self) -> bool {
179 self == BlockLike::Block
183 fn opt_visibility(p: &mut Parser) -> bool {
190 // test crate_visibility
191 // pub(crate) struct S;
192 // pub(self) struct S;
193 // pub(super) struct S;
195 // test pub_parens_typepath
196 // struct B(pub (super::A));
197 // struct B(pub (crate::A,));
198 T![crate] | T![self] | T![super] if p.nth(2) != T![:] => {
200 let path_m = p.start();
201 let path_segment_m = p.start();
202 let name_ref_m = p.start();
204 name_ref_m.complete(p, NAME_REF);
205 path_segment_m.complete(p, PATH_SEGMENT);
206 path_m.complete(p, PATH);
209 // test crate_visibility_in
210 // pub(in super::A) struct S;
211 // pub(in crate) struct S;
221 m.complete(p, VISIBILITY);
223 // test crate_keyword_vis
224 // crate fn main() { }
225 // struct S { crate field: u32 }
226 // struct T(crate u32);
228 // test crate_keyword_path
229 // fn foo() { crate::foo(); }
230 T![crate] if !p.nth_at(1, T![::]) => {
233 m.complete(p, VISIBILITY);
240 fn opt_rename(p: &mut Parser) {
247 m.complete(p, RENAME);
251 fn abi(p: &mut Parser) {
252 assert!(p.at(T![extern]));
256 abi.complete(p, ABI);
259 fn opt_ret_type(p: &mut Parser) -> bool {
263 types::type_no_bounds(p);
264 m.complete(p, RET_TYPE);
271 fn name_r(p: &mut Parser, recovery: TokenSet) {
277 p.err_recover("expected a name", recovery);
281 fn name(p: &mut Parser) {
282 name_r(p, TokenSet::EMPTY)
285 fn name_ref(p: &mut Parser) {
289 m.complete(p, NAME_REF);
291 p.err_and_bump("expected identifier");
295 fn name_ref_or_index(p: &mut Parser) {
296 assert!(p.at(IDENT) || p.at(INT_NUMBER));
299 m.complete(p, NAME_REF);
302 fn lifetime(p: &mut Parser) {
303 assert!(p.at(LIFETIME_IDENT));
305 p.bump(LIFETIME_IDENT);
306 m.complete(p, LIFETIME);
309 fn error_block(p: &mut Parser, message: &str) {
310 assert!(p.at(T!['{']));
314 expressions::expr_block_contents(p);
316 m.complete(p, ERROR);