1 //! The main parser interface.
3 #![feature(array_windows)]
4 #![feature(box_patterns)]
5 #![feature(crate_visibility_modifier)]
6 #![feature(if_let_guard)]
7 #![feature(let_chains)]
9 #![feature(never_type)]
10 #![recursion_limit = "256"]
16 use rustc_ast::token::{self, Nonterminal, Token, TokenKind};
17 use rustc_ast::tokenstream::{self, AttributesData, CanSynthesizeMissingTokens, LazyTokenStream};
18 use rustc_ast::tokenstream::{AttrAnnotatedTokenStream, AttrAnnotatedTokenTree};
19 use rustc_ast::tokenstream::{Spacing, TokenStream};
20 use rustc_ast::AstLike;
21 use rustc_ast::Attribute;
22 use rustc_ast::{AttrItem, MetaItem};
23 use rustc_ast_pretty::pprust;
24 use rustc_data_structures::sync::Lrc;
25 use rustc_errors::{Applicability, Diagnostic, FatalError, Level, PResult};
26 use rustc_session::parse::ParseSess;
27 use rustc_span::{FileName, SourceFile, Span};
32 pub const MACRO_ARGUMENTS: Option<&str> = Some("macro arguments");
36 use parser::{emit_unclosed_delims, make_unclosed_delims_error, Parser};
38 pub mod validate_attr;
40 // A bunch of utility functions of the form `parse_<thing>_from_<source>`
41 // where <thing> includes crate, expr, item, stmt, tts, and one that
42 // uses a HOF to parse anything, and <source> includes file and
45 /// A variant of 'panictry!' that works on a Vec<Diagnostic> instead of a single DiagnosticBuilder.
46 macro_rules! panictry_buffer {
47 ($handler:expr, $e:expr) => {{
48 use rustc_errors::FatalError;
49 use std::result::Result::{Err, Ok};
54 $handler.emit_diagnostic(&mut e);
62 pub fn parse_crate_from_file<'a>(input: &Path, sess: &'a ParseSess) -> PResult<'a, ast::Crate> {
63 let mut parser = new_parser_from_file(sess, input, None);
64 parser.parse_crate_mod()
67 pub fn parse_crate_attrs_from_file<'a>(
70 ) -> PResult<'a, Vec<ast::Attribute>> {
71 let mut parser = new_parser_from_file(sess, input, None);
72 parser.parse_inner_attributes()
75 pub fn parse_crate_from_source_str(
79 ) -> PResult<'_, ast::Crate> {
80 new_parser_from_source_str(sess, name, source).parse_crate_mod()
83 pub fn parse_crate_attrs_from_source_str(
87 ) -> PResult<'_, Vec<ast::Attribute>> {
88 new_parser_from_source_str(sess, name, source).parse_inner_attributes()
91 pub fn parse_stream_from_source_str(
95 override_span: Option<Span>,
97 let (stream, mut errors) =
98 source_file_to_stream(sess, sess.source_map().new_source_file(name, source), override_span);
99 emit_unclosed_delims(&mut errors, &sess);
103 /// Creates a new parser from a source string.
104 pub fn new_parser_from_source_str(sess: &ParseSess, name: FileName, source: String) -> Parser<'_> {
105 panictry_buffer!(&sess.span_diagnostic, maybe_new_parser_from_source_str(sess, name, source))
108 /// Creates a new parser from a source string. Returns any buffered errors from lexing the initial
110 pub fn maybe_new_parser_from_source_str(
114 ) -> Result<Parser<'_>, Vec<Diagnostic>> {
115 maybe_source_file_to_parser(sess, sess.source_map().new_source_file(name, source))
118 /// Creates a new parser, handling errors as appropriate if the file doesn't exist.
119 /// If a span is given, that is used on an error as the source of the problem.
120 pub fn new_parser_from_file<'a>(sess: &'a ParseSess, path: &Path, sp: Option<Span>) -> Parser<'a> {
121 source_file_to_parser(sess, file_to_source_file(sess, path, sp))
124 /// Given a `source_file` and config, returns a parser.
125 fn source_file_to_parser(sess: &ParseSess, source_file: Lrc<SourceFile>) -> Parser<'_> {
126 panictry_buffer!(&sess.span_diagnostic, maybe_source_file_to_parser(sess, source_file))
129 /// Given a `source_file` and config, return a parser. Returns any buffered errors from lexing the
130 /// initial token stream.
131 fn maybe_source_file_to_parser(
133 source_file: Lrc<SourceFile>,
134 ) -> Result<Parser<'_>, Vec<Diagnostic>> {
135 let end_pos = source_file.end_pos;
136 let (stream, unclosed_delims) = maybe_file_to_stream(sess, source_file, None)?;
137 let mut parser = stream_to_parser(sess, stream, None);
138 parser.unclosed_delims = unclosed_delims;
139 if parser.token == token::Eof {
140 parser.token.span = Span::new(end_pos, end_pos, parser.token.span.ctxt(), None);
148 /// Given a session and a path and an optional span (for error reporting),
149 /// add the path to the session's source_map and return the new source_file or
150 /// error when a file can't be read.
151 fn try_file_to_source_file(
154 spanopt: Option<Span>,
155 ) -> Result<Lrc<SourceFile>, Diagnostic> {
156 sess.source_map().load_file(path).map_err(|e| {
157 let msg = format!("couldn't read {}: {}", path.display(), e);
158 let mut diag = Diagnostic::new(Level::Fatal, &msg);
159 if let Some(sp) = spanopt {
166 /// Given a session and a path and an optional span (for error reporting),
167 /// adds the path to the session's `source_map` and returns the new `source_file`.
168 fn file_to_source_file(sess: &ParseSess, path: &Path, spanopt: Option<Span>) -> Lrc<SourceFile> {
169 match try_file_to_source_file(sess, path, spanopt) {
170 Ok(source_file) => source_file,
172 sess.span_diagnostic.emit_diagnostic(&mut d);
178 /// Given a `source_file`, produces a sequence of token trees.
179 pub fn source_file_to_stream(
181 source_file: Lrc<SourceFile>,
182 override_span: Option<Span>,
183 ) -> (TokenStream, Vec<lexer::UnmatchedBrace>) {
184 panictry_buffer!(&sess.span_diagnostic, maybe_file_to_stream(sess, source_file, override_span))
187 /// Given a source file, produces a sequence of token trees. Returns any buffered errors from
188 /// parsing the token stream.
189 pub fn maybe_file_to_stream(
191 source_file: Lrc<SourceFile>,
192 override_span: Option<Span>,
193 ) -> Result<(TokenStream, Vec<lexer::UnmatchedBrace>), Vec<Diagnostic>> {
194 let src = source_file.src.as_ref().unwrap_or_else(|| {
195 sess.span_diagnostic.bug(&format!(
196 "cannot lex `source_file` without source: {}",
197 sess.source_map().filename_for_diagnostics(&source_file.name)
201 let (token_trees, unmatched_braces) =
202 lexer::parse_token_trees(sess, src.as_str(), source_file.start_pos, override_span);
205 Ok(stream) => Ok((stream, unmatched_braces)),
207 let mut buffer = Vec::with_capacity(1);
208 err.buffer(&mut buffer);
209 // Not using `emit_unclosed_delims` to use `db.buffer`
210 for unmatched in unmatched_braces {
211 if let Some(err) = make_unclosed_delims_error(unmatched, &sess) {
212 err.buffer(&mut buffer);
220 /// Given a stream and the `ParseSess`, produces a parser.
221 pub fn stream_to_parser<'a>(
224 subparser_name: Option<&'static str>,
226 Parser::new(sess, stream, false, subparser_name)
229 /// Runs the given subparser `f` on the tokens of the given `attr`'s item.
230 pub fn parse_in<'a, T>(
234 mut f: impl FnMut(&mut Parser<'a>) -> PResult<'a, T>,
235 ) -> PResult<'a, T> {
236 let mut parser = Parser::new(sess, tts, false, Some(name));
237 let result = f(&mut parser)?;
238 if parser.token != token::Eof {
239 parser.unexpected()?;
244 // NOTE(Centril): The following probably shouldn't be here but it acknowledges the
245 // fact that architecturally, we are using parsing (read on below to understand why).
247 pub fn nt_to_tokenstream(
250 synthesize_tokens: CanSynthesizeMissingTokens,
252 // A `Nonterminal` is often a parsed AST item. At this point we now
253 // need to convert the parsed AST to an actual token stream, e.g.
254 // un-parse it basically.
256 // Unfortunately there's not really a great way to do that in a
257 // guaranteed lossless fashion right now. The fallback here is to just
258 // stringify the AST node and reparse it, but this loses all span
261 // As a result, some AST nodes are annotated with the token stream they
262 // came from. Here we attempt to extract these lossless token streams
263 // before we fall back to the stringification.
266 |tokens: Option<&LazyTokenStream>| Some(tokens?.create_token_stream().to_tokenstream());
268 let tokens = match *nt {
269 Nonterminal::NtItem(ref item) => prepend_attrs(&item.attrs, item.tokens.as_ref()),
270 Nonterminal::NtBlock(ref block) => convert_tokens(block.tokens.as_ref()),
271 Nonterminal::NtStmt(ref stmt) if let ast::StmtKind::Empty = stmt.kind => {
272 let tokens = AttrAnnotatedTokenStream::new(vec![(
273 tokenstream::AttrAnnotatedTokenTree::Token(Token::new(
279 prepend_attrs(&stmt.attrs(), Some(&LazyTokenStream::new(tokens)))
281 Nonterminal::NtStmt(ref stmt) => prepend_attrs(&stmt.attrs(), stmt.tokens()),
282 Nonterminal::NtPat(ref pat) => convert_tokens(pat.tokens.as_ref()),
283 Nonterminal::NtTy(ref ty) => convert_tokens(ty.tokens.as_ref()),
284 Nonterminal::NtIdent(ident, is_raw) => {
285 Some(tokenstream::TokenTree::token(token::Ident(ident.name, is_raw), ident.span).into())
287 Nonterminal::NtLifetime(ident) => {
288 Some(tokenstream::TokenTree::token(token::Lifetime(ident.name), ident.span).into())
290 Nonterminal::NtMeta(ref attr) => convert_tokens(attr.tokens.as_ref()),
291 Nonterminal::NtPath(ref path) => convert_tokens(path.tokens.as_ref()),
292 Nonterminal::NtVis(ref vis) => convert_tokens(vis.tokens.as_ref()),
293 Nonterminal::NtExpr(ref expr) | Nonterminal::NtLiteral(ref expr) => {
294 prepend_attrs(&expr.attrs, expr.tokens.as_ref())
298 if let Some(tokens) = tokens {
300 } else if matches!(synthesize_tokens, CanSynthesizeMissingTokens::Yes) {
301 return fake_token_stream(sess, nt);
304 "Missing tokens for nt {:?} at {:?}: {:?}",
307 pprust::nonterminal_to_string(nt)
312 fn prepend_attrs(attrs: &[Attribute], tokens: Option<&LazyTokenStream>) -> Option<TokenStream> {
313 let tokens = tokens?;
314 if attrs.is_empty() {
315 return Some(tokens.create_token_stream().to_tokenstream());
317 let attr_data = AttributesData { attrs: attrs.to_vec().into(), tokens: tokens.clone() };
318 let wrapped = AttrAnnotatedTokenStream::new(vec![(
319 AttrAnnotatedTokenTree::Attributes(attr_data),
322 Some(wrapped.to_tokenstream())
325 pub fn fake_token_stream(sess: &ParseSess, nt: &Nonterminal) -> TokenStream {
326 let source = pprust::nonterminal_to_string(nt);
327 let filename = FileName::macro_expansion_source_code(&source);
328 parse_stream_from_source_str(filename, source, sess, Some(nt.span()))
331 pub fn fake_token_stream_for_crate(sess: &ParseSess, krate: &ast::Crate) -> TokenStream {
332 let source = pprust::crate_to_string_for_macros(krate);
333 let filename = FileName::macro_expansion_source_code(&source);
334 parse_stream_from_source_str(filename, source, sess, Some(krate.spans.inner_span))
337 pub fn parse_cfg_attr(
339 parse_sess: &ParseSess,
340 ) -> Option<(MetaItem, Vec<(AttrItem, Span)>)> {
341 match attr.get_normal_item().args {
342 ast::MacArgs::Delimited(dspan, delim, ref tts) if !tts.is_empty() => {
343 let msg = "wrong `cfg_attr` delimiters";
344 crate::validate_attr::check_meta_bad_delim(parse_sess, dspan, delim, msg);
345 match parse_in(parse_sess, tts.clone(), "`cfg_attr` input", |p| p.parse_cfg_attr()) {
346 Ok(r) => return Some(r),
348 e.help(&format!("the valid syntax is `{}`", CFG_ATTR_GRAMMAR_HELP))
349 .note(CFG_ATTR_NOTE_REF)
354 _ => error_malformed_cfg_attr_missing(attr.span, parse_sess),
359 const CFG_ATTR_GRAMMAR_HELP: &str = "#[cfg_attr(condition, attribute, other_attribute, ...)]";
360 const CFG_ATTR_NOTE_REF: &str = "for more information, visit \
361 <https://doc.rust-lang.org/reference/conditional-compilation.html\
362 #the-cfg_attr-attribute>";
364 fn error_malformed_cfg_attr_missing(span: Span, parse_sess: &ParseSess) {
367 .struct_span_err(span, "malformed `cfg_attr` attribute input")
370 "missing condition and attribute",
371 CFG_ATTR_GRAMMAR_HELP.to_string(),
372 Applicability::HasPlaceholders,
374 .note(CFG_ATTR_NOTE_REF)