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 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) fn root(p: &mut Parser) {
50 items::mod_contents(p, false);
51 m.complete(p, SOURCE_FILE);
54 /// Various pieces of syntax that can be parsed by macros by example
55 pub(crate) mod fragments {
58 pub(crate) use super::{
59 expressions::block_expr, paths::type_path as path, patterns::pattern_single, types::type_,
62 pub(crate) fn expr(p: &mut Parser) {
63 let _ = expressions::expr_with_attrs(p);
66 pub(crate) fn stmt(p: &mut Parser) {
67 expressions::stmt(p, expressions::StmtWithSemi::No, true)
70 pub(crate) fn stmt_optional_semi(p: &mut Parser) {
71 expressions::stmt(p, expressions::StmtWithSemi::Optional, false)
74 pub(crate) fn opt_visibility(p: &mut Parser) {
75 let _ = super::opt_visibility(p);
78 // Parse a meta item , which excluded [], e.g : #[ MetaItem ]
79 pub(crate) fn meta_item(p: &mut Parser) {
83 pub(crate) fn item(p: &mut Parser) {
84 items::item_or_macro(p, true)
87 pub(crate) fn macro_items(p: &mut Parser) {
89 items::mod_contents(p, false);
90 m.complete(p, MACRO_ITEMS);
93 pub(crate) fn macro_stmts(p: &mut Parser) {
102 expressions::stmt(p, expressions::StmtWithSemi::Optional, true);
105 m.complete(p, MACRO_STMTS);
108 pub(crate) fn attr(p: &mut Parser) {
109 attributes::outer_attrs(p)
113 pub(crate) fn reparser(
115 first_child: Option<SyntaxKind>,
116 parent: Option<SyntaxKind>,
117 ) -> Option<fn(&mut Parser)> {
118 let res = match node {
119 BLOCK_EXPR => expressions::block_expr,
120 RECORD_FIELD_LIST => items::record_field_list,
121 RECORD_EXPR_FIELD_LIST => items::record_expr_field_list,
122 VARIANT_LIST => items::variant_list,
123 MATCH_ARM_LIST => items::match_arm_list,
124 USE_TREE_LIST => items::use_tree_list,
125 EXTERN_ITEM_LIST => items::extern_item_list,
126 TOKEN_TREE if first_child? == T!['{'] => items::token_tree,
127 ASSOC_ITEM_LIST => match parent? {
128 IMPL => items::assoc_item_list,
129 TRAIT => items::assoc_item_list,
132 ITEM_LIST => items::item_list,
138 #[derive(Clone, Copy, PartialEq, Eq)]
145 fn is_block(self) -> bool {
146 self == BlockLike::Block
150 fn opt_visibility(p: &mut Parser) -> bool {
157 // test crate_visibility
158 // pub(crate) struct S;
159 // pub(self) struct S;
160 // pub(super) struct S;
162 // test pub_parens_typepath
163 // struct B(pub (super::A));
164 // struct B(pub (crate::A,));
165 T![crate] | T![self] | T![super] | T![ident] if p.nth(2) != T![:] => {
167 let path_m = p.start();
168 let path_segment_m = p.start();
169 let name_ref_m = p.start();
171 name_ref_m.complete(p, NAME_REF);
172 path_segment_m.complete(p, PATH_SEGMENT);
173 path_m.complete(p, PATH);
176 // test crate_visibility_in
177 // pub(in super::A) struct S;
178 // pub(in crate) struct S;
188 m.complete(p, VISIBILITY);
190 // test crate_keyword_vis
191 // crate fn main() { }
192 // struct S { crate field: u32 }
193 // struct T(crate u32);
195 // test crate_keyword_path
196 // fn foo() { crate::foo(); }
197 T![crate] if !p.nth_at(1, T![::]) => {
200 m.complete(p, VISIBILITY);
207 fn opt_rename(p: &mut Parser) {
214 m.complete(p, RENAME);
218 fn abi(p: &mut Parser) {
219 assert!(p.at(T![extern]));
223 abi.complete(p, ABI);
226 fn opt_ret_type(p: &mut Parser) -> bool {
230 types::type_no_bounds(p);
231 m.complete(p, RET_TYPE);
238 fn name_r(p: &mut Parser, recovery: TokenSet) {
244 p.err_recover("expected a name", recovery);
248 fn name(p: &mut Parser) {
249 name_r(p, TokenSet::EMPTY)
252 fn name_ref(p: &mut Parser) {
256 m.complete(p, NAME_REF);
258 p.err_and_bump("expected identifier");
262 fn name_ref_or_index(p: &mut Parser) {
263 assert!(p.at(IDENT) || p.at(INT_NUMBER));
266 m.complete(p, NAME_REF);
269 fn lifetime(p: &mut Parser) {
270 assert!(p.at(LIFETIME_IDENT));
272 p.bump(LIFETIME_IDENT);
273 m.complete(p, LIFETIME);
276 fn error_block(p: &mut Parser, message: &str) {
277 assert!(p.at(T!['{']));
281 expressions::expr_block_contents(p);
283 m.complete(p, ERROR);