//! This is the actual "grammar" of the Rust language. //! //! Each function in this module and its children corresponds //! to a production of the formal grammar. Submodules roughly //! correspond to different *areas* of the grammar. By convention, //! each submodule starts with `use super::*` import and exports //! "public" productions via `pub(super)`. //! //! See docs for `Parser` to learn about API, available to the grammar, //! and see docs for `Event` to learn how this actually manages to //! produce parse trees. //! //! Code in this module also contains inline tests, which start with //! `// test name-of-the-test` comment and look like this: //! //! ``` //! // test function_with_zero_parameters //! // fn foo() {} //! ``` //! //! After adding a new inline-test, run `cargo test -p xtask` to //! extract it as a standalone text-fixture into //! `crates/syntax/test_data/parser/`, and run `cargo test` once to //! create the "gold" value. //! //! Coding convention: rules like `where_clause` always produce either a //! node or an error, rules like `opt_where_clause` may produce nothing. //! Non-opt rules typically start with `assert!(p.at(FIRST_TOKEN))`, the //! caller is responsible for branching on the first token. mod attributes; mod expressions; mod items; mod params; mod paths; mod patterns; mod type_args; mod type_params; mod types; use crate::{ parser::{CompletedMarker, Marker, Parser}, SyntaxKind::{self, *}, TokenSet, }; pub(crate) fn root(p: &mut Parser) { let m = p.start(); p.eat(SHEBANG); items::mod_contents(p, false); m.complete(p, SOURCE_FILE); } /// Various pieces of syntax that can be parsed by macros by example pub(crate) mod fragments { use super::*; pub(crate) use super::{ expressions::block_expr, paths::type_path as path, patterns::pattern_single, types::type_, }; pub(crate) fn expr(p: &mut Parser) { let _ = expressions::expr_with_attrs(p); } pub(crate) fn stmt(p: &mut Parser) { expressions::stmt(p, expressions::StmtWithSemi::No, true) } pub(crate) fn stmt_optional_semi(p: &mut Parser) { expressions::stmt(p, expressions::StmtWithSemi::Optional, false) } pub(crate) fn opt_visibility(p: &mut Parser) { let _ = super::opt_visibility(p); } // Parse a meta item , which excluded [], e.g : #[ MetaItem ] pub(crate) fn meta_item(p: &mut Parser) { fn is_delimiter(p: &mut Parser) -> bool { matches!(p.current(), T!['{'] | T!['('] | T!['[']) } if is_delimiter(p) { items::token_tree(p); return; } let m = p.start(); while !p.at(EOF) { if is_delimiter(p) { items::token_tree(p); break; } else { // https://doc.rust-lang.org/reference/attributes.html // https://doc.rust-lang.org/reference/paths.html#simple-paths // The start of an meta must be a simple path match p.current() { IDENT | T![super] | T![self] | T![crate] => p.bump_any(), T![=] => { p.bump_any(); match p.current() { c if c.is_literal() => p.bump_any(), T![true] | T![false] => p.bump_any(), _ => {} } break; } _ if p.at(T![::]) => p.bump(T![::]), _ => break, } } } m.complete(p, TOKEN_TREE); } pub(crate) fn item(p: &mut Parser) { items::item_or_macro(p, true) } pub(crate) fn macro_items(p: &mut Parser) { let m = p.start(); items::mod_contents(p, false); m.complete(p, MACRO_ITEMS); } pub(crate) fn macro_stmts(p: &mut Parser) { let m = p.start(); while !p.at(EOF) { if p.at(T![;]) { p.bump(T![;]); continue; } expressions::stmt(p, expressions::StmtWithSemi::Optional, true); } m.complete(p, MACRO_STMTS); } pub(crate) fn attr(p: &mut Parser) { attributes::outer_attrs(p) } } pub(crate) fn reparser( node: SyntaxKind, first_child: Option<SyntaxKind>, parent: Option<SyntaxKind>, ) -> Option<fn(&mut Parser)> { let res = match node { BLOCK_EXPR => expressions::block_expr, RECORD_FIELD_LIST => items::record_field_list, RECORD_EXPR_FIELD_LIST => items::record_expr_field_list, VARIANT_LIST => items::variant_list, MATCH_ARM_LIST => items::match_arm_list, USE_TREE_LIST => items::use_tree_list, EXTERN_ITEM_LIST => items::extern_item_list, TOKEN_TREE if first_child? == T!['{'] => items::token_tree, ASSOC_ITEM_LIST => match parent? { IMPL => items::assoc_item_list, TRAIT => items::assoc_item_list, _ => return None, }, ITEM_LIST => items::item_list, _ => return None, }; Some(res) } #[derive(Clone, Copy, PartialEq, Eq)] enum BlockLike { Block, NotBlock, } impl BlockLike { fn is_block(self) -> bool { self == BlockLike::Block } } fn opt_visibility(p: &mut Parser) -> bool { match p.current() { T![pub] => { let m = p.start(); p.bump(T![pub]); if p.at(T!['(']) { match p.nth(1) { // test crate_visibility // pub(crate) struct S; // pub(self) struct S; // pub(super) struct S; // test pub_parens_typepath // struct B(pub (super::A)); // struct B(pub (crate::A,)); T![crate] | T![self] | T![super] if p.nth(2) != T![:] => { p.bump_any(); let path_m = p.start(); let path_segment_m = p.start(); let name_ref_m = p.start(); p.bump_any(); name_ref_m.complete(p, NAME_REF); path_segment_m.complete(p, PATH_SEGMENT); path_m.complete(p, PATH); p.expect(T![')']); } // test crate_visibility_in // pub(in super::A) struct S; // pub(in crate) struct S; T![in] => { p.bump_any(); p.bump_any(); paths::use_path(p); p.expect(T![')']); } _ => (), } } m.complete(p, VISIBILITY); } // test crate_keyword_vis // crate fn main() { } // struct S { crate field: u32 } // struct T(crate u32); // // test crate_keyword_path // fn foo() { crate::foo(); } T![crate] if !p.nth_at(1, T![::]) => { let m = p.start(); p.bump(T![crate]); m.complete(p, VISIBILITY); } _ => return false, } true } fn opt_rename(p: &mut Parser) { if p.at(T![as]) { let m = p.start(); p.bump(T![as]); if !p.eat(T![_]) { name(p); } m.complete(p, RENAME); } } fn abi(p: &mut Parser) { assert!(p.at(T![extern])); let abi = p.start(); p.bump(T![extern]); p.eat(STRING); abi.complete(p, ABI); } fn opt_ret_type(p: &mut Parser) -> bool { if p.at(T![->]) { let m = p.start(); p.bump(T![->]); types::type_no_bounds(p); m.complete(p, RET_TYPE); true } else { false } } fn name_r(p: &mut Parser, recovery: TokenSet) { if p.at(IDENT) { let m = p.start(); p.bump(IDENT); m.complete(p, NAME); } else { p.err_recover("expected a name", recovery); } } fn name(p: &mut Parser) { name_r(p, TokenSet::EMPTY) } fn name_ref(p: &mut Parser) { if p.at(IDENT) { let m = p.start(); p.bump(IDENT); m.complete(p, NAME_REF); } else { p.err_and_bump("expected identifier"); } } fn name_ref_or_index(p: &mut Parser) { assert!(p.at(IDENT) || p.at(INT_NUMBER)); let m = p.start(); p.bump_any(); m.complete(p, NAME_REF); } fn lifetime(p: &mut Parser) { assert!(p.at(LIFETIME_IDENT)); let m = p.start(); p.bump(LIFETIME_IDENT); m.complete(p, LIFETIME); } fn error_block(p: &mut Parser, message: &str) { assert!(p.at(T!['{'])); let m = p.start(); p.error(message); p.bump(T!['{']); expressions::expr_block_contents(p); p.eat(T!['}']); m.complete(p, ERROR); }